Conservation and Management 

of Eastern Big-eared Bats

                        A Symposium

	 Edited by Susan C. Loeb, Michael J. Lacki, and Darren A. Miller

U.S. Department 

of Agriculture

Forest Service

Southern Research Station

General Technical Report 

SRS-145
DISCLAIMER

The use of trade or firm names in this publication is for reader information and does not imply 

endorsement by the U.S. Department of Agriculture of any product or service.

Papers published in these proceedings were submitted by authors in electronic media. Some editing 

was done to ensure a consistent format. Authors are responsible for content and accuracy of their 

individual papers and the quality of illustrative materials.

Cover photos: Large photo: Craig W. Stihler; small left photo: Joseph S. Johnson; small middle 

photo: Craig W. Stihler; small right photo: Matthew J. Clement.

December 2011

Southern Research Station

200 W.T. Weaver Blvd.

Asheville, NC 28804
Conservation and Management 

of Eastern Big-eared Bats: 

A Symposium

Athens, Georgia

March 9–10, 2010

Edited by:

Susan C. Loeb 

U.S Department of Agriculture Forest Service

Southern Research Station

Michael J. Lacki 

University of Kentucky

Darren A. Miller

Weyerhaeuser NR Company

Sponsored by:

Forest Service

Bat Conservation International

National Council for Air and Stream Improvement (NCASI)

Warnell School of Forestry and Natural Resources

Offield Family Foundation

iii

ContEntS

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Conservation and Management of Eastern Big-Eared Bats: An Introduction . . . . . . . 1

Susan C. Loeb, Michael J. Lacki, and Darren A. Miller

Distribution and Status of Eastern Big-eared Bats (Corynorhinus Spp .) . . . . . . . . . . .13

Mylea L. Bayless, Mary Kay Clark, Richard C. Stark, Barbara S. Douglas, 

and Shauna M. Ginger

Ecology of tree-Roosting Rafinesque’s Big-Eared Bats 

in the Eastern United States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Austin W. Trousdale

Diet and Foraging Behavior of Corynorhinus in Eastern north America . . . . . . . . . . 39

Michael J. Lacki and Luke E. Dodd

Conservation and Management of Eastern Big-Eared Bats 

(Corynorhinus Spp .) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Darren A. Miller, Craig W. Stihler, D. Blake Sasse, Rick Reynolds, Paul Van Deusen, 

and Steven B. Castleberry

Rafinesque’s Big-Eared Bat (Corynorhinus Rafinesquii) in Mississippi: 

Distribution, Current Status, and Conservation needs . . . . . . . . . . . . . . . . . . . . . . . . 63

Chester O. Martin, Alison S. McCartney, David Richardson, Austin W. Trousdale, 

and Monica S. Wolters

Status of the Virginia Big-Eared Bat (Corynorhinus Townsendii Virginianus) 

in West Virginia: twenty-Seven Years of Monitoring Cave Roosts . . . . . . . . . . . . . . . 75

Craig W. Stihler

Phylogenetic and Population Genetic Assessment 

of Rafinesque’s Big-Eared Bat (Corynorhinus Rafinesquii) . . . . . . . . . . . . . . . . . . . . 85

Antoinette J. Piaggio, David A. Saugey, and D. Blake Sasse

Characteristics of Roosts Used by Rafinesque’s Big-Eared Bat 

(Corynorhinus Rafinesquii) on Camp Mackall, north Carolina . . . . . . . . . . . . . . . . . .101

Piper L. Roby, Mark W. Gumbert, Price L. Sewell, and Steven W. Brewer
iv

Seasonal and Multiannual Roost Use by Rafinesque’s Big-eared Bats 

in the Coastal Plain of South Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

Susan C. Loeb and Stanley J. Zarnoch

Winter Roosting Behavior of Rafinesque’s Big-Eared Bat 

in Southwestern Arkansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .123

D. Blake Sasse, David A. Saugey, and Daniel R. England

Foraging and Roosting Ecology of Rafinesque’s Big-Eared Bat 

at the northern Edge of the Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129

Joseph S. Johnson and Michael J. Lacki

Radiotelemetry Studies of Female Virginia Big-Eared Bats 

(Corynorhinus Townsendii Virginianus) in Pendleton County, West Virginia . . . . . . .139

Craig W. Stihler

Comparison of Survey Methods for Rafinesque’s Big-Eared Bats . . . . . . . . . . . . . . .147

Matthew J. Clement and Steven B. Castleberry
v

PREFACE

In February 2007, the inaugural meeting of the Rafinesque’s 

Big-Eared Bat Working Group was held in Destin, FL. 

The goal of the working group was to provide a forum for 

communication on research, management, and conservation 

of Rafinesque’s big-eared bats (Corynorhinus rafinesquii), 

a rare and sensitive species. There was consensus among 

participants at the meeting that much information remained 

to be acquired before effective management of these animals 

was possible. It was also evident from the presentations and 

discussion that a considerable amount of research had been 

conducted on the species, especially over the past several 

years, but much of the research has not been published or is 

not readily available. Thus, potentially valuable information 

remained in filing cabinets and desk drawers and not in the 

hands of the people who need it most—the biologists and 

managers of State, Federal, and private lands that harbor 

these bats, and the State and Federal Agencies responsible 

for their conservation. It was also agreed that a similar 

situation likely existed for the two other taxa of big-eared 

bats in the Eastern United States, the Virginia big-eared bat 

(C. t. virginianus) and the Ozark big-eared bat (C. t. ingens), 

which are federally listed as endangered. Thus, it was 

decided to hold a symposium to encourage researchers 

and biologists to present and publish new information on 

the biology, ecology, and status of eastern big-eared bats 

and to synthesize existing information. A further goal 

of this symposium was to stimulate discussion on future 

conservation, management, and research needs of these bats. 

The symposium, held in Athens, GA, in March 2010, 

consisted of 7 invited presentations on general ecological 

topics, 15 contributed oral presentations and 3 poster 

presentations on more specific research results, and a panel 

discussion on future directions in research and management. 

Authors were encouraged, but not required, to submit 

their contributions for publication in these proceedings. 

The symposium was sponsored by Bat Conservation 

International; the National Council for Air and Stream 

Improvement; the U.S. Forest Service, Savannah River; the 

Offield Family Foundation; the Southeastern Bat Diversity 

Network; and the University of Georgia, Warnell School of 

Forestry and Natural Resources. The planning committee 

was chaired by Steven B. Castleberry, University of Georgia. 

Other members of the planning committee were Mary Kay 

Clark, Moonlight Environmental Consulting; Susan C. Loeb, 

U.S. Forest Service, Southern Research Station; Darren A. 

Miller, Weyerhaeuser NR Company; and David A. Saugey, 

U.S. Forest Service, Ouachita National Forest.

The goal of these proceedings is to provide an easily 

accessible publication that can be used by biologists 

and managers as they draft management strategies and 

policy, and to further the understanding of the ecology of 

these species. The papers in this volume were subjected 

to the scientific peer-review process. Each manuscript 

was assigned to one of the three editors and reviewed by 

two professionals familiar with the organisms and topic. 

Comments and suggestions by the reviewers improved 

the quality of the manuscripts and we are grateful to the 

following professionals for their time and expertise: Michael 

Baker, Troy Best, Eric Britzke, Timothy Carter, Brian Carver, 

Steven Castleberry, Matthew Clement, Chris Comer, Barbara 

Douglas, Mark Ford, Shauna Ginger, Joe Johnson, Matina 

Kalcounis-Rüeppell, Jim Kennedy, Dennis Krusac, Paul 

Leberg, Chester Martin, Darren Miller, Joy O’Keefe, Richard 

Reynolds, Christopher Rice, Lynn Robbins, Blake Sasse, 

David Saugey, Austin Trousdale, Maarten Vonhof, John 

Whitaker, and Bently Wigley. 

1

Piaggio and others 2009; Szymanski 2009; U.S. Fish and 

Wildlife Service 1995, 2008). Urbanization and development 

are projected to increase in the coming decades (Alig and 

others 2003, 2004) which will result in further habitat loss. 

Loss of forested and open areas will impact all taxa but 

could be particularly detrimental to Rafinesque’s big-eared 

bats, which often use trees for roosting. Further, although 

unknown at this time, the effects of white-nose syndrome, 

a newly emerging disease that has killed large numbers of 

cave-hibernating bats in the Northeastern United States 

(Turner and Reeder 2009), could greatly impact Ozark and 

Virginia big-eared bats and cave-dwelling Rafinesque’s bigeared bats. 

Research on biology, ecology, and conservation of bats 

has increased greatly worldwide in the past two decades 

(Arnett 2003). In North America, much of this work has 

concentrated on forest-dwelling bats, and many studies 

have used acoustic detectors (Brigham 2007). Because 

big-eared bats are “whispering bats” and have low-intensity 

echolocation calls (Fenton 1982), they are rarely recorded 

by ultrasonic detectors deployed to assess composition 

of bat communities, their habitat associations, and their 

responses to forest management. Due to their rarity and 

high maneuverability, big-eared bats are often difficult to 

capture, which further limits our ability to conduct research. 

Therefore, our objective was to conduct an overview of the 

current body of published literature on eastern big-eared bats 

INTRODUCTION

Big-eared bats (genus Corynorhinus) are some of the 

most striking and recognizable bats in the Eastern United 

States. They are distinguished from all other bats in the 

region by their large ears which are joined at the base, 

and by the enlarged glands between their eyes and nostrils 

(Whitaker and Hamilton 1998). Rafinesque’s big-eared 

bats (C. rafinesquii) have a wide distribution that ranges 

from West Virginia to Florida in the east and southern 

Illinois to eastern Texas in the west (fig. 1), but they appear 

to be sparsely distributed within their range (Whitaker 

and Hamilton 1998). Conversely, Virginia (C. townsendii 

virginianus) and Ozark big-eared bats (C. t. ingens) have 

restricted distributions and are isolated from the rest of 

the Townsend’s big-eared bat species complex (Hall 1981; 

fig. 1). All of the big-eared bats in the Eastern United States 

(hereafter in this paper these bats will be referred to as 

eastern big-eared bats) are species of special conservation 

concern. The Virginia and Ozark big-eared bats were listed 

as endangered in 1979 (U.S. Fish and Wildlife Service 

1979) and Rafinesque’s big-eared bats were Candidate 2 

Species until 1996 when the U.S. Fish and Wildlife Service 

discontinued this list (U.S. Fish and Wildlife Service 1996). 

Past and present threats to all these taxa include habitat loss, 

disturbance to hibernacula and maternity sites, contaminants, 

genetic isolation, and disease (Bayless and others 2011; 

CONSERVATION AND MANAGEMENT OF EASTERN BIG-EARED BATS: 

AN INTRODUCTION

Susan C. Loeb, Research Ecologist, U.S. Department of Agriculture Forest Service, 

Southern Research Station, Clemson, SC 29634

Michael J. Lacki, Professor, University of Kentucky, Department of Forestry, Lexington, KY 40546

Darren A. Miller, Manager, Weyerhaeuser NR Company, Southern Environmental Research, 

Columbus, MS 39704

Abstract—Three taxa of big-eared bats (genus Corynorhinus) inhabit the Eastern United States. Rafinesque’s bigeared bats (C. rafinesquii) are widely distributed from West Virginia to Texas whereas the Virginia big-eared bat 

(C. t. virginianus) and the Ozark big-eared bat (C. t. ingens) have limited ranges. Over the past 20 years, research on the 

biology, ecology, and conservation of bats throughout the world has increased, but research on big-eared bats of the Eastern 

United States has been less extensive. In evaluating the current state of knowledge, we reviewed the existing literature 

on big-eared bats that inhabit the Eastern United States and found 155 references, of which 101 were research notes, full 

articles, or review papers. In contrast, we found 239 references on the Indiana bat (Myotis sodalis), an endangered species 

with a similar geographic range size in the Eastern United States. Through our assessment of the literature on big-eared 

bats, we identified many gaps in our knowledge and understanding, including demography, population dynamics, social 

organization, hibernation and other aspects of physiological ecology, foraging behavior and diet, the effects of forest 

management, and the effects of conservation efforts. We also found that research on Virginia and Ozark big-eared bats 

has decreased in recent years while research on Rafinesque’s big-eared bats has increased. Papers in these proceedings 

fill many of the knowledge gaps but much research is still needed to provide managers with the information they need to 

conserve these sensitive species. 

Citation for proceedings: Loeb, Susan C.; Lacki, Michael J.; Miller, Darren A., eds. 2011. Conservation and management of eastern big-eared bats: 

a symposium. Gen. Tech. Rep. SRS-145. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 157 p.
2

State or States in which the research was conducted. For 

comparison, we conducted a similar search of the Indiana 

bat (Myotis sodalis) literature in BIOSIS and the Zoological 

Record databases and the Mammalian Species account 

(Thomson 1982). We chose the Indiana bat for comparison 

because it also inhabits the Eastern United States, is an 

endangered species, and has a similar geographic range size 

to that of eastern big-eared bats. 

We found 155 references on eastern big-eared bats. 

Of these references, 101 were research notes, full 

articles, or review papers (fig. 2). Although most of the 

101 published papers on eastern big-eared bats were 

in abstracted databases, many of them are not easily 

accessible by managers. For example, many of the papers 

are in proceedings of State academies of science, are not 

available online, and may not even be available at most 

university libraries. In contrast, we found 239 references 

on Indiana bats; 141 of these references were research 

notes or full articles. These numbers do not include the 27 

papers in the Indiana Bat symposium proceedings (Kurta 

and Kennedy 2002). Thus, even though the distribution of 

the Indiana bat is similar in size to that of eastern big-eared 

bats, considerably more research has been conducted on 

the ecology and management of Indiana bats than eastern 

big-eared bats. 

and present an analysis of the types of information available 

by taxa and topic. We then assessed areas that remain in 

greatest need of future research and introduce the papers of 

this symposium to illustrate how these papers fill some of the 

knowledge gaps. 

REVIEW OF EXISTING LITERATURE

We searched the BIOSIS and Zoological Record databases 

using Corynorhinus and Plecotus as keywords for literature 

on eastern big-eared bats. We exported all papers and 

abstracts that pertained to eastern big-eared bats to a 

citation database (EndNote X3®, Thomson Reuters, New 

York, NY). Because BIOSIS and Zoological Records cover 

only 1969 to the present, we also examined the literature 

cited sections in the Mammalian Species accounts for 

Townsend’s big-eared bats (Kunz and Martin 1982) and 

Rafinesque’s big-eared bats (Jones 1977). We included 

those papers that pertained to eastern big-eared bats, 

were in English, and were accessible. We did not include 

theses and dissertations in the database because most 

have been published and our inclusion would duplicate 

the material. We classified each reference by species and 

whether the reference was an abstract, research note, full 

research article, or review paper. We also determined the 

Corynorhinus townsendii

virginianus

Corynorhinus rafinesquii

Corynorhinus townsendii

ingens

Figure 1—Distribution of Virginia big-eared bats (Corynorhinus townsendii virginianus), Ozark big-eared bats (C. townsendii ingens), and 

Rafinesque’s big-eared bats (C. rafinesquii).
3

fewer studies on foraging and commuting habitat use of 

big-eared bats have been conducted because the data must be 

gained through more costly and labor-intensive techniques, 

such as radiotelemetry (e.g., Adam and others 1994, Clark 

and others 1993). 

Far more abstracts, papers, and notes have been published 

on Rafinesque’s big-eared bats than Virginia or Ozark bigeared bats (fig. 3). The greater number of publications on 

Rafinesque’s big-eared bats is not surprising, given the larger 

geographic distribution and population sizes of these bats. 

A comparable number of studies have been conducted on 

Virginia and Ozark big-eared bats. Research on Rafinesque’s 

big-eared bats has been relatively evenly distributed across 

the range, although Rafinesque’s big-eared bats in some 

States have received little research. For example, limited 

research has been conducted on Rafinesque’s big-eared 

bats in Alabama, Georgia, Tennessee, Virginia, and West 

Virginia, whereas several studies have been conducted in 

Arkansas, Louisiana, Kentucky, Mississippi, and Texas 

(fig. 4A). The number of references (abstracts and published 

papers) on Ozark big-eared bats is similar between Arkansas 

and Oklahoma, but there are approximately twice as many 

published papers on Ozark big-eared bats in Oklahoma 

than in Arkansas (fig. 4B). Most research on Virginia bigeared bats has been conducted in Kentucky, but several 

studies have also been conducted in West Virginia and 

Virginia (fig. 4C). There has been a considerable increase 

The larger body of literature on Indiana bats may be due to 

many factors. Although Indiana bats and Rafinesque’s bigeared bats have similar geographic range sizes, Rafinesque’s 

big-eared bats are not listed as an endangered species, and 

thus there has been less funding directed towards research 

and management of Rafinesque’s big-eared bats. Indiana 

bats are often found in association with more common 

species such as little brown bats (M. lucifugus) and northern 

long-eared bats (M. septentrionalis) during summer and 

winter. Studies of hibernacula use often focus on multiple 

species, including Indiana bats, but big-eared bats are rarely 

represented in these studies (e.g., Brack 2007, Davis and 

Reite 1967, Gates and others 1984, Raesly and Gates 1987). 

In contrast to big-eared bats, Indiana bats can be detected 

acoustically and thus are often included in studies that rely 

on bat detectors (e.g., Ford and others 2005, Owen and others 

2004, Schrimacher and others 2007, Yates and Muzika 2006). 

Because management of Indiana bat habitat is frequently in 

conflict with forest management and human development 

(e.g., Krusac and Mighton 2002, Whitaker and others 2004), 

considerable funding and research have been directed toward 

the Indiana bat in the past decade to provide the information 

necessary to mitigate these conflicts. Conversely, even 

though Virginia and Ozark big-eared bats are endangered, 

their year-round reliance on caves reduces potential conflicts 

with forest managers and other human enterprises other than 

caving (but see Miller and others 2011). Because big-eared 

bats cannot be reliably detected with ultrasonic detectors, 

Figure 2—Number of abstracts, full articles, research notes, and review papers on eastern big-eared 

bats (BEB) and Indiana bats (MYSO) through 2009 and additional articles as cited in Mammalian 

Species accounts.
4

bats (M. yumanensis; Frick and others 2007), and Leisler’s 

bats (Nyctalus leisleri; Schorcht and others 2009). Because 

eastern big-eared bats form small colonies and are often in 

easily accessible roost sites, similar demographic studies 

may be achievable for big-eared bats as well.

Additional areas in need of research include studies of 

foraging habitat use and selection. Although several studies 

have been conducted on the foraging behavior and habitat 

use of Virginia and Ozark big-eared bats (e.g., Adam and 

others 1994, Burford and Lacki 1995, Clark and others 1993, 

Wethington and others 1996, Wilhide and others 1998), only 

three studies have been conducted on foraging habitat use by 

Rafinesque’s big-eared bats (Hurst and Lacki 1999, Medlin 

and Risch 2008, Menzel and others 2001). Several studies 

have been conducted on food habits of each taxa, but relative 

to their large geographic range, fewer have been conducted 

on Rafinesque’s big-eared bats. Further, no study has been 

conducted on prey availability for Rafinesque’s big-eared 

bats, whereas several studies have investigated this aspect 

of the feeding ecology of Virginia and Ozark big-eared bats 

(Burford and others 1999, Dodd and others 2008, Leslie and 

Clark 2002). 

Physiological aspects of big-eared bat ecology also have 

been ignored. We found no study that examined hibernation 

energetics or seasonal patterns of hibernation in eastern 

big-eared bats. While other aspects of physiology, such as 

the energetics of growth and reproduction, are important, 

in the number of studies on Rafinesque’s big-eared bats 

over the past decade (fig. 5). In contrast, research on Ozark 

and Virginia big-eared bats peaked in the 1990s and has 

subsequently declined. The primary research emphasis areas 

for Rafinesque’s big-eared bats have been roosting ecology 

and studies of distribution and status, whereas research on 

Ozark and Virginia big-eared bats has primarily focused 

on foraging habitat use and diet along with reports on 

distribution and status (fig. 6). 

IDENTIFICATION OF KNOWLEDGE GAPS

The preceding examination of existing literature on eastern 

big-eared bats identifies several gaps in our knowledge 

base. One of the largest gaps concerns population ecology. 

There are no studies on demography, population dynamics, 

or social organization of any of the eastern big-eared 

bats, although recent studies of population genetics have 

shed some light on dispersal (Piaggio and others 2009). 

Estimating population sizes and demographic parameters 

such as reproductive success and survival is difficult for 

most bat species, but is easiest for those that use observable 

roosts, are colonial, and have relatively small colony sizes 

(e.g., < 1,000 individuals; Kunz and others 2009, O’Donnell 

2009). Several demographic studies have recently been 

conducted on colonial species that are faithful to artificial 

roosts such as big brown bats (Eptesicus fuscus; Ellison and 

others 2007), little brown bats (Frick and others 2010), Yuma 

Figure 3—Number of abstracts, full articles, research notes, and review papers through 2009 on 

Rafinesque’s big-eared bats (CORA), Ozark big-eared bats (COTOI), Virginia big-eared bats (COTOV), 

and ≥ two taxa (Multi). 
5

Figure 4—Number of abstracts and published papers by State through 2009 on (A) Rafinesque’s 

big-eared bats (CORA), (B) Ozark big-eared bats (COTOI), and (C) Virginia big-eared bats (COTOV). 

(AL = Alabama, AR = Arkansas, FL = Florida, GA = Georgia, IL = Illinois, IN = Indiana, KY = Kentucky, 

LA = Louisiana, MS = Mississippi, NC = North Carolina, SC = South Carolina, TN = Tennessee, 

TX = Texas, VA = Virginia, WV = West Virginia, ML = Multi, OK = Oklahoma, PA = Pennsylvania.)
6

Figure 5—Number of papers published through 2009 by time period on Rafinesque’s big-eared bats 

(CORA), Ozark big-eared bats (COTOI), Virginia big-eared bats (COTOV), and ≥ two taxa (Multi). 

(A) Abstracts and published papers and (B) published papers only.

understanding hibernation patterns of cave-roosting bigeared bats is particularly critical due to the advent of whitenose syndrome and its effects on bats during hibernation 

(Cryan and others 2010). Understanding hibernation 

energetics (e.g., fat storage, metabolic rates, arousal costs) 

will also allow biologists to predict effects of climate change 

and suitability of hibernacula under various climate scenarios 

(e.g., Humphries and others 2002). Further, we found few 

studies that examined roost use or selection of caves or 

mines by big-eared bats. Thus, we know little about basic 

characteristics such as temperature, humidity, or structural 

characteristics that make some caves or mines suitable and 

others unsuitable for use during summer or winter.

Effects of management activities on eastern big-eared bats 

have also received limited attention. A few papers have been 
7

management activities that could affect big-eared bats include 

wetlands management (e.g., alteration of water flow regimes), 

provisioning of artificial roosts, bridge maintenance and 

construction, and land use changes in surrounding landscapes. 

Although Clark (2003) outlined procedures for monitoring 

big-eared bats in bottomland hardwood forests, no study has 

tested the effectiveness of various survey and monitoring 

techniques for cave- or tree-roosting big-eared bats. 

published on cave gates for Virginia and Ozark big-eared 

bats (Martin and others 2000, White and Seginak 1987). 

Except for a study that examined effects of prescribed fire on 

Ozark big-eared bats (Caviness 2003), no empirical studies 

have tested effects of silvicultural practices (e.g., thinning, 

clearcut harvest, selective harvest, prescribed fire) for any of 

the species, although Adam and others (1994) suggested that 

logging may be detrimental to Virginia big-eared bats. Other 

Figure 6—Number of papers published through 2009 by topic on Rafinesque’s big-eared bats (CORA), 

Ozark big-eared bats (COTOI), Virginia big-eared bats (COTOV), and ≥ two taxa (Multi). (A) Abstracts and 

published papers and (B) published papers only.
8

the necessary information for effective management, and 

suggest some important management actions to conserve 

these animals.

The final nine papers of the proceedings provide new data 

on ecology and conservation of eastern big-eared bats. One 

of the first obstacles to managing big-eared bats is lack of 

information on the status and distribution of these species. 

Although Bayless and others provide a general overview 

of the status of big-eared bats across their range, specific 

information on status and distribution of big-eared bats is 

needed for effective management at the local level. Martin 

and others provide a detailed update on the status and 

distribution of Rafinesque’s big-eared bats in Mississippi, 

while Stihler reviews the status of Virginia big-eared bats 

based on 27 years of cave monitoring in West Virginia and 

documents an overall increase in the number of Virginia 

big-eared bats in West Virginia. Genetic tools can also be 

used to help understand the status of eastern big-eared 

bats; such tools include taxonomic status, genetic “health” 

such as inbreeding depression, and effective population 

size. Piaggio and others provide evidence to suggest that 

the previously named subspecies of Rafinesque’s big-eared 

bats are probably not valid, although there are two major 

clades within the species. They also analyzed mitochondrial 

and microsatellite DNA of Rafinesque’s big-eared bats 

from five roosts in Arkansas to determine genetic diversity, 

connectivity, and effective population size and illustrate the 

conservation consequences of these genetic data. Because of 

the dispersed nature of Rafinesque’s big-eared bats, much of 

the information on their status and distribution is unreliable 

(Bayless and other 2011). Gaining this information will 

require new tools and techniques for inventorying and 

monitoring this species, especially those that rely on trees 

for roosting. Clement and Castleberry tested three techniques 

for inventorying Rafinesque’s big-eared bats in Coastal Plain 

forests and compare their cost-effectiveness. 

Other than studies of hibernation, most bat research has been 

conducted during the summer reproductive period, and little 

is known about the ecology of bats during spring, fall, and 

winter (Weller and others 2009). Two papers address this gap 

for Rafinesque’s big-eared bats. Sasse and others describe 

winter roosting ecology of Rafinesque’s big-eared bats in 

Arkansas, and Loeb and Zarnoch examine year-round roost 

use by Rafinesque’s big-eared bats in the Coastal Plain of 

South Carolina. Although Rafinesque’s big-eared bat summer 

roost use in bottomland hardwood forests has received 

considerable study (Trousdale 2011), there is still much to be 

learned about the roosting ecology of this species and how 

it varies across the range. Summer roost characteristics of 

Rafinesque’s big-eared bats are described for two geographic 

areas that have received little attention. Roby and others 

describe roost characteristics of Rafinesque’s big-eared bats 

in the Coastal Plain of North Carolina, and Johnson and 

THIS VOLUME

In the previous section, we identified numerous gaps in our 

knowledge regarding ecology and management of eastern 

big-eared bats. Areas in need of research range from basic 

biology and ecology to methodology and management 

effects. In this section, we discuss how these information 

gaps are partially filled by papers in these proceedings.

The four succeeding papers summarize and synthesize 

existing knowledge on various aspects of big-eared bat 

ecology and conservation. These papers provide the first step 

in understanding the biology and ecology of these animals 

and are an entry into the published literature and reports 

for researchers, biologists, managers, and policymakers 

unfamiliar with big-eared bats. The first of these papers by 

Bayless and others provides an extensive overview of the 

status and distribution of eastern big-eared bats. Status and 

distribution data are essential for development of effective 

conservation strategies, and the authors provide a thorough 

summary of the historic and current distributions of all 

three taxa, estimates of current population numbers, and a 

discussion of population trends. Specific threats for each taxa 

are also discussed.

Roosts are one of the most critical resources for bats 

and understanding roost site use, selection, and fidelity 

are essential for effective conservation and management 

(Barclay and Kurta 2007, Kunz and Lumsden 2003). 

Roosting ecology is one of the most studied aspects 

of Rafinesque’s big-eared bats (fig. 6), and in the next 

paper, Trousdale synthesizes this research. In addition to 

summarizing what is known about roost use and selection 

at various spatial scales, Trousdale also discusses roost 

fidelity and intraspecific and interspecific interactions of 

tree-roosting Rafinesque’s big-eared bats.

There have been several food habit studies of eastern bigeared bats, yet we know little about the interactions between 

big-eared bats and their prey. Lacki and Dodd provide an 

extensive summary of the food habit studies of eastern 

big-eared bats and show that moths are the main component 

of the diet of all three taxa. The authors also show how 

these species have evolved a variety of morphological and 

behavioral adaptations that increase their success as moth 

predators. Lacki and Dodd also examine habitat use of bigeared bats in relation to habitat use of their moth prey. 

The final synthesis paper provides a context for future 

conservation and management of eastern big-eared bats. 

In addition to reviewing past conservation efforts, Miller 

and others examine current forest conditions in the South 

and how changes in forest conditions may impact big-eared 

bats. They also discuss challenges faced by managers of 

big-eared bats, identify research that is needed to provide 
9

with projections to 2050. Gen. Tech. Rep. PNW-587. Portland, 

OR: U.S. Department of Agriculture Forest Service, Pacific 

Northwest Research Station. 92 p.

Arnett, E.B. 2003. Advancing science and partnerships for the 

conservation of bats and their habitats. Wildlife Society Bulletin. 

31: 2-5.

Barclay, R.M.R.; Kurta, A. 2007. Ecology and behavior of bats 

roosting in tree cavities and under bark. In: Lacki, M.J.; 

Hayes, J.P.; Kurta, A., eds. Bats in forests: conservation and 

management. Baltimore, MD: Johns Hopkins University Press: 

17-59.

Bayless, M.L.; Clark, M.K., Stark, R.C. [and others]. 2011. 

Distribution and status of eastern big-eared bats (Corynorhinus 

spp.). In: Loeb, S.C.; Lacki, M.J.; Miller, D.A., eds. 

Conservation and management of eastern big-eared bats: a 

symposium. Gen. Tech. Rep. SRS-145. Asheville, NC: U.S. 

Department of Agriculture Forest Service, Southern Research 

Station: 13-25.

Brack, V., Jr. 2007. Temperatures and locations used by hibernating 

bats, including Myotis sodalis (Indiana bat), in a limestone mine: 

implications for conservation and management. Environmental 

Management. 40: 739-746.

Brigham, R.M. 2007. Bats in forests: what we know and what we 

need to learn. In: Lacki, M.J.; Hayes, J.P.; Kurta, A., eds. Bats 

in forests: conservation and management. Baltimore, MD: Johns 

Hopkins University Press: 1-15.

Burford, L.S.; Lacki, M.J. 1995. Habitat use by Corynorhinus

townsendii virginianus in the Daniel Boone National Forest. 

American Midland Naturalist. 134: 340-345.

Burford, L.S.; Lacki, M.J.; Covell, C.V., Jr. 1999. Occurrence 

of moths among habitats in a mixed mesophytic forest: 

implications for management of forest bats. Forest Science. 45: 

323-332.

Caviness, M. 2003. Effects of prescribed fire on cave environment 

and bat inhabitants. Bat Research News. 44: 130.

Clark, B.S.; Leslie, D.M., Jr.; Carter, T.S. 1993. Foraging activity of 

adult female Ozark big-eared bats (Plecotus townsendii ingens) 

in summer. Journal of Mammalogy. 74: 422-427.

Clark, M.K. 2003. Survey and monitoring of rare bats in bottomland 

hardwood forests. In: O’Shea, T.J.; Bogan, M.A., eds. 

Monitoring trends in bat populations of the United States and 

territories: problems and prospects. Inf. and Tech. Rep. USGS/

BRD/ITR-2003-003. Springfield, VA: U.S. Geological Survey, 

Biological Resources Division: 79-90.

Cryan, P.M.; Meteyer, C.U.; Boyles, J.G.; Blehert, D.S. 2010. 

Wing pathology of white-nose syndrome in bats suggests lifethreatening disruption of physiology. BMC Biology. 8(135): 

1-8.

Lacki describe summer roost characteristics of Rafinesque’s 

big-eared bats in floodplain forests of Kentucky. 

Information on big-eared bat foraging habitat is critical 

for managing landscapes surrounding roosts. As discussed 

previously, use of radiotelemetry is essential for obtaining 

data on foraging habitat use of big-eared bats and few data 

are available, particularly for Rafinesque’s big-eared bats. 

The paper by Johnson and Lacki, who address foraging 

behavior of Rafinesque’s big-eared bats in western Kentucky, 

helps to fill this gap, while Stihler provides further data on 

habitat use of Virginia big-eared bats in West Virginia.

CONCLUSIONS

Basic information on biology and management of big-eared 

bats in the Eastern United States is available but many gaps 

remain in our understanding of big-eared bat ecology and 

management. Papers in these proceedings fill some of the 

knowledge gaps but also point out many areas where our 

knowledge and understanding are lacking. While much of the 

needed information has direct application for conservation and 

management, we also lack basic ecological data. Although it 

is important to focus on immediate management needs, it is 

also essential to anticipate future threats and amass a body 

of knowledge and understanding that will permit managers 

to deal with these future threats. In addition to focusing on 

the basic life requisites of big-eared bats (e.g., roosting and 

foraging ecology), research also must target an understanding 

of the entire ecological context in which these animals exist, 

including interactions with conspecifics, other bat species, 

insect communities, predators and parasites, and other 

organisms in the ecosystems they inhabit (e.g., the fauna and 

flora that inhabit the caves, mines, and hollow trees in which 

these animals roost). This is a difficult task in research on any 

species, but perhaps more so in research on the particularly 

cryptic eastern big-eared bat species. We hope that current and 

future technology, coupled with interest from stakeholders, 

will provide the necessary resources to address issues relative 

to long-term conservation of these unique bat species.

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eastern big-eared bats: a symposium. Gen. Tech. Rep. SRS-145. 

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13

considered to be relatively uncommon and are vulnerable 

due to their apparent low tolerance to disturbance, habit 

of roosting near cave entrances (increases potential for 

disturbance), low population numbers, disjunct populations, 

and roost loss (Hahn 1908, Handley 1959, Harvey and others 

1999, Hurst and Lacki 1999, Mohr 1933, Miller and others 

2011, Piaggio and others 2011). 

Eastern populations of Townsend’s big-eared bat are limited 

to small ranges occupied by two endangered subspecies: 

Ozark big-eared bat (C. t. ingens) and Virginia big-eared 

bat (C. t. virginianus) as described by Handley (1959) in a 

revision of the genera Euderma and Plecotus (Corynorhinus

was formerly Plecotus). Although Rafinesque’s bigeared bats are more widely distributed, their range is 

not well documented. The distribution map published in 

Handley’s 1959 revision became the baseline map for future 

publications on the U.S. big-eared bats, and later maps for 

the eastern taxa (e.g., Barbour and Davis 1969, Whitaker 

and Hamilton 1998) show little change from the original 

INTRODUCTION

Bats of the genus Corynorhinus are among the most 

distinctive in North America, easily recognizable by large 

glandular masses on their muzzle and enormous ears which 

extend about one-third of the total body length of the bat. 

The genus appears throughout the Southeastern and Western 

United States, southwestern Canada, and northern and central 

Mexico (Jones 1977, Kunz and Martin 1982). Corynorhinus

species are gregarious, typically roosting in caves, mines, 

hollow trees, buildings, and under bridges (Jones 1977, Kunz 

and Martin 1982, Miller and others 2011, Trousdale 2011). 

Their exotic appearance has historically made them targets 

of both collection and intensive observation (U.S. Fish and 

Wildlife Service 1984). 

There are three Corynorhinus species, two of which 

occur in the Eastern United States: Rafinesque’s bigeared bat (C. rafinesquii) and Townsend’s big-eared bat 

(C. townsendii). Both Eastern United States species are 

DIsTRIbUTION aND sTaTUs Of EasTERN bIg-EaRED baTs 

(Corynorhinus spp.)

Mylea L. bayless, Conservation Biologist, Bat Conservation International, Austin, TX 78716

Mary Kay Clark, Biologist, Moonlight Environmental Consulting, Raleigh, NC 27614

Richard C. stark, Fish and Wildlife Biologist, U.S. Fish and Wildlife Service, 

Oklahoma Ecological Services Field Office, Tulsa, OK 74129

barbara s. Douglas, Senior Endangered Species Biologist, U.S. Fish and Wildlife Service, 

West Virginia Field Office, Elkins, WV 26241

shauna M. ginger, Wildlife Biologist, U.S. Fish and Wildlife Service, Mississippi Field Office, 

Jackson, MS 39213

Abstract—Recent information describing distribution and status of Rafinesque’s big-eared bat (Corynorhinus rafinesquii)

and Townsend’s big-eared bat (C. townsendii) in the Eastern United States is currently scattered among the scientific and 

gray literature. Therefore, our objective was to collate available information to better enable managers and researchers 

to use known distribution and population data relative to conservation for these species. The two eastern subspecies of 

C. townsendii [Ozark big-eared bat (C. t. ingens) and Virginia big-eared bat (C. t. virginianus)] have been listed as federally 

endangered since 1979, and recent 5-year reviews recommend retaining their endangered status because recovery criteria 

have not been met. These species remain vulnerable due to existence of only small, widely separated remnant populations. 

Surveys to locate additional sites for these endangered taxa are warranted, although locating new colonies is unlikely to 

change their status. Rafinesque’s big-eared bat is listed as a species of concern throughout its range although exact status 

remains undetermined largely due to challenges of assessing population trends for this species. Historical loss of mature, 

bottomland hardwood forests, assumed to represent a loss of natural roosting structure, suggests population declines. 

Recent research has improved distributional data for this species, including recognition of a distributional gap in the 

Piedmont region separating Coastal Plain and karst populations. Improved methods for population estimation are needed, 

although the means of establishing a baseline for monitoring population trends over time remains unclear. In parts of the 

range where Rafinesque’s big-eared bat primarily uses tree cavities, it may be possible to use structure-based monitoring to 

provide an index of abundance in a given area. More traditional methods of monitoring population size in caves and mines 

may be usable in areas where significant hibernation and maternity colonies occupy these structures. Consistent monitoring 

requires funding that is often lacking for this species. While distribution and abundance are reasonably well documented 

for the two subspecies of C. townsendii, additional work to fill-in distribution gaps and assess population status is needed 

for C. rafinesquii. In the interim, conservation of natural and manmade roosts appears to be a critical need.

Citation for proceedings: Loeb, Susan C.; Lacki, Michael J.; Miller, Darren A., eds. 2011. Conservation and management of eastern big-eared bats: 

a symposium. Gen. Tech. Rep. SRS-145. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 157 p.
14

reviews, and unpublished monitoring data (U.S. Fish and 

Wildlife Service 1984, 1995, 2008a, 2008b). Much of the 

Rafinesque’s big-eared bat distribution and status data were 

obtained through a partnership begun in 2008 to create a 

conservation strategy for Rafinesque’s big-eared bat and the 

southeastern bat (Myotis austroriparius). To derive the most 

current information on distribution for these two species, a 

2-year data-gathering period was established in which data 

were compiled from State natural heritage agencies and other 

sources. Additionally, local experts were involved in two 

multiday workshops (Raleigh, NC, September 24–25, 2008; 

Nashville, TN, March 31 to April 1, 2009) to gather expert 

opinion. This multipartner conservation project will result in 

a white-paper working strategy (currently being drafted by 

Bayless and others) through cooperative agreements with Bat 

Conservation International (Bat Conservation International, 

P.O. Box 162603, Austin, TX 78716). The data-gathering 

effort was supported in part by the National Fish and Wildlife 

Foundation (Protecting America’s Bats—III project no. 

2008-0094-000; Bayless and Clark 2009). 

DIsTRIbUTION

Ozark big-Eared bat 

The Ozark big-eared bat is endemic to the Ozark Highlands 

and Boston Mountains ecoregions (Omernik 1987) where it 

occurs in oak-hickory (Quercus spp.-Carya spp.) hardwood 

forests (Clark 1991, Leslie and Clark 2002, U.S. Fish and 

Wildlife Service 1995). At the time of listing, the Ozark bigeared bat was known from only a few caves in northwestern 

Arkansas, southwestern Missouri, and northeastern 

Oklahoma. Since listing, additional caves used by maternity 

colonies in the summer and as hibernacula have been 

discovered in Oklahoma and Arkansas (Miller and others 

2011, U.S. Fish and Wildlife Service 2008a). However, the 

bats have abandoned other caves including all known sites in 

Missouri and are, therefore, considered extirpated from that 

State (U.S. Fish and Wildlife Service 2008a; but see Elliot 

and others 1999). Consequently, the current range of the 

Ozark big-eared bat is limited to northeastern Oklahoma and 

northwestern and northcentral Arkansas. 

In Oklahoma, Ozark big-eared bats currently are known to 

occur in Adair, Cherokee, and Sequoyah Counties. They 

were historically known from two caves in Delaware County, 

but have not been observed there recently. Twelve caves 

considered essential (defined in the recovery plan as caves 

that are necessary for the bat’s continued existence because 

they are used as maternity sites and/or hibernacula; U.S. 

Fish and Wildlife Service 1995) for the continued existence 

of the Ozark big-eared bat occur in Oklahoma. In Arkansas, 

the Ozark big-eared bat is known to occur in Crawford, 

Marion, Searcy, Washington, and Franklin Counties. Seven 

map, with the singular change being that the more recent 

maps include the few findings of new sites for the Ozark 

and Virginia big-eared bats (U.S. Fish and Wildlife Service 

2008a, 2008b). 

The endangered status determination of the two Townsend’s 

big-eared bat taxa was based on the small population sizes 

and disjunct populations (U.S. Fish and Wildlife Service 

2008a, 2008b). Both taxa were among the first to be listed 

under the Endangered Species Act (1979). However, the 

status of Rafinesque’s big-eared bat has always been in 

question with many authors over time suggesting that it is 

rare. For example, Barbour and Davis (1969) state that is 

not well known and “It is nowhere abundant, but is readily 

available for study at many localities.” Thirty years later, 

Harvey and others (1999) stated similarly that this species is 

one of the least known of all bats in the Eastern United States 

and that it is uncommon throughout its range. 

Previous investigations of Ozark and Virginia big-eared 

bats were initiated by researchers per requirements of 

the Endangered Species Act and continue to yield new 

information on population trends for those taxa (U.S. Fish 

and Wildlife Service 2008a, 2008b). Additionally, in the 

past 10 to 15 years, there has been a rise in the number 

of investigations on Rafinesque’s big-eared bat (e.g., this 

symposium; Bennett and others 2008, Hurst and Lacki 

1999, Lacki 2000, Trousdale and Beckett 2004). The result 

should be that for all the eastern Corynorhinus there is more 

data for conservation and management planning. However, 

much of the current distribution and status information for 

the eastern Corynorhinus, in particular for Rafinesque’s 

big-eared bat, is found in unpublished literature (e.g., 

Clark 1999, Clark and DeTour 1995, Clark and Williams 

1993, Harvey 1999, Horner and Maxey 2007; see also 

Martin and others 2011) and is not readily available. As 

such, land managers, conservationists, and others have 

difficulty finding basic information that can assist them with 

much needed investigations. To that end, our objectives 

were: (1) to provide a more current distribution map for 

eastern Corynorhinus; (2) summarize what is known about 

distribution, status, and population trends; and (3) identify 

gaps and areas where future work on eastern Corynorhinus

can better guide investigations of the distribution, status, and 

population trends of these species. 

METHODs

We reviewed published and unpublished literature on status 

and distribution of eastern Corynorhinus taxa and consulted 

experts on these species for additional information. Material 

presented for both the Ozark big-eared bat and the Virginia 

big-eared bat was primarily derived from U.S. Fish and 

Wildlife Service reports including recovery plans, 5-year 
15

Rafinesque’s big-Eared bat

Rafinesque’s big-eared bats are found sporadically 

throughout much of the Southeastern United States. 

Historically, populations occurred from eastern Texas to 

southern Missouri in the western part of its range, north 

to southern Illinois, Indiana, and Ohio, eastward to West 

Virginia and Virginia, then south along the coast through 

central Florida (Harvey and others 1999, Jones 1977). 

Harvey and Saugey (2001) defined the species’ distribution 

as including portions of all Southern States, except 

northwestern Arkansas and northern Virginia. Although they 

continue to be widespread in the Eastern United States, and 

are still found throughout most of their historic range, they 

are now apparently absent from Ohio, Indiana, and eastern 

Illinois (fig. 1). The reasons for their absence along the 

northern edge of the range are unclear. 

Most authors illustrate distribution of Rafinesque’s big-eared 

bat as continuous across the Southeastern United States (e.g., 

Whitaker and Hamilton 1998), but careful plotting of records 

indicates that this bat has a somewhat sporadic distribution 

(fig. 1; Bayless and Clark 2009). Absence of records from 

the Piedmont region (fig. 1) of the Southern States suggest 

that the bats may not be found there, although this could be 

an artifact of sampling as most studies have been conducted 

in mountain (Hurst and Lacki 1999, Lacki and LaDeur 2001) 

and Coastal Plain regions (e.g., Carver and Ashley 2008, 

Clark 1990, Gooding and Langford 2004, Mirowsky and 

others 2004; also see Trousdale and 2011 for a summary). 

Further surveys may provide additional information to clarify 

this apparent gap in distribution. For example, systematic 

surveys of bridges in South Carolina documented most roosts 

(94.7 percent) in the upper and lower Coastal Plains of that 

State, but did identify 5.3 percent of roosts in the Piedmont 

(Bennett and others 2008). 

Rafinesque’s big-eared bat has demonstrated preferences for 

specific features (e.g., Carver and Ashley 2008, Gooding and 

Langford 2004, Hurst and Lacki 1999, Trousdale 2011) that 

do not occur evenly across the landscape, which may account 

for its sporadic distribution. Mountain regions contain karst 

features such as rock shelters and caves that are used for 

hibernation and maternity sites. Barbour and Davis (1969) 

described this species as a bat of the southeastern forests and 

subsequent field work has demonstrated a strong affiliation 

for both age class (Carver and Ashley 2008, Gooding and 

Langford 2004, Trousdale and Beckett 2005) and tree species 

that hollow readily (Stevenson 2008). Coastal Plain forests 

of the Eastern United States include mature forests that are 

preferred by this species (Trousdale 2011). In particular, 

mature cypress-gum swamp forests (Taxodium spp-Nyssa

spp.) have been found to provide both roosting and foraging 

habitat (Clark 2003, Gooding and Langford 2004, Trousdale 

essential caves occur in Arkansas. In addition to known sites, 

this species may potentially occur in additional Arkansas 

counties (Baxter, Benton, Boone, Carroll, Logan, Newton, 

Johnson, Madison, and Pope) based on evidence of probable 

use (neatly clipped moth wings and guano characteristic of 

this species feeding behavior), proximity to known range, 

and presence of suitable roosting and foraging habitat (U.S. 

Fish and Wildlife Service 2008a). Recent surveys have 

documented possible evidence of this species in Stone and 

Barry Counties in Missouri (Elliott and others 1999).

Virginia big-Eared bat

Virginia big-eared bats roost in a wide range of caves, 

rock shelters, and other karst features year round and are 

typically located in karst regions dominated by oak-hickory 

or beech-maple-hemlock (Fagus spp.-Acer spp.-Tsuga spp.) 

associations (Barbour and Davis 1969, Lacki and others 

1993). At the time of listing (1979), the Virginia big-eared 

bat was documented from Jackson, Lee, Powell, and Rowan 

Counties, KY; Tazewell County, VA; and Pendleton, Grant, 

Randolph, Hardy, Tucker, and Preston Counties, WV (U.S. 

Fish and Wildlife Service 1984).1

 Currently, the population 

is documented from four States: Kentucky, North Carolina, 

Virginia, and West Virginia (fig. 1). Virginia big-eared bats 

are known to have significant active colony sites in Lee 

County, KY; Avery County, NC; Tazewell and Highland 

Counties, VA; and Pendleton, Grant, Tucker, and Fayette 

Counties, WV, with occasional or low-level use of sites in 

West Virginia (Hardy and Randolph Counties), Virginia 

(Bath, Bland, Highland, Rockingham, and Shenandoah 

Counties) and Kentucky (Bath, Estill, Jackson, Menifee, 

Morgan, Powell, Rockcastle, Rowan, and Wolfe Counties) 

(U.S. Fish and Wildlife Service 2008b, see footnote 1). 

A review of several theories regarding the break in 

distribution of Townsend’s big-eared bats and emergence of 

the Virginia subspecies was discussed in the recovery plan 

(U.S. Fish and Wildlife Service 1984: appendix 2). Recent 

phylogenetic investigations (Piaggio and others 2009b) have 

found divergence from Handley’s (1959) original description. 

The apparent loss of connectivity among populations within 

this range has resulted in four genetically unique populations 

that should be considered distinct evolutionary units: 

Pendleton and Grant Counties, WV, and Highland County, 

VA; Fayette County, WV; Tazewell County, VA; and Lee, 

Estill, and Jackson Counties, KY (Piaggio and others 2009b).

1

 Personal communication. 2010. Traci Hemberger, Wildlife Biologist, 

Kentucky Department of Fish and Wildlife Resources, #1 Sportsman’s 

Lane, Frankfort, KY 40601. Personal communication. 2010. Rick Reynolds, 

Wildlife Biologist, Virginia Department of Game and Inland Fisheries, 

4010 West Broad Street, Richmond, VA 23230. Personal communication. 

2010. Craig Stihler, Wildlife Biologist, West Virginia Division of Natural 

Resources, 324 Fourth Avenue, South Charleston, WV 25303.
16

needed in other forest types to clarify habitat relationships 

for this species.

pOpULaTION DaTa

Ozark big-Eared bat 

At time of listing, the entire population of Ozark big-eared 

bats was estimated to consist of about 100 to 200 individuals 

(U.S. Fish and Wildlife Service 1984). Since listing, Ozark 

big-eared bat populations at essential hibernacula and 

maternity sites have been monitored using minimal census 

techniques at each essential site to obtain estimates on 

colony size and population trends (Harvey and others 2006, 

Puckette 2009). Monitoring data have revealed a disparity 

between summer and winter population estimates with 

numbers of Ozark big-eared bats estimated from summer 

2011). This bottomland forest type is restricted to certain 

hydrologic conditions where it develops adjacent to slowmoving river systems (Conner and others 1981, Faulkner 

and others 2009). In surveys conducted in high-quality 

bottomland tracts in North Carolina (Roanoke River 

bottomlands) and South Carolina (Francis Beidler Forest), 

Rafinesque’s big-eared bats were captured more frequently 

than other species (Clark 1999, Clark and Black 1997). 

Menzel and others (2001) have also radio tracked male 

Rafinesque’s big-eared bat foraging over young pine (Pinus 

spp.) forests where the roost site was in a building near 

bottomland forest. Although many of the records used for 

creating the updated distribution map for Rafinesque’s bigeared bat (fig. 1; Bayless and Clark 1990) were based on the 

recent studies in bottomland hardwood forests, Rafinesque’s 

big-eared bat is known to use a variety of manmade roost 

sites that occur in other forest types (Martin and others 

2011). Therefore, more roosting and foraging studies are 

Figure 1—Geographic range of Corynorhinus rafinesquii, C. townsendii ingens, and C. townsendii virginianus in the Eastern 

United States. Black stars indicate occurrence records outside the contiguous range of C. rafinesquii.
17

Rafinesque’s big-Eared bat

A minimum of 1,138 known roost sites for Rafinesque’s 

big-eared bats were recorded during a data compilation 

effort in 2008 and 2009 spanning a time period from 1864 

to 2009 (Bayless and Clark 2009). Some detailed data 

exist for the largest populations of bats in karst areas, 

but limited survey data are available for the remaining 

colonies which occur throughout the Southeastern United 

States in groups typically ranging from 1 to 50 individuals 

throughout the year, with several larger maternity colonies 

numbering around 100 adults (Bayless and Clark 2009). The 

largest colonies of Rafinesque’s big-eared bats have been 

documented in Kentucky, North Carolina, and Tennessee 

where roughly 4,100 hibernate in 10 significant hibernacula 

in the Appalachian Mountains and central plateaus. Recent 

hibernation surveys for these 10 sites reported the following 

colony size estimates: 2 abandoned mines in Great Smoky 

Mountains National Park, NC (1,294 bats4); 2 sandstone rock 

shelters in Daniel Boone National Forest, KY (607 bats5

); 

4 caves in Mammoth Cave National Park (1,345 bats6); 

and 2 privately owned caves in Kentucky and Tennessee 

(935 bats7). Mammoth Cave National Park has documented 

13 maternity colonies which contain roughly 700 to 800 

Rafinesque’s big-eared bats (see footnote 6). Burghardt 

(2003) reported that one maternity chamber at the Eagle 

Creek Copper Mine in the Great Smoky Mountains National 

Park, NC, undoubtedly hosted many more bats at one time 

than known to inhabit the site, as attested by numerous guano 

piles up to 0.6 m in height. 

Information on population trends is generally lacking for 

Rafinesque’s big-eared bat for a number of reasons. First, 

methods of acquiring population trend data for Ozark and 

Virginia big-eared bats do not apply to Rafinesque’s bigeared bat over most of its range. Most data used for colonial 

bat population monitoring are obtained at cave and mine 

roosts where significant numbers of bats are predictably 

roosting for the hibernation or maternity season. A few cave 

and mine roosts with significant colonies have been regularly 

monitored in Kentucky, Tennessee, and North Carolina, 

but for the most part no regular monitoring is in place for 

4

 Personal communication. 2010. Dan Nolfi, Biological Science Technician, 

Resource Management and Science, Great Smoky Mountains National Park, 

107 Park Headquarters Road, Gatlinburg, TN 37738.

5

 Personal communication. 2010. Brooke Slack, Bat Ecologist, Kentucky 

Department of Fish and Wildlife Resources, #1 Sportsman’s Lane, 

Frankfort, KY 40601.

6

 Personal communication. 2010. Steven C. Thomas, National Park Service 

Monitoring Program Leader, Cumberland Piedmont Network, P.O. Box 8, 

Mammoth Cave, KY 42259.

7

 Personal communication. 2010. Jim Kennedy, Conservation Specialist, Bat 

Conservation International, P.O. Box 162603, Austin, TX 78716; Personal 

communication. 2010. Dan Nolfi, Resource Management and Science, Great 

Smoky Mountains National Park, 107 Park Headquarters Road, Gatlinburg, 

TN 37738.

maternity counts being larger than those found during winter 

hibernacula counts. For example, during the last year in which 

a representative count of both Ozark big-eared bat hibernacula 

and maternity sites occurred (2003), 701 bats were counted at 

hibernacula while maternity counts resulted in an estimate of 

about 1,600 bats (U.S. Fish and Wildlife Service 2008a). This 

indicates there are likely major hibernacula that have not yet 

been located. Population estimates and trends are, therefore, 

based on maternity colony counts. The population is estimated 

to currently consist of about 1,600 to 1,800 individual bats 

with about 400 to 600 in Arkansas and 1,200 to 1,400 in 

Oklahoma.2 Recent population trend analyses were recently 

published for all known essential sites, and pooled. Results 

indicate an increasing population trend for seven colonies and 

a declining trend for three colonies, while the count data for 

four colonies were too variable to detect any trend (Graening 

and others 2011).

Virginia big-Eared bat 

When the recovery plan was drafted, the known population 

of Virginia big-eared bats within maternity colonies was 

approximately 3,600 and the known hibernating population 

was approximately 2,585 (U.S. Fish and Wildlife Service 

2008b). Since listing, all States within the range of the 

Virginia big-eared bat have implemented a periodic 

monitoring program at both hibernacula and maternity 

sites, but a standardized survey protocol has not been 

formalized (U.S. Fish and Wildlife Service 2008b). Estimates 

derived during 2009 hibernacula surveys approximate the 

Virginia big-eared bat population at 15,000 individuals; 

approximately 12,000 of these bats hibernate in West 

Virginia (U.S. Fish and Wildlife Service 2009). Summer 

estimates at rangewide maternity colonies the same year 

accounted for 8,400 individuals.3 Thirteen caves support 

hibernating colonies of ≥ 20 Virginia big-eared bats, and 

only 8 of these contain over 100 hibernating individuals. 

Maternity sites are limited to 17 caves and 6 other caves 

support summer bachelor colonies with ≥ 20 individuals. 

The U.S. Fish and Wildlife Service determined in their 

5-year review that although there have been fluctuations and 

population declines within individual caves, the rangewide 

population within both hibernacula and maternity colonies 

has increased since the time of listing (U.S. Fish and Wildlife 

Service 2008b). They further note that the documented range 

of the species has expanded with discovery of additional 

occupied caves, including one significant hibernaculum in 

Avery County, NC (Clark and Lee 1987). 

2

 Personal communication. 2010. Richard C. Stark, Fish and Wildlife 

Biologist, U.S. Fish and Wildlife Service, Oklahoma Ecological Services 

Field Office, 9014 East 21st Street, Tulsa, OK 74129.

3

 Personal communication. 2010. Barbara S. Douglas, Senior Endangered 

Species Biologist, U.S. Fish and Wildlife Service, West Virginia Field 

Office, 694 Beverly Pike, Elkins, WV 26241.
18

on November 30, 1979, due to its small population size, 

reduced and limited distribution, and vulnerability to 

human disturbance (U.S. Fish and Wildlife Service 1984). 

The original U.S. Fish and Wildlife Service recovery plan 

was approved in 1984 and included both federally listed 

subspecies of Corynorhinus townsendii (Ozark big-eared 

bat and Virginia big-eared bat). In 1995, a revised recovery 

plan was developed to update the information and recovery 

tasks specifically for Ozark big-eared bats. In this plan, both 

downlisting (to threatened status) and delisting criteria were 

outlined (U.S. Fish and Wildlife Service 1995). Habitat 

loss, disturbance, predation, and pollutants are among 

the identified threats in the recovery plan (U.S. Fish and 

Wildlife Service 2008b). Although significant recovery 

accomplishments have occurred over the 32 years since 

listing, vulnerability of Ozark big-eared bats to extinction 

remains high due to the same factors that justified its 

designation. During the recent 5-year review on the current 

status of the Ozark big-eared bat, the U.S. Fish and Wildlife 

Service (2008a) determined that neither the downlisting 

nor delisting criteria identified in the current recovery plan 

(U.S. Fish and Wildlife Service 1995) had been met, and 

that the Federal endangered status of the species was still 

valid because significant threats to this species persist. For 

example, although additional essential caves have been 

discovered and protected since the time of listing, not all 

known caves have been afforded some form of protection, 

e.g., a cave gate/grill, signs, fee-title purchase, conservation 

easement. In addition to the threats that justified the original 

listing designation, vandalism, human population growth, 

climate change, and white-nose syndrome have been 

identified as factors that may impact the future status of 

Ozark big-eared bat populations (Bogan 2003, Leslie and 

Clark 2002, Wethington and others 1996; see footnote 2). 

Rafinesque’s big-eared bats. Agencies generally prioritize 

listed species, thus financial and other resources are often 

lacking for baseline survey and monitoring activities for nonfederally protected species. 

Second, much of the range of Rafinesque’s big-eared bat 

is devoid of karst features; in these areas bats roost in tree 

hollows and manmade structures (Bennett and others 2008, 

Mirowsky and others 2004, Trousdale 2011). These sites 

present special challenges for monitoring. In bottomland 

hardwood forests, Rafinesque’s big-eared bats often switch 

roost trees (Carver and Ashley 2008, Clark 2003, Gooding 

and Langford 2004, Rice 2009, Stevenson 2008) making it 

difficult to know which tree to monitor. Lastly, due to cavity 

configuration and other logistics associated with tree roosts, 

it is difficult to observe and count bats entering and exiting 

these types of roosts, particularly during winter months (Rice 

2009). Additionally, mark-recapture models for estimating 

populations are not generally used for bats due to the low 

recapture rates of banded bats (O’Shea and Bogan 2003). 

sTaTUs

Ozark big-Eared bat 

Although the Townsend’s big-eared bat has been listed as 

a species of least concern (LC) by the World Conservation 

Union’s 2004 IUCN Red List of Threatened Species 

(International Union for Conservation 2010), the Ozark 

subspecies is ranked as a critically imperiled subspecies 

by NatureServe (2008) and is either extirpated or critically 

imperiled in every State where it occurs (tables 1 and 2). 

The Ozark big-eared bat was federally listed as endangered 

Table 1—state-level natural heritage rankings for eastern Corynorhinus are listed for the 18 Eastern states in which one 

or more Corynorhinus taxa occura

Corynorhinus taxa AL AR FL GA IL IN KY LA MS MO NC OH OK SC TN TX VA WV

C. townsendii 

ingens

— S1 — — — — — — — SX — — S1 — — — — —

C. townsendii 

virginianus

— — — — — — S1 — — — S1 — — — — — S1 S2

C. rafinesquii S2 S3 S2 S3? S1 SH S3 S3/S4 S2 SU S3 SH S1 S2? S3 S3 S2 S1

— = not applicable.

AL = Alabama; AR = Arkansas; FL = Florida; GA = Georgia; IL = Illinois; IN = Indiana; KY = Kentucky; LA = Louisiana; MS = Mississippi; 

MO = Missouri; NC = North Carolina; OH = Ohio; OK = Oklahoma; SC = South Carolina; TN = Tennessee; TX = Texas; VA = Virginia; WV = West 

Virginia.

a The conservation status of a species or ecosystem is designated by a number from 1 to 5, preceded by a letter reflecting the appropriate 

geographic scale of the assessment (S = subnational). The numbers have the following meaning: 1 = critically imperiled; 2 = imperiled; 

3 = vulnerable; 4 = apparently secure; 5 = secure; X = presumed extinct or extirpated; H = possibly extinct or extirpated; U = unrankable; 

? = inexact numeric rank.

Source: NatureServe (2008).
19

Table 2—Designations from Comprehensive Wildlife Conservation strategies prepared by state wildlife agencies are 

shown for eastern Corynorhinus that occur in 18 Eastern states; designation terminology is not consistent among 

states, making it difficult to compare status between statesa

State C. townsendii ingens C. townsendii virginianus C. rafinesquii

Alabama — — Species of greatest conservation 

need; highest conservation 

concern; P1

Arkansas Species of greatest conservation 

need; critically imperiled; S1; 

endangered

— Species of greatest conservation 

need; imperiled; S2

Florida — — Species of greatest conservation need

Georgia — — Species of greatest conservation 

need; high priority species; rare

Illinois — — Species of greatest conservation 

need; endangered

Indiana — — Species of greatest conservation 

need; special concern

Kentucky — Species of greatest conservation 

need; critically imperiled/stable; 

S1; endangered

Species of greatest conservation 

need; vulnerable/stable; S3

Louisiana — — Not listed

Mississippi — — Species of greatest conservation 

need; needs timely conservation 

action; tier 2

Missouri Extirpated/endangered — Not listed

North Carolina — Priority wildlife species; 

endangered

Priority wildlife species; threatened

Ohio — — Species of greatest conservation 

need; species of concern

Oklahoma Species of greatest conservation 

need; tier 1; endangered

— Species of greatest conservation 

need; tier 2; special concern 

South Carolina — — Priority species; high; endangered

Tennessee — Species of greatest conservation 

need; potentially occurring; SP

Species of greatest conservation 

need; rare and uncommon; S3; 

special concern (deemed in need of 

management)

Texas — — Priority species; threatened

Virginia — Species of greatest conservation 

need; tier 2; endangered

Species of greatest conservation 

need; tier 1; endangered

West Virginia — Species of greatest conservation 

need; S2; endangered

Species of greatest conservation 

need; S1

— = not applicable.

a

 The conservation status of a species or ecosystem is designated by a number from 1 to 5, preceded by a letter reflecting the appropriate 

geographic scale of the assessment (S = subnational). The numbers have the following meaning: 1 = critically imperiled; 2 = imperiled; 

3 = vulnerable; 5 = secure; X = presumed extinct or extirpated; H = possibly extinct or extirpated; U = unrankable; ? = inexact numeric rank.

Source: Alabama Department of Conservation and Natural Resources (2005); Anderson (2006); D.J. Case & Associates (2005); Florida Fish and 

Wildlife Conservation Commission (2005); Georgia Department of Natural Resources (2005); Illinois Department of Natural Resources (2005); 

Kentucky’s Comprehensive Wildlife Conservation Strategy (2010); Lester and others (2005); Mississippi Museum of Natural Science (2005); 

Missouri Department of Conservation (2005); North Carolina Wildlife Resources Commission (2005); Ohio Department of Natural Resources, 

Division of Wildlife (2005); Oklahoma Department of Wildlife Conservation (2005); South Carolina Department of Natural Resources (2005); 

Tennessee Wildlife Resources Agency (2005); Texas Parks and Wildlife Department (2005); Virginia Department of Game and Inland Fisheries 

(2005); West Virginia Division of Natural Resources (2006). 
20

Carolina, and Tennessee) have reported population declines 

based on sound documentation. Populations in Indiana and 

Ohio probably have been extirpated (Arroyo-Cabrales and 

Castaneda 2008). Four other States (Alabama, Arkansas, 

Illinois, and North Carolina) reported suspected declines 

(Arroyo-Cabrales and Castaneda 2008). 

Rafinesque’s big-eared bats are identified on State priority 

species lists within the State wildlife action plans of every 

State within their range, except Louisiana and Missouri (table 

2) and considered a species of special concern by U.S. Fish 

and Wildlife Service (2010). The U.S. Forest Service Southern 

Region designates them as sensitive species (U.S. Department 

of Agriculture Forest Service 2009). Because this species is 

known or suspected to be declining in more than half (10 out 

of 18) of the States within its range, the U.S. Fish and Wildlife 

Service is currently conducting a rangewide review of the 

species (Arroyo-Cabrales and Castaneda 2008).8

DIsCUssION

Baseline data on distribution and status of Ozark and 

Virginia big-eared bat populations were established in the 

years following Federal listing. Subsequent work to locate 

new colonies has resulted in discovery of a limited number 

of additional sites. Although it is unlikely that many new 

sites will be found, field investigations for new locations are 

warranted. For example, in 2002, Virginia big-eared bats 

were found using abandoned mine portals in Fayette County, 

WV, within the National Park Service’s New River Gorge 

National River (Johnson and others 2003). This was a new 

locality and the first documented occurrence of Virginia bigeared bats using this habitat type (Johnson and others 2003). 

Importantly, genetic analyses indicate that this population is 

genetically distinct (Johnson and others 2003, Piaggio and 

others 2009b). 

Because these endangered taxa have high-site fidelity and 

low tolerance to disturbance, protection of each known cave 

roost has contributed significantly to recovery of individual 

bat colonies (U.S. Fish and Wildlife Service 2008a). The 

Federal “endangered” status provides regulatory protection 

for the Ozark and Virginia big-eared bats and facilitates the 

application of resources (personnel and money) toward their 

recovery. Because these populations are small and disjunct, 

vulnerability of these taxa to catastrophic events, e.g., whitenose syndrome, is high. These factors also contribute to 

problems that may occur due to reduced gene flow among 

populations. Research on phylogeny of the Townsend’s bigeared bat subspecies in the Eastern United States and effects 

8

 Personal communication. 2010. Mike Armstrong, U.S. Fish and Wildlife 

Biologist, U.S. Fish and Wildlife Service, 330 W. Broadway, Frankfort, KY 

40601.

Virginia big-Eared bat 

The Virginia big-eared bat is ranked as an imperiled 

subspecies by NatureServe (2008) and are either critically 

imperiled or imperiled in every State where they occur 

(tables 1 and 2). Virginia big-eared bats have been listed 

as a federally endangered species and managed as such by 

the U.S. Fish and Wildlife Service since 1979 (U.S. Fish 

and Wildlife Service 1984). As noted above, the original 

U.S. Fish and Wildlife Service recovery plan was approved 

in 1984 and included both federally listed subspecies of 

Corynorhinus townsendii (Virginia big-eared bat and Ozark 

big-eared bat). Virginia big-eared bats were originally listed 

as federally endangered due to small population size, limited 

distribution, and vulnerability to human disturbance (U.S. 

Fish and Wildlife Service 1984). Habitat loss, disturbance, 

predation, and pollutants are among the identified threats in 

the recovery plan (U.S. Fish and Wildlife Service 2008b). 

The U.S. Fish and Wildlife Service in its 1984 recovery plan 

outlined criteria for downlisting to threatened status, which 

they believed could be achieved through long-term roost site 

protection, subsequent stable or increasing populations over 

a 5-year period, protection of foraging areas, and establishing 

a monitoring program. 

According to the 5-year review, the recovery plan is in need 

of revision to address current species information, including 

genetics, distribution, and emerging threats (U.S. Fish and 

Wildlife Service 2008b). Although the recovery potential 

for the Virginia big-eared bat is relatively high, at this time 

three of the four approved recovery criteria have not been 

met. Thus, the U.S. Fish and Wildlife Service currently 

recommends retaining endangered listing status because 

gains made in cave protection and population increases do 

not sufficiently offset continuing and emerging threats to the 

species (U.S. Fish and Wildlife Service 2008b). Mortality 

from wind turbines, white-nose syndrome, predation, 

vandalism, and natural changes in cave conditions pose 

potential emerging threats to Virginia big-eared bats in 

addition to those that were originally listed (U.S. Fish and 

Wildlife Service 2008b).

Rafinesque’s big-Eared bat

Although they are widely distributed over much of the 

Southeastern United States, Rafinesque’s big-eared bats 

have never been considered common (Barbour and Davis 

1969, Harvey 1999, Whitaker and Hamilton 1998). Globally, 

Rafinesque’s big-eared bats are listed as a species of LC 

by the World Conservation Union’s IUCN Red List of 

Threatened Species (Arroyo-Cabrales and Castaneda 2008), 

but are ranked as a vulnerable species by NatureServe 

(2008). NatureServe (2008) does not provide consistent 

State ranks (table 1) and no rangewide statistics on trends 

are available, but four States (Georgia, West Virginia, South 
21

big-eared bat distribution and data that can assist with 

population status assessments. Using Forest Inventory and 

Analysis (FIA) data derived by the U.S. Forest Service may 

be one approach for beginning to understand distribution 

of potential roosting areas (Miller and others 2011), but 

care should be taken with pooled FIA data as they may not 

capture the local impacts of forest growth and loss trends. 

North Carolina, for example, lost 5.5 percent of its forests 

between 1990 and 2002. However, at the county level, some 

counties lost between 25 and 35 percent of their forests in 

that time period (Brown 2004). Additionally, colonies of 

Rafinesque’s big-eared bats that roost and forage in forested 

wetlands may be significantly affected by small-scale forest 

loss because this species does not move far from roosts for 

foraging or overwintering (Clark 2003, Clark and Black 

1977, Rice 2009).

Although Rafinesque’s big-eared bat populations are not as 

isolated as Ozark and Virginia big-eared bats, there appears 

to be potential for reduced gene flow, indicating a need 

for more research on phylogenetics of Rafinesque’s bigeared bats (Piaggio and others 2011). Remnants of mature 

bottomlands that are not connected by forested corridors may 

create an isolating effect similar to the disjunct populations 

with Townsend’s big-eared bat in the Eastern United States. 

Additionally, the gap in the Piedmont region may isolate 

interior populations from those in the Coastal Plain. This 

work is now possible due to recently developed microsatellite 

markers for Rafinesque’s big-eared bat (Piaggio and others 

2009a) which provide variability for estimation of population 

connectivity, demographic parameters, and genetic diversity. 

This information will be necessary for future status 

determinations. 

aCKNOWLEDgMENTs

We thank those who contributed data to update range and 

distribution information for Rafinesque’s big-eared bats. 

Many records were provided by participants working on 

a conservation strategy for this species at two workshops 

in 2008 and 2009. Partial funding was provided by the 

National Fish and Wildlife Foundation (Protecting America’s 

Bats—III project no. 2008-0094-000), the Offield Family 

Foundation, and the Beneficia Foundation. Two anonymous 

referees and T. Bayless provided valuable comments on an 

earlier draft. 

LITERaTURE CITED

Alabama Department of Conservation and Natural Resources, 

Wildlife and Freshwater Fisheries Division. 2005. Conserving 

Alabama’s wildlife: a comprehensive strategy. Montgomery, AL. 

322 p.

of isolation are likely to provide some of the most relevant 

management information to maintain viable populations in 

the future (Piaggio and others 2011). 

For Rafinesque’s big-eared bat, there is a wealth of 

new data on distribution and other aspects of its natural 

history, although much of it is not yet in the published 

literature (Bayless and Clark 2009, Rice 2009, Stevenson 

2008). Recent investigations have focused on bottomland 

hardwood forests of the Coastal Plain regions (Trousdale 

2011). Even so, many gaps in our knowledge of this 

species’ distribution remain for both this region and more 

interior parts of the range. For example, there are few 

records of winter hibernacula in the Coastal Plain regions 

of the Eastern United States and few summer records in 

interior regions. An absence of this species in the Piedmont 

of coastal States appears when records are individually 

plotted, but it is not clear whether this is an artifact of 

sampling. More field work to accurately delineate the 

distribution is needed. 

Because Rafinesque’s big-eared bats are more widespread 

than the other eastern big-eared bats and use a much broader 

range of roosts (structurally, seasonally, and geographically), 

baseline inventory and monitoring is more challenging. 

The status of this species remains unclear. Roosting habits 

and unknown aspects of demography confound efforts to 

devise a reliable means of assessing their status. Estimating 

abundance of bats, necessary for establishing baselines 

and for documenting change in population size, typically 

relies on complete enumeration (Kunz and Parsons 2009). 

Counting methods for bats roosting in caves and mines 

have been established and have been used in some cases 

for Rafinesque’s big-eared bats (see footnote 6). However, 

for the more widely dispersed populations occurring in 

forested areas, a method of estimating populations needs 

to be established. Given that Rafinesque’s big-eared bats 

have preferences for certain tree species [e.g., Nyssa spp. 

and bald cypress (T. distichum)] and structural types of tree 

roosts (extensive hollows in large diameter trees), it may be 

possible to develop structure-based monitoring (Clark 2003, 

Kunz and Parsons 2009). For example, tracking abundance, 

characteristics, and distribution of mature cypress-gum 

swamp forest could provide an index to abundance in that 

habitat type.

Mature bottomland hardwood forest has experienced 

significant declines in the past (Miller and others 2011) 

and loss of this forest type continues in some areas. Loss 

of mature stands of bottomland forests, especially those 

containing cypress-gum communities, likely decreases 

number of roosts available for Rafinesque’s big-eared 

bat which may have a detrimental effect on population 

numbers. Monitoring of mature bottomland hardwood forest 

may provide information about potential for Rafinesque’s 
22

1-800-553-6847), or the Defense Technical Information Center, 

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Clark, M.K.; Lee, D.S. 1987. Big-eared bat, Plecotus townsendii, in 

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Clark, M.K.; Williams, S.B. 1993. Results of a survey for the eastern 

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Conner, W.H.; Gosselink, J.G.; Parrando, R.T. 1981. Comparison 

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27

and others 2005). Bats that use cavities and crevices of trees 

require forests to meet their ecological demands, because 

tree-roosting bats move among roosts to varying extents, both 

among and within species, and because roosts are dynamic 

in quality and quantity (Barclay and Kurta 2007). KalcounisRüeppell and others (2005) quantitatively summarized patterns 

in characteristics of trees used by cavity- and crevice-roosting 

bats in North America. These authors established a “profile” of 

roost trees as being relatively tall with large diameter at breast 

height (d.b.h.) and located within comparatively open stands 

of high snag density and close proximity to water relative to 

randomly available trees.

Here I summarize the current state of knowledge of the 

behavior of tree-roosting C. rafinesquii in the Eastern 

United States. I discuss the extent to which C. rafinesquii

conforms to the generalizations of Kalcounis-Rüeppell 

and others (2005), and review the dimensions and thermal 

characteristics of cavity roosts reported. In addition to 

roost selection, I explore behavioral patterns, such as roost 

switching and sociality, of tree-roosting populations of this 

species. My synthesis of these diverse but interrelated topics 

identifies broad generalizations that hopefully enhance the 

formulation and implementation of conservation strategies 

for C. rafinesquii in the Eastern United States. 

ROOST SELECTION

The proximate goal of resource selection by an individual 

organism is to satisfy an immediate need, while the ultimate 

goal is to maximize fitness. Hence, the decision of where 

INTRODUCTION

Tree-roosting big-eared bats (genus Corynorhinus) in 

the Eastern United States are represented exclusively by 

Rafinesque’s big-eared bat (C. rafinesquii). Although Fellers 

and Pierson (2002) documented Townsend’s big-eared bat 

(C. townsendii) roosting in tree hollows in Western North 

America, populations of eastern subspecies (C. t. ingens and 

C. t. virginianus) roost exclusively in caves and abandoned 

mines (Kunz and Martin 1982, Whitaker and Hamilton 1998). 

The distribution of C. rafinesquii includes Southeastern and 

South Central North America (Barbour and Davis 1969), and 

use of hollow trees of various species as roosts by C. rafinesquii

has been reported for populations across its range (table 1). 

Tree roosts are especially important to C. rafinesquii in the 

Mississippi Alluvial Valley and Gulf Coastal Plain where caves 

are scarce (Clark 2003). This bat also roosts in anthropogenic 

structures (Clark 1990; England and others 1990; Ferrara and 

Leberg 2005a, 2005b; Hoffmeister and Goodpaster 1963; 

Lance and others 2001) and in some areas moves among 

artificial structures and trees (Lance and others 2001, Trousdale 

and Beckett 2005, Trousdale and others 2008).

Roosts are essential to all bats, and characteristics of these 

roost types have driven morphological, physiological, and 

behavioral adaptations in bats (Kunz and Lumsden 2003). 

Likewise, constraints in availability of roosts at local scales, 

and the vulnerability of bats while using these structures, 

may adversely affect bat populations (O’Shea and Bogan 

2003). Descriptions of roosts, and an understanding of their 

spatio-temporal use by bats, are important for design and 

implementation of effective conservation strategies (Sherwin 

ECOLOGY OF TREE-ROOSTING RAFINESQUE’S BIG-EARED BATS 

IN ThE EASTERN UNITED STATES

Austin W. Trousdale, Assistant Professor of Biology, Lander University, 

Department of Biology, Greenwood, SC 29649

Abstract—Tree-roosting big-eared bats in the Eastern United States are represented solely by Rafinesque’s big-eared bat 

(Corynorhinus rafinesquii). Studies of tree-roosting C. rafinesquii have been largely descriptive rather than manipulative, 

and habitat selection of this species beyond the scale of the roost tree is poorly understood. Regardless, general trends 

in the roosting ecology of this species are evident. C. rafinesquii roosts primarily in hollows of live trees in bottomland 

hardwood forest, especially tupelos, e.g., Nyssa aquatica and N. sylvatica. Dimensions, type, access, and thermal 

characteristics are factors in cavity selection. In selecting tall trees (mean = 21.5 m) of large diameter (mean = 110 cm), 

C. rafinesquii conforms to broad trends in roosting preferences of North American forest-dwelling bats. Roost trees are 

often clumped in distribution, enabling bats to travel short distances (usually < 1 km) among day roosts. C. rafinesquii

exhibits low daily fidelity to tree roosts yet remains faithful to tree roosts over years. Overlap in species of trees used for 

roosting exists between C. rafinesquii and syntopic southeastern myotis (Myotis austroriparius), but differences in tree 

size and position of individuals within cavities may minimize interspecific competition. The interaction of roost abundance 

and quality with local population dynamics warrants further attention, as does the importance of internal microclimate to 

the value of roosts. Incorporating the needs of tree-roosting big-eared bats in reforestation strategies remains an important 

conservation measure in bottomland hardwood forests in the Eastern United States. 

Citation for proceedings: Loeb, Susan C.; Lacki, Michael J.; Miller, Darren A., eds. 2011. Conservation and management of eastern big-eared bats: 

a symposium. Gen. Tech. Rep. SRS-145. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 157 p.
28

experimental. Lastly, habitat selection of tree-roosting bats is 

hierarchical (Perry and others 2008); however, most studies 

of C. rafinesquii have worked at small spatial scales, i.e., the 

roost tree and habitat immediately surrounding it. Thus, we 

are still a long way from a comprehensive view of the treeroosting ecology of C. rafinesquii. 

Species and Condition of Roost Trees

Roosts of C. rafinesquii in trees have been located by 

opportunistic searches of tree hollows and other structures 

to roost should reflect the physiological and ecological 

requirements of bats (Barclay and Kurta 2007). These may 

differ within an individual, e.g., by season, and among 

individuals, e.g., pregnancy versus lactation. Unfortunately, 

authors have often pooled data among bat species and 

demographic categories in an effort to increase statistical 

power, potentially obscuring important distinctions (Miller 

and others 2003). Further, knowledge of the tree-roosting 

ecology of C. rafinesquii has been derived from observational 

rather than manipulative studies. Consequently, demonstrated 

roost selection has more often been inferential rather than 

Table 1—Tree species used as day roosts by Corynorhinus rafinesquii by geographic location in the 

Eastern United States; all reported roosting sites were in tree cavities

Tree species 

Scientific name Common name Location

Carya glabra Pignut hickory Mississippia

C. ovata Shagbark hickory Mississippia

Fagus grandifolia American beech Kentuckyb, Mississippia, Texasc

Liquidambar styraciflua Sweetgum Mississippia, South Carolinad

Magnolia grandiflora Southern magnolia Mississippie

Nyssa aquatica Water tupelo Arkansasf, Louisianag,h, Mississippie

N. sylvatica Black tupelo Louisianaj, Mississippia

Platanus occidentalis American sycamore Mississippia

Populus deltoides Eastern cottonwood Mississippia

Quercus alba White oak Mississippia

Q. lyrata Overcup oak Mississippia

Q. michauxii Swamp chestnut oak Mississippia

Q. nigra Water oak Mississippia

Q. pagoda Cherrybark oak Mississippia

Q. phellos Willow oak Mississippia

Taxodium distichum Bald cypress Georgiak, Louisianah, Mississippia, South Carolinad

a

 Stevenson (2008).

b Hurst and Lacki (1999).

c

 Mirowsky and others (2004).

d Lucas (2009).

e Trousdale and Beckett (2005).

f

 Cochran (1999).

g

 Gooding and Langford (2004).

h

 Rice (2009).

i

Carver and Ashley (2008).

j

Lance and others (2001).

k Clement and Castleberry (2008).
29

(n = 7; see table 2). When compared to random trees, 

tree roosts of C. rafinesquii had greater d.b.h. in western 

Tennessee (Carver and Ashley 2008) and in Congaree 

Swamp, SC (Lucas 2009). In Louisiana, tree diameter and 

internal height of the cavity of tree roosts were significantly, 

positively related (Rice 2009). Average height of roost trees 

reported from studies across the species’ distribution was 

21 m (n = 5; see table 2). Trees containing maternity roosts 

were significantly taller than random trees in BLHs (Lucas 

2009). Although tree height may simply reflect age, in some 

cases the advantage to an individual bat in locating the 

tree at the stand and landscape scale likely increases with 

height (Britzke and others 2003, Campbell and others 1996, 

Vonhof and Barclay 1996). A taller stem may also enable 

the individual bat to roost at sufficient height to benefit 

from increased solar exposure on the stem and by extension, 

a warmer roost microclimate, although this relationship 

has been much better documented in crevice and bark 

roosts (Kurta and others 1993) than for roosts in hollows. 

Considering that hollow trees occupied by C. rafinesquii

have greater cavity volumes than unoccupied hollow trees 

(Clement and Castleberry 2008), a preference for taller trees 

may highlight the importance of a spacious cavity (Gellman 

and Zielinski 1996, Lucas 2009, Stevenson 2008). 

Cavity Type, Dimensions, and Orientation

C. rafinesquii is known to roost in tree cavities accessible via 

triangular basal entrances (fig. 1). Use of this roost type by 

C. rafinesquii is predominant in BLHs in Louisiana (Gooding 

and Langford 2004), northern Mississippi (Stevenson 

2008), the Francis Beidler Forest in South Carolina (Clark 

2003), western Tennessee (Carver and Ashley 2008), and 

eastern Texas (Mirowsky and others 2004). However, 

C. rafinesquii also makes use of trunk hollows (Trousdale 

and Beckett 2005) or cavities accessible via a single or 

multiple openings higher on the stem. The terms “upper bole 

cavities” (Lucas 2009) and “chimneys” (Rice 2009) have 

also been used to describe these roosts. Trunk hollows made 

up nearly all tree roosts of C. rafinesquii found in a mixed 

hardwood-pine system in southern Mississippi (Trousdale 

and Beckett 2005) and a considerable portion of roosts found 

in Congaree Swamp (Lucas 2009). The configuration of 

trunk hollows may promote a more favorable microclimate 

for entering and maintaining torpor when food is scarce, 

considering that cold air entering a trunk hollow would sink 

whereas warm air entering a basal cavity would rise (Rice 

2009). Trunk hollows are probably less likely than basal 

cavities to be inundated by winter flooding, a predictable 

occurrence in BLHs (Clark 2003, Gooding and Langford 

2004), and seasonally high water coincides with absence of 

C. rafinesquii from basal cavities in Louisiana (Rice 2009). 

If trunk hollows were also less accessible to predators of 

C. rafinesquii than basal openings (Cochran 1999), allowing 

bats to enter deep torpor more safely (Lausen and Barclay 

and by radio tracking individuals following their capture 

on the wing or at other roosts. Studies have largely been 

conducted in bottomland hardwood forests (BLHs) within 

and adjacent to river floodplains. Although the species is by 

no means restricted to these systems (Hurst and Lacki 1999, 

Menzel and others 2001), BLHs contain the tree species that 

dependably form cavities in which bats may roost (Stevenson 

2008). Past land use may continue to influence tree roost 

selection by C. rafinesquii; individual trees currently used 

by the species might have been spared from logging due to 

their relative inaccessibility. Association of C. rafinesquii

with water tupelo (Nyssa aquatica) and black tupelo 

(N. sylvatica) has been well documented (table 1). Nyssa is 

capable of producing extensive hollows due to erosion of 

the heartwood (Burns and Honkala 1990). Roosts have also 

been reported from other cavity-forming BLH trees that 

provide entrances either at the base or in branch scars higher 

on the stem (table 1). Based on this diversity, C. rafinesquii

more likely discriminates among individual trees by physical 

characteristics rather than species (Stevenson 2008), a 

generalization that can be extended to forest-roosting bats 

inhabiting different ecosystems (Barclay and Kurta 2007, 

Vonhof and Barclay 1996).

C. rafinesquii roosts are located within live trees more 

frequently than snags (Carver and Ashley 2008, Lucas 2009, 

Mirowsky and others 2004, Stevenson 2008, Trousdale 

and Beckett 2005). A proximal advantage of selecting a 

cavity in a live tree instead of a snag may be enhanced 

thermoregulation facilitated by a more stable microclimate. 

In forested systems outside the distribution of C. rafinesquii, 

live trees better retain heat at night than do snags (Coombs 

and others 2010, Paclik and Weidinger 2007), although 

cavities in live trees appear to heat more slowly than ones 

in snags (Kalcounis and Brigham 1998). Cavity-denning 

endotherms may benefit from the relative thermal stability 

conferred by the intact, water-containing woody tissue of a 

live tree (McComb and Noble 1981), and it follows that the 

comparatively thick bark of a live stem may enable its hollow 

to better retain heat (Sedgeley and O’Donnell 1999). The 

ultimate benefit to C. rafinesquii of preferentially roosting 

in live trees may be formation and maintenance of “roost 

networks” that facilitate information transfer (Rhodes 2007, 

Rhodes and others 2006). This outcome is perhaps better 

facilitated when structures remain intact and available to the 

local population for generations (Barclay and Kurta 2007). 

Dimensions of Roost Trees

Authors typically comment on the large size of roost trees 

used by C. rafinesquii (table 2). Aside from possessing 

sizeable cavities and accessible entrances, the most important 

characteristic of trees appears to be that they possess 

relatively large d.b.h. Average d.b.h. of roost trees reported 

from studies across the species’ distribution was 110 cm 
30

Orientation of a cavity opening is a predictor of roost use 

by some tree-roosting bats, e.g., big brown bats (Eptesicus

fuscus) (Kalcounis and Brigham 1998), but this variable 

apparently does not influence occupancy by C. rafinesquii. 

For C. rafinesquii, aspect did not differ from random in 

Louisiana (Gooding and Langford 2004), and a wide range 

of values for orientation were reported in Mississippi 

(Trousdale and Beckett 2005). In western Tennessee, 

C. rafinesquii roosts tend toward a north-northeasterly 

direction, but orientation of these cavities does not differ 

from that of available tree hollows (Carver and Ashley 2008).

Location of the roost cavity in relation to forest structure 

is potentially relevant to its use by bats. Cavities used 

by maternity colonies of Nyctalus and C. tuberculatus

are located further from nearby trees or other vegetation 

and placed higher off the ground than are unused cavities 

(Ruczy ́nski 2006, Sedgeley and O’Donnell 1999). A cavity 

situated in a relatively uncluttered environment would 

seem to be particularly important to C. rafinesquii, as other 

plecotine bats are known to find potential roosts using 

2006), these cavities would be particularly valuable winter 

roosts. Supporting data are lacking for this hypothesis.

It remains unclear whether minimum dimensions of cavity 

entrance, height, and width must be met for C. rafinesquii to 

use potential roost trees. Cochran (1999) noted use of two 

water tupelos by C. rafinesquii that each contained a central 

cavity accessible only via a knothole opening ≤ 8 cm across. 

Some cavity-roosting bats, e.g., the New Zealand long-tailed 

bat (Chalinolobus tuberculatus), Leisler’s bat or the lesser 

noctule (Nyctalus leisleri), and the noctule bat (N. noctula), 

prefer spaces with smaller entrances, perhaps to reduce 

susceptibility to predation or convective heat loss (Ruczy ́nski 

2006, Sedgeley 2001). Internal cavity height averaged 6.4 m 

across studies (n = 5; see table 2). Stevenson (2008) found 

that this variable was greater by > 300 cm for tree roosts than 

for cavities from which C. rafinesquii was not documented. 

C. rafinesquii appears to use a fission-fusion behavioral 

strategy (see below) that may compensate for occasional 

limitations in cavity volume that prevent all members of a 

colony from roosting concurrently.

Table 2—Means (SE), unless noted otherwise, of characteristics of tree roosts of Corynorhinus rafinesquii in the Eastern 

United States

Author (date) Tree height D.b.h. Cavities

Height of 

cavity roosta

Width of cavity 

entrance 

Interior height of 

cavity

n m cm no. ---------------------cm--------------------- m

Carver and Ashley (2008)

24

26 (1.3) 124 (7.5) 1.6 (0.1) 120 (15.3) 40 (5.2) 9 (0.7)

Clark (1990) 

 1

1 170 70 5

Cochran (1999) 

 3

11 (1.9)b 155 (26.8) 1

Gooding and Langford (2004)

44

25 (0.6) 120 (3.5) 1.7 (0.1) 132 (10) 48 (4) 6 (0.3)

Lance and others (2001)

 4

{59, 103}

Lucas (2009)

43

27 (1.3) 107 (4.7)

Rice (2009)

26

82 (25.4)b 104 (54.5) 46 (40.3) 6 (2.8)

Stevenson (2008)

49

100 (5.4) 70 (9.4) 40 (4.5) 6 (0.5)

Trousdale and Beckett (2005)

14

18 (10.7)b 79 (18.9) 1.1 (0.4)

D.b.h. = diameter at breast height.

a Largest entrance if multiple cavities.

b SD reported by author.
31

anthropogenic structures (Hurst and Lacki 1999, Jones and 

Suttkus 1975). In North Carolina, daily spring temperatures 

fluctuate more in abandoned buildings than in C. rafinesquii

roost tree cavities (Clark 1990). Rice (2009) performed 

the most comprehensive study of thermal relations of 

tree-roosting C. rafinesquii to date. He compared internal 

temperatures of Nyssa among individual trees grouped by 

cavity opening type: trunk, basal, or both and found that 

temperatures within all cavity types were generally milder 

than ambient conditions regardless of season. During 

summer, mean cavity temperature (approximately 22 °C) 

did not differ by tree configuration, nor did C. rafinesquii

select any particular cavity type. However, on occasions 

when the previous night’s temperature did not exceed 

17 °C, individuals largely restricted tree use to roosts with 

trunk hollows only. During winter, temperatures in trunk 

hollows were more stable than those of basal cavities and 

cavities with both basal and chimney openings. Within 

these trunk hollows, C. rafinesquii seasonally adjusts its 

relative roosting height, occupying the bottom half of the 

cavity in late summer and roosting near the top during 

winter. Such movement is consistent with the prediction 

that each individual selects the height in the chamber where 

microclimate is most favorable (fig. 2), assuming that 

temperatures are stratified within the cavity (Rice 2009).

Thermal characteristics of a tree cavity or crevice appear to 

play an important role in resource selection by insectivorous 

bats that roost in these structures (Barclay and Kurta 2007, 

Crampton and Barclay 1998, Kalcounis and Brigham 1998, 

Kerth and others 2000, Sedgeley 2001). Microclimates 

of vacant roosts of C. tuberculatus, situated in knotholes, 

possess higher minimum temperatures than do available, 

presumably unused cavities. These sites also sustain their 

echolocation while hovering at close distance from the 

stem surface (Ruczy ́nski and others 2009). Nevertheless, 

canopy closure at tree roosts of C. rafinesquii is high (> 90 

percent) in southeastern Mississippi, although proximity to 

streambeds may reduce clutter surrounding cavity entrances 

(Trousdale and Beckett 2005).

Thermal Characteristics of Roosts

Over much of its distribution, C. rafinesquii is resident year 

round within its home range (Jones 1977, Mirowsky and 

others 2004, Rice 2009, Stevenson 2008, Trousdale 2008), 

yet roosting ecology of the species has traditionally been 

studied during warmer seasons (but see Rice 2009) and the 

temperature requirements of the species inside tree roosts are 

only beginning to be understood [see Hurst and Lacki (1999) 

for discussion of temperature relations of C. rafinesquii in a 

cave roost]. As endotherms that possess a large surface area 

to volume ratio, bats are susceptible to a high rate of heat 

loss (Speakman and Thomas 2003). For insectivorous bats 

living in the temperate zone this problem is compounded by 

the seasonal scarcity of prey. C. rafinesquii uses daily torpor 

to reduce its energy expenditure, especially during cool 

weather, and enters hibernation during extended periods of 

unfavorable conditions (Hoffmeister and Goodpaster 1963, 

Jones 1977, Pearson 1962). Success of this strategy depends 

on an individual roosting at a temperature just low enough to 

reduce energetic requirements and within a space effectively 

insulated to minimize fluctuations in temperature that could 

trigger periodic arousals (Neuwiler 2000).

Data on temperatures inside C. rafinesquii roosts have been 

collected from relatively little of the species’ distribution. 

However, C. rafinesquii generally favors roosts with 

microclimates that are stable over the short term. Changes 

in air temperature apparently prompt C. rafinesquii to 

alter roosting locations within and among caves and 

Figure 1—A roost tree of Corynorhinus rafinesquii accessed 

through a basal entrance. (Photo by Brian D. Carver)

Figure 2—View of a maternity colony of Corynorhinus rafinesquii

with bats roosting at varying heights inside the cavity of a tree roost. 

(Photo by Christopher L. Rice)
32

1990). Past land use, e.g., timber extraction, that shapes 

current vegetation is also influential in determining the 

distribution of tree roosts (Gooding and Langford 2004). 

Patches of forest with a high density of potential roosts may 

be characterized by even-aged stands of older trees (Clark 

2003), and inhabiting these areas is likely advantageous 

to C. rafinesquii. Given that C. rafinesquii has a low wing 

loading and aspect ratio (Jones and Suttkus 1971, Norberg 

and Rayner 1987), the flight of this species is highly 

maneuverable but also energetically expensive (Norberg and 

Rayner 1987). Therefore, individuals would be expected to 

travel conservative distances when foraging or commuting 

(Entwistle and others 1996, Lacki and Dodd 2011). For 

example, in a population that uses both trees and bridges 

as day roosts, individuals moved among sequential tree 

roosts at an average of approximately 360 m (Trousdale 

and Beckett 2005), comparable to 234 m moved in BLHs 

in Louisiana (Rice 2009). Furthermore, roosts of solitary 

males and females in maternity colonies are concentrated in 

areas averaging < 3 ha, based on minimum convex polygons 

surrounding point locations of trees used by C. rafinesquii in 

Congaree National Park (Lucas 2009).

Selection at Stand and Landscape Scales

Species composition of stands seems to more consistently 

influence roost selection of C. rafinesquii than does stand 

structure. The dominant vegetation within these stands 

generally corroborates the notion that C. rafinesquii depends 

on BLHs or, at least, a substantial hardwood component 

within the forest types used for roosting. In a mixed pinehardwood system, 10 of 14 C. rafinesquii roosts were 

in stands characterized by the U.S. Forest Service as 

bottomland hardwood, with the remainder in loblolly pine 

(Pinus taeda) or laurel oak (Quercus laurifolia)-willow oak 

(Q. phellos) stands (Trousdale and others 2008). In oldgrowth BLHs, > 76 percent of roosts were located in a bald 

cypress (Taxodium distichum)-water tupelo-Carolina ash 

(Fraxinus caroliniana) association, with separate complexes 

of sweetgum (Liquidambar styraciflua), hackberry (Celtis 

laevigata), and beech (Fagus grandifolia) also represented 

(Lucas 2009). A Louisiana stand containing 44 roosts used 

over a 3-month span was almost entirely comprised of water 

tupelo (Gooding and Langford 2004). 

The relative importance of basal area and canopy closure 

in determining suitability of stands for roost locations 

of C. rafinesquii is somewhat ambiguous. Gooding and 

Langford’s (2004) study area supported a mean basal area of 

72.3 m2

/ ha, while that of Stevenson (2008) was 21.8 m2/ ha. 

Plots containing tree roosts of C. rafinesquii have a higher 

basal area (120.5 m2

/ ha) than do random plots (71.3 m2/ ha) 

in Congaree National Park (Lucas 2009). Conversely, 

neither basal area nor canopy closure differs between stands 

containing roosts and random trees in Mississippi, where 

maximum temperatures and humidity for a significantly 

longer time than cavities of both comparable and dissimilar 

configurations (Sedgeley 2001). Bat pups are born naked; 

as neonates their ability to thermoregulate is poor (Kunz 

1987). When adult females leave the roost to forage, pups 

are dependent upon heat retained within the roosting 

structure to remain warm (Ruczy ́nski 2006, Sedgeley 2001). 

A thicker stem wall should promote a more stable internal 

microclimate (Sedgeley and O’Donnell 1999); this variable 

is positively correlated with tree d.b.h. of C. rafinesquii

roosts in Mississippi (Stevenson 2008). An optimal 

roost for a social species like C. rafinesquii should also 

provide space sufficient to contain the group size at which 

thermoregulatory benefits materialize; future research efforts 

are needed to elucidate this relationship. C. rafinesquii forms 

large aggregations when roosting in anthropogenic structures 

during cold weather (Hoffmeister and Goodpaster 1963) 

and some tree-roosting populations conform to this pattern. 

For example, Stevenson (2008) reported a very large group 

(> 200 individuals) roosting within a tree cavity in winter in 

Mississippi.

The geographic distribution of C. rafinesquii includes areas 

that experiences very warm, humid summers. Heat stress 

could, therefore, become a problem during the day and may 

influence roost selection by individuals and colonies during 

this time of year. Relief from heat may help explain why 

this bat often roosts underneath concrete bridges in summer, 

even when tree cavities are located nearby (Trousdale and 

others 2008). Roosting flush with the concrete wall of a 

compartment enables an individual to contact a surface 

considerably cooler than ambient daytime temperatures 

(Ferrara and Leberg 2005a). This pattern has not been 

demonstrated using summer temperature data from tree 

roosts of C. rafinesquii. However, avoidance of heat stress 

may influence E. fuscus in Saskatchewan, Canada, to roost 

in live-tree cavities that are cooler than afternoon ambient 

temperatures and cooler in the mornings than cavities in 

snags (Kalcounis and Brigham 1998).

Distribution of Tree Roosts

Authors have noted that tree roosts of C. rafinesquii tend 

to be located in close proximity to one another (Carver and 

Ashley 2008, Clark 2003, Gooding and Langford 2004, 

Trousdale and Beckett 2005). However, mean distance to 

nearest cavity tree is greater for tree roosts than nonused 

trees in Mississippi (Stevenson 2008), implying a more 

uniform dispersion pattern. In contrast, Lucas (2009) 

identified a clustered dispersion pattern in Congaree Swamp. 

Roost distribution across the landscape is likely affected 

by a combination of hydrology and soil chemistry that 

shape floodplain plant communities (Mitsch and Gosselink 

2007), and characteristics of the biology of cavity-forming 

trees tolerant of these conditions (Burns and Honkala 
33

that are likely insufficient to reflect shifts in food supply, 

thus, having little impact on an individual’s daily energy 

budget (Barclay and Kurta 2007).

The low roost fidelity of C. rafinesquii to trees and the 

tendency of female individuals to roost communally during 

the reproductive season have important consequences for 

the species’ behavior. Fenton (2003) argued that a colony 

is more than simply an aggregation of individuals that 

cooccupy a roost at a given time, but rather a discrete social 

unit. Groups of C. rafinesquii that cohabit tree cavities 

appear to be colonies that exhibit fission-fusion social 

behavior (Kerth and König 1999). Marked individuals 

associate together among multiple roosts in southeastern 

Mississippi (Trousdale and Beckett 2005), and several other 

investigations (Gooding and Langford 2004, Lucas 2009, 

Rice 2009) noted variable group size within and among 

roosts based on daytime cavity surveys or exit counts. 

Fluidity in composition may be an adaptation, used in 

combination with recurrent roost switching, to maintain 

group cohesion despite differences in size of cavities among 

trees (Willis and Brigham 2004, Willis and others 2006). 

In proximal terms, the mobility that such loosely cohesive 

group living offers might benefit the individual by decreasing 

parasite loads and lessening the length of time before odors 

accumulate within a roost, potentially attracting predators 

guided by olfaction (Lewis 1995). Regular movement 

among tree cavities may also familiarize the individual with 

locations of alternate roosts (Kurta and others 2002). In this 

context, behavior of individuals which habitually roost apart 

from a colony, e.g., adult males, would be less subject to 

these factors and, predictably, should switch roosts less often 

(Rice 2009, Trousdale 2008). Data from Congaree National 

Park indicate that solitary-roosting C. rafinesquii show 

higher fidelity to roosts than bats from maternity colonies 

(Lucas 2009).

RELATIONShIP WITh 

MYOTIS AUSTRORIPARIUS

In the Coastal Plain and the Mississippi Alluvial Valley, 

C. rafinesquii is syntopic with southeastern myotis 

(M. austroriparius), another rare bat dependent on hollow 

trees in BLHs for roosting (Barbour and Davis 1969, 

Clark 2003, Gooding and Langford 2004). Southeastern 

myotis and C. rafinesquii cohabit tree hollows throughout 

most of the year in Louisiana (Rice 2009) and Mississippi 

(Stevenson 2008), and share anthropogenic roosts during 

winter in Texas (Mirowsky and others 2004). However, 

resource partitioning between the two species with respect 

to roosts likely occurs (table 3). In western Tennessee, tree 

diameter is greater for roosts of C. rafinesquii than those 

trees used only by southeastern myotis, and the particular 

trees that the two species share are among the largest 

canopy closure exceeds 90 percent (Stevenson 2008). 

Although C. rafinesquii follows the general trend of roosting 

in stands with a high density of potential roosts (i.e., snags, 

Kalcounis-Rüeppell and others 2005), its preferences 

apparently do not include open canopies surrounding roosts.

Stand- and landscape-level characteristics seem to be 

less important than those of individual roost trees for 

C. rafinesquii (Lucas 2009, Stevenson 2008). In Mississippi, 

distance to the nearest hollow tree is the only landscape 

variable that predicts cavity use by C. rafinesquii, as tree 

roosts are located farther away from these structures than 

nonroost trees (Stevenson 2008). In Lucas’ (2009) analysis, 

multivariate models that included landscape variables poorly 

explained roost selection in this species. However, maternity 

colonies roost in trees significantly farther from edge habitat 

than random trees, suggesting that interior forest is more 

optimal for cavity formation or associated with less predation 

pressure (Lucas 2009). Selection of roost trees away 

from edge habitats to reduce predation pressure has been 

purported for foliage-roosting red bats (Lasiurus borealis) 

(Hutchinson and Lacki 2000).

ROOST FIDELITY AND SOCIAL BEhAVIOR

During warm weather, C. rafinesquii shows limited dayto-day fidelity to tree roosts but strong fidelity to the 

patch of forest enclosing these roosts within and across 

years (Clark 2003, Gooding and Langford 2004, Lucas 

2009, Stevenson 2008, Trousdale and Beckett 2005). In 

this sense, roost fidelity for the species is scale-dependent 

and resembles behavior of other bats, e.g., big brown bat 

(Willis and others 2003), Indiana bat (Myotis sodalist) 

(Kurta and Murray 2002), and tri-colored bat (Perimyotis

subflavus) (Veilleux and Veilleux 2004). The lower daily 

fidelity that C. rafinesquii shows to tree roosts compared 

to anthropogenic roosts may be due to these bats seeking 

optimal microclimates relative to ambient temperatures and 

the individual’s physiological demands (Kerth and others 

2000, Rice 2009). Alternatively, if roosts in buildings or 

under bridges possess a more stable, agreeable microclimate 

than do tree cavities, or are subject to relaxed parasitism 

or predation pressures, such circumstances may remove 

incentives to switch more frequently. Lewis (1995) argued 

that relative densities of roosts within the landscape or their 

differences in degree of permanence could lead bats to adjust 

roost fidelity accordingly; C. rafinesquii met this prediction 

where roosts varied in these attributes over the landscape 

(Trousdale and others 2008). Proximity to adequate foraging 

habitat surrounding a cave also likely contributes to fidelity 

of C. rafinesquii to a cave in Kentucky (Hurst and Lacki 

1999). In contrast, where multiple roosts are concentrated 

within the same forest patch, recurrent roost switching by 

C. rafinesquii and other insectivorous bats involves distances 
34

are often awake (evident by their noise) even prior to 

observation. Differences in dispersion of individuals inside 

cavity chambers suggest each species’ own microclimatic 

preferences within roosts (Rice 2009).

IMPLICATIONS FOR CONSERVATION 

AND MANAGEMENT

The effects of timber extraction on roost selection by 

C. rafinesquii have not been examined. Although selective 

logging could be used to avoid particular cavity-containing 

trees, exposure of roosts to increased solar radiation would 

likely occur due to thinning of the canopy (Carver and Ashley 

2008). This change is potentially important considering that 

basal area in stands surrounding tree roosts may be high 

(Gooding and Langford 2004, Lucas 2009), as is canopy 

closure (Gooding and Langford 2004, Trousdale and Beckett 

2005). Opening up the canopy and midstory, whether by 

mechanical thinning or by fire (in upland areas), could alter 

the microclimate within cavities of relict trees, as well as 

encourage the growth of understory vegetation surrounding the 

entrance to cavities (Carver and Ashley 2008).

In locations where BLHs remain largely intact, I encourage 

managers interested in conserving habitat of C. rafinesquii

to promote survival and recruitment of large (≥ 50-cm 

d.b.h.) trees, especially water tupelo and black tupelo. 

American beech, sweetgum, American sycamore (Platanus

occidentalis), and bald cypress are species of trees that 

should also receive priority due to their propensity to form 

cavities (Stevenson 2008). Where BLHs have been removed 

used by southeastern myotis, but among the smallest used 

by C. rafinesquii (Carver and Ashley 2008). Stevenson 

(2008) noted a similar partitioning of tree roosts, with 

southeastern myotis preferring smaller trees (d.b.h. = 40 

to 70 cm) than C. rafinesquii as solitary roosts, whereas 

overall, C. rafinesquii more frequently roosting in the 

largest cavity-bearing trees (≥ 100 cm d.b.h.) in the study 

area. Overall, C. rafinesquii select trees ≥ 80 cm in d.b.h., 

whereas southeastern myotis use trees at random with regard 

to species and size (Stevenson 2008). In some cases, the 

two species may discriminate between tree roosts based on 

number and type of cavities present. C. rafinesquii tree roosts 

average 1.58 entrances compared to 1.0 opening in roosts of 

southeastern myotis (Carver and Ashley 2008). In Louisiana, 

southeastern myotis roost in hollow trees with basal openings 

exclusively, while C. rafinesquii roost in trees with basal and 

trunk hollows (Rice 2009). 

Further evidence of niche separation between C. rafinesquii

and southeastern myotis comes from observations of their 

roosting habits and behavior. Although the two species both 

use particular trees during summer in western Tennessee, 

they do so on different occasions (Carver and Ashley 

2008). In Mississippi, maternity colonies of C. rafinesquii

and southeastern myotis segregated, occupying different 

individual trees (Stevenson 2008). Investigators have noted 

that groups of C. rafinesquii tend to roost along the sides 

of the chamber and easily awaken, but southeastern myotis 

generally cluster at the “ceiling” and typically appear 

less disturbed by cavity inspections (Carver and Ashley 

2008, Stevenson 2008), although Rice (2009) noted that 

larger aggregations of day-roosting southeastern myotis 

Table 3—Grand means of tree roost characteristics of Corynorhinus rafinesquii and Myotis austroriparius

in the Eastern United States

Bat species Tree height D.b.h. Cavities

Height of 

cavity roosta

Width of cavity 

entrance 

Interior height 

of cavity

m cm no. -------------------------cm------------------------- m

CORA

MYAU

21

 26b

110

 93c

1.3

1.3d

119

103e

49

 39f

6

 7g

D.b.h. = diameter at breast height; CORA = Corynorhinus rafinesquii; MYAU = Myotis austroriparius.

a Largest entrance if multiple cavities.

b n = 2. Carver and Ashley (2008), Gooding and Langford (2004).

c n = 5. Carver and Ashley (2008), Gooding and Langford (2004), Hofmann and others (1999), Rice (2009), Stevenson (2008).

d n = 3. Carver and Ashley (2008), Gooding and Langford (2004), Hofmann and others (1999).

e n = 5. Carver and Ashley (2008), Gooding and Langford (2004), Hofmann and others (1999), Rice (2009), Stevenson (2008).

f n = 5. Carver and Ashley (2008), Gooding and Langford (2004), Hofmann and others (1999), Rice (2009), Stevenson (2008).

g n = 4.Carver and Ashley (2008), Hofmann and others (1999), Rice (2009), Stevenson (2008).
35

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propagate these trees. In floodplains, restoration of a 

hydrologic regime with pulses of inundation to seasonally 

promote hydric/hypoxic soil conditions should especially 

favor tupelo and bald cypress trees over less-desirable 

species. Within a matrix of commercial timber lands, 

streamside management zones or buffer strips adjacent 

to wetland habitats could help fulfill this purpose. As 

reforestation proceeds, deployment of artificial structures 

that mimic natural cavities in configuration and dimensions 

might aid in nurturing local populations of C. rafinesquii 

until suitable trees develop natural cavities for roosting.

CONCLUSIONS

C. rafinesquii roosts in hollow trees possessing cavities 

accessible either by basal entrances or upper bole openings. 

Like other forest-dwelling bats, C. rafinesquii seems to 

prefer tall, live trees with large diameters often situated in 

areas with higher densities of potential tree roosts. In contrast 

to trees occupied by other cavity-roosting bat species of 

North America (Kalcounis-Rüppell and others 2005), those 

of C. rafinesquii are surrounded by closed canopies. The 

apparent fission-fusion behavior of colonies, coupled with 

low daily fidelity shown by individuals and colonies to tree 

roosts highlights the importance of stands surrounding cavity 

trees. Opportunity to enhance thermoregulation may lead C. 

rafinesquii to seek different tree roosts at different times of 

the year and may possibly explain movements by individuals 

in the short term. Based on my review of the literature, 

conservation of tree-roosting C. rafinesquii populations is 

not likely to succeed by merely protecting single-roosting 

structures. Instead, managers will benefit by identifying, 

retaining, and understanding the relationships among 

patches of roosting habitat, consistent with the blueprint for 

successful conservation of diverse tree-roosting bats that 

depend on forests (Brigham 2007).

Effective survey techniques to assess and monitor abundance 

of C. rafinesquii in BLHs and upland mixed pine-hardwood 

systems continue to be developed (Clark 2003, Clement 

and Castleberry 2011). Research should be directed toward 

investigating the interaction of roost density and quality 

with the local abundance of bats. For example, the efficacy 

of artificial roosts to adequately compensate for diminished 

supply of natural structures should be evaluated. The 

extent to which the internal microclimate of a tree cavity 

determines its value as a roost should be measured during 

the reproductive season and winter hibernation period, 

and applied to both solitary individuals and colonies. As 

fragmentation of remaining forests continues, and managed 

lands are expected to provide multiple uses on decreasing 

available acreage, roost selection at larger spatial scales 

should be explored.
36

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39

foraging, (4) review studies that address foraging habitat use 

and aboveground movement, and (5) discuss the implications 

of these findings with respect to conservation needs of these 

bats. Where appropriate, data for Western North American 

species of Corynorhinus are compared, along with findings 

from studies on other plecotine bats.

MORPHOLOGY AND GLEANING

Plecotine bats, including all bats of the genus Corynorhinus,

possess a suite of morphological adaptations that facilitate 

foraging tactics which involve slow-maneuverable flight, 

where prey can be captured in air or from the surface of 

objects. The long ears or pinnae are part of an auditory 

system that is highly sensitive to low-frequency sound, 

including frequencies below those used in echolocation 

(Swift 1998). Coles and others (1989) demonstrated that the 

large pinnae in the brown long-eared bat (Plecotus auritus) 

produce acoustic gains up to 20 dB at frequencies between 

8 and 20 kHz. This enhanced sensitivity at low frequencies 

likely aids in detection of prey moving on substrate surfaces, 

but also permits Corynorhinus species to use low-frequency 

calls (ca. 20 kHz) of low intensity during echolocation 

INTRODUCTION

North American big-eared bats of the genus Corynorhinus

are one of five genera that comprise the plecotine group or 

“long-eared bats” (Koopman and Jones 1970) within the 

family Vespertilionidae. Corynorhinus occupy a specialized 

feeding niche as lepidopteran specialists (Hurst and Lacki 

1997, Lacki and others 2007, Ross 1967), which is facilitated 

by possession of enlarged and elongated pinnae or ears 

(Handley 1959); their use of low intensity echolocation 

calls (Griffin 1958, Grinnell 1963, Obrist and others 1993); 

and their ability to use passive listening to locate stationary 

prey (Fenton 1984). These adaptations along with their 

occurrence in North America, where the number of species 

of bats that glean is fewer than in other regions of the 

northern temperate zone (Swift 1998), allow Corynorhinus

to effectively use both gleaning and aerial hawking foraging 

strategies in the successful capture of moths (Fenton 1990, 

Kunz and Martin 1982). Nevertheless, recent studies have 

added greatly to our understanding of foraging behavior, 

habitat use, and diet of eastern Corynorhinus. In this paper 

we: (1) overview morphological adaptations associated with 

foraging in eastern Corynorhinus, (2) evaluate data from 

dietary studies, (3) describe activity patterns as they relate to 

DIET AND FORAGING BEHAVIOR OF CORYNORHINUS

IN EASTERN NORTH AMERICA

Michael J. Lacki, Professor, University of Kentucky, Department of Forestry, Lexington, KY 40546

Luke E. Dodd, Post-Doctoral Scholar, University of Kentucky, Department of Forestry, 

Lexington, KY 40546

Abstract—Big-eared bats of the genus Corynorhinus occupy a specialized feeding niche due to their possession of 

enlarged and elongated ears and their use of low-intensity echolocation calls. These adaptations, along with passive 

listening to locate moving prey, allow Corynorhinus to effectively use both gleaning and aerial hawking foraging strategies 

in specializing on the capture of moths. A total of 114 species/genera and 11 families of moths are recorded in the diet of 

eastern Corynorhinus, along with 11 other orders of insects. Lepidopteran prey comprises > 80 percent volume of the diet 

of all Corynorhinus species. Noctuidae are the most commonly eaten moths at > 39 percent for eastern Corynorhinus, with 

Geometridae, Notodontidae, Sphingidae, and Arctiidae comprising > 10 percent of the culled wings found beneath feeding 

perches of at least one Corynorhinus species. Average maximum wingspan size for all species eaten is 47.0 mm ± 1.3 (SE), 

and eastern Corynorhinus differentially select by size from among available moth prey within the Geometridae, Noctuidae, 

Sphingidae, Arctiidae, and Saturniidae. Average foraging area size appears to be greater for Rafinesque’s big-eared bats 

(C. rafinesquii) (137.4 ha) than for Ozark big-eared bats (C. townsendii ingens) (71.5 ha) and average maximum flight 

distances are shorter for eastern Corynorhinus (1 to 6.3 km) than western big-eared bats (C. t. pallescens) (14.7 km), which 

occupy pine forests throughout much of Western United States. Edges at the forest-clearing interface and both forested 

and riparian corridors are habitats consistently selected by Corynorhinus when foraging. Nevertheless, edge habitats are 

avoided and riparian habitats preferred by most families of moths eaten by eastern Corynorhinus, suggesting selection of 

foraging habitats by Corynorhinus is predicated on both structural configuration of the habitat, i.e., availability of vertical 

and horizontal surface area for gleaning, and the local abundance of preferred moths. The majority (> 71 percent) of moth 

species eaten by eastern Corynorhinus depend entirely on woody plant hosts for their larval development. Nineteen species 

(16.7 percent) of moths eaten by eastern Corynorhinus are pests in the larval stage, thus, these bats may serve as natural 

controls of pest species in areas where they occur. Long-term conservation of eastern Corynorhinus will require managing 

forested habitat in ways that promote local woody plant diversity, sustaining indirectly the diversity of moth species in 

landscapes where these bats feed.

Citation for proceedings: Loeb, Susan C.; Lacki, Michael J.; Miller, Darren A., eds. 2011. Conservation and management of eastern big-eared bats: 

a symposium. Gen. Tech. Rep. SRS-145. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 157 p.
40

others 2007). Data indicate these bats also feed on 11 other 

orders of insects, including some at > 10 percent frequency 

in the diet such as Coeloptera, Diptera, Homoptera, and 

Blattodea. It is likely that these groups are captured 

opportunistically. Spiders (Araneae) are a prey group used 

as an indicator of gleaning in insectivorous bats (Whitaker 

2004). In Corynorhinus, spiders have only been found in the 

diet of Virginia big-eared bats (C. t. virginianus) and only at 

≤ 0.02 percent volume (Sample and Whitmore 1993), further 

evidence that Corynorhinus bats are lepidopteran specialists. 

Based upon combined data for percent volume and percent 

frequency, it appears that Townsend’s big-eared bat, western 

big-eared bat (C. t. pallescens), and the Virginia big-eared 

bat eat moths more exclusively than do Rafinesque’s bigeared bat and the Ozark big-eared bat (C. t. ingens). The diet 

of the Mexican big-eared bat (C. t. mexicanus) has yet to be 

studied (Tumlison 1992). 

Other members of the plecotine group (Plecotus) do not 

exhibit the same degree of specialization for moths observed 

in Corynorhinus (Swift 1998). For example, Lepidoptera are 

< 41 percent frequency of the diet of brown long-eared bats in 

Scotland (Swift and Racey 1983), Sweden (Rydell 1989), and 

Ireland (Shiel and others 1991). Populations of the grey longeared bat (P. austriacus) in Czech Republic eat lepidopterans 

at only 72 percent frequency of the diet (Bauerova 1982). 

Swift (1998) hypothesized that the degree of specialization 

for moths observed in Corynorhinus, not seen in other 

plecotine species, is a direct result of a lower density of 

gleaning species in North America relative to other temperate 

zone regions, leading to reduced interspecific competition for 

the gleaning foraging niche among North American bats.

Early studies of the diet of Corynorhinus based their findings 

on bats captured or collected during flight, resulting in 

limited data due to difficulty of capture and the tendency for 

these bats to possess empty stomachs (Ross 1967, Whitaker 

and others 1977). Ross (1967) concluded from the limited 

samples obtained that western Corynorhinus ate mostly 

moths and emphasized microlepidopterans (wingspan = 3 to 

10 mm) in their diet. Subsequent studies demonstrated that 

eastern Corynorhinus use feeding roosts, i.e., sites where 

bats perch to eat their prey and discard inedible parts such 

as wings or elytra, especially along cliffs and canyon walls 

(Lacki and LaDeur 2001, Lacki and others 1993). Surveys at 

feeding roosts of eastern Corynorhinus have demonstrated 

consumption of 114 species/genera and 11 families of moths 

by these bats (appendix). Most species of moths recorded in 

the diet of these bats are macrolepidopterans, with an average 

wingspan of 47.0 mm ± 1.3 (SE); much larger than the 6-mm 

average proposed by Ross (1967) for western big-eared 

bats. However, microlepidopterans have also been recovered 

beneath feeding roosts of eastern Corynorhinus including 

Lasiocampidae, Lymantriidae, Megalopygidae, Pyralidae, 

and Thyatiridae.

(Grinnell 1963, Kunz and Martin 1982). Plecotine bats, 

including Corynorhinus, also possess enlarged nostrils which 

are believed to be used in the production of ultrasonic sounds 

(Howard 1995, Swift 1998). Long ears impart constraints 

due to the drag produced in flight that results in higher 

energetic costs (Norberg 1976) especially as flight speeds 

increase (Rayner 1987). Thus, use of low-frequency sounds 

during echolocation combined with a slow agile flight, allow 

Corynorhinus to effectively use their enlarged pinnae in 

locating and capturing prey resting on substrate surfaces, 

while minimizing energetic costs due to drag.

Corynorhinus possess wingspans and wing areas that result 

in relatively low wing loadings [Townsend’s big-eared bat 

(C. townsendii): 0.052 to 0.087 gr/cm2

, Farney and Fleharty 

(1969); Rafinesque’s big-eared bat (C. rafinesquii): 0.057 to 

0.077 gr/cm2, Jones and Suttkus (1971)]. Low wing loadings 

aid in maneuverability in flight, and in the use of hovergleaning to catch prey from surfaces (Norberg and Rayner 

1987). Wing loadings are higher for newly volant young, 

due to smaller wing areas (Jones and Suttkus 1971), and this 

likely hinders flight capability in young bats until the wings 

are fully developed; around 25 days after birth in brown 

long-eared bats (De Fanis and Jones 1995).

Swift (1998) has detailed the advantages of gleaning as 

a foraging strategy. Gleaning bats are not dependent on 

having insect prey actively flying during foraging bouts, 

thus, gleaning bats can feed later in the night and at cooler 

temperatures than bats which rely solely on aerial hawking 

to capture prey. Barclay (1991) demonstrated that gleaning 

bats were able to reproduce successfully in cooler climates 

when aerial-hawking bats did not; he attributed this pattern 

to the ability of gleaning bats to forage successfully on 

more nights and for a longer period of the season than 

aerial-hawking bats. Gleaning also permits larger prey, 

including moths, to be captured and consumed as they do 

not have to be handled or carried in flight (Swift 1998). 

Lacki and others (2007), however, have suggested that even 

among gleaners there appear to be upper limits to the size 

of prey captured and eaten. Moths at rest are especially 

vulnerable to gleaning bats because species that are capable 

of detecting and reacting to bat calls have few options for 

escape when at rest (Werner 1981). Existing data indicate 

that moths have yet to develop adequate defenses against 

gleaning bats (Swift 1998), and because of this gleaning 

bats have been labeled “predatory cheaters” in the evolution 

of bat-moth interactions (Faure and others 1993).

SPECIALIZATION ON LEPIDOPTERA

Lepidopteran prey comprise > 80 percent volume of the diet 

of all Corynorhinus (table 1), consistent with the suggestion 

that Corynorhinus bats are “foraging specialists” (Lacki and 
41

Corynorhinus bats choose species that are smaller than 

average in size (table 3). Conversely, among families of 

smaller sized moths, such as Geometridae (31.6 mm; 

t = 4.65, df = 22, P < 0.01), Noctuidae (41.0 mm; t = 2.53, 

df = 61, P < 0.01), and Arctiidae (40.6 mm; t = 2.84, df = 5, 

P < 0.05), eastern Corynorhinus bats select species that are 

larger in size (table 3). Although sample sizes are small, data 

for microlepidopterans eaten by eastern Corynorhinus also 

indicate a preference for species larger than average in size 

(appendix). Results for Notodontidae were not significant 

(t = 0.97, df = 9, P > 0.1), suggesting moths of this family 

are taken by size in proportion to their availability (table 3).

The importance of size, i.e., wingspan, in the selection of 

moth prey by eastern Corynorhinus has been suggested in 

several studies (Burford and Lacki 1998, Hurst and Lacki 

1997, Lacki and LaDeur 2001). Lacki and LaDeur (2001) 

demonstrated that overall wingspan size of moth prey of 

Rafinesque’s big-eared bat varied little throughout spring, 

summer, and autumn regardless of the mix of species eaten. 

Burford and Lacki (1998) were the first to suggest that 

Corynorhinus bats differentially select among moths by size 

within families, although their conclusion that smaller than 

average species of Noctuidae are eaten was not supported by 

our analyses (table 3). Nevertheless, average wingspan size 

of moth prey appears similar for all eastern Corynorhinus

Noctuidae are the most commonly eaten moths at > 39 percent 

of culled wings recovered for all eastern Corynorhinus, 

with Geometridae, Notodontidae, Sphingidae, and Arctiidae 

comprising > 10 percent of the culled wings found beneath 

feeding perches of at least one eastern Corynorhinus species 

(table 2). More species of Noctuidae (n = 62) have been 

recorded in the diet of eastern Corynorhinus than any other 

moth family, followed by Geometridae (n = 23), Notodontidae 

(n = 10), and Arctiidae (n = 6, appendix). This is consistent 

with data for other plecotine species, e.g., Plecotus, 

demonstrating the importance of noctuid moths in the diet 

relative to other moth families (Robinson 1990, Thompson 

1982, Walhovd and Hoegh-Guildberg 1984). 

We compared average wingspan size for all species of 

moths eaten by eastern Corynorhinus to values presented 

in Covell (1984) for species of moths available in Eastern 

North America. We generated grand means for wingspan 

size for individual families of moths (table 3), and tested 

these values against the averages for species eaten in these 

families using t-tests for single population means (Daniel 

1974). Within families of moths, eastern Corynorhinus bats 

differentially select by size from among available moth 

prey. Among families of larger sized moths, Sphingidae 

(88.5-mm wingspan; t = 5.93, df = 4, P < 0.01) and 

Saturniidae (98.2 mm; t = 3.8, df = 1, P < 0.1), eastern 

Table 1—Average percent volume and percent frequency of insect orders in the diet of Corynorhinus

C. rafinesquii C. t. virginianus C. t. ingens C. townsendiia

Order % v % f % v % f % v % f % v % f

Lepidoptera 80.4 89.2 96.4 99.3 85.2 66.5 99.7 96.0

Coleoptera 2.6 41.8 1.8 35.2 3.4 18.9 — 2.6

Diptera 16.6 38.4 1.0 13.6 3.7 6.5 — 1.3

Hymenoptera trb 3.8 0.9 6.2 1.5 1.3 — 1.3

Neuroptera — — tr 0.4 0.1 0.8 — 1.3

Orthoptera — — — 1.4 — 0.1 — 1.3

Homoptera 0.2 14.0 0.1 — 1.7 2.2 — —

Hemiptera tr 5.8 tr 0.6 — — 0.3 3.4

Trichoptera tr 1.4 — — 0.3 1.0 — —

Odonata — — — — — 0.2 — —

Plecoptera — — tr — — — — —

Blattodea — — — — — 13.4 — —

% v = percent volume; % f = percent frequency; — = not found in samples.

a

 Includes data for C. t. townsendii and C. t. pallescens.

b

 Trace amounts. 

Source: Bauer (1992), Dalton and others (1986), Dodd and Lacki (2007), Ellis (1993), Hurst and Lacki (1997), Leslie and Clark 

(2002), Ross (1967), Sample and Whitmore (1993), Whitaker and others (1977). 
42

with overall wingspan size of moths eaten ranging from 14 to 

178 mm.

ACTIVITY AND FORAGING BEHAVIOR

Corynorhinus bats are late flyers, emerging from roosts after 

dark to feed (Barbour and Davis 1969). Typically, they circle 

[Ozark big-eared bat = 48.0 mm (Dodd and Lacki 2007), 

Rafinesque’s big-eared bat = 45.4 mm (Hurst and Lacki 

1997), Virginia big-eared bat = 47.0 mm (Burford and Lacki 

1998)], suggesting that upper and lower limits to prey size 

may be governed by the ability of these bats to optimally 

capture and handle individual moths (Lacki and others 2007). 

Evidence presented here suggests that the average wingspan 

size for moth prey has an approximate range of 40 to 65 mm, 

Table 2—Relative abundance and number of species of families of moths eaten by eastern Corynorhinus 

C. rafinesquii C. t. virginianus C. t. ingens

Moth family Total Species Total Species Total Species

% n % n % n

Arctiidae 12.1 3 3.8 3 4.8 3

Geometridae 24.2 8 20.2 14 15.9 9

Lasiocampidae — — 1.6 1

Megalopygidae 3.0 1 — —

Lymantriidae — 1.3 1 —

Noctuidae 39.4 11 54.4 43 54.0 27

Notodontidae 9.1 1 11.4 6 11.1 6

Pyralidae — — 3.2 2

Saturniidae — — 3.2 2

Sphingidae 12.1 3 7.6 5 6.3 2

Thyatiridae — 1.3 1 —

— = not found in samples.

Source: Burford and Lacki (1998), Dalton and others (1989), Dodd and Lacki (2007), Hurst and Lacki (1997), Lacki and LaDeur 

(2001), Sample and Whitmore (1993).

Table 3—Average wingspans for families of moths in Eastern North America compared with average 

wingspans of families of moths eaten by eastern Corynorhinus

Available species Moth species eaten

Wingspan (mm) Wingspan (mm)

Moth family Mean SE Mean SE P-value

Arctiidae 40.6 1.6 61.8 7.5 < 0.05

Geometridae 31.6 0.6 41.7 2.2 < 0.01

Noctuidae 41.0 0.7 45.3 1.7 < 0.01

Notodontidae 46.8 1.3 49.1 2.4 NS

Saturniidae 98.2 7.7 73.5 6.5 < 0.1

Sphingidae 88.5 3.6 68.4 3.4 < 0.01

SE = standard error; NS = [not sampled].

Source: Burford and Lacki (1998), Covell (1984), Dalton and others (1989), Dodd and Lacki (2007), Hurst and Lacki (1997), Lacki 

and LaDeur (2001), Sample and Whitmore (1993).
43

and along cliffs and canyon walls (Adam and others 1994a, 

Caire and others 1984). These behaviors are consistent 

with bats that glean insects from the surface of objects and, 

thus, rely on the structural configuration of the habitat, i.e., 

availability of vertical and horizontal surface area, when 

capturing prey. These bats are also known to fly close to 

ground level, especially over the vegetation of open fields 

and agricultural areas (Clark 1991, Dalton and others 

1989); this behavior is believed to be the explanation for the 

presence of male tabanid flies in the diet of Rafinesque’s bigeared bat (Ellis 1993). When flying over open areas, Virginia 

big-eared bats exhibit horizontal sweeps of up to 6 m, with 

vertical flights approximately 0.6 to 1.0 m above the surface 

of vegetation (Dalton and others 1989). This behavior is 

often interrupted with deeper vertical drops of 2 to 30 m as 

bats shift back and forth between the surface of clearings and 

the edge of forest canopies (Dalton and others 1989, Fellers 

and Pierson 2002). 

FORAGING AREAS

Average size of foraging areas of Corynorhinus reported in 

the literature range from 10 to 262.8 ha (table 4), suggesting 

that there likely is substantial variation in the amount of area 

used for foraging among seasons and sex and reproductive 

condition of individual bats. Average foraging area size 

appears to be greatest for Rafinesque’s big-eared bat 

(137.4 ha) and least for Ozark big-eared bat (71.5 ha). Length 

of maximum flight distance does not appear to be linked 

to size of foraging areas among species; however, average 

maximum flight distances are shorter for eastern (1 to 6.3 km) 

than western big-eared bats (14.7 km), which are widespread 

inside roosts for up to 30 minutes before sunset (Clark and 

others 1993), often “light sampling” or briefly emerging and 

reentering during this preemergence phase. Bats then begin 

exiting roosts approximately 26 to 60 minutes after dark 

(Clark and others 1993, 2002; Dobkin and others 1995). 

Emergence of Ozark big-eared bats is not impeded by light 

to moderate rainfall (Clark and others 2002). Corynorhinus

exhibit a bimodal pattern of activity in spring and early 

summer (Cockrum and Cross 1964, Pierson and others 1991) 

that shifts to a trimodal pattern during lactation (Clark and 

others 1993, Lacki and others 1994). During postlactation, 

the frequency of foraging bouts declines and bats do not 

reenter roosts until sunrise in late summer and early autumn 

(Clark and others 1993, Lacki and others 1994). Level 

of flight activity in Virginia big-eared bats is negatively 

associated with moon phase and wind speed, and directly 

related to percent relative humidity (Adam and others 

1994b); the authors postulate that these bats reduce activity 

at low humidity to avoid extreme vapor pressure deficits and 

subsequent dehydration due to water loss.

Flight behavior in Corynorhinus has been observed 

directly using light tagging (Caire and others 1984, Clark 

1991, Dalton and others 1989, Fellers and Pierson 2002), 

or inferred indirectly due to the composition of the diet 

(Ellis 1993), or behavior of radiotagged bats (Adam and 

others 1994a, Clark and others 1993, Hurst and Lacki 

1999). Corynorhinus has been observed foraging along 

the perimeter of tree canopies (Dalton and others 1989, 

Fellers and Pierson 2002, Hurst and Lacki 1999), the edges 

of forests (Clark and others 1993, Dalton and others 1989, 

Fellers and Pierson 2002), traveling in and out of riparian 

corridors (Caire and others 1984, Fellers and Pierson 2002), 

Table 4—Average size and ranges of foraging areas and maximum flight 

distances of Corynorhinus

Species Foraging area sizea Maximum flight distance 

ha km

C. rafinesquii 137.4 (93.1–165) 1.1 (1–1.2)

C. t. virginianus 113.1 (24.6–262.8) 6.3 (3.6–8.4)

C. t. ingens 71.5 (10–156.9) 3.2 (0.8–5.5)

C. t. pallescens — 14.7 (8–24)

C. t. townsendii — 2.25 (1.3–3.2)

— = no data.

a Methods for calculating foraging areas varied among sources and include 100 and 95 percent 

polygons, calculated using kernel estimators or minimum convex polygons.

Source: Adam and others (1994a), Clark and others (1993), Dobkin and others (1995), England 

and Saugey (1998), Fellers and Pierson (2002), Hurst and Lacki (1999), Menzel and others 

(2001), Saugey (2000), Stihler (unpublished data), and Wethington and others (1996). 
44

with the opposite observed for Virginia big-eared bats (Adam 

and others 1994a). Results for Ozark big-eared bats are 

inconclusive, as length of flight distances were reported to 

be greater for males (Wilhide and others 1998), while no 

difference was observed between the sexes by Wethington 

and others (1996). Flight distances of reproductively active 

female Ozark big-eared bats increased from lactation to 

postlactation, with individual Ozark big-eared bats using 

up to four foraging sites during 10-day tracking periods 

(Clark and others 1993). Flight distances of female Ozark 

big-eared bats declined in length during the prehibernation 

phase in late autumn (Wethington and others 1996). There 

appears to be no difference in length of flight distances or 

size of foraging areas between male and female Rafinesque’s 

big-eared bats, although published data are limited (Hurst 

and Lacki 1999, Menzel and others 2001). Size of foraging 

areas also was not different between male and female Ozark 

big-eared bats (Wethington and others 1996) and Virginia 

big-eared bats (Adam and others 1994a), respectively.

HABITAT USE

Considerable variation exists in use of foraging habitat 

among Corynorhinus (table 6). Much of the variation is 

attributable to differences in habitat associations, i.e., what 

habitats are actually available to the bats in the region where 

they occur. For example, Virginia big-eared bats and Ozark 

big-eared bats occur in upland hardwoods, especially those in 

proximity to cliffs and rocky bluffs (Adam and others 1994a, 

Clark and others 1993). Nevertheless, their use of mature 

versus successional forested habitats varies across locations 

(table 6). In turn, western big-eared bats and Townsend’s bigeared bats are largely found in pine forests. Rafinesque’s bigeared bats appear to be a forest habitat generalist relative to 

the other Corynorhinus species, as these bats inhabit upland 

throughout coniferous forests in Western United States. The 

longer flight distances of western big-eared bats appear to be 

associated with their occupation of drier forests (Dobkin and 

others 1995, Pierson and others 1999), where xeric conditions 

likely result in sporadic sources of water and less frequent and 

predictable patches of prey. This is supported by behavior of 

Townsend’s big-eared bats inhabiting wet coastal forests in 

California, where maximum flight distances were similar to 

those of eastern Corynorhinus species and did not exceed 3.2 

km (Fellers and Pierson 2002).

Size of foraging areas of Corynorhinus appears surprisingly 

consistent across hardwood forests, mixed (forest/

agriculture) habitats, or pine forests (ca. 97.5 ha), although 

data for bats inhabiting pine forests are limited due to the 

lack of information on western subspecies of Corynorhinus

(table 5). Nevertheless, maximum flight distances are 

greater for Corynorhinus in pine forests than hardwood 

forests or mixed habitats due to the extreme values reported 

for western big-eared bats (Dobkin and others 1995). It is 

generally accepted that other plecotine bats, particularly 

Plecotus species, forage close to their roosts (Swift 1998), 

with maximum flight distances of 1.1 km (Swift and Racey 

1983) and 3.3 km (Fuhrmann and Seitz 1992). These values 

are comparable in length to those of Corynorhinus in Eastern 

North America.

Behavioral differences in foraging between the sexes is less 

clear for Corynorhinus because few studies have tracked 

both males and females simultaneously, and most studies 

that have tagged both sexes have tagged far fewer males 

than females (Adam and others 1994a, Dobkin and others 

1995, Fellers and Pierson 2002, Wethington and others 

1996). Available data indicate that females travel further 

distances than males in Townsend’s and western big-eared 

bats (Dobkin and others 1995, Fellers and Pierson 2002), 

Table 5—Average size and ranges of foraging areas and maximum flight distances of 

Corynorhinus by forested habitat

Forested habitat Foraging area sizea Maximum flight distance 

ha km

Upland hardwoods 95.4 (10–262.8) 3.0 (0.5–8.4) 

Mixed (upland hardwoods/agriculture) 104.1 (65.5–156.9) 4.3 (2–7)

Pine 93.1 (—) 9.7 (1.3–24)

— = no data.

a

 Methods for calculating foraging areas varied among sources and include 100 and 95 percent polygons, 

calculated using kernel estimators or minimum convex polygons.

Source: Adam and others (1994a), Clark and others (1993), Dobkin and others (1995), England and Saugey 

(1998), Fellers and Pierson (2002), Hurst and Lacki (1999), Menzel and others (2001), Saugey (2000), 

Stihler (unpublished data), Wethington and others (1996). 
45

Dodd and others (2008) found many families were positively 

associated with riparian and upland forest, with forested 

edges, sapling stands, and pastures typically avoided or used 

at random. The avoidance of forested edges and open areas, 

combined with the preference for riparian habitats by moth 

families commonly eaten by Corynorhinus, suggests an 

intriguing interplay between moths and Corynorhinus. An 

overriding pattern is a preference by Corynorhinus for abrupt 

changes in vertical structure, such as along forested and 

riparian corridors and forest/edge interfaces (table 6). The 

vertical surfaces possibly help Corynorhinus in capturing 

stationary moth prey. Regardless, because most of these 

same habitats are avoided by families of moths eaten by 

Corynorhinus (table 7), we suggest these data further support 

the idea that use of foraging habitats by Corynorhinus

is predicated on structural configuration of the habitat, 

i.e., availability of vertical and horizontal surface area for 

gleaning, as much as on the local abundance of preferred 

moth prey.

hardwoods, pine forests, and bottomland hardwood forests. 

Presently, only one study exists on use of foraging habitats 

by Rafinesque’s big-eared bats in bottomland forests (Medlin 

and Risch 2008). Data for plecotine bats demonstrate the 

importance of flyways, i.e., linear landscape elements, 

during flight, including fence lines, streambanks, and railway 

lines (Swift 1998). Swift (1998) hypothesized that flyways 

are used as navigational cues and for avoidance of aerial 

predators, and it is likely these same explanations apply 

to Corynorhinus. Flyways are used repeatedly throughout 

summer, with flight speeds often exceeding those used in 

foraging flight (Barataud 1990, Howard 1995). 

Habitat affinities of families of moths eaten by Corynorhinus

demonstrate variability between studies and geographic 

locations (table 7). Burford and others (1999) captured 

the majority of moths in mature timber and found several 

families avoid clearings or open habitats, including 

Limacodidae, Geometridae, Notodontidae, and Arctiidae. 

Table 6—Habitats preferred, used at random, and avoided by Corynorhinus

Habitats

Species MUHW SUHW BHW MPINE SPINE OPEN CORR EDGE AQUATIC 

C. rafinesquii P, R R A A P R P, A — R, A

C. t. virginianus P, A A — — — P, A P, A P — 

C. t. ingens P, A — — — — R P P, R —

C. t. pallescens — — — P A P P P —

C. t. townsendii — — — — — A P P —

— = no data; MUHW = mature upland hardwood; SUHW = successional upland hardwood; BHW = bottomland hardwood; MPINE = mature 

pine; SPINE = successional pine; OPEN = open (old fields, croplands, etc.); CORR = corridor (forested and riverine corridors); 

EDGE = edge (forest/field, scrub or clearcut interface); AQUATIC = aquatic (open water); P = preferred; R = random; A = avoided.

Source: Adam and others (1994a), Burford and Lacki (1995), Caire and others (1984), Clark and others (1993), Dalton and others 

(1989), Dobkin and others (1995), Fellers and Pierson (2002), Hurst and Lacki (1999), Leslie and Clark (2002), Medlin and Risch 

(2008), Menzel and others (2001), Wethington and others (1996), Wilhide and others (1998). 

Table 7—Habitats preferred, used at random, and avoided by families of moths eaten by Corynorhinus 

Habitats

Family Sawtimber Poletimber Open areasa Forested edge Riparian

Arctiidae P P A A P

Geometridae P, A P, R R, A A P

Noctuidae R, A R R A P

Notodontidae P, R P, R A A R

P = preferred; R = random; A = avoided.

a

 Includes old fields and clearcuts.

Source: Burford and others (1999), Dodd and others (2008).
46

for their thoughtful comments and suggestions. This is a 

project of the Kentucky Agricultural Experiment Station 

(KAES No. 09-09-080) and is published with the approval 

of the director. 

LITERATURE CITED

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of environmental conditions on flight activity of Plecotus

townsendii virginianus (Chiroptera: Vespertilionidae). 

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Barataud, M. 1990. Eléments sur le comportement alimentaire des 

Oreillards brun et gris, Plecotus auritus (Linnaeus, 1758) et 

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Bauer, E.D. 1992. The summer food habits of a bachelor colony of 

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CONCLUSIONS

The foraging behavior of eastern Corynorhinus is 

inextricably linked to their life history strategy which 

emphasizes moths in the diet (Lacki and others 2007). 

This specialization is accompanied by morphological and 

behavioral adaptations that allow these bats to preferentially 

capture and eat moths, using both gleaning and aerial 

hawking strategies, while foraging in habitats with substrate 

conditions conducive to a gleaning foraging behavior 

(Fenton 1984, Griffin 1958, Grinnell 1963, Handley 

1959, Obrist and others 1993). Regardless of where or 

how eastern Corynorhinus bats locate food, the majority 

(> 71 percent) of moth species eaten depends entirely on 

woody plant hosts for their larval development (appendix). 

Sustaining landscapes with sufficient acreage in forest, while 

providing for corridors and other forest/edge interfaces, 

will be important in the long-term conservation of eastern 

Corynorhinus (Burford and others 1999, Dodd and others 

2008). What constitutes “sufficient” acreage of forested 

habitat, however, remains to be determined. Lepidopteran 

diversity appears to be resilient to moderate levels of timber 

harvesting in temperate zone forests, but requires a diversity 

and abundance of local plant species (Summerville and 

Crist 2002, 2003). Therefore, management of habitats for 

Corynorhinus should promote woody plant diversity to help 

ensure the prey base needed to sustain these bats (Burford 

and others 1999, Dodd and others 2008). Big-eared bats are 

usually not abundant numerically and are not likely to be a 

major factor in regulating insect populations. Regardless, 19 

species (16.7 percent of total) of moths known to be eaten by 

eastern Corynorhinus are pests in the larval stage, so these 

bats do serve as one of several natural controls of insect 

pests. Further, because they specialize on moth prey, their 

ability to affect the numbers of lepidopteran pest species 

in an area may be underappreciated and warrants further 

study. We suggest that long-term conservation of eastern 

Corynorhinus will require managing forest habitat in ways 

that promote local woody plant diversity to help sustain moth 

diversity. 

ACKNOWLEDGMENTS

The lead author is grateful to the sponsors who contributed 

and supported his research program on Corynorhinus

over the past 20 years including the U.S. Forest Service, 

U.S. Fish and Wildlife Service, Kentucky Department of 

Fish and Wildlife Resources, Arkansas Game and Fish 

Commission, East Kentucky Power, Natural Bridge State 

Park, and Kentucky State Nature Preserves Commission. 

The authors thank D. Saugey for providing unpublished 

data on Corynorhinus. Support for preparation of this 

manuscript was provided by the University of Kentucky, 

College of Agriculture. We thank the anonymous reviewers 
47

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49

Appendix—List of moth species eaten by Corynorhinus in Eastern North America

Family/species CR CTV CTI Larval habitat Wingspana

mm

Arctiidae

Apantesis sp. x Field 42

Ecpantheria scribonia x x Field/For 91

Estigmene acreab x Field 68

Grammia virgo x Field 70

Halysidota tessellaris x x x For 45

Haploa sp. x For 55

Geometridae

Anticlea multiferata x Field 25

Campaea perlata x x For 51

Dichorda iridaria x Field 30

Ectropis crepuscularia x For 37

Epimecis hortaria x x x For 55

Euchlaena amoenaria x Unknown 49

E. irraria x For 48

E. pectinaria x x For 46

E. tigrinaria x For 41

Eusarca confusaria x Field 41

Eutrapela clemataria x x For 56

Hydria prunivorata x For 35

Hypagyrtis unipunctata x For 47

Itame pustularia b x For 27

Melanolophia canadaria x For 36

Nacophora quernaria x For 56

Patalene olyzonaria x For 21

Plagodis fervidaria x For 31

Probole nyssaria x x For 35

Prochoerodes transversatab x For 50

Selenia kentaria x x For 52

Tetracis cachexiata x x For 50

Xanthotype urticaria x Field/For 40

Lasiocampidae

Malacosoma americanumb x For 44

Lymantriidae

Dasychira basiflava x For 54

continued
50

Appendix—List of moth species eaten by Corynorhinus in Eastern North America 

(continued)

Family/species CR CTV CTI Larval habitat Wingspana

mm

Megalopygidae

Lagoa crispata x For 40

Noctuidae

Abagrotis alternatab x x x For 42

Acronicta americana x x For 65

A. innotata x For 40

A. lobeliae x For 60

A. radcliffei x For 38

A. spinigera x For 48

Agrotis ipsilonb x x Field 51

Allagrapha aerea x Field 42

Allotria elonympha x For 45

Amphipyra pyramidoides x x For 52

Argyrogrammia basigera x Unknown 33

Autographa biloba x Field 40

Caenurgina erechteab x Field 42

Callopistria cordata x For 28

Catocala epione x For 65

C. ilia x For 82

C. neogama x For 85

C. paleogama x For 70

C. vidua x For 85

Chaetaglaea sericea x For 45

Chytonix palliatricula x Field 33

Cosmia calami x For 34

Crocigrapha normani x For 40

Euparthenos nubilis x x For 70

Euplexia benesimilis x Field 36

Eupsilia sp. x Field/For 40

Euxoa bostoniensisb x Field 45

E. immixta x Unknown 40

Heliothis zeab x Field 45

Hypsoropha hormos x For 34

H. monilis x For 42

Lacinipolia renigerab x x Field 30

Leucania multilinea x Field 50

continued
51

Appendix—List of moth species eaten by Corynorhinus in Eastern North America 

(continued)

Family/species CR CTV CTI Larval habitat Wingspana

mm

Lithophane antennatab x For 42

L. hemina x For 38

Metalectra discalis x Unknown 29

Metaxaglaea semitaria x For 54

Oligia modica x Unknown 32

Orthodes cynica x Field 34

Orthosia alurina x For 40

O. hibiscib x For 42

O. rubescens x For 40

Paectes pygmaea x For 23

Panopoda carneicosta x For 46

P. rufimargo x x x For 46

Panthea furcilla x For 50

Parallelia bistriarisb x x For 43

Peridroma sauciab x Field 52

Platysenta sutor x Field 38

Polia latex x For 51

P. purpurissata x For 55

Protolampra brunneicollis x Field 43

Pseudaletia unipunctab x x x Field 47

Pseudorthodes vecors x Field 35

Renia fraternalis x For 25

Scolecocampa liburna x x For 43

Scoliopteryx libatrix x For 45

Spaelotis clandestinab x Field/For 43

Xestia dolosab x Field 46

Zale bethunei x For 40

Z. lunata x For 55

Zanclognatha sp. x For 35

Notodontidae

Datana angusii x For 48

Heterocampa guttivitta x For 45

H. umbrata x For 62

Lochmaeus bilineata x For 40

L. manteob x x For 50

Nadata gibbosa x x x For 59

continued
52

Appendix—List of moth species eaten by Corynorhinus in Eastern North America 

(continued)

Family/species CR CTV CTI Larval habitat Wingspana

mm

Notodontidae (continued)

Nerice bidentata x For 40

Peridea angulosa x For 55

Schizura sp. x For 47

Symmerista albifrons x For 45

Pyralidae

Blepharomastix ranalis x Field 20

Pantographa limatab x For 37

Saturniidae

Automeris io x For 80

Sphingicampa bicolor x For 67

Sphingidae

Darapsa myron x x x For 65

D. pholus x x For 75

Deidamia inscripta x x For 70

Laothoe juglandis x x For 75

Lapara coniferarum x For 57

Thyatiridae

Euthyatira pudens x For 46

CR = Corynorhinus rafinesquii; CTV = C. townsendii virginianus; CTI = C. t. ingens.

a Source: Covell (1984).

b Denotes pest species in the larval stage.
53

44(232): 69206-69208) due to restricted ranges; dependence 

on few caves; overutilization, e.g., intentional killing and 

scientific study/collection; and inadequacy of existing 

regulations. Additionally, recent genetic evidence suggests 

that the disjunct VBEB populations should be considered 

evolutionary significant units (ESUs; Piaggio and others 

2009, U.S. Fish and Wildlife Service 2008b). 

Rafinesque’s big-eared bat has a broader distribution than 

either eastern Townsend’s subspecies, occurring across 

the Southeastern United States, bordered to the north by 

Kentucky and West Virginia, southeastern Missouri and 

southeast Virginia, as far south as most of Florida, and west 

into eastern Texas (Bayless and others 2011, Whitaker and 

Hamilton 1998). However, even with this broad distribution, 

this species is designated as a species of concern by the U.S. 

Fish and Wildlife Service [http://ecos.fws.gov/speciesProfile/

profile/speciesProfile.action?spcode=A0AI#status (Date 

accessed: January 25, 2010)] and has some type of listing 

status in almost every State in which it occurs (Bayless and 

others 2011). The primary reason for status as species of 

INTRODUCTION

Two species of big-eared bats [Corynorhinus (formerly 

Plecotus) spp.] occur in the Eastern United States: 

Rafinesque’s big-eared bat (C. rafinesquii; RBEB) and 

Townsend’s big-eared bat (C. townsendii) (Whitaker and 

Hamilton 1998). There are two recognized subspecies 

of Townsend’s big-eared bats in the region—the Ozark 

big-eared bat (C. t. ingens; OBEB) (Sealander and Heidt 

1990) and the Virginia big-eared bat (C. t. virginianus; 

VBEB) (Whitaker and Hamilton 1998). Both Townsend’s 

subspecies have restricted ranges with the OBEBs occurring 

only in northwestern and northcentral Arkansas; southwest 

Missouri [but not observed there since 1971 (U.S. Fish and 

Wildlife Service 2008a), but see Elliott and others 1999]; 

and eastern Oklahoma (Sealander and Heidt 1990) and the 

VBEBs only occurring in five disjunct areas (two in West 

Virginia and one each in Virginia, North Carolina, and 

Kentucky) (U.S. Fish and Wildlife Service 2008b). Both 

OBEBs and VBEBs were listed as federally endangered by 

the U.S. Fish and Wildlife Service in 1979 (Federal Register 

CONSERVATION AND MANAGEMENT OF EASTERN BIG-EARED BATS 

(CORYNORHINUS SPP.)

Darren A. Miller, Southern Environmental Research Manager, Southern Timberlands Technology, 

Weyerhaeuser NR Company, P.O. Box 2288, Columbus, MS 39704

Craig W. Stihler, Wildlife Biologist, West Virginia Division of Natural Resources, 

P.O. Box 67, Elkins, WV 26241

D. Blake Sasse, Nongame Mammal Program Coordinator, Arkansas Game 

and Fish Commission, 213A Highway 89 South, Mayflower, AR 72106

Rick Reynolds, Wildlife Biologist, Virginia Department of Game and Inland Fisheries, 

4010 West Broad Street, Richmond, VA 23230

Paul Van Deusen, Principal Research Scientist, National Council for Air 

and Stream Improvement, 600 Suffolk Street, Lowell, MA 01854

Steven B. Castleberry, Professor, University of Georgia, Daniel B. Warnell School of Forestry 

and Natural Resources, Athens, GA 30602

Abstract—There are two species of big-eared bats in the Eastern United States, Rafinesque’s big-eared bat (RBEB) 

(Corynorhinus rafinesquii) and Townsend’s big-eared bat (C. townsendii). The two eastern subspecies of C. townsendii

[Ozark big-eared bat (OBEB) (C. t. ingens) and Virginia big-eared bat (VBEB) (C. t. virginianus)] are listed as federally 

endangered and C. rafinesquii is both a Federal species of concern and State-listed in many States where it occurs. These 

bats occur across a broad geographic area encompassing different ecoregions and forest associations. Current primary 

threats for RBEBs include habitat loss, primarily due to urbanization, and loss of natural and manmade roosts. Current 

primary threats for OBEBs and VBEBs include small population sizes, limited cave/karst areas, wind energy development, 

and potential reduction of food resources/foraging areas. White-nose syndrome (WNS) is a potential threat to all three 

big-eared bats but most immediately concerns OBEB and VBEB populations. Conservation actions for OBEBs and 

VBEBs include protection of caves, e.g., reduction of disturbance, developing responses to WNS, and identifying new 

summer caves and hibernacula. For RBEBs, habitat conservation, protection of caves, provisioning of artificial roosts, 

and protection of existing manmade roosts appear key. A large amount of potential RBEB habitat occurs on private lands 

and bat conservation efforts need to involve private landowners, who own 87 percent of forested lands in the Southeastern 

United States. A lack of research is a conservation need as, in many cases, critical data are lacking for making informed 

management decisions.

Citation for proceedings: Loeb, Susan C.; Lacki, Michael J.; Miller, Darren A., eds. 2011. Conservation and management of eastern big-eared bats: 

a symposium. Gen. Tech. Rep. SRS-145. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 157 p.
54

and Federal Agencies.1 However, effects of widespread 

deforestation, extensive drainage, and channelization make 

ecological restoration of these systems difficult. 

The largest threat to future forest cover in the Southeastern 

United States is urbanization (National Commission on 

Science for Sustainable Forestry 2005, Smith and others 

2009, Wear and Greis 2002). Between 1992 and 2040, an 

estimated 12.5 million ha of forest land in the region could 

be lost to urbanization (Wear and Greis 2002). In spite of 

this threat, Wear and Greis (2002) projected that gains in 

forest cover will be made primarily through conversion of 

agricultural lands to forests (4 million ha between 1992 

and 2020 and an additional 6 million ha afforested between 

2020 and 2040). Areas of largest potential gain in forest 

cover appear to be in the lower Gulf Coastal Plain, including 

large areas of Arkansas, Mississippi, and Louisiana with no 

projected net loss in total forest cover and current annual 

forest growth exceeding removals by 70 percent (Smith 

and others 2009). However, trends within forest types are 

expected to vary. Although Wear and Greis (2002) predicted 

acreage of planted pine (Pinus spp.) to increase between 1995 

and 2040, more recent analyses, based on market conditions, 

suggest acreage of plantations (22 percent of all forests are of 

planted origin; Smith and others 2009) may remain relatively 

unchanged (National Commission on Science for Sustainable 

Forestry 2005, Smith and others 2009). Regardless, slight 

declines in acreage of natural pine, mixed oak-pine, upland 

hardwoods, and bottomland hardwoods are expected during 

1995 to 2040 (Wear and Greis 2002).

Although only slight declines in acreage of bottomland 

hardwood forests are projected through 2040, structure of 

these forests may not currently be suitable for RBEBs, which 

appear to require specific, older aged portions of bottomland 

hardwood forests for roosting (Whitaker and Hamilton 

1998). Within the bottomland forest type, most roosts occur 

in large [> 50 cm diameter at breast height (d.b.h.)] water 

tupelo (Nyssa aquatica), with other tree species, such as bald 

cypress (Taxodium distichum), red maple (Acer rubrum), 

and oaks (Quercus spp.) comprising a small percentage 

of roosts (Gooding and Langford 2004, Lance and others 

2001, Trousdale and Beckett 2005). Although RBEBs 

routinely roost in manmade structures such as bridges and 

culverts (Bennett and others 2008, Lance and others 2001, 

Trousdale and Beckett 2004); abandoned buildings (Clark 

1990, England and others 1990, Menzel and others 2001, 

Mirowsky and others 2004); and artificial roost structures,2

1

 Personal communication. 2010. Kevin Nelms, Wildlife Biologist, National 

Resource Conservation Service, 517 Brentwood Avenue, Greenwood, MS 

38930.

2

 Personal communication. 2010. Mylea Bayless, Biologist, Bat 

Conservation International, 500 N. Capital of Texas Highway, Building 1, 

Suite 200, Austin, TX 78746.

conservation concern is perceived population declines and 

loss of habitat (Arroyo-Cabrales and Castenada 2008).

Given the conservation needs of these species, it is 

imperative to understand current and potential conservation 

actions that may be used to help conserve these species. 

Additionally, emerging threats, such as white-nose syndrome 

(WNS), will require an understanding of conservation issues 

so these needs can be considered as new challenges arise. To 

date, however, we are unaware of any efforts to collectively 

discuss conservation challenges and solutions for eastern 

big-eared bats. Therefore, our objectives were to (1) examine 

the current threats facing these three taxa, (2) review past 

and current efforts to conserve these species, and (3) identify 

research needs relative to management and conservation of 

these species.

CONCERNS AND THREATS

Changes in Forest Cover and Structure

Although VBEBs and OBEBs appear to be habitat 

generalists relative to foraging (Dalton and others 1989, 

Stihler 2011a, Wethington and others 1996) and are strongly 

affiliated with karst and other rock features used for roosting 

and hibernation, bats are obviously impacted by trends in 

forest cover, which also may be an indicator of ecosystem 

health. Additionally, RBEBs are strongly associated with 

bottomland hardwood forests throughout the Coastal Plain 

(Clark 1990, Gooding and Langford 2004, Lance and others 

2001, Mirowsky and others 2004, Trousdale and Beckett 

2005) and to other forest types in karst areas (e.g., Hurst 

and Lacki 1999) where this species roosts in caves. Within 

Coastal Plain populations of RBEBs, forest trends are 

particularly important because habitat loss and adequacy 

(type and abundance) of roost sites are the greatest perceived 

threats for this species (Arroyo-Cabrales and Castaneda 

2008). Finally, it is important to understand the projected 

landscape context within the geographic range of these 

species to help frame conservation needs. 

Overall, area of forest land remained relatively stable in the 

Southeastern United States during the early 1900s to 2007 

(Smith and others 2009) with upland hardwoods increasing 

in acreage between 1953 and 1999 (Wear and Greis 2002). 

Although the area of bottomland hardwood forests in the 

Southeastern United States declined over 80 percent since 

pre-European settlement primarily due to conversion to 

agriculture (Wear and Greis 2002), during 1970 to 1992 area 

of this forest type remained essentially stable (Wear and Greis 

2002). Restoration of former bottomland hardwood forests 

through afforestation, particularly in the lower Mississippi 

Alluvial Valley, has been a focus among private landowners 
55

Associated with urbanization is an increase in human 

population, which is of particular concern for OBEBs as 

much of the area inhabited by this species has experienced 

rapid population growth in the last few decades. During 

1990 to 2000, human population increased by 14, 25, 39, 

and 59 percent in the four counties of eastern Oklahoma 

and northwestern Arkansas where most OBEB sites are 

concentrated (U.S. Fish and Wildlife Service 2008a). 

Increased development is also a concern within foraging 

areas for VBEBs (U.S. Fish and Wildlife Service 2008b). 

This development potentially reduces availability of foraging 

areas and may increase potential for human intrusion into 

caves used by these species. Additionally, Stein and others 

(2010) identified areas within the Southeastern United States 

that are at greatest risk of future housing development; many 

of the “medium change” to “high change” areas are currently 

occupied by big-eared bats.

Small Population Size and Limited 

Habitat Features

The small populations of VBEBs in each core population 

area (Piaggio and others 2009) and of OBEBs (U.S. 

Fish and Wildlife Service 2008a), coupled with limited 

dispersal distances (e.g., Weyandt and others 2005), makes 

both subspecies susceptible to extirpation and possible 

use of these structures varies seasonally (Loeb and Zarnoch 

2011, Trousdale and Beckett 2004) and may indicate 

natural roost sites are critically important even in areas with 

abundant manmade roost sites.

To provide an initial assessment of potential availability 

of RBEB roosting habitat, we used U.S. Forest Service 

Forest Inventory and Analysis (FIA) data [http://fia.fs.fed.

us/. (Date accessed: March 11, 2010)] to estimate area of 

potential, natural RBEB roosting habitat within the Coastal 

Plain. Our search criterion was presence of water tupelo 

> 50 cm d.b.h. We calculated area by forest ownership 

category for the nine Southeastern States that contain the 

most bottomland hardwood forest (table 1). Our analysis 

indicates there are 308 000 ha of forest containing water 

tupelo > 50 cm d.b.h. with most (29 percent) occurring 

in Louisiana (table 1). Most (72 percent) of the potential 

roosting habitat occurred on privately owned land. These 

results should be considered preliminary, with ground 

truthing and further investigation required to more precisely 

quantify area of potential roosting habitat, suitability of 

these areas, and if they are currently occupied by RBEBs. 

Additionally, this search did not include presence of other 

species of potential roost trees. However, we suggest FIA 

data may be another resource to estimate and monitor 

trends in habitat availability for big-eared bats.

Table 1—Area of potential Rafinesque’s big-eared bat roosting habitat in the Coastal 

Plain of nine States in the Southeastern United States by ownership type; potential 

habitat was defined as stands containing stands of water tupelo (Nyssa aquatica) 

trees > 50 cm d.b.h.a

Land ownership

State

U.S. Forest 

Service

Other 

Federal State/local Private Total

---------------------------------------------thousands of ha---------------------------------------------

Alabama 4.9 16.5 21.4

Arkansas 2.4 2.8 23.5 28.7

Florida 6.1 2.4 33.6 14.2 56.3

Georgia 2.4 21.5 23.9

Louisiana 4.9 4.9 80.6 90.4

Mississippi 7.3 12.6 19.9

North Carolina 4.0 30.8 34.8

South Carolina 2.4 2.4 2.4 16.6 23.8

Texas 2.4 7.3 9.7

Total 8.5 25.8 51.0 223.6 308.9

a

 Data based on U.S. Forest Service Forest Inventory and Analysis plots, 2010.
56

but this threat is probably most relevant for OBEB and 

VBEB populations. Even though there are no documented 

occurrences of big-eared bat deaths at wind turbine sites 

in the United States, there is a record of a plecotine bat 

(Plecotus austriacus) being killed at a wind turbine site in 

Germany (Dürr and Bach 2004), and placement of wind 

facilities near or adjacent to maternity sites and hibernacula 

may impact these populations (U.S. Fish and Wildlife 

Service 2008b). Currently, there are proposed wind facilities 

near known big-eared bat sites in Arkansas, Virginia, and 

West Virginia. The proposed wind facility in Virginia is 

within 8.5 km of a known maternity site and within 21 km 

of the only hibernaculum in the Tazewell County, VA, core 

area. Although inactive at this time, another proposed facility 

in West Virginia is within 8.3 km of six VBEB hibernacula 

and two maternity colonies and within 16.7 km of the largest 

known hibernaculum for this bat. If these sites are developed, 

then two of the five VBEB ESUs, including the largest 

known population, may be potentially impacted by wind 

energy development.

Food Resources

Although moths, the primary prey of big-eared bats (Dalton 

and others 1986, Dodd and Lacki 2007, Ross 1967, Whitaker 

and others 1977), do not appear to negatively respond to forest 

management practices (Lacki and Dodd 2011), research has 

documented reduced moth abundance and diversity in pastures 

and cleared areas compared to forested sites (Burford and 

others 1999, Dodd and others 2008). However, VBEBs in West 

Virginia forage over hay fields and old fields although they 

seldom forage over grazed pastures (Stihler 2011a). These 

seemingly contradictory results may be explained by different 

vegetation structure in different types of cleared areas, which 

affect invertebrate abundance (e.g., Hermann and others 1998) 

and landscape or regional differences between study areas. 

Regardless, for VBEBs, it appears that some amount of open 

areas, with appropriate vegetation structure, may be important. 

These open areas could be lost due to natural succession, 

lack of management, and/or development. In portions of the 

range of VBEBs, gypsy moth (Lymantria dispar) infestations 

and gypsy moth control methods, especially nonselective 

treatments, could impact local forest moth populations. 

Impacts to local moth populations through pesticides, habitat 

conversion, or degradation may affect foraging distance and 

prey selection for these species. 

CURRENT CONSERVATION AND 

MANAGEMENT ACTIONS

Ozark Big-Eared Bats

Conservation of OBEBs has primarily focused on acquiring 

caves, protecting caves, and addressing WNS. Of the 

extinction. Related to small populations are the very 

limited numbers of known hibernacula and maternity 

and bachelor sites (U.S. Fish and Wildlife Service 2008a, 

2008b). Within the core area with the largest number of 

VBEBs, over 95 percent of known hibernating VBEBs 

are concentrated in just three caves (Stihler 2011b). The 

combination of low vagility, geographic isolation of ESUs 

for VBEBs, and a reproductive output of only one pup per 

year (Kunz and Martin 1982) raises concern regarding 

maintenance of genetic diversity and long-term persistence 

of these subspecies. Additionally, the low number of 

known caves used by these subspecies leads to potential for 

stochastic events, e.g., vandalism, flooding, contaminants, 

disturbance, to have a catastrophic impact on populations 

(U.S. Fish and Wildlife Service 2008b). Although RBEBs 

are more widespread, they may also be suffering from 

reduced genetic diversity and gene flow among populations 

due to relatively recent isolating mechanisms (i.e., habitat 

loss; Piaggio and others 2011). 

The key habitat components that underlie protection and 

management of big-eared bats in karst areas are caves which 

are used throughout the year as hibernacula, maternity and 

bachelor caves, and swarming sites (Barbour and Davis 

1969). In particular, the limited number of sites available and 

used by OBEBs and VBEBs make these habitat components 

critical for conservation of this species. While core areas 

for VBEBs are predominately rural and somewhat isolated, 

potential impacts to habitat features include lack of sufficient 

protection for caves and the area immediately surrounding 

caves, adjoining rural development, and other potential site 

disturbances (e.g., limestone quarrying, oil drilling activities; 

U.S. Fish and Wildlife Service 2008a, 2008b).

White-Nose Syndrome

The discovery of WNS in the Northeastern United States and 

associated high-mortality rates in cave-dwelling bats, and 

the rapid spread of WNS southward through Pennsylvania, 

West Virginia, Virginia, and westward to Oklahoma has 

raised concerns for all species of cave-dwelling bats in 

affected States (Blehert and others 2009). WNS has not been 

documented in VBEBs. A recent visit (February 2010) to 

Hellhole Cave in West Virginia, which houses the largest 

single winter concentration of VBEBs, revealed no VBEB 

deaths and no live VBEBs exhibiting signs of WNS even 

though a large number of dead and living little brown bats 

(Myotis lucifugus) and tri-colored bats (Perimyotis subflavus) 

showed signs of WNS. However, it is too early to determine 

if WNS will affect big-eared bat populations. 

Wind Energy Development

Wind energy development is a potential threat for all 

of the eastern big-eared bats (Arnett and others 2007), 
57

the U.S. Fish and Wildlife Service captured and transported 

40 VBEBs from Pendleton County, WV, to the Smithsonian 

Conservation Biology Institute near Front Royal, VA, to 

examine feasibility of maintaining VBEBs in captivity. This 

effort was mostly a failure due to mortality of captive bats.

As of 2008, 7 of 13 “major” (> 200 bats) maternity colonies 

have long-term protection (U.S. Fish and Wildlife Service 

2008b). Evidence suggests reduction of disturbance has 

led to increased population numbers at protected caves 

(U.S. Fish and Wildlife Service 2008b). In the early 1980s, 

many sites were gated using round-bar gates. All of these 

have subsequently been regated using more bat-friendly 

and more secure angle-iron gates. Also, the Monongahela 

National Forest’s management plan addresses activities 

within 61 m of VBEB cave entrances and buildings near 

caves that may serve as night roosts or roosts for small 

numbers of male VBEBs (U.S. Department of Agriculture 

Forest Service 2006). The Daniel Boone National Forest 

management plan has direction to maintain mature forest 

cover 30 m above and 60 m below cliffline communities 

and provide a 0.4-km buffer around all maternity, bachelor, 

and hibernation sites for all Corynorhinus species (U.S. 

Department of Agriculture Forest Service 2004). Prohibited 

activities within buffers include construction of roads, trails, 

wildlife openings, cutting of overstory vegetation, prescribed 

burning, and pesticide application. In addition to site 

protection, management efforts have focused on identifying 

additional sites that support summer or winter populations. 

For example, in Tazewell County, VA, the number of 

breeding females is lower than expected based on the winter 

numbers and, assuming a 1:1 sex ratio, suggests additional 

undiscovered maternity sites. Unlike bat populations in 

Virginia, the number of bats in West Virginia hibernacula 

is lower than expected based on summer numbers and, 

assuming a 1:1 sex ratio, suggests there are additional 

undiscovered hibernation sites. 

Rafinesque’s Big-Eared Bat

Because of the wide distribution and relatively large 

populations of RBEBs (as compared to OBEBs and 

VBEBs), it is difficult to summarize specific conservation 

efforts. However, it appears that besides the obvious need 

for continued conservation and management of bottomland 

hardwood forests, current management activities for RBEBs 

most often involve identification and protection of roost sites. 

This includes manmade roosting structures, e.g., cisterns, 

buildings, etc.; natural tree roosts; caves; and creation of 

artificial roost structures. For example, the Arkansas Game 

and Fish Commission signed management agreements with 

two private landowners and Deltic Timber Corporation to 

manage five wells used by RBEBs as winter hibernacula and 

placed steel covers over the wells that allow bat access but 

alleviate human safety concerns. To date, the most successful 

19 known essential OBEB sites (caves that are used as 

hibernacula and/or maternity sites that are essential to 

continued existence of OBEBs; U.S. Fish and Wildlife 

Service 1995), 9 are in public ownership or management, 

1 is managed by the National Speleological Society, and 

1 is managed by The Nature Conservancy. One notable 

aspect of OBEB conservation is the formation of the Ozark 

Plateau National Wildlife Refuge specifically created to 

protect endangered bats. This refuge was established in 

1986 as the Oklahoma Bat Caves National Wildlife Refuge 

and redesignated with its current name in 1995. Its 1517 ha 

contain three essential OBEB caves that have been protected 

by purchase, conservation easement, and cooperative 

agreements managed by the U.S. Fish and Wildlife Service. 

The potential acquisition boundary for the refuge in eastern 

Oklahoma was increased to 6073 ha in 2005 (U.S. Fish 

and Wildlife Service 2008a). All of the essential caves (one 

hibernacula and two maternity colony caves) associated with 

the northcentral Arkansas population of OBEBs have been 

purchased by the Arkansas Natural Heritage Commission 

or are managed by The Nature Conservancy. One essential 

maternity colony is owned by the U.S. Forest Service, and a 

complex of essential hibernacula is found within Devil’s Den 

State Park, owned by the Arkansas Department of Parks and 

Tourism (U.S. Fish and Wildlife Service 2008a). 

Four essential OBEB maternity caves, two hibernacula, 

and one other cave site have been protected with bat gates 

(Martin and others 2000, U.S. Fish and Wildlife Service 

2008a). In Oklahoma, 11 nonessential sites have been gated 

and 1 fenced.3

 Two essential sites in Arkansas have closure 

signs, one of which is also fitted with an alarm system. 

Upon sensing light within the cave’s dark zone, an alarm 

is triggered and transmitted to the agency which can then 

dispatch law enforcement personnel to the site (Harvey 1996, 

U.S. Fish and Wildlife Service 2008a). 

With the recent discovery in Missouri and Oklahoma of 

Geomyces destructans, the fungus associated with WNS, 

this pathogen is a possible threat for OBEBs. There have 

been discussions regarding potential establishment of captive 

OBEB colonies as was attempted for VBEBs (see below).

Virginia Big-Eared Bats

Conservation actions for management of VBEBs have largely 

focused on WNS, protecting caves, and reducing disturbance 

to bats while they are in caves. The unexpected presence of 

WNS in the Pendleton County ESU triggered an emergency 

response by the U.S. Fish and Wildlife Service to consider 

captive holding and propagation as a management tool to 

preserve the species. In consultation with State agencies, 

3

 Personal communication. 2009. Steve Hensley, Biologist, Ozark Plateau 

National Wildlife Refuge, Route 1, Box 18A, Vian, OK 74962.
58

sites can be difficult as OBEBs use caves that range from a 

small crevice to caves > 14.5 km in length (U.S. Fish and 

Wildlife Service 2008a). 

Integration of RBEB habitat needs with easement programs 

on private lands, such as the Natural Resources Conservation 

Service (NRCS) Wetland’s Reserve Program (WRP) [http://

www.nrcs.usda.gov/PROGRAMS/wrp/. (Date accessed: 

February 25, 2010)], may be an opportunity to ensure habitat 

needs for this species in the Coastal Plain. Similar to the 

Conservation Reserve Program (CRP), WRP uses economic 

incentives to encourage private landowners to restore natural 

wetland systems to former agricultural lands. This includes 

tree plantings, restoration of natural hydrology, and/or 

natural regeneration. The potential impact of this program 

is substantial. Throughout the Southeastern United States, 

five States (Arkansas, Florida, Louisiana, Missouri, and 

Mississippi) have > 40 000 ha in WRP easements; three 

States (North Carolina, South Carolina, and Tennessee) 

have > 12 000 ha of easements; and two States (Georgia and 

Kentucky) have > 6000 ha of WRP easements (see footnote 

1). In Mississippi, there are currently 68 623 ha under WRP 

contract with 52 672 ha restored to bottomland hardwoods 

(see footnote 1). Species planted in hardwood restoration 

are usually site-dependent but include a wide variety of oak 

species and potential roost tress for RBEBs, such as bald 

cypress, sweetgum (Liquidambar styraciflua), and tupelo 

gum (Clark 1990, Rice 2009, Stevenson 2008).

Forest ownership patterns are important to understand to 

direct conservation efforts. In 1999, private, nonindustrial 

landowners owned 69 percent of southern forest land, 

followed by forest industry (20 percent), national forest 

(6 percent), and other public ownership (5 percent). Later 

assessments verify approximately 87 percent of forest 

land in the South is privately owned [www.fia.fs.fed.us/

program-features/rpa/. (Date accessed: March 4, 2010)]. The 

U.S. Fish and Wildlife Service (2008a) has acknowledged the 

need to work with private landowners to conserve foraging 

areas for OBEBs. 

This need also exists for VBEBs as they may move up to 

approximately 11 km from maternity caves to foraging sites 

(Stihler 2011a). As noted previously, many opportunities 

exist for managing RBEBs on private land. However, 

a challenge for big-eared bat conservation on private 

land is a continuing shift in forest ownership patterns 

with parcelization of large blocks of private forest land 

leading to a larger number of owners of smaller parcels 

of land (Smith and other 2009, Wigley and others 2007). 

This is exacerbated by fragmentation due to urbanization 

(Mehmood and Zhang 2001) and the reduced ability to 

manage forests on landscapes with increasing human 

populations (Wear and others 1999). Additionally, many 

artificial roost structures appear to be cinder block towers 

(Bayless 2006). There are also research projects underway 

or recently completed to identify natural roosts for RBEBs 

(e.g., Rice 2009, Stevenson 2008, Trousdale and Beckett 

2005) and examine microclimate characteristics of artificial 

and natural RBEB roosts to aid in development of effective 

artificial roosts and conservation of natural roost structures 

(Bayless 2006, Rice 2009). Measures to conserve cave roosts 

for RBEBs are similar to those for OBEBs and VBEBs, 

which include reducing disturbance and documenting 

additional cave roosts.

CONSERVATION NEEDS

For all three big-eared bat taxa, there is a strong need for 

research to better understand basic ecology and examine 

effectiveness of conservation actions (Loeb and others 

2011). However, the most pressing need for conservation 

of OBEBs, VBEBs, and cave and mine roosting RBEBs 

at this time is addressing WNS. Although establishment 

of a captive colony may be a critical step (see above), 

there is much to be learned about husbandry protocols 

and propagation of insectivorous bats, especially bigeared bats, in captivity. Detailed genetic information is 

needed to insure the captive population reflects the genetic 

diversity of the wild population, and this information is 

being gathered. There is also a need to develop an effective 

treatment for WNS which can be applied in the field and 

which will not harm the bats or other cave life. Based on 

comparisons of the number of bats observed in summer and 

winter, it appears very likely there are additional unknown 

summer colony roosts and hibernacula for VBEBs that 

should be located and protected (U.S. Fish and Wildlife 

Service 2008b). Efforts to understand effects of wind 

energy facilities on VBEBs and ways to mitigate these 

effects are also needed. Wind energy projects should not be 

sited in areas where there is a high risk to VBEBs [http://

www.fws.gov/habitatconservation/Service%20Interim%20

Guidelines.pdf. (Date accessed: March 8, 2010)], and 

effective strategies for minimizing bat kills (e.g., Arnett 

and others 2007) should be developed, implemented, and 

evaluated at sites where VBEBs are not present before wind 

facilities are considered in areas where VBEBs are likely to 

occur.

For OBEBs, much progress has been made in the discovery 

of occupied caves, but continued searches for new caves are 

warranted, particularly in the vicinity of essential caves that 

have not been paired with caves used by that population in 

the opposite season (U.S. Fish and Wildlife Service 2008a). 

For example, the Devil’s Den complex in western Arkansas 

has one of the largest winter populations in the State, but it is 

not known where these bats spend the summer. Finding such 
59

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might it be changing? Journal of Forestry. 108(2): 61-70.

Stevenson, C.L. 2008. Availability and seasonal use of diurnal 

roosts by Rafinesque’s big-eared bat and southeastern myotis 

in bottomland hardwoods of Mississippi. Starkville, MS: 

Mississippi State University. 109 p. M.S. thesis.

Stihler, C.W. 2011a. Radiotelemetry studies of female Virginia bigeared bats (Corynorhinus townsendii virginianus) in Pendleton 

County, West Virginia. In: Loeb, S.C.; Lacki, M.J.; Miller, D.A., 

eds. Conservation and management of eastern big-eared bats: 

a symposium. Gen. Tech. Rep. SRS-145. Asheville, NC: U.S. 

Department of Agriculture Forest Service, Southern Research 

Station: 139–146.

Stihler, C.W. 2011b. Status of the Virginia big-eared bat 

(Corynorhinus townsendii virginianus) in West Virginia: 

twenty-seven years of monitoring cave roosts. In: Loeb, S.C.; 

Lacki, M.J.; Miller, D.A., eds. Conservation and management of 

eastern big-eared bats: a symposium. Gen. Tech. Rep. SRS-145. 

Asheville, NC: U.S. Department of Agriculture Forest Service, 

Southern Research Station: 75-84.

Trousdale, A.W.; Beckett, D.C. 2004. Seasonal use of bridges 

by Rafinesque’s big-eared bat, Corynorhinus rafinesquii, in 

southern Mississippi. Southeastern Naturalist. 3(1): 103-112.

Trousdale, A.W.; Beckett, D.C. 2005. Characteristics of tree roosts 

of Rafinesque’s big-eared bat (Corynorhinus rafinesquii) in 

southeastern Mississippi. American Midland Naturalist. 154(2): 

442-449.

U.S. Department of Agriculture Forest Service. 2004. Land and 

resources management plan for the Daniel Boone National 

Forest. 286 p. http://www.fs.fed.us/r8/boone/documents/

63

the most up-to-date information for assessing species status 

and making management decisions. Herein, we describe 

distribution of known populations, status of roost sites and 

maternity colonies, management practices implemented 

to conserve the species and provide roosting habitat, and 

conservation needs for Rafinesque’s big-eared bats in 

Mississippi.

DISTRIBUTION AND STATUS

Historical records of Rafinesque’s big-eared bats in 

Mississippi indicated that the species was uncommon in the 

State. Big-eared bats catalogued in the Mississippi Museum 

of Natural Science (MMNS) Natural Heritage Database 

during 1894 to 1941 consisted of specimens collected in 

Hinds, Pearl River, Rankin, Simpson, Washington, Wayne, 

and Yazoo Counties (fig. 1). No additional specimens were 

deposited in the museum until 1990. Wolfe (1971) stated 

that although not common, big-eared bats were distributed 

throughout the State and had been reported from buildings, 

caves (usually near the entrance), and hollow bald cypress 

(Taxodium distichum) trees. At that time populations were 

known to occur in eight counties, five of which were 

INTRODUCTION

Rafinesque’s big-eared bat (Corynorhinus rafinesquii) occurs 

throughout the Southeastern United States but is considered 

uncommon over most of its range, including Mississippi 

(Harvey and others 1999). The species is State-listed as 

endangered, threatened, or of special concern in all States 

where it occurs, and it is listed as a “Species of Greatest 

Conservation Need” in Mississippi (Mississippi Museum of 

Natural Science 2005). Prior to the early 1990s, Rafinesque’s 

big-eared bats had been reported only from scattered 

localities from 12 counties in Mississippi, but recent surveys 

throughout portions of the State have documented their 

occurrence in 15 additional counties (fig. 1). Although 

several recent big-eared bat studies conducted in Mississippi 

have been published in professional journals (e.g., Trousdale 

and Beckett 2002, 2004, 2005; Trousdale and others 2008), 

results of most field studies are currently available only 

in unpublished theses (Sherman 2004, Stevenson 2008, 

Wilf 2004) and agency reports (e.g., Martin and others 

2007, 2008; McCartney 2007). Thus, we identified a need 

to examine recent published and unpublished studies and 

consolidate information on this species for Mississippi. 

This was necessary to provide researchers and managers 

RAFINESQUE’S BIG-EARED BAT (Corynorhinus rafinesquii) 

IN MISSISSIPPI: DISTRIBUTION, CURRENT STATUS, 

AND CONSERVATION NEEDS

Chester O. Martin, Research Emeritus, U.S. Army Engineer Research & Development Center, 

Environmental Laboratory, Vicksburg, MS 39180

Alison S. McCartney, Natural Resource Specialist, U.S. Bureau of Land Management, 

Jackson, MS 39206

David Richardson, Wildlife Biologist, U.S. Fish and Wildlife Service, Noxubee National Wildlife Refuge, 

Brookeville, MS 39739

Austin W. Trousdale, Assistant Professor, Lander University, Department of Biology, 

Greenwood, SC 29649

Monica S. Wolters, Student, Mississippi College, Education Department, Clinton, MS 39206

Abstract—Rafinesque’s big-eared bat (Corynorhinus rafinesquii) is a “Species of Greatest Conservation Need” in 

Mississippi that is potentially negatively affected by habitat changes resulting from natural and anthropogenic events. 

Historical records and recent investigations indicate that the species is widespread in Mississippi, but surveys and 

monitoring sufficient to ascertain status of its populations have been limited in spatial and temporal scope. To date, bigeared bats have been documented in 27 counties. The species is typically associated with mature bottomland hardwood 

forests but also occurs in upland mixed woodlands, and several maternity roosts have been found in abandoned houses 

in upland pine (Pinus spp.) forests. Most studies in Mississippi have yielded data on current distribution and extent 

that artificial structures serve as maternity roosts. There is a need to further investigate use of natural roosts using 

radiotelemetry in certain forest types, e.g., bottomlands within the floodplain of large rivers and mixed woodlands of 

the Loess Hills. Studies of winter roosts and foraging habitat also are needed to gain a more complete understanding of 

ecology of the species. Management should include identification and protection of natural and artificial roosts, location 

and protection of wells and cisterns that potentially serve as winter roosts, selective management for appropriate cavityproducing trees, and improved coordination and cooperation among government agencies and private landowners. 

Citation for proceedings: Loeb, Susan C.; Lacki, Michael J.; Miller, Darren A., eds. 2011. Conservation and management of eastern big-eared bats: 

a symposium. Gen. Tech. Rep. SRS-145. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 157 p.
64

edge of the State and C. r. macrotis throughout the rest of 

Mississippi. Specimens catalogued in the MMNS during 

1990 to 2001 were collected in Clay, Hancock, Perry, and 

Wayne Counties.

Recent studies have revealed Rafinesque’s big-eared bats in 

several additional areas in Mississippi. Trousdale and Beckett 

(2002, 2004) conducted surveys in southern Mississippi and 

located colonies beneath bridges in five counties (Jones, 

Perry, Stone, Wayne, and Wilkinson). Most bridges surveyed 

were within or near the DeSoto or Bienville National 

represented by specimens in the MMNS and three of which 

were reported in the literature. These included counties in the 

northeastern (Oktibbeha and Lowndes), northern (Panola), 

westcentral (Yazoo and Rankin), southwestern (Wilkinson), 

and southern (Wayne, Pearl River, and Hancock) parts of 

the State. Kennedy and others (1974) listed records from the 

following nine counties, all of which were derived from the 

literature: Hancock, Kemper, Lowndes, Panola, Pearl River, 

Rankin, Wayne, Wilkinson, and Yazoo. Jones and Carter 

(1989) stated that the species was statewide in occurrence, 

with the subspecies C. r. rafinesquii along the northern 

Choctaw

Figure 1—Known distribution of Rafinesque’s big-eared bat based on early museum and literature records 

(pre-1990) and recent surveys (1998 to 2009).
65

October 11, 2000 (Martin and others 2005). Finally, one 

specimen was captured during a mist net survey conducted 

by the Mississippi Bat Working Group (MBWG) in Attala 

County in July 2007. 

ROOST SITES

Rafinesque’s big-eared bats roost in natural sites and a 

variety of humanmade structures throughout their range 

(Bennett and others 2008, Clark 1990, Gooding and 

Langford 2004, Jones 1977, Lance and others 2001, 

Trousdale and Beckett 2004, Trousdale and others 2008). 

Although Wolfe (1971) indicated that big-eared bats were 

known from sites near openings of caves in Mississippi, 

use of caves in Mississippi has not been documented during 

more recent surveys. McCartney (2007) surveyed 22 caves 

in Mississippi (primarily on private property) in 11 counties 

during 2005 to 2007 and found no evidence of big-eared 

bats. Trousdale and Beckett (2002) surveyed five of these 

caves and three additional caves in two counties and likewise 

did not observe big-eared bats. 

In Mississippi, big-eared bats have been documented using a 

variety of roosts including tree cavities, bridges, culverts, wells, 

cisterns, abandoned structures, and specially designed artificial 

roosts. They were observed in 18 hollow trees and 3 abandoned 

buildings on Noxubee NWR (Stevenson 2008); 14 trees, 16 

bridges, and 3 abandoned houses on DeSoto NF (Trousdale 

and Beckett 2005, Trousdale and others 2008); 6 additional 

bridge sites, an abandoned house, and a well in southwestern 

Mississippi (Claiborne and Jefferson Counties); 5 abandoned 

buildings on St. Catherine Creek NWR (Sherman 2004); an 

abandoned house, an old well, and a bald cypress tree on the 

Delta NF in western Mississippi (Wilf 2004); old bunkers and 

the digester tank of an abandoned water treatment plant on 

Camp Shelby JFTC in southern Mississippi (Martin and others 

2007); and cinder block artificial roosts on St. Catherine Creek 

NWR (McCartney 2007) and DeSoto NF.3

 Big-eared bats once 

were observed roosting in elongated airstrip culverts in eastern 

Mississippi (Martin and others 2005). 

Studies of natural roosts of big-eared bats in Mississippi have 

only been conducted on DeSoto NF (Trousdale and Beckett 

2005) and Noxubee NWR (Richardson 2007, Stevenson 

2008). Trees used as roosts on DeSoto NF were hollow 

tupelo and southern magnolia (Magnolia grandiflora), 

most of which were alive, relatively large (mean d.b.h. = 

79.4 cm), and possessed openings to cavities located well 

above the base of the tree. Roosts were in 14 trees, all of 

which were within bottomland hardwood or loblolly pine 

3

 Personal communication. 2010. Stephanie Steele, Wildlife Biologist, U.S. 

Forest Service, Chickasawhay Ranger District, 968 Highway 15 South, 

Laurel, MS 39443.

Forests (NF). Terrain consisted of a mosaic of habitat types 

including upland and lowland mixed hardwood-pine (Pinus

spp.) forest, upland mesic hardwood forest, bottomland 

hardwoods, and bald cypress/tupelo (Nyssa spp.) swamps. 

Other locations in southern Mississippi include several sites 

on Camp Shelby Army National Guard Training Site, now 

referred to as the Camp Shelby Joint Forces Training Center 

(JFTC) in Forrest and Perry Counties. Sites on Camp Shelby 

where big-eared bats were captured with mist nets primarily 

were narrow riparian corridors adjacent to pine-hardwood 

forests (Martin and others 2007). 

Several studies also have documented occurrence in western 

and southwestern counties. Wilf (2004) captured a single 

male in a mist net on Delta NF in Sharkey County. Sherman 

(2004) examined maternity colonies roosting in abandoned 

houses on St. Catherine Creek National Wildlife Refuge 

(NWR) in Adams County. One of the colonies was reported 

to contain 60 individuals in 1990 (Sherman 2004). St. 

Catherine Creek NWR consisted of a mixture of bottomland 

hardwoods, upland mixed hardwoods, and open water areas 

managed primarily for waterfowl. Big-eared bats also have 

been documented using bridges as roosts at crossings along 

tributaries of Bayou Pierre in Claiborne County. One of the 

bridges supports a maternity colony of about 30 individuals 

(Wolters and Martin 2000, 2011); the surrounding area was 

primarily recently harvested hardwood forest. In August 

2009, a large population consisting of about 150 individuals 

was located in an abandoned building in Jefferson County.1

This represents the largest known maternity colony of 

Rafinesque’s big-eared bats in Mississippi.

Limited surveys for big-eared bats have been conducted 

in northcentral and eastern counties, except for studies 

of roosting habitat in bottomland hardwood areas on the 

Noxubee NWR (Richardson 2007, Stevenson 2008). Several 

colonies have been located in hollow bald cypress and 

American sycamore (Platanus occidentalis) trees on this 

refuge in Oktibbeha, Winston, and Noxubee Counties. An 

abandoned house in Clay County has served as a maternity 

roost since 1988. A maternity colony recently discovered 

in an abandoned seismograph building in Lafayette County 

in northcentral Mississippi was reported to contain 85 to 

100 individuals during summer 2008.2 We confirmed that 

this structure contained about 70 hibernating Rafinesque’s 

big-eared bats on March 3, 2009. Big-eared bats were 

documented from Lauderdale County in eastern Mississippi 

when five individuals were observed roosting in an elongated 

airstrip culvert on Naval Air Station (NAS) Meridian on 

1

 Personal communication. 2009. Lann M. Wilf, Deer Program Biologist, 

Mississippi Department of Wildlife, Fisheries and Parks, 30095 Peacely 

Ferry Road, Aberdeen, MS 39730.

2

 Personal communication. 2009. Edmund Keiser, Professor (retired), 

University of Mississippi, Biology Department, 211 Saint Andrews Circle, 

Oxford, MS 38655.
66

Maternity Roosts

Most investigations of Rafinesque’s big-eared bat roost sites 

in Mississippi have focused on maternity roosts (herein 

defined as a roost site occupied by multiple females and where 

birthing apparently has taken place) in artificial structures 

(table 1). However, few studies of maternity colonies in natural 

roosts have been conducted and these data should be viewed 

only as estimates. Maternity roosts in tree cavities have only 

been documented on DeSoto NF (Trousdale and Beckett 2005, 

Trousdale and others 2008) and Noxubee NWR (Stevenson 

2008). Seven tupelo and southern magnolia trees on DeSoto 

NF were used by multiple individuals and considered to be 

maternity roosts (Trousdale and Beckett 2005). Stevenson 

(2008) located maternity roosts in four relict bald cypress 

(P. taeda)-hardwood stands. Stevenson (2008) documented 

relative abundance of cavities in trees and their use by 

big-eared bats within bottomland hardwood forests. Large 

hollow trees (mean d.b.h. = 100 cm) were used most often 

as roosts, but some bats used cavities in trees as small as 

41 cm d.b.h. Rafinesque’s big-eared bats most often selected 

roosts in cavities of bald cypress, black tupelo (N. sylvatica), 

American sycamore, pignut hickory (Carya glabra), and 

two oak (Quercus spp.) species—swamp chestnut oak 

(Q. michauxii) and water oak (Q. nigra). Other species 

that provided roost sites were sweetgum (Liquidambar 

styraciflua), American beech (Fagus grandifolia), overcup 

oak (Q. lyrata), shagbark hickory (C. ovata), cherrybark oak 

(P. pagoda), eastern cottonwood (Populus deltoides), willow 

oak (Q. phellos), and white oak (Q. alba) (Stevenson 2008).

Table 1—County and status of recently surveyed maternity roosts of Rafinesque’s big-eared bats in Mississippia

Location Type of roost Bats

Date of 

last survey Source

no.

Adams County 3 artificial roostsb 70 July 2007 McCartney (2007)

Claiborne County Concrete bridge 30+ June 2009 Wolters (unpub. data)

Clay County Abandoned house 75–90 2008 Richardson (unpub. data)

George County 1 concrete bridge 11 July 2001 Trousdale (2008)

Jefferson County Abandoned stone building 150 Aug 2009 Wilf (pers. commun.)

Jones County (West localityc

) 2 concrete bridges 30+ July 2005 Trousdale (2008)

Lafayette County Abandoned stone building 85–100 June 2008 Keiser (pers. commun.)

Perry County (Benndalec

) 3 concrete bridges 30 July 2004 Trousdale (2008)

Perry County (Cypress Creekc

) 1 concrete bridge 4 July 2004 Trousdale (unpub. data)

Perry County (Leaf River WMAc

) 2 concrete bridges 8 July 2004 Trousdale (2008)

Wayne County (East localityc

) 2 concrete bridges 6 May 2005 Trousdale (2008)

Wayne County (North localityc

) 2 concrete bridges 12 June 2004 Trousdale (2008)

Wayne County (Hollis Creekc

) 2 concrete bridges 10 July 2005 Trousdale (2008)

Wayne County (Thompson Creekc

) 2 concrete bridges 6 June 2004 Trousdale (2008)

DeSoto National Forest 14 tree roosts 33 Aug 2004 Trousdale (pers. commun.)

Noxubee National Wildlife Refuge 4 tree roosts 160 2007 Stevenson (pers. commun.)

WMA = Wildlife Management Area.

Numbers of bats associated with bridges represent values recorded on the most recent survey when bats were present; most bridges were 

surveyed multiple times over at least a 3-year period and numbers were quite variable. 

a

 Number of bats includes adult females and young at highest count made during the latest survey.

b

 Previously in abandoned house.

c

 Locality [see Trousdale (2008) for description].
67

(fig. 2). Surveys of this bridge, four other bridges, and an 

abandoned house with an adjacent well were conducted 

during 2000 to 2009.5 The maternity colony has fluctuated 

considerably since first observed (32 bats in 2000), with 

an estimate of 20 in 2001 to 30 in 2009. The other bridges 

surveyed did not support maternity colonies but commonly 

were used as day roosts by individual or small numbers 

of bats. Surveys on Camp Shelby JFTC in southcentral 

Mississippi documented big-eared bats roosting in seven 

cement structures, including observation point bunkers, an 

abandoned building, the digester tank of an old wastewater 

treatment plant, and two bridges. The bridges on Camp 

Shelby supported about 11 and 25 bats in 1999 (Trousdale 

and Beckett 2002). The digester tank historically supported a 

maternity population of 45 big-eared bats, but recent surveys 

have documented only a few individuals using the structure 

(Martin and others 2007). Small maternity colonies presently 

occur beneath two concrete bridges on secondary roads on the 

installation. Surveys of bridges in other regions of Mississippi 

have revealed little use by big-eared bats. No bats were 

roosting beneath 42 bridges examined on Noxubee NWR 

and vicinity in 2007 to 2008 (Stevenson 2008), 24 bridges 

on Theodore Roosevelt NWR in 2008, and 15 bridges in 

southeastern Mississippi along the Pascagoula River Basin in 

2009 (McCartney 2010). 

5

 Personal observation. M. Wolters and C.O. Martin.

trees (d.b.h. > 127.0 cm) with top openings on Noxubee 

NWR. The maximum number of bats in the 4 trees combined 

was estimated at 160, with 50 bats being the largest number 

estimated in a single roost at one time.4

Trousdale and Beckett (2002) surveyed 99 bridges in southern 

Mississippi and identified 6 bridges in 5 counties inhabited 

by big-eared bats. Repeated visits to these sites and other 

locations revealed that 36 bridges located on or near DeSoto 

NF were used at least once during 2002 to 2004, with 1 to 

25 bats observed (Trousdale and Beckett 2004). All bridges 

used by bats were made of concrete and had rectangular 

compartments or girders on the underside. Additionally, 

Trousdale (2008) radio tracked big-eared bats to 25 roost 

structures in his study area. Besides the previously noted 

tree roosts, 11 were humanmade (8 bridges, 2 abandoned 

houses, and 1 empty oil storage tank). Maternity roosts were 

documented beneath 20 bridges, in 1 house, and in an oil tank 

(Trousdale and Beckett 2004). Populations roosting in bridges 

also have been documented in westcentral Mississippi. A 

maternity roost with 32 big-eared bats was discovered in 

April 2000 beneath a bridge over a tributary of Bayou Pierre 

in Claiborne County about 1 km from the Mississippi River 

(Wolters and Martin 2000, 2011). The bridge was a concrete 

girder structure with multiple compartments on each side 

4

 Personal communication. 2010. Candice Stevenson, Refuge Operations 

Specialist, U.S. Fish and Wildlife Service, Merritt Island National Wildlife 

Refuge, P.O. Box 2683, Titusville, FL 32781.

Figure 2—Concrete girder bridge in Claiborne County, MS, used as a maternity roost by 

> 30 Rafinesque’s big-eared bats in 2009. (Photo by Monica Wolters)
68

Sherman (2004) examined artificial roosts used by 

Rafinesque’s big-eared bats on St. Catherine Creek NWR 

and vicinity in southwestern Mississippi. Big-eared bats 

were observed using seven abandoned buildings, three of 

which were confirmed maternity colonies. Three of the sites 

were in bottomland hardwood swamp forest, two in upland 

mixed hardwood forest, and one in upland mixed hardwoodpine forest (McCartney 2007). The primary structure 

was a multilevel abandoned house that was historically 

a maternity roost containing 40 to 60 bats (fig. 3). This 

population declined substantially in the 1990s as the building 

deteriorated. The house contained 50 individuals in May 

2002 (McCartney 2007). However, concrete culvert towers 

designed to mimic hollow trees were later installed on the 

refuge, and 70 big-eared bats were observed using the roosts 

in July 2007 (fig. 4). We observed another large maternity 

colony in 2008 in an abandoned house on private property 

in Clay County with numbers of bats ranging from 75 to 90. 

The MBWG attempted unsuccessfully to obtain permission 

to adopt the house and make minor structural improvements 

to ensure protection of the roost in 2007, but the request 

was declined by the property owner. The large colonies in 

abandoned buildings in Lafayette and Jefferson Counties 

likely represent maternity roosts but data on these sites are 

incomplete. We visited the Jefferson County site on May 21, 

2010 and counted 147 big-eared bats in what appeared to be 

a maternity colony (fig. 5). However, no pups were present at 

that time and we were not able to return later to verify it as a 

maternity roost.

Figure 4—Concrete culvert tower roost installed on St. Catherine 

Creek National Wildlife Refuge. Seventy big-eared bats were 

observed using three of the structures in July 2007. (Photo by Alison 

McCartney)

Figure 3—Abandoned house on St. Catherine Creek National Wildlife Refuge that historically 

served as a maternity roost for 40 to 60 Rafinesque’s big-eared bats. (Photo by Alison McCartney)
69

MANAGEMENT 

Most management efforts for Rafinesque’s big-eared bats 

in Mississippi have focused on provision and improvement 

of artificial roosts. In 2002, an alternative bat house with a 

shed design was constructed by personnel of St. Catherine 

Creek NWR near the original known primary roost site. 

Winter Roosts

Winter roosts of big-eared bats in Mississippi are relatively 

unknown. Searches on Noxubee NWR revealed only a 

few large, old bald cypress trees that were used as winter 

roosts (Stevenson 2008). We observed about 200 wintering 

big-eared bats in a tree on Noxubee NWR in 2009. Several 

bridges checked by Trousdale (2008) on DeSoto NF were 

used as roosts by bats in torpor during winter. Big-eared 

bats hibernate in cisterns and wells in the northern part of 

their range (Harvey and Saugey 2001, Harvey and others 

1999), but only limited surveys of these structures have been 

conducted in Mississippi. We observed clusters of 12 to 25 

individuals during November through January 2001 to 2004 

in a dilapidated well adjacent to an abandoned house in 

Claiborne County. We also observed big-eared bats during 

winter in a partially covered well in Winston County. Bigeared bats were not observed in any of 10 cisterns surveyed 

in southwestern Mississippi (McCartney 2007, Sherman 

2004). However, big-eared bats have been documented 

from cisterns in other States (Harvey and Saugey 2001) 

and potentially occur in these structures in Mississippi. 

Single individuals were observed occasionally during 

winter in houses on St. Catherine Creek NWR in 2002 to 

2003, and one big-eared bat was in a culvert on private land 

adjacent to the refuge in February 2003 (Sherman 2004). 

As previously noted, Rafinesque’s big-eared bats have been 

observed hibernating in an abandoned concrete structure in 

northcentral Mississippi (fig. 6).

Figure 5—Abandoned building in Jefferson County, MS, recently discovered as a roost site 

for > 150 Rafinesque’s big-eared bats. (Photo by Chester Martin)

Figure 6—Cluster of Rafinesque’s big-eared bats hibernating in a 

concrete structure in northcentral Mississippi. (Photo by Barry Moss)
70

sites where suitable trees are rare or when entrances are too 

small for big-eared bats. 

An important aspect of big-eared bat management in 

Mississippi has been development of outreach programs. 

The MBWG was formed in 2001 with the primary goal 

of promoting conservation of bats in the State through 

research, habitat management, and education. MBWG 

includes an ad hoc committee on education and outreach, 

and members routinely make presentations to local groups 

and civic organizations. Information on big-eared bat 

conservation and management is generally included in these 

presentations. Additionally, updates on big-eared bat research 

and management efforts are included in presentations at the 

MBWG annual meeting and professional conferences. 

CONSERVATION NEEDS

A major threat to populations of Rafinesque’s big-eared bats 

in Mississippi is loss of habitat, especially mature forest 

stands used for roosting. The documented association of 

big-eared bats with mature bottomland forest (Clark 1990, 

Cochran 1999, Gooding and Langford 2004, Lance and 

others 2001, Rice 2009) suggests that declines of this forest 

type have negatively affected the species. Historical records 

indicate that in the Mississippi Alluvial Valley (MAV) 

approximately 78 percent of forested wetlands (mostly 

bottomland hardwoods) had been converted to other land 

uses by the mid-1970s (MacDonald and others 1979), and 

bottomland hardwoods along the lower Mississippi River were 

being cleared for agriculture in tracts as large as 12,000 ha 

during the 1980s (Gosselink and Lee 1989). By the mid1980s, the MAV forested landscape had been reduced to a 

highly fragmented 20 percent of its historical extent (Haynes 

2004, Wilson and others 2007). Currently, about 19 percent 

of Mississippi’s forest land is composed of bottomland 

hardwoods, and forested area in the Mississippi Delta has 

increased by 12 percent since 1994 (King and others 2006, 

Oswalt and others 2009). Additionally recent Natural Resource 

Conservation Service (NRCS) data shows that, under the 

Wetland Reserve Program (WRP), there are 68,623 ha of 

land under WRP contract in Mississippi, including 52,672 ha 

restored to bottomland hardwoods (Miller and others 2011). 

However, forests containing large-diameter trees suitable 

as Rafinesque’s big-eared bat roost sites likely will not be 

available for decades since Rafinesque’s big-eared bats 

appear to prefer to roost in large (> 50 cm d.b.h.) trees within 

bottomland hardwood forests (Stevenson 2008, Trousdale 

2011). Significant populations of big-eared bats also have 

been documented from upland mixed forests, and males have 

been found foraging in sapling-stage pines (Menzel and others 

2001). It is worthwhile to note that three of the four largest 

known roost sites in Mississippi are located in abandoned 

buildings in upland pine forests. Thus, other forest types 

This structure was not accepted by the bats as a roost site, so 

three additional roosts constructed of triple-stacked circular 

concrete culvert blocks were erected near the site in 2004. 

All three of the roosts have been occupied by big-eared bats 

and two appear to have served as alternative maternity roosts 

(McCartney 2007). Artificial roosts installed on DeSoto NF 

include 4 cinder block structures, 4 tall wooden roosts, and 

18 plastic culvert roosts. To date, only solitary occurrences of 

big-eared bats have been observed in the cinder block roosts, 

and none have been observed in the wooden or plastic roosts. 

However, most of the structures have not been checked 

consistently since their construction (see footnote 3). Also, 

the U.S. Army Corps of Engineers at Sardis Lake project 

office has developed plans to construct a cinder block tower 

roost near the abandoned seismograph building in Lafayette 

County. The building is showing signs of decay and the 

proposed structure is intended to provide an alternate roost 

site for big-eared bats. The U.S. Fish and Wildlife Service is 

experimenting with a variety of designs on Noxubee NWR. 

A structure recently installed on the refuge consists of a 

9.1-m tall by 76.2-cm diameter steel culvert with a wooden 

top and a 76.2- by 122-cm opening at the bottom, which is 

used during spring and autumn by 1 to 12 big-eared bats. 

Although bridge roosting populations have been documented 

in several regions of Mississippi, few attempts have been 

made to protect these sites except on some Federal lands. 

The two bridges occupied by big-eared bats on Camp 

Shelby JFTC have been identified as protected sites, and 

one of the bridges recently was rebuilt using the “Choctaw 

style,” a modification of the concrete girder T-beam design. 

Additionally, the U.S. Forest Service has developed 

specifications for replacement of bridges on secondary 

roads within the National Forests in Mississippi. The U.S. 

Forest Service and Mississippi Department of Transportation 

(MDOT) currently are collaborating on replacement 

guidelines for bridges using bat-friendly designs in southern 

Mississippi. 

The U.S. Fish and Wildlife Service, in collaboration with 

Mississippi State University, has conducted studies of 

roosting habitat of big-eared bats and management needs in 

bottomland hardwood forests on Noxubee NWR (Stevenson 

2008). About 650 randomly selected hollow trees were 

inspected during the study; it was determined that American 

beech and sweetgum have a high tendency to produce 

cavities, whereas this is not the case for oaks (Richardson 

2007, Stevenson 2008). This research was used to provide 

recommendations for reforestation and silviculture that 

can be incorporated into land management practices for 

conserving big-eared bats and their habitat. Richardson 

(2007) also reported an experiment for increasing use of 

hollow trees without openings by cutting portals to allow 

access by bats to these chambers; this technique potentially 

provides an opportunity to increase naturally occurring roost 
71

Defense installations (Camp Shelby, Camp McCain, NAS 

Meridian), one national park (Vicksburg National Military 

Park), and several State wildlife management areas in the 

Pascagoula River Basin, many areas of the State have never 

been surveyed. Also, traditional surveys have not proven 

suitable for determining roost habitat by big-eared bats, 

and few studies, except those conducted on DeSoto NF 

(Trousdale and Beckett 2004, 2005; Trousdale and others 

2008), have attempted to locate roosts using radiotelemetry. 

There is also a need to conduct studies of foraging habitat in 

different areas of the State. Further, an apparent continuum 

of populations along the Loess Hills corridor in western 

Mississippi needs to be more extensively surveyed. Little 

information is available on ecology of Rafinesque’s bigeared bats in winter, except for the study by Rice (2009) in 

bottomland hardwoods of northeastern Louisiana. Similar 

studies need to be conducted in Mississippi to provide 

information useful to identify forest management practices 

that benefit big-eared bats. 

Management should include identification and protection 

of natural and artificial roosts. Roost switching has been 

well documented in Rafinesque’s big-eared bats (Gooding 

and Langford 2004, Lance and others 2001, Trousdale 

and Beckett 2005), and populations use a combination 

of natural and artificial roost sites. Trousdale and others 

may also be important, and further work is needed to fully 

understand habitat needs for this species. 

Conservation of natural roosts is critical for conservation 

efforts to be effective. Hollow, large-diameter trees often 

are rare on the landscape due to management practices 

and natural events, e.g., tornadoes and hurricanes. For 

example, 14 percent of live trees in Mississippi’s southern 

forest survey unit experienced wind-related damage during 

Hurricane Katrina in 2005 (Oswalt and others 2009). These 

included mature hardwood trees blown down on DeSoto 

NF and Camp Shelby, some of which had been documented 

previously as roosts. Therefore, known and potential 

roost trees should be protected, and forest management 

prescriptions should ensure a future supply of large trees, 

especially in lowland areas near water (fig. 7). Efforts should 

consider retention of bald cypress, water tupelo, blackgum, 

sweetgum, American beech, southern magnolia, and 

American sycamore which have the propensity to develop 

cavities used by big-eared bats. 

Additional surveys are needed to locate natural roosts and 

roosts in artificial structures. Although extensive studies 

have been conducted on national forests (DeSoto and 

Delta), national wildlife refuges (St. Catherine Creek, 

Noxubee, and Theodore Roosevelt), U.S. Department of 

Figure 7—Forest management prescriptions in Mississippi should ensure a future supply of large 

trees that have the propensity to develop cavities used by Rafines que’s big-eared bats. Preferred 

species include bald cypress, water tupelo, blackgum, American beech, southern magnolia, 

sweetgum, and American sycamore. (Photo by Candice Stevenson)
72

ACKNOWLEDGMENTS

We thank the following agencies and organizations for 

providing logistical support for studies of Rafinesque’s 

big-eared bat in Mississippi: Mississippi Museum of 

Natural Science, U.S. Fish and Wildlife Service, U.S. 

Army Engineer Research and Development Center 

(ERDC), U.S. Forest Service, U.S. Army National Guard 

Bureau, U.S. Naval Station Meridian, University of 

Southern Mississippi (USM), Mississippi State University 

(MSU), Jackson State University, Mississippi College, 

and Weyerhaeuser Company. D. Beckett (USM) provided 

direction for studies conducted in southern Mississippi. 

Field support was provided by M. McCartney (Mississippi 

Department of Environmental Quality, Jackson, MS); M.C. 

Like (3D Environmental, Longview, TX); and R.F. Lance, 

B. Sabol, P. Bailey, and K. Richards (ERDC). M. Bayless 

(Bat Conservation International) assisted with surveys 

and provided guidelines for artificial structures. An early 

version of the manuscript was reviewed by M.W. Ford and 

E.R. Britzke (ERDC). 

LITERATURE CITED

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Clark, M.K. 1990. Roosting ecology of the eastern big-eared bat, 

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Cochran, S.M. 1999. Roosting and habitat use by Rafinesque’s 

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ecosystem. Jonesboro, AR: Arkansas State University. 50 p. 

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Gooding, G.; Langford, J.R. 2004. Characteristics of tree roosts of 

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Gosselink, J.G.; Lee, L.C. 1989. Cumulative impact assessment in 

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Harvey, M.J.; Altenbach, J.S.; Best, T.L. 1999. Bats of the United 

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64 p.

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Haynes, R.J. 2004. The development of bottomland forest 

restoration in the lower Mississippi Alluvial Valley. Ecological 

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(2008) also demonstrated that roost fidelity of a population 

of big-eared bats in southeastern Mississippi varied with 

habitat type and recommended that conservation and roost 

monitoring programs include this flexibility with regard to 

potential movements among roosts within relatively short 

periods. Lance and others (2001) determined that amount 

of mature forest surrounding a bridge was a primary factor 

in determining occupancy by big-eared bats. Use of bridges 

may also be associated with tendency of the species to 

switch roosts frequently with bridges, abandoned buildings, 

and hollow trees serving as alternate roosts (Trousdale and 

Beckett 2004). Roosting in bridges may also result from 

limited availability of natural roosts. Bridges commonly 

were used by big-eared bats on the DeSoto NF where 

suitable roost trees were deficient (Trousdale and Beckett 

2005) and in an area dominated by recently harvested forest 

stands along Bayou Pierre and its tributaries in westcentral 

Mississippi (Wolters and Martin 2000, 2011). Conversely, 

big-eared bats were never observed using bridges in more 

naturally forested areas with extensive stands of mature 

hardwoods in Noxubee NWR, Theodore Roosevelt NWR, 

and at sites along the Pascagoula River.

The largest maternity colonies documented in Mississippi 

occur in abandoned structures on private lands. These sites 

degrade through time and ultimately become unsuitable as 

roosting habitat. Wooden structures especially are subject 

to degradation and collapse, and remote buildings often 

are vandalized. A worthwhile effort would be to obtain 

permission to protect and stabilize important roost sites. 

However, landowners may be suspicious of actions that in 

their view cede control over their property to government 

agencies or conservation organizations, as was the case 

with the house in Clay County. Nevertheless, more effective 

interaction is needed among conservation organizations and 

private landowners regarding protection and management 

of bat habitat, especially as most (78 percent) Mississippi 

timberlands are privately owned (Oswalt and others 2009) 

and given that Miller and others (2011) calculated that 

there currently are approximately 19,900 ha of potential 

big-eared bat roosting habitat in Mississippi, with most 

potential suitable habitat (12,600 ha) on private land. There 

needs to be greater involvement with organizations such as 

Bat Conservation International when developing projects to 

protect roosts. Additionally, there needs to be more effective 

coordination with State offices and MDOT regarding 

protection of bridge roosting sites and use of bat-friendly 

designs when new bridges are constructed. Finally, both 

Federal and State agencies should acknowledge the need to 

protect and manage Rafinesque’s big-eared bats by providing 

funding for research and habitat management. Conservation 

of the species ultimately will be tied to landscape-level 

management of forests.
73

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Mississippi State University. 109 p. M.S. thesis. 

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bat, Corynorhinus rafinesquii, in southeastern Mississippi. 

Hattiesburg, MS: The University of Southern Mississippi. 107 p. 

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recorded from mist-net and bridge surveys in southern Mississippi. 

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southern Mississippi. Southeastern Naturalist. 3: 103-112.

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of Rafinesque’s big-eared bat (Corynorhinus rafinesquii) in 

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166-172.

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aircraft and use of culverts under runways by bats at U.S. Naval 

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survey of the bat fauna and habitat management considerations 

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final report. Final report prepared for HQ, Mississippi Army 

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U.S. Army Engineer Research and Development Center, 

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Environmental Department, U.S. Naval Air Station; final report. 

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Air Station Meridian, Meridian, MS, by the Environmental 

Laboratory, U.S. Army Engineer Research and Development 

Center, Vicksburg, MS. 184 p.

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big-eared bat (Corynorhinus rafinesquii) and southeastern 

myotis (Myotis austroriparius) in Mississippi. Jackson, MS: 

U.S. Fish and Wildlife Service; final report. 66 p.

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in Jackson, George, Stone, Perry, and Harrison Counties, 

Mississippi, January–December, 2009. Jackson, MS: 

Mississippi Department of Wildlife, Fisheries, and Parks; final 

report. 30 p.

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Home range and habitat use of male Rafinesque’s big-eared bats 
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Mississippi Museum of Natural Science. 44 p.

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hairless bridge-roosting Rafinesque’s big-eared bats in westcentral Mississippi [Abstract]. Bat Research News. 42: 150.

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Rafinesque’s big-eared bats (Corynorhinus rafinesquii) beneath 

a concrete bridge. Southeastern Naturalist. 10: 178-180.

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442-449.

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roost fidelity of Rafinesque’s big-eared bat (Corynorhinus 

rafinesquii) varies with habitat. Journal of Mammalogy. 89: 

477-484. 

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populations in Delta National Forest, Mississippi. Jonesboro, 

AR: Arkansas State University. 84 p. M.S. thesis. 

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Venture Office. 88 p.
75

Barbour and Davis (1969) wrote, “In West Virginia the species 

is still rather abundant in certain caves. . . . The bats seem to 

be abandoning more caves each year, apparently as a result 

of ever increasing human disturbance as spelunking becomes 

more popular. The species is destined to perish in the eastern 

United States, unless the caves it uses receive protection.”

In an October 15, 1976, letter addressed to Lynn Greenwalt, 

Director, U.S. Fish and Wildlife Service (USFWS), John S. 

Hall and Michael J. Harvey petitioned the USFWS to list two 

subspecies of C. townsendii, C. t. virginianus, and C. t. ingens

as federally endangered. They noted in their cover letter that 

“It was the unanimous opinion of the Southeastern Section 

of the Wildlife Society... that these two bat subspecies 

should be considered endangered.” For C. t. virginianus, 

the petition focused on the population in West Virginia, 

which included most of these bats, and where Hall had 

conducted surveys documenting population declines. The 

population was estimated at 2,500 to 3,000 individuals with 

an additional “few hundred individuals” in Kentucky and 

Virginia. The petition notes that the range of the subspecies 

did not appear to have been reduced, but number of bats was 

declining throughout its range. These declines appeared to 

be due to increased disturbance of bats in caves as a result 

of increasing spelunking activities. Three examples of recent 

population declines were provided for maternity colonies in 

Pendleton County, WV. The population in Hoffman School 

Cave declined from approximately 1,000 bats in 1962 to 

450 individuals in 1975. During the same time period, the 

colony in Sinnett Cave declined from 250 to 20 bats and 

the population in Cave Mountain Cave declined from 1,000 

to 800 bats. The petition noted that these bats were more 

dispersed in the winter, although subsequent data proved this 

not to be the case. One other factor considered in the petition 

INTRODUCTION

Although both the common and scientific names of this 

bat have changed numerous times over the past decades, 

the Virginia big-eared bat (Corynorhinus townsendii 

virginianus), the easternmost subspecies of Townsend’s 

big-eared bat, has long been recognized as a component 

of the cave fauna of West Virginia (fig. 1). These bats use 

caves year round and, during the active period, forage 

in both open areas and forests surrounding their roosts 

(Stihler 2011). Reese (1934) noted occurrence of this bat in 

two caves in Pendleton County and one cave in Randolph 

County. The holotype for this subspecies was collected in 

Schoolhouse Cave, Pendleton County, on November 12, 

1939 (U.S. National Museum 269163). Kellogg (1937) noted 

occurrence of C. t. virginianus in Preston County, although 

no locations for the Preston County records were given. 

Wilson (1946) reported collection of two specimens from 

a cave in Hardy County in October 1944, and Frum (1947) 

reported specimens collected from a Grant County cave. 

Wilson (1948) and Kellogg (1937) noted that this species 

should be widespread in West Virginia although neither cited 

records to support these claims. In his review of the genera 

Euderma and Plecotus, Handley (1959) noted unpublished 

records from Frum of C. t. virginianus in a cave in Tucker 

County. He also noted that this bat had a “limited and 

apparently discontinuous distribution . . . within the bounds 

of the Appalachian Highlands” and was not known from the 

“well explored” karst regions in Pocahontas, Greenbrier, and 

Monroe Counties. 

While these early reports rarely mention information regarding 

number of bats present when the caves were visited, by the 

late 1960s there was concern that populations were declining. 

STATUS OF THE VIRGINIA BIG-EARED BAT (CORYNORHINUS TOWNSENDII 

VIRGINIANUS) IN WEST VIRGINIA: TWENTY-SEVEN YEARS OF MONITORING 

CAVE ROOSTS

 Craig W. Stihler, Wildlife Biologist, West Virginia Division of Natural Resources, Elkins, WV 26241

Abstract—Maternity colonies and hibernacula of federally endangered Virginia big-eared bats (Corynorhinus townsendii 

virginianus) in West Virginia have been monitored annually since 1983 during June and biennially during winter to 

examine population trends after these sites were closed to human traffic when bats were present. Seven maternity colonies 

contained 3,073 bats in 1983 and 5,487 bats in 2009, an increase of 77 percent. These 7 colonies, with 3 additional 

maternity colonies discovered since 1983, bring the number of known bats to 7,245 during summer 2009 with mean colony 

size of 725 bats (range 235 to 1,298 bats). Twenty-five or more hibernating C. t. virginianus have been documented in 8 

West Virginia caves with the largest known hibernating concentration of this subspecies in Hellhole (10,025 bats in winter 

2010). In winter 1988 to 1989, the State’s 3 largest hibernacula contained 5,170 C. t. virginianus (96 percent of observed 

bats). In 2009, these caves contained 11,559 individuals (124 percent increase) with the total number of hibernating bats 

estimated at 12,059. By early 2010, white-nose syndrome (WNS) was documented in five caves used by C. t. virginianus

in Pendleton County including Hellhole. To date, no affected big-eared bats have been observed, but WNS could 

potentially decimate this population which has been increasing as a result of cave protection.

Citation for proceedings: Loeb, Susan C.; Lacki, Michael J.; Miller, Darren A., eds. 2011. Conservation and management of eastern big-eared bats: 

a symposium. Gen. Tech. Rep. SRS-145. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 157 p.
76

by C. t. virginianus colonies in West Virginia, all of which 

were used as summer colonies, and 6 of which were used by 

hibernating bats. By the time the recovery plan was written, 

5 of these 10 caves had been gated or fenced to reduce 

disturbance. Based on surveys conducted in 1981 and 1982, 

the recovery plan estimated the number of C. t. virginianus

in maternity colonies in West Virginia to be approximately 

3,450 individuals. 

In recent years, surveys conducted at entrances of abandoned 

coal mines in the New River Gorge National River, Fayette 

County, by National Park Service personnel and their 

contractors during the late summer and fall swarming 

period have captured small numbers (usually less than five 

bats per portal per night) of C. t. virginianus using several 

mine portals (Varner 2008). No large colonies have been 

discovered in this area. The relationship of these bats to other 

populations is unclear, although this population appears to be 

genetically distinct and most closely related to the Tazewell 

County, VA, population (Piaggio and others 2009). The 

West Virginia Division of Natural Resources (WVDNR) has 

not received reports of C. t. virginianus captured at mine 

portals in other areas of the State. Because few data are 

available for the Fayette County population, this paper will 

focus on the more studied C. t. virginianus population in 

the Pendleton County area, the largest known concentration 

was presence of a limestone quarry only a few hundred yards 

from one significant C. t. virginianus cave, Hellhole.

In December 1977, the “Proposed endangered listing and 

critical habitat determination for the Virginia and Ozark bigeared bats” (Ozark big-eared bat = C. t. ingens) was published 

in the Federal Register (42 FR 61290 61292). In the proposal, 

six caves were proposed as critical habitat for C. t. virginianus. 

Five of these were in West Virginia: four caves were in 

Pendleton County [Cave Mountain Cave (maternity colony 

and minor winter use), Hellhole (hibernaculum and bachelor 

colony), Hoffman School Cave (maternity colony and minor 

winter use), and Sinnett Cave (maternity colony and minor 

winter use)]; and Cave Hollow/Arbogast Cave system was in 

Tucker County (maternity colony and hibernaculum). The final 

rule was published in November 1979 (44 FR 69206 69208) 

and, effective December 31, 1979, both subspecies were listed 

as endangered, and five caves in West Virginia were listed as 

critical habitat for C. t. virginianus. The sixth cave, located in 

Kentucky, was not listed because the landowner was already 

protecting the site and did not want to draw attention to it by 

publishing it in the Federal Register.

The recovery plan for the two big-eared bat subspecies was 

completed in May 1984 (U.S. Fish and Wildlife Service 

1984). At that time, there were 10 caves known to be used 

Fayette

Randolph

Pendleton

Tucker

Preston

Hardy

Grant

Figure 1—Location of West Virginia counties with records of Corynorhinus 

townsendii virginianus.
77

below) was turned on, and observation of the cave entrance 

began shortly before the bats were expected to emerge from 

the cave (approximately 20h55m EDT in June). Emergences 

usually lasted 70 to 90 minutes.

Since 1983, night-vision scopes and a variety of lights fitted 

with infrared filters have been used to conduct emergence 

counts. Beginning in 2005, camcorders with night-vision 

capabilities (Sony® DCR-TRV38, Sony Corporation, Tokyo, 

Japan) were also used. Because these camcorders do not 

amplify available light, a brighter light source was needed, 

and high-intensity LED infrared lights (Wildlife Engineering, 

Tucson, AZ) were employed. 

Caves with summer colonies of C. t. virginianus often 

contained a few (≤ 10) bats of other species during the summer 

(Myotis spp. and Perimyotis subflavus) which emerged in 

the evening. Because C. t. virginianus echolocation calls are 

lower in frequency and much quieter than those of other bats 

using the caves, since counts began in 1983, ultrasonic “bat 

detectors” were used to distinguish non-big-eared bats. When 

a non-big-eared bat emerged, a strong echolocation call was 

picked up if the detector was set at 50 to 55 kHz and pointed 

toward the cave entrance; a faint call or no call at all was heard 

when a big-eared bat emerged. Bat size and flight pattern also 

aided in distinguishing non-big-eared bats.

Prior to use of camcorders, all counts were done “live” 

with an observer watching bats exit the cave and recording 

observations on a microcassette recorder with a time mark 

recorded at 5-minute intervals. At the end of each emergence, 

the tape, with a recording such as “five bats out, five bats out, 

one bat in, two bats out, time . . .” was replayed, and numbers 

of bats were tallied for each 5-minute period. If the emergence 

had been videotaped, the tape was reviewed if there were any 

5-minute time blocks where the observer felt the observations 

needed to be verified. Since 2005, emergences at four of the 

maternity colonies caves with large entrances and a large 

number of bats (Arbogast entrance of Cave Hollow/Arbogast 

Cave system, north entrance of Cliff Cave, and Mystic and 

Schoolhouse Caves) were recorded and counted later by two 

observers; one person counted only bats exiting, and the other 

counted only bats going back into the cave. 

Hibernacula surveys were generally conducted in January 

or February in odd-numbered years between 1983 and 

2010, although the Cave Hollow/Arbogast Cave system was 

sometimes surveyed during the last 2 weeks of December 

because access could be difficult later in the season due to 

snow and ice. Small crews (two to four people) entered the 

caves and conducted the surveys as quickly as possible. 

Because Hellhole is a large and complex cave with several 

areas within the cave where large numbers of bats hibernate, 

multiple crews were sometimes used, and each examined a 

different portion of the cave. Surveyors tallied and recorded 

number of C. t. virginianus in each cluster. Large clusters 

of this subspecies, and will examine population trends and 

effectiveness of cave protection activities.

METHODS

Because C. t. virginianus use caves during summer and winter, 

population trends can be examined at both maternity colonies 

and hibernacula. Maternity colony counts were conducted by 

tallying bats as they emerged from the caves in the evening; 

winter counts required entering caves to enumerate hibernating 

bats. Annual monitoring of C. t. virginianus in maternity 

colonies in West Virginia began in 1983 using the protocol of 

Bagley and Jacobs (1985). This method used infrared lights 

(mining lights fitted with infrared gel filters) to illuminate the 

cave entrance and night-vision scopes to watch and tally bats 

as they emerged in the evening to feed. As new technologies 

and information have become available, the methodology 

has evolved but still remains much like the original protocol. 

USFWS biologists provided technical advice and a loan of 

equipment during the first 5 years of monitoring; the WVDNR 

conducted the counts after that period.

As suggested by Bagley and Jacobs (1985), surveys were 

conducted in June before bats give birth when the entire 

colony usually emerges from the cave early in the night to 

forage. Once lactation begins, portions of the colony may be 

in the cave throughout the night as bats come and go to nurse 

their young.1

 Based on cave monitoring and radiotelemetry 

data collected by WVDNR personnel, the survey period 

was refined so that surveys were usually conducted between 

June 1 and June 20, with the surveys completed by June 15, 

when feasible. Because females in Cave Mountain Cave 

were documented to give birth earlier than the other colonies 

(e.g., young were observed on June 13, 1994,2), this cave was 

one of the first surveyed each summer beginning in 1995. 

Counts were conducted on warm nights (≥ 12 °C) when 

precipitation was not anticipated. If it rained during a count, 

the count was repeated on a later date. In addition, if any 

count was ≥ 10 percent lower than the previous year’s count, 

the emergence was recounted later in the season to determine 

if the population was actually lower or if not all bats emerged 

during the first count. 

Most emergence counts were conducted outside the cave at the 

entrance, but at two caves with large entrances (the Arbogast 

entrance of the Cave Hollow/Arbogast Cave system and 

Schoolhouse Cave) a more accurate count could be obtained 

by conducting the count a short distance into the cave at a 

location where the cave passage was more constricted. At 

both sites, this could be done without disturbing the colony 

which roosted farther back in the cave. Multiple entrances for 

the same cave were surveyed simultaneously. Equipment (see 

1

 West Virginia Division of Natural Resources, unpublished data.

2

 West Virginia Division of Natural Resources, unpublished data.
78

colony roosted. In 1989, only 286 bats were present. In August 

1996, the cave entrances were gated with angle iron gates. 

Since 1988, there has been no further vandalism at the site. 

Twenty years after the vandalism and population decline, the 

colony in this cave has rebounded to only 75 percent of the 

1988 level (fig. 2). This emphasizes how slow recovery can 

be following significant population declines and importance 

of protecting cave roosts. In 2009, 57 percent of the C. t. 

virginianus in maternity colonies in West Virginia were at sites 

protected with angle iron gates, although all known maternity 

colony sites were closed to human traffic during the summer.

The second example is Lambert Cave which was impacted 

by changing habitat structure at the cave entrance. There 

were 132 bats in the colony in June 1994, before the cave was 

gated (angle iron gate) in October 1994. Following gating, 

number of bats remained fairly stable for a few years and 

then declined to just 29 bats in 2000 (fig. 3). This cave was 

located in a hayfield with a small tree growing at the edge of 

the sinkhole containing the cave entrance. This tree died in 

1999 and increased sunlight allowed burdock (Arctium minus) 

to grow rampantly in the sinkhole, blocking the cave entrance. 

Removal of the burdock allowed an American hornbeam 

(Carpinus caroliniana) to grow large enough to once again 

shade the sinkhole. In 2009, this colony contained 430 bats.

Third, domestic cat predation on C. t. virginianus at the 

entrance of Sinnett Cave was a problem for several years. 

Just inside the cave entrance, the passage is < 1 m high, and 

the original round bar steel gate placed at the cave entrance 

(March 1981) caused bats to circle behind the gate, providing 

cats with increased opportunities to capture bats. In October 

1998, the round bar gate was replaced with an angle iron 

gate constructed several m inside the cave where the cave 

ceiling is several m high. Once the bats passed through 

this gate, they no longer had an obstacle to negotiate in the 

low passage leading out of the cave, and mortality due to 

predation by cats has almost been eliminated at this site and 

the population is increasing (fig. 4).

Lastly, the maternity colony in Cave Mountain Cave has 

decreased in size over the last two and a half decades even 

though the cave has been protected with round bar, and later, 

angle iron gates. The reason for this decline is not known 

although there are two possible causes. First, sporadic 

observations over several years show that the bats begin 

returning to this colony as early as the third week in March. 

Therefore, the closure dates recommended by the USFWS3

 for 

summer C. t. virginianus colonies (April 1 through September 

15) may not have begun early enough to prevent disturbance of 

this colony, especially if human traffic in the cave increased in 

late March as cavers try to get into the cave before it was closed 

for the summer. Secondly, as bat numbers in Cave Mountain 

3

 Personal communication. 1987. Leonard Walker, Wildlife Biologist, U.S. 

Fish and Wildlife Service, Elkins, WV 26241.

(approximately 100 bats or more) were counted by 2 surveyors 

and the average of the 2 counts recorded. In three instances, a 

large cluster was photographed and enumerated later. 

C. t. virginianus using Elkhorn Mountain Cave were 

monitored by WVDNR biologists summer through fall 

1996 and spring through early summer 1997. Mist netting 

was used to capture bats to obtain information on sex 

and reproductive condition, and night-vision counts were 

conducted to obtain population estimates. 

RESULTS

Distribution

Surveys conducted since 1983 documented presence 

of C. t. virginianus in all counties with historic records 

except Preston County. Maternity colonies and hibernacula 

containing more than 25 individuals were located in Grant, 

Pendleton, and Tucker Counties.

Summer Colonies

Maternity colonies—Although there have been population 

declines at certain caves over the 27-year monitoring period, 

the overall trend has been that of a population increase after 

human disturbance at these caves was curtailed (table 1). 

Number of bats at the 7 maternity colonies examined since 

1983 increased 77 percent with 3,073 individuals observed 

in 1983 and 5,420 bats observed in 2009 (table 1). Three 

additional maternity colonies were discovered in Pendleton 

County after 1983: Lambert Cave in 1984, Cliff Cave in 

1992, and Mill Run Cave in 1993. In June 1993, the first year 

all 10 maternity colonies were examined, these caves held 

5,487 bats. In June 2009, these 10 caves contained 7,245 

individuals. During this same period, number of bats in the 

“new” colonies increased 18 percent, from 1,540 to 1,816 

bats (table 1). Therefore, the current estimated number of 

C. t. virginianus in maternity colonies in West Virginia is 

7,245 in 10 colonies in 3 counties (Grant County, 1 colony; 

Pendleton County, 8 colonies; and Tucker County, 1 colony; 

table 1). This represents an increase of 4,172 individuals 

since 1983, including 1,816 bats in colonies discovered after 

1983. In June 2009, colony sizes ranged from 235 to 1,298 

bats with a mean colony size of 725 bats.

In spite of these increases, four examples illustrate potential 

site-specific problems. First, Cave Hollow/Arbogast Cave 

system, the only C. t. virginianus maternity colony cave on 

the west side of the Allegheny Front, had 1,137 bats in 1988 

representing the largest maternity colony in the State at that 

time. The cave was protected by 3-m chain-link fences around 

the several entrances of the cave system. However, vandals 

were able to get past the fence, enter the cave, and build a fire 

inside the cave near where the largest portion of the maternity 
79

Table 1—Number of Corynorhinus townsendii virginianus recorded at maternity colonies via annual, summer 

emergence counts in West Virginia, 1983 to 2009

Cave name

Year

1983 1984 1985 1986 1987 1988 1989 1990 1991

Cave Hollow/Arbogast 605 800 739 1,080 1,015 1,137 286 325 420

Cave Mountain 808 728 812 703 861 773 931 881 826

Cliff

Hoffman School 755 755 771 739 780 930 753 711 777

Lambert 209a 230 277 96 58 49 65 116

Mill Run 

Mystic 254 250 209 239 267 283 274 287 253

Peacock 160 183 207 239 254 326 396 466 497

Schoolhouse 338 378 368 547 548 515 537 449 719

Sinnett/Thorn Mountain 153 216 238 338 426 454 560 538 560

Total 3,073 3,519 3,574 4,162 4,247 4,476 3,786 3,722 4,168

Cave name

Year

1992 1993 1994 1995 1996 1997 1998 1999 2000

Cave Hollow/Arbogast 423 454 491 559 513 454 538 620 618

Cave Mountain 805 762 796 742 768 736 637 568 529

Cliff 1,350b 1,292 1,350b 1,350b 1,243 1,004 1,179 1,250 1,250c

Hoffman School 906 942 857 849 980 970 828 850 890

Lambert 112 134 132 122 126 123 131 106 29

Mill Run 114 153 204 167 231 293 335 312

Mystic 338 357 319 367 377 397 406 488 485

Peacock 573 635 652 730 772 800 862 827 858

Schoolhouse 612 629 673 649 701 815 732 655 718

Sinnett/Thorn Mountain 466 168 304 418 344 279 187 183 245

Total 5,585 5,487 5,727 5,990 5,991 5,809 5,793 5,882 5,934

Cave name

Year

2001 2002 2003 2004 2005 2006 2007 2008 2009

Cave Hollow/Arbogast 614 596 691 664 648 698 756 728 850

Cave Mountain 529 622 532 512 510 564 432 424 357

Cliff 1,250c 1,002 933 1,027 976 910 880 880c 1,151

Hoffman School 910 902 931 1,050 928 1,175 1,029 1,077 1,208

Lambert 177 225 252 202 267 288 295 305 430

Mill Run 136 165 181 154 125 131 178 203 235

Mystic 465 479 510 552 536 576 569 598 618

Peacock 900 1,004 959 982 1,038 979 985 1,013 1,119

Schoolhouse 762 700 808 782 665 630 710 726 795

Sinnett/Thorn Mountain 167 202 148 313 297 361 430 419 482

Total 5,910 5,897 5,945 6,238 5,990 6,312 6,264 6,373 7,245

a Colony discovered in late summer 1984; first count conducted August 28, 1984.

b Estimate based on size of cluster observed in cave; not an emergence count.

c Count not conducted this year and colony size assumed to be the same as when last count was conducted.
80

was one of the “maternity” colony caves monitored in 

1983 and USFWS and WVDNR biologists continued to 

monitor this site annually through 2001. However, biologists 

observing emergences at this cave noted that the bats did not 

seem to exhibit the same “urgency” to exit the cave in the 

evening and emergences often took longer than at the other 

sites. Harp trapping at the cave entrance in July 1999 resulted 

Cave decreased, a new colony was discovered in Mill Run 

Cave 7.9 km away (C. t. virginianus were not observed in this 

cave in previous surveys), making it plausible that that some 

bats from Cave Mountain Cave founded this colony.

Bachelor colonies—C. t. virginianus bachelor colonies are 

largely unknown. Minor Rexrode Cave, Pendleton County, 

0

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Figure 2—Number of Corynorhinus townsendii virginianus in the Cave Hollow/Arbogast Cave system maternity colony, Tucker County, 

WV, 1983 to 2009.

Figure 3—Number of Corynorhinus townsendii virginianus in the Lambert Cave maternity colony, Pendleton County, WV, 1984 to 2009.
81

subsequently observed in four hibernacula up to 31.4 km 

from Elkhorn Mountain Cave. 

Transitional caves—In addition to bachelor colony 

and maternity colony caves, there is a third category of 

cave used by C. t. virginianus in West Virginia. These 

are “transitional” caves used by significant numbers of 

C. t. virginianus (≤ 200+ bats) only in late summer and 

early fall as the bats move from summer colonies to their 

hibernacula. Three transitional caves have been identified 

and all are in Pendleton County: Blood Cave, Flute Cave, 

and Trout Cave.4

 None of these caves house significant 

numbers of C. t. virginianus during summer or winter.

Hibernacula

Most of the known C. t. virginianus hibernating in West 

Virginia are concentrated in a small number of caves with 

over 95 percent of the known hibernating C. t. virginianus

in just three caves. The bats hibernate in densely packed 

clusters, typically in the same specific areas of the caves 

each winter. Hellhole contains the largest hibernating 

concentration of C. t. virginianus anywhere. In the listing 

petition (letter from Michael Harvey and John Hall to Lynn 

Greenwalt, U.S. Fish and Wildlife Service, October 15, 

1976), Hall noted that in West Virginia C. t. virginianus

are more dispersed in winter than in summer. This was 

largely because early surveys in Hellhole failed to locate 

4

 West Virginia Department of Natural Resources, unpublished data.

in the capture of 30 C. t. virginianus, of which 28 were 

males. Although only three C. t. virginianus were trapped at 

the cave on July 13, 2001, all were males. Adult male bats 

of four other species were also captured: Eptesicus fuscus,

M. lucifugus, M. septentrionalis, and P. subflavus. Therefore, 

it appears Minor Rexrode Cave harbors a bachelor colony, 

although occasionally females, probably from one of the two 

maternity colonies located nearby in the same valley, use 

the cave. Bachelor colonies have also been documented in 

Hellhole, Pendleton County (U.S. Fish and Wildlife Service 

1984) and by WVDNR biologists in Elkhorn Mountain Cave, 

Grant County (Stihler and others 1997).

During studies at Elkhorn Mountain Cave, Grant County, in 

late 1996 and early 1997, number of C. t. virginianus in the 

cave increased in the spring from 3 bats on April 4, 1997, 

to a maximum of 159 bats on August 29, 1996, and then 

declined in the fall to 12 bats on October 31, 1996 (fig. 5). As 

the number of bats increased toward the end of summer, the 

sex ratio shifted. Whereas only males were captured on June 

30, 6.9 percent were females on July 2, 44.7 percent were 

females on September 11, and 16.0 percent were females 

on October 22. This finding contrasts with a study in Lee 

County, KY, which found that number of males in bachelor 

colonies declined in mid-August, coinciding with onset of 

mating (Lacki and others 1994). Bachelor colony sites may 

be important breeding locations in late summer and fall and 

may facilitate genetic mixing of bats from various summer 

and winter concentrations. This is evidenced by bats banded 

at Elkhorn Mountain Cave during summer and fall being 

Figure 4—Number of Corynorhinus townsendii virginianus in the Sinnett/Thorn Mountain Cave system maternity colony, Pendleton 

County, WV, 1983 to 2009.

0

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200

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600

19831984198519861987198819891990199119921993199419951996199719981999200020012002200320042005200620072008

2009 

Year

Number of Bats
82

WHITE-NOSE SYNDROME

White-nose syndrome (WNS), a condition that appears to 

be caused by the fungus Geomyces destructans (Gargas 

and others 2009), has resulted in the deaths of over a 

million bats in the Northeastern United States since it 

was first observed near Albany, NY, in 2006 (Blehert 

and others 2008). In January and February 2009, WNS 

was confirmed by the U.S. Geological Service National 

Wildlife Health Center (Madison, WI) in bats collected 

in Pendleton County, WV, and WNS was detected in four 

caves in that county (Cave Mountain Cave, Hamilton 

Cave, Trout Cave, and Cliff Cave). Cliff Cave is used by 

significant numbers of C. t. virginianus in both winter 

and summer; Cave Mountain Cave contains a maternity 

colony and a small number of bats in the winter, and the 

other two caves receive occasional use by this species. 

Although C. t. virginianus were present in three of the 

WNS-affected caves in 2009, none exhibited signs of 

WNS. In January 2010, WNS was confirmed by the 

Southeastern Cooperative Wildlife Disease Study (Athens, 

GA) in M. lucifugus from Hellhole. P. subflavus and M. 

lucifugus collected from Sinnett Cave in March 2010 also 

tested positive. In February and early March 2010, 12,059 

hibernating C. t. virginianus were observed, including 

10,025 in Hellhole and 199 in Sinnett Cave, and again, no 

C. t. virginianus exhibited visible signs of WNS. However, 

all other cave bat species within the current range of WNS 

some areas of the cave which contained concentrations of 

hibernating C. t. virginianus. The first survey to include all 

areas where C. t. virginianus are now known to hibernate 

was conducted in 1986 when 2,914 C. t. virginianus were 

counted. A survey conducted in February 2010 documented 

10,025 hibernating C. t. virginianus in Hellhole. However, 

the previous survey (February 2007) located only 5,006 C. 

t. virginianus in these areas. It seems possible that this large 

increase (100 percent in 3 years) may be a result of the 

bats shifting locations within the cave due to a reduction in 

human activity in the cave beginning in September 2007.5

In addition, 2 other caves (Sinnett and Schoolhouse) were 

visited in 2010 and, based on the 2010 data for these 3 

caves and the 2009 survey data for 10 other C. t. virginianus hibernacula, number of C. t. virginianus known to 

hibernate in West Virginia caves was estimated at 12,059 

individuals with 10,025 (83 percent) in Hellhole. Also, 

based on these data, three caves (Cave Hollow/Arbogast 

Cave system, Hellhole, and Schoolhouse Cave) contain 96 

percent (11,559 individuals) of the known hibernating C. 

t. virginianus in West Virginia. This is an increase of 124 

percent compared to the first complete count of these caves 

(1988 to 1989; 5,170 bats).

5

 Personal communication. 2010. Gordon Brace, Germany Valley Karst 

Survey, Falls Church, VA 22043.

0

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06/14/9706/23/97

Date

Number of Bats

Figure 5—Number of Corynorhinus townsendii virginianus in the Elkhorn Mountain Cave bachelor colony, Grant County, WV, June 14, 

1996 through June 23, 1997. 
83

2009 to 2010 of 66 percent (West Virginia Department of 

Natural Resources data)], G. destructans may not grow 

as well as at sites where M. lucifugus and P. subflavus

hibernate and where relative humidity is high and the 

bats are often covered with condensation. Although no 

visible G. destructans has been observed on hibernating 

C. t. virginianus, the fungus may still affect these bats 

without presenting the classic external fungal growth 

usually associated with WNS.

Because C. t. virginianus in the Pendleton County area 

of West Virginia and adjacent Virginia has a restricted 

range (an area approximately 48 km by 58 km in extent) 

and most of these bats are concentrated in a small number 

of caves, if WNS causes large-scale mortality events in 

C. t. virginianus, it is likely that most of the bats in this area 

will be impacted relatively quickly. C. t. virginianus in the 

New River Gorge National River (at the time of writing, 

approximately 97 km from WNS-affected sites) may not be 

impacted as soon. In 2009, with the largest concentration 

of C. t. virginianus in the world within the range of WNS, 

the USFWS, in consultation with State agencies and 

species experts, developed a captive propagation plan for 

C. t. virginianus. In November 2009, 40 C. t. virginianus

from Pendleton County, WV, were transported to the 

Smithsonian Conservation Biology Institute near Front 

Royal, VA, where a protocol for the captive holding of these 

bats was developed with the hope of establishing a captive 

security population of C. t. virginianus isolated from WNS 

(Smithsonian Institution project proposal submitted to 

USFWS, September 2009).

Maternity colony counts conducted in June 2010 were the 

second highest on record and only 103 bats (1.4 percent) less 

than the 2009 total (7,245). In addition, counts conducted at 

5 of the 10 maternity colonies in late July and early August 

2010, after the young were volant, showed a 21 percent 

increase in number of bats over June 2010 numbers, 

suggesting the colonies were successful in producing young. 

Monitoring C. t. virginianus for impacts of WNS will 

continue to be a high priority. 

ACKNOWLEDGMENTS

The author thanks the owners of C. t. virginianus caves for 

their cooperation and assistance in protecting important bats 

roosts; the USFWS for providing funding through section 6 

grants for monitoring and protection of C. t. virginianus and 

their cave roosts; the U.S. Department of Agriculture Forest 

Service, Monongahela National Forest, for managing caves 

to benefit these bats and for providing WVDNR biologists 

access to these caves for monitoring C. t. virginianus

populations; and the American Cave Conservation 

Association and numerous volunteers who have assisted in 

have been affected with several species experiencing 

mortality levels in excess of 90 percent in affected 

hibernacula (Turner and Reeder 2009). 

CONCLUSIONS

When C. t. virginianus was listed as federally endangered 

in 1979, populations of this bat using West Virginia cave 

roosts were declining, probably as a result of increased 

disturbance related to increased speleological use of these 

caves. Protection of cave roosts through cave closures and 

installation of fences and gates at cave entrances resulted in 

increases in numbers of bats at known maternity colonies 

of 77 percent. I believe changes in land cover were minimal 

over the study period and were not a factor in the observed 

population increase. For example, a comparison of land 

cover data from 1992 and 2009 [National Land Cover 

Dataset 1992 (Vogelmann 1998) and Landscape Fire and 

Resource Management Planning Tools Project (Ryan and 

others 2006)] show the changes in open and forest cover 

types in the three-county area where maternity colonies 

occur was < 1.6 percent during this 17-year period. 

C. t. virginianus readily adapts to gates, including angle 

iron gates, which are both secure and bat friendly. Several 

important C. t. virginianus caves in West Virginia are not 

currently gated with angle iron gates and, where feasible, 

these caves should be protected with angle iron gates when 

there are opportunities to do so. Future research should 

attempt to locate and protect additional caves and mines used 

by C. t. virginianus. 

Monitoring of both maternity colonies and hibernacula 

confirmed increases in bat numbers after cave protection 

measures were implemented. In West Virginia, maternity 

colony data probably provide a better indication of 

population trends because of the difficulty of getting a 

complete survey of a large and complex hibernaculum such 

as Hellhole. Summer emergence counts before parturition 

provide good estimates of colony size even if the roost sites 

within the cave are not known.

While most efforts to date have focused on maternity colony 

and hibernation sites, importance of bachelor colonies 

and transitional caves should be further investigated. 

Although not the focus of this paper, status and conservation 

importance of the C. t. virginianus population in the New 

River Gorge National River area in Fayette County should be 

determined.

While the most serious threat to C. t. virginianus may be 

WNS, to date there is no evidence that WNS is affecting 

this species. Because C. t. virginianus often hibernate in 

the drier portions of caves [e.g., mean relative humidity 

in winter at the hibernation site in Schoolhouse Cave, 
84

endangered C. t. virginianus. Conservation Genetics. 10: 

169-176.

Reese, A.M. 1934. The fauna of West Virginia caves. Proceedings of 

the West Virginia Academy of Science. 7: 39-53.

Ryan, K.C.; Lee, K.M.; Rollins, M.G. Z. [and others]. 2006. 

Landfire: Landscape Fire and Resource Management Planning 

Tools project. In: Andrews, P.L.; Butler, B.W., comps. Fuels 

management-how to measure success: conference proceedings. 

RMRS-P-41. Fort Collins, CO: U.S. Department of Agriculture 

Forest Service, Rocky Mountain Research Station: 193-200. 

[Data updated to 2009].

Stihler, C.W. 2011. Radiotelemetry studies of female Virginia bigeared bats (Corynorhinus townsendii virginianus) in Pendleton 

County, West Virginia. In: Loeb, S.C.; Lacki, M.J.; Miller, D.A., 

eds. Conservation and management of eastern big-eared bats: 

a symposium. Gen. Tech. Rep. SRS-145. Asheville, NC: U.S. 

Department of Agriculture Forest Service, Southern Research 

Station: 139-146.

Stihler, C.W.; Wallace, J.; Jones, A.; Mitchell, D. 1997. Endangered 

species Federal assistance performance report. Proj. E-1-14. 

Charleston, WV: West Virginia Division of Natural Resources. 

57 p.

Turner, G.G.; Reeder, D.M. 2009. Update of white nose syndrome 

in bats, September 2009. Bat Research News. 50(3): 47-53.

U.S. Fish and Wildlife Service. 1984. A recovery plan for the Ozark 

big-eared bat and Virginia big-eared bat. Fort Snelling, MN: 

U.S. Fish and Wildlife Service. 119 p.

Varner, M.S. 2008. Spring emergence and fall swarm bat 

monitoring at New River Gorge National River Program. Report 

NPS/NER/NERI-1428-07B. Glen Jean, WV: U.S. Department of 

the Interior, National Park Service, New River National River. 

Vogelmann, J.E.; Sohli, T.L.; Campbell, P.V.; Shaw, D.M. 1998. 

Regional land cover characterization using Landsat Thematic 

Mapper data and ancillary data sources. Environmental 

Monitoring and Assessment. 51: 415-428.

Wilson, L.W. 1946. Notes on bats from eastern West Virginia. 

Journal of Mammalogy. 29(1): 85-86.

Wilson, L.W. 1948. An introduction to the mammals of West 

Virginia. Charleston, WV: West Virginia Conservation 

Commission. 20 p.

gating C. t. virginianus caves to reduce disturbance to these 

bats. The author also thanks those WVDNR employees 

who have dedicated many days and nights working on 

C. t. virginianus bat projects, especially Jack Wallace and 

Rick Doyle, and Tabitha Viner, a volunteer who has donated 

considerable vacation time to help monitor summer colonies 

of C. t. virginianus in West Virginia. Michael Dougherty 

(WVDNR) assisted with land cover data analyses. The 

Nature Conservancy’s assistance with the WVDNR’s 

acquisition and protection of an important C. t. virginianus

cave was greatly appreciated.

LITERATURE CITED

Bagley, F.; Jacobs, J. 1985. Census technique for endangered bigeared bats proving successful. Endangered Species Technical 

Bulletin. 10(3): 5-7.

 Barbour, R.W.; Davis, W.H. 1969. Bats of America. Lexington, 

KY: University Press of Kentucky. 286 p.

Blehert, D.S.; Hicks, A.C.; Behr, M. [and others]. 2008. Bat whitenose syndrome: an emerging fungal pathogen? Science Express. 

DOI: 10.1126/science.1163874.

Frum. W.G. 1947. Bats of West Virginia. Morgantown, WV: West 

Virginia University. 17 p. M.S. thesis.

Gargas, A.; Trest, M.T.; Christensen, M. [and others]. 2009. 

Geomyces destructans sp. nov. associated with bat white-nose 

syndrome. Mycotaxon. 108: 147-154.

Handley, C.O. 1959. A revision of the American bats of the genera 

Euderma and Plecotus. Proceedings of the U.S. National 

Museum. 110(3417): 95-246.

Kellogg, R. 1937. Annotated list of West Virginia mammals. 

Proceedings of the U.S. National Museum. 84(3022): 448-450.

Lacki, M.J.; Adam, M.D.; Shoemaker, L.G. 1994. Observations 

on seasonal cycle, population patterns and roost selection 

in summer colonies of Plecotus townsendii virginianus in 

Kentucky. American Midland Naturalist. 131(1): 34-42. 

Piaggio, A.J.; Navo, K.W.; Stihler, C. 2009. Intraspecific 

comparison of population structure, genetic diversity, and 

dispersal among three subspecies of Townsend’s big-eared bats, 

Corynorhinus townsendii townsendii, C. t. pallescens, and the 
85

(Bayless and others 2011, Kentucky State Nature Preserves 

Commission 1996, Lance 1999). 

In spite of conservation concerns, little is known about 

evolutionary relationships, genetic diversity, and gene flow 

among populations of C. rafinesquii. For any species of 

concern, it is important that evolutionary relationships, or 

taxonomy, of that species is understood. In a taxonomic 

revision of the genus Corynorhinus based on morphological 

characters, Handley (1959) designated two subspecies of 

C. rafinesquii assigning populations from the Southeastern 

United States (Alabama, Arkansas, Florida, Georgia, 

Louisiana, Mississippi, North Carolina, eastern Oklahoma, 

South Carolina, eastern Texas, and coastal Virginia) to 

C. r. macrotis and populations from East Central United States 

(northern Alabama, Arkansas, northern Georgia, Kentucky, 

southern Illinois, southern Indiana, northern Mississippi, 

eastern Missouri, western North Carolina, southern Ohio, 

eastern Oklahoma, western South Carolina, Tennessee, 

western Virginia, western West Virginia) to C. r. rafinesquii,

with areas where the two subspecies overlapped (Handley 

1959:152). More recently, Piaggio and Perkins (2005) tried 

to elucidate evolutionary relationships of C. rafinesquii using 

INTRODUCTION

Rafinesque’s big-eared bat (Corynorhinus rafinesquii) is a 

medium-sized bat that ranges across a broad portion of the 

Southeastern United States (fig. 1; Bayless and others 2011). 

However, there has been concern about its status since the 

mid-20th century due to low population numbers and patchy 

distribution. Handley (1959) expressed concern for the status 

of this species based on lack of known large colonies and 

limited numbers of museum specimens. He concluded that 

populations had declined due to anthropogenic impacts in 

parts of their range. Jones and Suttkus (1975) published 

data from a 9-year study in Louisiana and concluded that 

these bats were rare likely due to severe population declines. 

They also concluded that reduction occurred because 

C. rafinesquii is sensitive to disturbance from humans at 

vulnerable maternity roost sites which were principally 

found in abandoned manmade structures. Based on concerns 

over status of this species, it was listed as vulnerable to 

extinction on the 2004 International Union for Conservation 

of Nature Red List, a Federal species at risk (U.S. Fish and 

Wildlife Service 1985), and a species of concern in every 

State, except Virginia, where they are considered endangered 

PHYLOGENETIC AND POPULATION GENETIC ASSESSMENT OF 

RAFINESQUE’S BIG-EARED BAT (CORYNORHINUS RAFINESQUII)

Antoinette J. Piaggio, Research Biologist, U.S. Department of Agriculture, Wildlife Services, 

National Wildlife Research Center, 4101 LaPorte Avenue, Fort Collins, CO 80521

David A. Saugey, Wildlife Biologist, U.S. Department of Agriculture Forest Service, 

Ouachita National Forest, P.O. Box 189, Jessieville, AR 71949-0189

D. Blake Sasse, Nongame Mammal/Furbearer Program Leader, Arkansas Game and Fish Commission, 

213A Highway 89 South, Mayflower, AR 72106

Abstract—Rafinesque’s big-eared bat (Corynorhinus rafinesquii) is distributed across the Southeastern United States. 

Due to habitat loss and low population numbers, this species is a Federal species of concern and protected by every State 

within its range. Effective management of any species of concern is dependent on an unambiguous understanding of 

taxonomic relationships. However, for this species, there are discordant inferences about subspecific designations from 

previous studies. Further, there have been no assessments of population genetic status for this species. Such assessments 

could provide information on genetic diversity and population connectivity and increase our understanding of the 

need for management and conservation of this species. Therefore, our goals were to assess population level genetic 

diversity and connectivity among 5 colonies in Arkansas (139 individuals) and to infer the evolutionary relationships of 

these bats to C. rafinesquii collected across its distribution (additional 216 individuals). We used mitochondrial DNA 

control region sequences and 11 microsatellite loci to infer genetic relationships, estimate levels of genetic diversity, 

and examine population connectivity among 5 colonies in Arkansas. Although we identified two phylogenetically 

divergent mitochondrial DNA lineages, these correspond to neither current subspecific designation nor nonoverlapping 

geographical groups. Genetic diversity and population connectivity estimated from mitochondrial DNA was high in 

Arkansas populations probably due to occurrence of both evolutionary lineages within each colony. However, estimates 

from microsatellite DNA of genetic diversity, population connectivity, and effective population sizes in these populations 

were low. Further, our results suggested a weak signal of population bottleneck in Arkansas colonies and low genetic 

connectivity. Current conservation efforts should continue to focus on protection of roosts and improvement of habitat 

corridors to connect populations.

Citation for proceedings: Loeb, Susan C.; Lacki, Michael J.; Miller, Darren A., eds. 2011. Conservation and management of eastern big-eared bats: 

a symposium. Gen. Tech. Rep. SRS-145. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 157 p.
86

Figure 1—Distribution of Corynorhinus rafinesquii with Arkansas roosts sampled shown in detail 

(AR1, AR2, AR3, AR4, and AR5) and number of individuals sampled per colony noted. (Map from the 

University of Texas, Austin, TX, Perry Casteñeda Library map collection online http://www.lib.utexas.edu/

maps/.)

AR 1 N=48

AR 2 N=14

AR 5 N=19

AR 3 N=15

AR 4 N=20

limited sampling from portions of the species’ range and both 

mitochondrial and nuclear DNA sequences. That study found 

that there was no correlation between the two designated 

subspecies of C. rafinesquii, from Handley (1959), and the 

molecular phylogeny. Piaggio and Perkins (2005) concluded 

that a more detailed study of C. rafinesquii including more 

samples representing a greater portion of their range was 

required to determine if any subspecific designation was 

warranted. To correctly determine conservation status of this 

species, it is critical that evolutionary relationships, and, thus, 

taxonomy and geographical boundaries of taxonomic units, 

are understood. A molecular phylogenetic approach such as 

the one used in Piaggio and Perkins (2005) with additional 

samples from across the range of C. rafinesquii could provide 

such information.

Piaggio and Perkins (2005) found that there were two 

divergent evolutionary lineages of C. rafinesquii. However, 

both clades had samples from Arkansas and some samples in 

each clade were from the same colonies. After more than 10 
87

MATERIALS AND METHODS

Study Area

We collected samples from across the Southeastern United 

States. The study area in Arkansas included widely spaced 

locations in Columbia, Dallas, and Ouachita Counties 

within the Tertiary Uplands of the southcentral Plains and 

Prairie County within the Grand Prairie of the Mississippi 

River Alluvial Plain, Arkansas (Arkansas Natural Heritage 

Commission 2003). The Tertiary Upland sites were dominated 

by commercial shortleaf and loblolly pine (Pinus echinata

and P. taeda) plantations that largely replaced native oakhickory-pine (Quercus spp.-Carya spp.) forests except in 

narrow streamside zones (Woods and others 2004). Forested 

tracts were interspersed with bayous and by pasture for 

grazing cattle. Most of the large bottomland hardwood timber 

had been harvested (Dahl 1990). The Grand Prairie was a 

loess-covered terrace that once contained an extensive tall 

grass prairie converted to cropland in the early 20th century 

(Holder 1970). Average precipitation was 127 cm, and average 

temperatures are highest in July (average 32 °C) and lowest 

in January (7 °C). Expansive areas of rice, soybeans, cotton, 

corn, and wheat were cultivated in the area (Woods and others 

2004). Braided bayous were found throughout this area with 

bottomland hardwood forests occurring along drainages and 

floodplains, upland hardwood forests along hills and bluffs, 

and hardwood savannas along the edges of prairie terraces. 

Forested acres had been reduced by more than half through 

conversion to croplands and development (Shepherd 1984). 

The eastern border of the Grand Prairie was adjacent to the 

White River riparian area that contained some of the most 

extensive areas of remaining bottomland hardwood forests in 

Arkansas (Woods and others 2004).

Sample Collection

We collected tissue samples during 2000 to 2005 at five 

roosts in Arkansas (fig. 1). Sites AR1 (48 individuals), AR2 

(14 individuals), and AR5 (33 individuals) were maternity 

roosts; AR3 (15 individuals) and AR4 (29 individuals) were 

hibernacula. However, the hibernacula used by individuals 

from AR1 and AR5 and the maternity roosts for individuals 

from AR3 and AR4 were known and adjacent to sites where 

samples were collected, e.g., abandoned house used as a 

maternity roost and adjacent well used as a hibernaculum. 

Therefore, we assumed that each of these sites represented a 

single and separate colony. Further, based on approximately 

12 years of mark-recapture data representing 3,500 

captures of bats at these sites, exchange of individuals was 

uncommon among sampled sites even when they were 

proximate (< 14 km) to one another. Therefore, we assumed 

that each sampled maternity roost or hibernation site was 

a single colony. We also sequenced DNA from 216 other 

individuals from other parts of the range of C. rafinesquii 

(Florida, Kentucky, Mississippi, North Carolina, Tennessee, 

years of study, there have been only five known continually 

active colonies of C. rafinesquii in Arkansas, all of which 

occupy abandoned humanmade structures (Saugey 2000). 

These colonies are found in a region of Arkansas that was 

historically dominated by bottomland hardwood forests 

which have been largely converted to agricultural uses and 

are one of the most endangered forest types in the United 

States (Abernathy and Turner 1987, The Nature Conservancy 

1992, Turner and others 1981). It is assumed that mature, 

hollow trees in the bottomland hardwood forests represent 

historical roosting habitat for C. rafinesquii (Clark 1990, 

1991). Therefore, it appears that these bats may use abandoned 

manmade structures because of loss of natural roosts. Because 

all of the known C. rafinesquii colonies in Arkansas were 

located in abandoned manmade structures, there was concern 

that these colonies were remnant populations and that they 

may have lost connectivity and suffered reduced genetic 

diversity due to the loss of contiguous bottomland habitat. 

Further, these colonies were considered threatened due to the 

ephemeral nature of their roosts. 

Maintenance of genetic diversity within populations and 

connectivity among genetically diverse populations is crucial 

for sustaining the evolutionary potential of a species (England 

and others 2003). A loss of population connectivity as a 

result of reduced and/or fragmented habitat may increase 

susceptibility to a population bottleneck (Cornuet and Luikart 

1996), which can allow genetic drift to affect a population 

resulting in low effective population size, loss of genetic 

diversity, and inbreeding. Such populations are likely more 

susceptible to disease, ecological catastrophes, and eventual 

extinction, thus, impacting evolutionary potential of that 

species (Altizer and others 2003, Lacy 1997). Analyses of 

maternally inherited mitochondrial DNA (mtDNA) and 

biparentally inherited autosomal microsatellites can be 

used to infer genetic relationships and to estimate various 

population parameters including genetic diversity, population 

connectivity, and effective population sizes (Avise 1995, Avise 

and Hamrick 1996, Haig 1998). If populations exhibit genetic 

evidence of population bottlenecks, reduced genetic diversity, 

and/or reduced effective population sizes, then targeted 

conservation efforts and management practices are needed.

Given the conservation status of C. rafinesquii and lack of 

data regarding genetic diversity for this species, we employed 

genetic markers, both mtDNA and microsatellites, to infer 

evolutionary relationships of C. rafinesquii with samples from 

across its range and to estimate genetic diversity, connectivity 

among populations, and effective population sizes among 

Arkansas colonies. We predicted that due to past habitat loss 

and subsequent disjunction and/or population reduction, 

we would detect population bottlenecks. If true, estimates 

of genetic diversity and population connectivity would be 

low and there might also be inbreeding and low effective 

population sizes. This, in turn, would guide recommendations 

for species’ conservation from a genetic perspective.
88

1991). We used half of each wing punch to extract genomic 

DNA using a DNeasy Blood & Tissue Kit (QIAGEN Inc., 

Valencia, CA) following the manufacturer’s protocol.

DNA Amplification, Sequencing, 

and Genotyping

We amplified genomic DNA from each sample and 

the mtDNA control region was sequenced, following 

protocols described in Piaggio and Perkins (2005). We 

genotyped C. rafinesquii from Arkansas roosts (AR1, 48 

individuals; AR2, 11 individuals; AR3, 15 individuals; 

AR4, 20 individuals; and AR5, 18 individuals) using 11 

loci: EF15B, EF20C, EF21, EF14 (Vonhof and others 

2002), NN8 (Petri and others 1997), PAUR 05 (Burland 

and others 1998), Cora_ D12_D12, Cora_E07_E07, Cora_

H07_C05, Cora_ B07_ H12, and Cora_E10_G03 (Piaggio 

South Carolina, Louisiana, and Texas) and 5 other Arkansas 

individuals, and we included these in our phylogenetic 

analysis (table 1; fig. 1). 

We captured individual C. rafinesquii in Arkansas colonies 

found in wells using a method employing an umbrella 

(England and Saugey 1999). When bats were found in 

abandoned buildings, we used hand nets for capture. Bats 

collected outside of Arkansas were captured using mist nets. 

We collected a 3-mm tissue biopsy from the right wing 

(Worthington Wilmer and Barratt 1996) before releasing 

bats at site of capture. Capture and sampling protocols 

were reviewed and approved by the University of Colorado, 

Boulder’s Institutional Animal Care and Use Committee. We 

preserved samples in a 20-percent dimethyl sulfoxide and a 

0.25M-ethylenediaminetetraacetic acid solution saturated with 

sodium chloride and optimized at pH 8.0 (Seutin and others 

Table 1—Genetic samples of Rafinesque’s big-eared bats (Corynorhinus rafinesquii) sequenced and analyzed with 

localities, ownership/donator, and GenBank accession numbers indicated

Taxon Localitya Donor/ownerb Popc Acc nod

C. mexicanus Guanaceví, Durango, Mexico CIIDIR CRD 3110

Celia López-González

AY713590

Guanaceví, Durango, Mexico CIIDIR CRD 3125

Celia López-González

AY713591

Guanaceví, Durango, Mexico CIIDIR CRD 3115

Celia López-González

AY713593

Milpa Alta, Distrito Federal, Mexico Rafael Avila-Flores AY713785

C. rafinesquii Arkansas, Columbia USFS David Saugey AR1 AY713635–AY713643

AY713666–AY713675

AY713684–AY713696

AY713717–AY713731

Arkansas, Prairie AGFC Blake Sasse AR2 AY713652–AY713665

Arkansas, Ouachita USFS David Saugey AR3 AY713900–AY713909

AY775995–AY775999

Arkansas, Ouachita USFS David Saugey AR4 AY713910–AY713919

AY775976–AY775985

HQ239099–HQ239102

HQ239107–HQ239111

Arkansas, Dallas USFS David Saugey AR5 AY713920–AY713929

AY775986–AY775994

HQ239095–HQ239098

HQ239112–HQ239121

Florida, Osceola Laura Finn

Kelli Deichmueller

AY713789–AY713790

Florida, Holmes FFWCC Jeff Gore AY713818

Kentucky, Estill KDFWR Traci Wethington AY713877–AY713878

AY713881–AY713882

Kentucky, Bath Eric Britzke AY713786–AY713788

Louisiana, Union Parish Chris Rice HQ239178–HQ239194

continued
89

Table 1—Genetic samples of Rafinesque’s big-eared bats (Corynorhinus rafinesquii) sequenced and analyzed with 

localities, ownership/donator, and GenBank accession numbers indicated (continued)

Taxon Localitya Donor/ownerb Popc Acc nod

C. rafinesquii 

(continued)

Mississippi, Perry Austin Trousdale AY713842–AY713854

Mississippi, Wayne Austin Trousdale AY713855–AY713860

Mississippi, Jones Austin Trousdale AY713861

Mississippi, Noxubee USFWS David Richardson HQ239077–HQ239092

North Carolina, Bladen Mary Kay Clark AY713595–AY713620

South Carolina, Charleston Heather Thomas AY713698–AY713701

AY713751–AY713756

HQ239093–HQ239094

HQ239103–HQ239106

South Carolina, Oconee SCDNR Mary Bunch AY713767

South Carolina, Pickens SCDNR Mary Brunch AY713768

South Carolina, Richland SCDNR Mary Bunch AY713792

South Carolina, Dorchester Piaggio AY713791

South Carolina, Orangeburg Frances Bennett AY713819–AY713820

AY713822

South Carolina, Kershaw Frances Bennett AY713821

South Carolina, Barnwell Frances Bennett AY713823

South Carolina, Williamsburg Frances Bennett AY713824–AY713825

AY713827–AY713828

South Carolina, Georgetown Frances Bennett AY713826

South Carolina, Colleton Frances Bennett AY713829–AY713830

Tennessee, Chester Brian Carver HQ239122–HQ239152

Tennessee, Fentress Mary Kay Clark HQ239153–HQ239177

Texas, Harrison Leigh Stuemke/Chris 

Comer

HQ239208–HQ239209

HQ239213–HQ239215

HQ239218–HQ239220

HQ239223–HQ239225

HQ239228–HQ239230

Texas, Liberty Leigh Stuemke/Chris 

Comer

HQ239199

HQ239203–HQ239207

HQ239210–HQ239212

HQ239216–HQ239217

HQ23922–HQ239222

HQ239226–HQ239227

HQ239231–HQ239232

Texas, Polk Leigh Stuemke/Chris 

Comer

HQ239195–HQ239198

HQ239200–HQ239202

CIIDIR = Colección Regional Durango (Vertebrados), CIIDIR Durango, Instituto Politécnico Nacional, México; USFS = U.S. Forest Service, 

Ouachita National Forest; AGFC = Arkansas Game and Fish Commission; FFWCC = Florida Fish and Wildlife Conservation Commission; 

KDFWR = Kentucky Department of Fish and Wildlife Resources; USFWS = U.S. Fish and Wildlife Service, Noxubee National Wildlife Refuge; 

SCDNR = South Carolina Division of Natural Resources. 

a State, county (or city, State, country).

b Person and/or organization that donated tissue and/or owns sample; museum catalog numbers provided when possible.

c Population belongs to; applicable only to Arkansas populations surveyed in detail in this study.

d GenBank accession number.
90

of unique haplotypes, haplotype diversity, nucleotide 

diversity (Nei 1987), parsimony informative sites, and 

average pairwise differences within Arkansas populations 

and other populations where there was adequate sample 

size for comparison (Union Parish, LA, n = 17; Noxubee 

County, MS, n = 16; Blanden County, NC, n = 26; Chester 

County, TN, n = 31; Fentress County, TN, n = 25; Liberty 

County, TX, n = 17). To evaluate how genetic diversity 

was distributed among Arkansas populations, we first 

estimated population differentiation using FST (Weir and 

Cockerham 1984) and ascertained significant substructure 

between populations with 5,000 randomization tests. We 

used sequential Bonferroni corrections to compute critical 

significance levels for these data (Rice 1989). We then 

evaluated the relationship between population differentiation 

(Slatkin’s linear FST/(1 – FST); Slatkin 1993) and logtransformed geographic distances (log10km) to determine 

if there was isolation-by-distance (IBD). We also used this 

method to test for IBD across the range of the species by 

using the Arkansas populations and other populations from 

across the range where adequate sample size was collected 

(see above). We appraised nested levels of variation among 

colonies and within colonies using an analysis of molecular 

variance (AMOVA; Excoffier and others 1992) with 9,000 

permutations. We performed these evaluations using Arlequin 

ver. 3.1 (Excoffier and others 2005) except for the calculation 

of the parsimony informative sites, which we evaluated with 

PAUP* 4.0b (Swofford 2002). 

Microsatellite Analyses

We assessed microsatellite loci for null alleles using MicroChecker (Van Oosterhout and others 2004). We also tested loci 

for significant departures from Hardy-Weinberg equilibrium 

(HWE) with 9,000 steps of a Markov chain and significant 

evidence of linkage disequilibria among loci using Arlequin 

ver. 3.1 (Excoffier and others 2005). We used sequential 

Bonferroni corrections to compute critical significance levels 

for multiple tests using these data (Rice 1989). We maintained 

genotype data in a spreadsheet, and then we used the software 

Convert (Glaubitz 2004) to transform this file into input files 

for other software packages used in further analyses. 

We quantified intrapopulation genotypic variability as mean 

number of alleles (A), allelic richness (a), and number of 

private alleles (pa) per locus. We estimated the withinpopulation inbreeding coefficient, FIS, and tested for significant 

departure from zero with 1,000 randomizations. We performed 

these analyses with FSTAT 2.9.3 (Goudet 2001). We also 

estimated effective population size (Ne) for each population 

using the linkage disequilibrium model method for single 

sampling efforts implemented in the LDNE program (Waples 

and Do 2008). This program includes a bias correction from 

Waples (2006) for uneven sample sizes relative to Ne. We 

conducted estimates of Ne with parametric confidence intervals 

(CI) to include alleles with a frequency of ≥ 0.02.

and others 2009a). We amplified products from these loci 

via polymerase chain reaction (PCR) with one primer endlabeled with TET, FAM, or HEX fluorescent label (SigmaGenosys Co., USA). We amplified each microsatellite 

PCR for the primers designed from other bat species in a 

standard 25 μl reaction which contained optimized amounts 

of PCR water; 5X buffer C (Invitrogen by Life Technologies 

Corp., USA); 2.5 μl of dNTP (10 mM; Invitrogen by Life 

Technologies Corp., USA); 2.5 μl of each primer (1 pM/ μl); 

Taq DNA polymerase (Promega Corp., USA); and 1 μl 

of genomic DNA. Amplification consisted of an initial 

denaturation at 94 °C for 2 minutes followed by 30 cycles 

of denaturing at 94 °C for 30 seconds, annealing at 56 °C 

(PAUR05 and EF15), 52 °C (EF21), or 46 °C (EF14, EF20C, 

and NN8) for 45 seconds, and extension at 72 °C for 45 

seconds with a final extension period of 7 minutes at 72 °C. 

Amplification protocols for the C. rafinesquii primers are 

described in Piaggio and others (2009a).

We visualized genotypes from the primers designed 

from other bat species and some sequencing products on 

acrylamide gels on a MJ BaseStation 51TM sequencer (MJ 

Bioworks, Inc., Sauk City, WI). We scored microsatellite 

alleles with Cartographer 1.2.6 software (MJ Bioworks, Inc., 

Sauk City, WI) and confirmed these by manual examination. 

We visualized the C. rafinesquii specific microsatellites and 

remaining sequences on an AB 3130 (Applied Biosystems by 

Life Technologies Corp., Foster City, CA) automated genetic 

analyzer and scored with ABI GeneMapper® Software.

Sequence Analyses

We generated alignments of mtDNA control region 

sequences using Sequencher® 4.9 (Gene Codes Corp., Ann 

Arbor, MI) and checked by eye. We used C. mexicanus

sequences generated from a previous study (Piaggio and 

Perkins 2005) as an outgroup for phylogenetic analyses 

because this is the sister taxon to C. rafinesquii (Hoofer 

and Van Den Bussche 2001, Piaggio and Perkins 2005). 

We completed maximum likelihood phylogenetic analyses 

using RAxML (Stamatakis 2006, Stamatakis and others 

2008) available through Web-based Cyberinfrastructure for 

Phylogenetic Research (CIPRES) supercomputer [http://

www.phylo.org/. (Date accessed: November 19, 2010)]. We 

implemented the estimation of the general time reversible 

substitution model with gamma distributed rate variation 

estimation using RAxML (Stamatakis and others 2005). We 

evaluated bootstrap analysis of nodal support with number of 

pseudoreplicates automatically generated by the program. We 

visualized the maximum likelihood tree output and edited for 

publication and a radial tree layout of this tree was generated 

in FigTree v.1.2.1 [http://tree.bio.ed.ac.uk/software/figtree/. 

(Date accessed: November 19, 2010)].

We quantified genetic diversity from DNA sequence data as 

number of individuals sequenced per population, number 
91

from both rooting strategies provided the same topology, 

so we omitted the outgroup to improve readability. We 

considered 1,064 base pairs from the control region. 

In the HVII region there was a C-repeat that varied in 

length among the samples. Often during the sequencing 

process, the polymerase failed in this repeat region, and 

determining number of repeats accurately was not possible. 

Therefore, we eliminated this repeat region across all 

samples for all analyses. Among the sequences, there were 

810 constant sites, 68 variable sites that were parsimony 

uninformative, and 186 parsimony informative sites. Within 

the 360 C. rafinesquii sequences, there were 318 unique 

haplotypes. The maximum likelihood tree had 2 statistically 

supported lineages (clades A and B; figs. 2 and 3) after 

1,000 bootstrap iterations. Average uncorrected sequence 

divergence between these lineages was 4.0 percent (fig. 

2). Clade A contained individuals from across the species 

range, including individuals from each of the five Arkansas 

colonies (AR1 through AR5) and all other regions sampled 

(figs. 2 and 3). This clade had no significant bootstrap 

support (< 50 percent), and there was up to 2-percent 

sequence divergence within clade A. Clade B’s members 

were only from each of the five known roosts in Arkansas 

(AR1 through AR5), Texas, and Louisiana. Clade B 

was well supported with significant bootstrap support 

We estimated population differentiation based on 

microsatellites for comparison to mtDNA estimates using 

traditional FST values (Weir and Cockerham 1984); we 

ascertained significance based on 9,000 randomizations 

with Monte Carlo simulations and Bonferroni corrections 

(Rice 1989). We further analyzed genetic structuring with an 

AMOVA using 9,000 permutations to determine significant 

deviations from random. We partitioned data in the same 

manner as the mtDNA AMOVA. We performed IBD tests as 

described for mtDNA. FST estimates, AMOVA evaluations, 

and IBD analyses were carried out using Arlequin ver. 3.1 

(Excoffier and others 2005). 

We used software Bottleneck (Cornuet and Luikart 1996) to 

examine evidence for a recent reduction in Ne as suggested 

by loss of rare allele classes. This program is a coalescentbased method for testing the hypothesis that a recent reduction 

in effective population size has occurred. We used 9,000 

iterations to test the infinite alleles (IAM), stepwise mutation 

model (SMM), and two-phase model (TPM) with 70-percent 

SMM and 30-percent variance assuming drift-mutation 

equilibrium. We tested significance using a one-tailed 

Wilcoxon signed-rank test (α = 0.05) performed in Bottleneck. 

RESULTS

Phylogeny

Although C. mexicanus is the closest relative to C. 

rafinesquii, a large genetic divergence (> 15 percent; 

Piaggio and Perkins 2005) between these species was too 

great to provide any greater statistical reliability for ingroup 

relationships than midpoint rooting analyses. Therefore, 

we also generated trees using midpoint rooting. Trees 

Figure 2—Radial tree layout of maximum likelihood tree inferred from Corynorhinus rafinesquii

mitochondrial DNA control region. Model parameters of the GTR+G model parameters were 

estimated and enforced. Both midpoint-rooting and rooting with closest sister taxon strategies 

provided the same topology, so outgroup taxa were omitted to increase clarity. Samples from across 

C. rafinesquii’s range are shown as States where they were collected. 
92

Arkansas populations were higher (15.73 to 24.62) than the 

range of pairwise differences within the exclusively clade 

A populations (4.13 to 8.37). Pairwise differences among 

colonies in Arkansas were similar to within population 

differences but ranged lower (18.51 to 26.30) than between 

Arkansas and any other populations (96.79 to 115.07). 

Pairwise differences between Texas/Louisiana and North 

Carolina, Mississippi, and Tennessee populations were 

similar to within Arkansas (23.43 to 29.27) and lower among 

North Carolina, Mississippi, and Tennessee populations (6.55 

to 19.18). The lowest pairwise differences were between 

Mississippi and Tennessee populations (6.55 to 7.64). 

Pairwise FST estimates from mtDNA control region 

sequences ranged from 0.00 to 0.24, and 2 of 10 estimates 

revealed significant population structure (table 3). The 

correlation between pairwise genetic differentiation and 

geographical distance was not significant (R = 0.15, 

P = 0.11) among the Arkansas colonies. Across the species 

range, IBD was significant (R = 2.5, P = 0.006). The 

AMOVA suggested that 94 percent of genetic variation was 

within Arkansas colonies (P = 0.001), while the remaining 

genetic differentiation distributed among populations was 

significant, albeit low (6 percent; P = 0.02).

(100 percent), and it had < 1 percent sequence divergence. 

Lineages that were at least 4 percent divergent comprise the 

membership within Texas, Louisiana, and each of the five 

sampled Arkansas populations.

Mitochondrial DNA Sequence Diversity 

among Populations

The number of unique haplotypes found in each Arkansas 

colony ranged from 14 to 47, which for each colony is a 

high proportion of the total haplotypes (table 2). As a result, 

haplotype diversity was high, ranging from 0.99 to 1.00. 

Haplotype diversity was also high in other populations (0.87 

to 0.99); Louisiana and Texas had the lowest (0.87 to 0.90). 

Nucleotide diversity was 0.005 to 0.027 within Arkansas 

colonies, and parsimony informative sites ranged from 45 to 

61. The other populations had the same nucleotide diversity 

(0.005 to 0.024), but number of parsimony informative 

sites was lower (9 to 46). When examined more closely, 

Arkansas (except AR3 and AR5), Louisiana, and Texas, 

which are found in both clades, have at least twice as much 

nucleotide diversity and parsimony informative sites as North 

Carolina, Mississippi, and Tennessee populations which 

are only in clade A. Pairwise differences within only the 

Figure 3—Maximum likelihood phylogram inferred from mitochondrial DNA control region. The GTR+G 

model parameters were estimated and enforced. Both midpoint-rooting and rooting with closest sister 

taxon strategies provided the same topology, so in presented trees outgroup taxa were omitted to improve 

readability. Support for nodes shown as ML bootstrap. Samples of Corynorhinus rafinesquii are shown as 

States where they were collected. 
93

Microsatellite Genetic Diversity 

among Populations

Loci demonstrated linkage equilibria in all pairwise 

comparisons. There were six significant deviations from 

HWE after sequential Bonferroni corrections due to lower 

than expected heterozygosity (table 4). Null alleles can 

result in departures from HWE. Null alleles were possible 

in four of five colonies based on Micro-Checker analyses 

(Van Oosterhout and others 2004). Locus PAUR05 

accounted for some of the null allele detections and 

departures from HWE in three colonies; therefore, we 

dropped this locus from further analyses. The remaining 

departures from HWE were found in one colony at locus 

EF15, in another at Cora_H07F_C05R, and another at 

locus NN8. We did not drop these loci because they were 

not out of equilibrium in most of the sampled colonies. 

Further, three of the departures from HWE and evidence of 

null alleles were from a single colony, AR3. 

Genetic diversity, expressed as number of alleles per locus, 

ranged from 2 to 16 with the average across loci and colonies 

being 7.7 (table 5). Average a overall was 4.17, and pa were 

infrequent, ranging from 0 to 4 per locus and per colony. 

Average within population expected heterozygosity ranged 

Table 2—Diversity statistics estimated from 

mitochondrial DNA control region sequences of five 

Corynorhinus rafinesquii colonies sampled in Arkansas 

and populations sampled from other locations within the 

overall range of this species 

Pop N H h SE π SE PI

AR1 48 47 0.999 0.005 0.023 0.001 61

AR2 14 14 1.000 0.027 0.027 0.001 51

AR3 15 14 0.991 0.028 0.005 0.003 45

AR4 29 28 0.998 0.010 0.024 0.012 52

AR5 33 32 0.998 0.008 0.010 0.008 54

LA 17 9 0.904 0.044 0.021 0.011 44

TX 17 7 0.868 0.050 0.024 0.013 46

NC 26 24 0.990 0.015 0.010 0.005 22

MS 16 14 0.983 0.028 0.004 0.003 9

TN (Chester) 31 28 0.994 0.010 0.005 0.003 23

TN (Fentress) 25 21 0.967 0.030 0.005 0.003 14

Pop = population belongs to; N = number of individuals sequenced 

is reported for each sampling area; H = diversity is measured 

within colonies or populations as the number of unique haplotypes; 

h = haplotype diversity; SE = standard error; π = nucleotide diversity; 

PI = parsimony informative sites; LA = Louisiana; TX = Texas; 

NC = North Carolina; MS = Mississippi; TN = Tennessee.

Table 3—Pairwise FST estimated from mitochondrial DNA 

control region sequences and microsatellite loci for each 

of the five Corynorhinus rafinesquii Arkansas colonies

AR1 AR2 AR3 AR4 AR5

AR1 0.09 0.01 0.03 0.14a

AR2 0.11a 0.09 0.11 0.24a

AR3 0.001 0.15a 0.00 0.07

AR4 0.04a 0.26a 0.00 0.06

AR5 0.04a 0.13a 0.02 0.08a

Pairwise FST estimated from mitochondrial DNA are above the 

diagonal, and estimates from microsatellite DNA are below the 

diagonal and in boldface type.

a P ≤ 0.05 after Bonferroni corrections.

from 0.56 to 0.59. Inbreeding (FIS) estimated for each colony 

ranged from 0.06 to 0.18 and was not significantly different 

from zero except in AR3 and AR4 (P = 0.05). Estimated Ne

for each colony were low [AR1, 76 (CI 43-218); AR2, –17 

(CI 19-∞); AR3, –81 (CI 56-∞); AR4, 19 (CI 11-39); AR5, 

24 (CI 13-62)]. 

Results from the microsatellite DNA AMOVA were similar 

to the mtDNA AMOVA results; 96 percent of the overall 

genetic variation found within colonies (P < 0.001), while 

among-population variation was significant (4 percent; 

P = 0.002). The range of pairwise FST values estimated from 

microsatellite loci (table 3) was 0.00 to 0.24, comparable 

to the FST values estimated from mtDNA. However, a 

higher number of pairwise comparisons, 7 out of 10, were 

significantly differentiated. Pairwise linearized FST estimates 

from microsatellite DNA were not significantly correlated 

with log-transformed geographical distances (R = 0.19, 

P = 0.06). Therefore, there was no signal of IBD in Arkansas. 

Finally, there was significant heterozygosity excess detected 

by the Wilcoxon signed-rank test in two (AR1 and AR4) of 

the five Arkansas colonies under the IAM but not SMM or 

TPM in software Bottleneck. 

DISCUSSION

Phylogeny

The mtDNA phylogeny (figs. 2 and 3) suggested there are 

two major divergent lineages within C. rafinesquii with an 

average of 4 percent sequence divergence between them. 

Our results are consistent with other data from control 

region, cytochrome b, and nuclear DNA sequence data 

(Lance 1999, Piaggio and Perkins 2005) that indicates a 
94

lineage (clade B) that is restricted to Arkansas, Louisiana, 

and Texas, and another lineage (clade A) that is more 

cosmopolitan and occurs over the entire range of the species. 

Both clades co-occur in Arkansas, Louisiana, and Texas; 

and, specifically, both occur within each of the five sampled 

Arkansas colonies. We did not find these lineages to correlate 

to subspecies as proposed by Handley (1959). The mtDNA 

clade comprising only Arkansas, Texas, and Louisiana 

individuals (clade B) has the best statistical support, 

suggesting that these bats have been in this region for long 

enough to allow for this coalescence. Conversely, the mtDNA 

clade with members from across the range of C. rafinesquii

(clade A) had no statistical support and shorter branches, 

suggesting this lineage dispersed more recently into the same 

region as clade B. Sequence pairwise differences within 

each Arkansas population were as high as among colonies. 

Other diversity measures (nucleotide diversity and parsimony 

informative sites) from Arkansas, Louisiana, and Texas were 

high when compared to populations that group entirely into 

clade A. This reflects the two divergent maternal lineages 

co-occurring within each colony in Arkansas and in regions 

of Texas and Louisiana. Because both lineages can be found 

in the same populations, this pattern shows evidence of some 

maternal structuring but cannot be considered to represent 

subspecies. Rather, this phylogeographic pattern could 

indicate that an isolation event or population bottleneck 

occurred in Arkansas resulting in the loss of clade A in 

Arkansas and, at a later time, there was another dispersal 

event or secondary contact (Marjoram and Donnelly 1994) 

where clade A was reintroduced. Phylogeographic patterns 

in other taxa suggest existence of a glacial refugium in the 

Interior Highlands, which includes Arkansas, Louisiana, 

and Texas, and the eastern highlands (see Mayden 1985, 

Zamudio and Savage 2003, Zeisset and Beebee 2008). 

Therefore, it is possible the phylogeographic pattern in C. 

rafinesquii reflects secondary contact between groups that 

occupied separate refugia, one in the Interior Highlands and 

the other possibly in the eastern highlands. Alternatively, 

presence of these divergent clades in the same Arkansas 

roosts and sampled areas of Texas and Louisiana could 

suggest multiple dispersal events from one or more source 

populations. Interestingly, the lowest mtDNA haplotype 

diversity was found in the Texas and Louisiana populations, 

but they shared the highest nucleotide diversity measures 

with Arkansas populations (except AR3 and AR5). Thus, 

this area harbors haplotypes that are more different from 

each other than haplotypes from the rest of the range. This 

may suggest that this area (Arkansas, Louisiana, and Texas) 

harbors older lineages than in the other sampled regions, 

and this is supported by the high bootstrap support of clade 

B (Hewitt 1996, 2000). Conversely, the short branch lengths 

and low nucleotide diversity coupled with high haplotype 

diversity within clade A suggest this lineage represents a 

recent expansion of this lineage which subsequently spread 

across the current range of C. rafinesquii.

Table 4—Expected heterozygosity and observed 

heterozygosity estimated for each microsatellite locus for 

each Corynorhinus rafinesquii Arkansas colony 

Pop AR1 AR2 AR3 AR4 AR5

EF15

 Ho 0.76 0.56 0.31 0.58 0.74

 He 0.81 0.81 0.82a 0.73 0.78

EF21

 Ho 0.70 0.80 0.60 0.45 0.50

 He 0.55 0.54 0.56 0.38 0.64

EF20

 Ho 0.31 0.63 0.25 0.35 0.37

 He 0.32 0.73 0.24 0.34 0.32

NN8

 Ho 0.33 0.22 0.07 0.21 0.26

 He 0.50 0.52 0.52a 0.48 0.51

EF14

 Ho 0.02 0.00 0.20 0.10 0.05

 He 0.02 0.00 0.19 0.10 0.05

Cora_D12_D12

 Ho 0.67 0.44 0.73 0.45 0.28

 He 0.64 0.58 0.62 0.61 0.34

Cora_E07_E07

 Ho 0.82 0.63 0.73 0.63 0.78

 He 0.82 0.77 0.77 0.77 0.82

Cora_H07_C05

 Ho 0.36 0.25 0.27 0.37 0.50

 He 0.58a 0.24 0.51 0.63 0.44

Cora_B07_H12

 Ho 0.83 1.00 0.73 0.90 0.89

 He 0.89 0.88 0.78 0.91 0.88

Cora_E10_G03

Ho 0.82 0.50 0.93 0.80 0.74

 He 0.82 0.68 0.85 0.86 0.84

Pop = population belongs to; Ho = observed heterozygosity; 

He = expected heterozygosity.

a

 Indicates significant departures from Hardy-Weinberg equilibrium 

(P < 0.05) after sequential Bonferroni corrections (Rice 1989).
95

Table 5—Diversity estimates and estimated effective population size from microsatellite loci genotyped for individuals 

from five Corynorhinus rafinesquii Arkansas colonies and inbreeding coefficients of each 

EF15 EF21 EF20 NN8 EF14

Pop FIS h Ne A a pa A a pa A a pa A a pa A a pa

AR1 0.06 0.51+/−0.28 76 (43, 218) 10 5.49 1 3 2.75 0 3 2.49 0 2 2.00 0 2 1.15 0

AR2 0.13 0.33+/−0.20 −17 (19, ∞) 6 5.69 0 3 2.70 0 4 3.88 1 2 2.00 0 1 1.00 0

AR3 0.18* 0.55+/−0.30 −81 (56, ∞) 7 6.10 0 4 3.57 1 3 2.42 0 2 2.00 0 2 1.86 0

AR4 0.17* 0.55+/−0.30 19 (11, 39) 6 4.74 0 3 2.68 0 3 2.32 0 2 2.00 0 2 1.58 0

AR5 0.10 0.53+/−0.29 24 (13, 62) 6 5.23 0 3 2.98 0 3 2.52 0 2 2.00 0 2 1.37 0

All — — — 10 5.85 1 4 3.01 1 4 2.58 1 2 0 3 1.40 0

Cora_D12_D12 Cora_E07_E07 Cora_H07_C05 Cora_B07_H12 Cora_E10_G03

Pop A a pa A a pa A a pa A a pa A a pa

AR1 3 2.97 0 9 5.85 1 5 3.19 1 16 8.03 0 11 6.02 2

AR2 3 3.00 0 5 4.75 1 3 2.75 0 7 7.00 0 6 5.50 0

AR3 4 3.43 1 7 5.38 0 5 3.39 0 12 7.30 0 7 6.01 0

AR4 3 2.96 0 6 5.02 0 4 3.22 0 13 8.47 1 10 6.68 1

AR5 3 2.56 0 7 5.47 0 4 2.77 1 13 7.73 0 11 7.11 1

All 4 3.00 1 10 5.69 2 7 3.19 2 18 8.42 1 15 6.60 4

Pop = population belongs to; FIS = the inbreeding coefficient of each colony; diversity estimates are: h = gene diversity averaged across loci; 

Ne = effective population size; A = number of alleles; a = allelic richness; pa = private alleles; * P = 0.05.

Genetic Diversity within Populations

We predicted that due to habitat loss and subsequent 

disjunction and/or population reduction, we would detect 

population bottlenecks in Arkansas C. rafinesquii colonies. 

If true, estimates of genetic diversity and population 

connectivity would be low, and there might also be 

inbreeding and low effective population sizes. In fact, we 

found low genetic diversity across microsatellite loci. We 

also found significantly high pairwise FST estimates which 

indicate low colony connectivity in Arkansas. Further, our 

results showed that the microsatellite loci were out of shortterm linkage equilibrium more than chance would suggest 

and, without evidence of significant linkage among the 

loci, revealed low effective population sizes within the last 

generation for each colony in Arkansas. This, paired with 

significantly high pairwise FST estimates from microsatellite 

data, is surprising over short distances for vagile, volant 

mammals. High microsatellite pairwise FST estimates 

and low Ne along with the detection of two loci very near 

fixation, with two (NN8) and three (EF14) alleles, can be 

taken as weak possible evidence of a population bottleneck 

in Arkansas colonies. 

Our analyses detected population bottlenecks in two 

colonies. However, our data are at the lower limit for number 

of loci and per population sample size for robust bottleneck 

detection. Alternatively, it is possible that population 

bottlenecks have happened more recently than can be 

detected by these tests. Effective population sizes in AR2 and 

AR3 were negative, and the CI’s included infinity, meaning 

these are either large populations or the estimate was 

meaningless. These two populations had the smallest sample 

sizes and, therefore, may not have allowed robust estimates. 

Nonsignificant FIS estimates within each population (AR3 

and AR4 were both P = 0.05, which may or may not be 

biologically relevant), and the AMOVAs, which suggested 

that most variation was attributed to within population 

differentiation, implies that any population bottleneck has 

not resulted in inbreeding. Violations of HWE and evidence 

of null alleles in AR3 may reflect low sample size and/or a 

Wahlund effect (the sampling of allelic differentiation of two 

subpopulations within a single sampled colony) due to our 

samples coming from a hibernaculum where it is possible 

that multiple unsampled populations may have congregated 

(Piaggio and others 2009b). However, this does not appear 

to be the case for AR4 which is also a hibernaculum. 
96

show clear population differentiation among most Arkansas 

colonies and low effective population sizes.

Implications for Conservation 

and Management 

Based on results of the phylogenetic analysis, it is not 

appropriate to manage for two subspecies of C. rafinesquii 

as designated by Handley (1959). Rather, it is important 

to manage and conserve the lineages within C. rafinesquii

that reflect the evolutionary history of this species. In 

particular, the lineage with the most limited range (clade 

B), found only in Arkansas, Louisiana, and Texas, harbors 

the greatest genetic diversity and includes haplotypes from 

both lineages. 

Over the last 100 to 200 years, bottomland hardwood forests 

of Arkansas have been systematically cleared of timber, 

drained, and converted for agricultural use (Dahl 1990, 

Holder 1970, Woods and others 2004). Today < 10 percent 

of the original hardwood forests remain. If C. rafinesquii

relied mostly on these forests for roosts (Clark 1990, 1991), 

then these bats have experienced habitat destruction and 

loss of preferred roosts. Further, C. rafinesquii in Arkansas 

now appear to largely occupy human-made structures which 

are ephemeral and may not provide the long-term habitat 

necessary to maintain stable populations. We predicted that 

if habitat loss has resulted in loss of connectivity and/or 

reduction of populations, then estimates of genetic diversity 

would be low within the Arkansas colonies. In fact, our 

estimates of diversity from microsatellite loci is comparable 

to populations of the federally endangered sister taxon 

C. t. virginianus whose populations are fragmented in four 

regional populations which are significantly differentiated 

from each other (Piaggio and others 2009b). This is 

especially noteworthy given the ongoing problem of loss 

of manmade structures in Arkansas. For example, AR4 is a 

hibernaculum in a well that was, until recently, adjacent to 

an abandoned house used by a maternity roost each summer. 

A routine check led to the discovery that the house had been 

demolished. Further, AR1 and AR5 were maternity roosts 

in abandoned houses, but these houses are now gone. All 

remaining known roosts of C. rafinesquii in Arkansas should 

be protected and efforts made to identify others and protect 

those as well. 

Dispersal of individuals between populations is critical to 

maintain population connectivity and genetic diversity, and 

promoting this is crucial for management or conservation 

plans. Dispersal produces gene flow over geographic 

distances. Currently, it appears that dispersal among 

sampled Arkansas colonies is limited. Further efforts 

to locate populations of C. rafinesquii in remaining 

bottomland forests and management for forested corridors 

in bottomlands to provide natural roosts may be needed. 

Alternatively, the HWE violations in AR3, lowest mtDNA 

nucleotide diversity, and parsimony informative sites

may be evidence of a recent population bottleneck which 

was not detected in our bottleneck analysis. Population 

bottlenecks in Arkansas colonies may also account for the 

lack of a significant signal of isolation by distance, which 

suggests there is something other than geography influencing 

differentiation. Alternatively and more likely, the influence 

of IBD could have been missed because of low power due 

to low number of populations sampled. Indeed, significant 

IBD was detected across the species range where higher 

sample sizes were obtained. So, either limited sampling in 

Arkansas accounts for the lack of IBD or there is another 

factor, i.e., barriers to gene flow, or factors affecting colonies 

in Arkansas differently than across the species range. In 

summary, gene flow was restricted among colonies of 

C. rafinesquii in Arkansas, and low effective population sizes 

suggest that genetic drift is the dominant force on allelic 

frequencies. 

Our within-population diversity estimates from mtDNA and 

autosomal microsatellites are disparate for each colony in 

Arkansas. The mtDNA control region sequence diversity was 

high within colonies and equivalent to the estimated mtDNA 

control region diversity within populations of the widely 

distributed migratory bat (Nyctalus noctula) (Petit and 

Mayer 2000). Mitochondrial diversity within C. rafinesquii 

populations was similar or only slightly higher than mtDNA 

diversity within the sister taxon C. townsendii (Piaggio 

and others 2009b). Conversely, microsatellite genetic 

diversity within Arkansas colonies was low (Schlötterer 

and Pemberton 1994) in general. There are several potential 

explanations for the disparity in our estimates of genetic 

diversity between mtDNA and microsatellite loci. First, the 

mtDNA diversity may be large due to occurrence of two 

divergent lineages within each Arkansas colony. Second, 

half of the microsatellite markers we used were generated 

from other bat species (Vespertilionidae: Eptesicus fuscus, 

Plecotus auritus, and N. noctula) which may pose a problem 

due to ascertainment bias (Ellergren and others 1995, 

Webster and others 2002) and result in low estimates of 

genetic diversity. Third, these two markers are differentially 

inherited. Autosomal microsatellites are biparentally 

inherited; whereas, mtDNA is matrilineally inherited and 

has a smaller effective population size than nuclear DNA. 

Therefore, demographic processes will affect these markers 

differently. The different estimates of genetic diversity from 

mtDNA and microsatellites may then be evidence of very 

recent and rapid population bottlenecks in Arkansas. Indeed, 

although haplotype diversity is high in mtDNA, genetic 

diversity may have been lost (Kuro-o and others 2010). This 

may be supported by the high nucleotide diversity in some 

of the Arkansas colonies, which suggests that intermediate 

haplotypes have been lost. Although there may not be strong 

evidence of population bottlenecks, microsatellite results 
97

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This may help establish connectivity among populations and 

increase genetic diversity. Without these efforts, colonies 

of C. rafinesquii in Arkansas may be susceptible to disease 

(Spielman and others 2004), ecological catastrophes, and 

extinction due to low genetic diversity and small effective 

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ACKNOWLEDGMENTS

We thank Paul Leberg, Mark Brigham, David Armstrong, 

Robert Guralnick, Susan Perkins, and anonymous reviewers 

for their comments. We are deeply indebted to Eric Routman 

for crucial and patient efforts to improve the manuscript. 

We extend sincere gratitude to institutions and individuals 

for tissue samples including the following: Celia LópezGonzález, Colección Regional Durango (Vertebrados), 

CIIDIR Durango, Instituto Politécnico Nacional; Jeff Gore, 

Florida Fish and Wildlife Conservation Commission; Traci 

Wethington, Kentucky Department of Fish and Wildlife 

Resources; Mary Bunch, South Carolina Department of 

Natural Resources; Dr. Richard Lance, U.S. Army; Robert 

Curry and David Richardson, U.S. Fish and Wildlife Service; 

Brian Carver, Freed-Hardeman University; Leigh Stuemke 

and Chris Comer, Stephen F. Austin State University; 

Christopher Rice; Frances Bennett; Eric Britzke; Mary Kay 

Clark; Kelli Deichmueller; Laura Finn; Rafael Avila-Flores; 

Heather Thomas; Austin Trousdale; and Maarten Vonhof. 

This study was partially supported by an American Museum 

of Natural History - Theodore Roosevelt Memorial Grant; 

an American Society of Mammalogists Grants-in-Aid; a 

University of Colorado Museum William H. Burt Grant; 

and the Department of Ecology and Evolutionary Biology, 

University of Colorado at Boulder.

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Van Oosterhout, C.; Hutchinson, W.F.; Wills, D.P.M.; Shipley, P. 

2004. Micro-Checker: software for identifying and correcting 

genotyping errors in microsatellite data. Molecular Ecology 

Notes. 4: 535.

Vonhof, M.J.; Davis, C.S.; Fenton, M.B.; Strobeck, C. 2002. 

Characterization of dinucleotide microsatellite loci in big brown 

bats (Eptesicus fuscus), and their use in other North American 

verspertilionid bats. Molecular Ecology Notes. 2: 167-170.

Waples, R.S. 2006. A bias correction for estimates of effective 

population size based on linkage disequilibrium at unlinked gene 

loci. Conservation Genetics. 7: 167-184. 

101

Fort Bragg was established as Camp Bragg in September 

1918 in southcentral North Carolina among a large expanse 

of pine forests and sandy soil and was renamed Fort Bragg 

upon becoming a permanent post in September 1922 (Fort 

Bragg 2002). As the base expanded, forests were removed 

for development, timber, and agriculture, resulting in the 

reduction of a diverse ecosystem and the Federal listing of 

many endemic species (Britcher 2006). Two bat species 

with at least two levels of State status (Legacy Resource 

Management Program 2005) are known from Fort Bragg 

and Camp Mackall, NC: Rafinesque’s big-eared bat 

(Corynorhinus rafinesquii) and southeastern myotis (Myotis 

austroriparius). These species are also designated as species 

of concern by the U.S. Fish and Wildlife Service (U.S. Fish 

and Wildlife Service 2010). 

Loss of natural habitat has prompted the need for 

information on roosting and foraging requirements of 

C. rafinesquii so that land holdings can be managed 

appropriately for the species. Forests provide roost trees 

and foraging areas; however, anthropogenic structures could 

be significant roost structures, particularly where there is a 

lack of sufficient tree roosts, e.g., in younger aged forests. 

C. rafinesquii also exhibits frequent roost switching (Clark 

and others 1997, Gooding and Langford 2004, Lance 

and others 2001, Trousdale and others 2008); therefore, 

this species may benefit from greater roost diversity and 

INTRODUCTION

The Sikes Act was amended in 1997 to direct military 

installations to create integrated natural resources 

management plans (Boice 2006). These plans must be 

reviewed at least every 5 years to ensure that military lands 

are managed to conserve and rehabilitate natural resources 

in their charge (Legacy Resource Management Program 

2005). The 12 million ha managed by the U.S. Department 

of Defense houses three times more federally listed or 

imperiled species than all other Federal lands despite 

comprising only 3 percent of Federal land holdings (Stein 

and others 2008). Military land is relatively protected from 

urban encroachment and is presumably less inundated 

with potential agricultural pollutants, such as fertilizer and 

pesticides, than surrounding rural areas. This permits military 

lands to be a safe haven for species that might otherwise 

be negatively affected by human interactions. In some 

cases, military activity may even benefit some species. For 

example, Jentsch and others (2009) found that some pioneer 

plant species thrived after ground disturbance such as tank 

activity on a retired military base in Germany. Alternately, 

managing for some species can be beneficial to the military. 

Maintaining open stands in pine (Pinus spp.) forests for 

the red-cockaded woodpecker (Picoides borealis) created 

optimal training areas for troops by supplying open areas for 

maneuvers (Beaty and others 2003). 

CHARACTERISTICS OF ROOSTS USED BY RAFINESQUE’S BIG-EARED BAT 

(CORYNORHINUS RAFINESQUII) ON CAMP MACKALL, NORTH CAROLINA

Piper L. Roby, Biologist, Copperhead Consulting, Paint Lick, KY 40461

Mark W. Gumbert, Principal Biologist, Copperhead Consulting, Paint Lick, KY 40461

Price L. Sewell, Biologist, Copperhead Consulting, Paint Lick, KY 40461

Steven W. Brewer, Plant Ecologist and Statistician, Copperhead Consulting, Paint Lick, KY 40461

Abstract—Military bases are charged with stewardship of threatened and endangered species, and data collection on 

species of concern is important for management of these species on military land holdings. We studied roosting behavior of 

Rafinesque’s big-eared bat (Corynorhinus rafinesquii) during a multiyear inventory on Camp Mackall and Fort Bragg, NC. 

From 2006 to 2009, C. rafinesquii were captured (n = 24), banded, and/or radio-tagged to gain information on roosting 

habits within and adjacent to bottomland hardwood forests. Twenty roosts were identified: 11 trees [9 tupelo (Nyssa spp.) 

and 2 bald cypress (Taxodium distichum)] and 9 anthropogenic structures. Bats used these roosts in similar proportions and 

switched roosts often (every 1.2 days). Diameter at breast height of roost trees (x = 83.0±6.7 cm) used by C. rafinesquii

was smaller than reported elsewhere for this species. In 2008, temperature data were collected in anthropogenic structures 

used as roosting sites. None of these roosts housed large numbers of bats, but the range of temperatures for two different 

roosts, each housing one pregnant female, was 24.5 to 46.0 °C for an attic roost on May 27, 2008, and 19.0 to 27.0 °C 

for a cistern roost on May 30, 2008. A female that roosted in the attic while pregnant then roosted in the basement of the 

same building the following September when she was postlactating. The significantly warmer attic temperatures may 

have allowed the female to avoid torpor, thereby contributing more metabolic resources to the developing fetus. Other 

temperature data collected suggest that bat use of other roosts was not affected by roost temperature. Choice of trees and 

anthropogenic structures used as roosting sites by C. rafinesquii was comparable to published studies of these bats in 

similar habitats, demonstrating the importance of these features to the persistence of local populations.

Citation for proceedings: Loeb, Susan C.; Lacki, Michael J.; Miller, Darren A., eds. 2011. Conservation and management of eastern big-eared bats: 

a symposium. Gen. Tech. Rep. SRS-145. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 157 p.
102

and Beckett 2005). Bottomland hardwood forest in the 

riparian zone of Drowning Creek has an open understory 

and is comprised primarily of tupelo trees (Nyssa spp.) with 

scattered T. distichum and oaks. This habitat type accounts 

for 8.6 percent of all vegetation types on Camp Mackall 

as calculated using a Geographic Information System 

Fort Bragg vegetation layer for ArcView ver. 9.2/3 (Esri, 

Redlands, CA). Temperatures in this area ranged from 13 to 

33 °C with an average of 22 °C during the study period when 

roost temperatures were collected in 2008.

METHODS

We deployed mist nets over creeks, water-filled road ruts, 

wildlife ponds, open bottomland forest, and dry road 

corridors in varying habitat types, e.g., bottomland hardwood 

forest, planted pine stands, and small sandy streams, twice 

a year from 2004 to 2009 in two of the following three 

seasons: spring (April, May, and June), summer (July and 

August), and fall (September and October). We deployed 

nets at sunset and typically left them in place for at least 5 

hours after sunset. In most years, we netted 10 sites twice 

per year, but as many as 17 sites were netted in 2009. Each 

year we also visited a varying number of buildings, bridges, 

and other anthropogenic structures to search for bats. We 

conducted a total of 214 searches of structures (range: 13 to 

102, mean: 35.7) from 2004 to 2009. From 2006 to 2009, 

no structure was searched during December, January, or 

February. We recorded data on captured bats including 

age (adult or juvenile), sex, body mass (g), and forearm 

length (mm). After a banding program was established at 

Camp Mackall and Fort Bragg in 2006, forearms of all 

C. rafinesquii caught (n = 18) were fitted with uniquely 

numbered aluminum alloy lipped identification bands (bat 

rings; Porzana Ltd., East Sussex, UK). We also fitted 11 

C. rafinesquii with 0.48-g radio transmitters (model LB2; Holohil Systems Ltd., Ontario, Canada) in May, June, 

or July depending on the year. We clipped a small amount 

of hair from between the scapulae, and a transmitter was 

applied using Skin Bond® adhesive (Smith & Nephew, Inc., 

Largo, FL). We held bats for 5 to 10 minutes after transmitter 

placement to ensure secure attachment prior to release at or 

near the point of capture. 

Tracking commenced the day after bats were radiotagged to 

locate day roosts. We drove roads, on and off the base, while 

listening for signals using a receiver (model TRX-1000S) 

and a 3- or 5-element Yagi antenna (receiver and antenna; 

Wildlife Materials, Inc., Carbondale, IL). Once a roosting 

site was located, we attempted visual confirmation in roost 

trees with a basal opening and in anthropogenic structures 

used as roosts. When feasible, we estimated the height (m) 

at which the bats were roosting and the number of bats 

using the roost either visually or by conducting exit counts 

increased availability across the landscape. Variation in 

roost microclimate is required by these bats when roosting 

(Clark 1990, Hoffmeister and Goodpaster 1963, Hurst and 

Lacki 1999, Lewis 1995), and evidence suggests that the 

environment surrounding roosts, such as roads, water, and 

canopy cover (Clark 1990, Lance and others 2001), can be as 

important as the surrounding landscape in providing foraging 

opportunities (Menzel and others 2001). 

Because no prior study of bats had been conducted on Camp 

Mackall and Fort Bragg, our objectives during this 6-year 

project were to: (1) document the presence of bat species 

on the base, (2) locate and characterize roosts used by C. 

rafinesquii, and (3) conduct an exploratory examination 

of temperature variation among roosts of this species. We 

expected to find a small population of C. rafinesquii at the 

site due to a limited amount of bottomland hardwood forest 

that contained relatively young trees with few roosting 

opportunities (Gooding and Langford 2004), and we 

predicted extensive use of anthropogenic structures by these 

bats.

STUDY AREA

The 65,084 ha of Camp Mackall and Fort Bragg (39°26 ́N, 

123°48 ́W) are located within six counties in the sandhills 

ecoregion of the inner Coastal Plain physiographic region 

of North Carolina (Griffith and others 2002). The sandhills 

upland complex consists of mesic and wetland plant 

communities including pine/scrub oak sandhill and xeric 

sandhill scrub, coastal plain small stream swamp, and 

streamhead pocosin (Fort Bragg 2005). Woodlands on the 

base are composed primarily of loblolly pine (P. taeda) and 

shortleaf pine (P. echinata) in association with bald cypress 

(Taxodium distichum) and a mixture of hardwoods including, 

but not limited to, water tupelo (Nyssa aquatica), black 

tupelo (N. sylvatica), sweetgum (Liquidambar styraciflua), 

red maple (Acer rubrum), tuliptree (Liriodendron tulipifera), 

water oak (Quercus nigra), post oak (Q. stellata), blackjack 

oak (Q. marilandica), and turkey oak (Q. laevis).

Camp Mackall encompasses 3,211 ha of the total land 

holdings and lies 64.4 km west of the Fort Bragg cantonment 

in a rural region interspersed with small towns and villages. 

The area is surrounded by upland forest, agriculture, rural 

housing, and nonforested military training areas and airfields. 

Drowning Creek, a fourth-order blackwater stream, flows 

through Camp Mackall and is accompanied by bottomland 

hardwood forest in adjacent habitats. This forest type is 

important because although C. rafinesquii use several types 

of roosts, when the species is documented in trees, those 

trees are often located in bottomland hardwood forests 

(Carver and Ashley 2008, Gooding and Langford 2004, 

Lance and others 2001, Menzel and others 2003, Trousdale 
103

number of roosts used between sexes and in tree size by 

genus. We used a Kruskal-Wallis test to compare temperature 

differences among three levels of roosts in building 104 and 

used Student’s t-tests to examine differences between two 

different anthropogenic structure roosts and their associated 

ambient temperatures when bats were and were not present 

in the roosts. We chose to use nonparametric tests for most 

analyses due to low and unequal sample sizes. We conducted 

statistical analyses using XLSTAT (Addinsoft USA, New 

York, NY) and SYSTAT (Systat Software, Inc., Chicago, IL). 

ArcView ver. 9.3 (Esri, Redlands, CA) was used to measure 

distances from roosts to landscape features. 

RESULTS

From 2004 to 2009 we made 840 bat observations, i.e., 

captures, recaptures, and visual observations, on Camp 

Mackall and Fort Bragg representing 10 species: 317 

evening bats (Nycticeius humeralis, 37.7 percent); 234 

red bats (Lasiurus borealis, 27.9 percent); 77 big brown 

bats (Eptesicus fuscus, 9.2 percent); 76 C. rafinesquii (first 

capture in 2006, 9.0 percent); 64 tri-color bats (Perimyotis 

subflavus, 7.6 percent); 54 Seminole bats (L. seminolus, 6.4 

percent); 10 Myotis austroriparius (1.2 percent); 4 silverhaired bats (Lasionycteris noctivagans, 0.5 percent); 2 

hoary bats (Lasiurus cinereus, 0.2 percent); and 2 Brazilian 

free-tailed bats (Tadarida brasiliensis, 0.2 percent). At Camp 

Mackall we captured 24 individual C. rafinesquii and made 

76 observations of the species in trees and structures on and 

around the post. There were five captures in mist nets, but 

four of them were at a roost tree and three of the four were 

recaptures. Only one C. rafinesquii was caught in a mist net 

not placed near a roost. Of the 94 bats we banded, 18 were 

C. rafinesquii (4 adult males, 8 adult females, 4 juvenile 

males, and 2 juvenile females). We recaptured 39 percent 

of all banded C. rafinesquii (7 out of 18) with 58 percent 

of banded adults (7 out of 12) recaptured. We attached 11 

transmitters to 9 individuals over 4 years (2 adult females 

were radio-tagged twice in 2 different years); bats A0798 

and A0800 were lactating when radio-tagged on July 10, 

2007, and pregnant when radio-tagged on May 29, 2008, 

and May 26, 2008, respectively. All remaining adult females 

fitted with radio transmitters were also reproductively 

active (one pregnant, two lactating, and one postlactating), 

but three adult males radio-tagged C. rafinesquii were 

nonreproductive. 

We located 20 roosts used by C. rafinesquii, including 11 

trees and 9 structures. Bats used an average of 3.0±0.3 

(SE) roosts with a tracking duration between 3 and 7 days 

( x = 5) depending on year of sampling. Males (n = 3) used 

3.7±0.9 roosts (range: 2 to 5), and females (n = 8) used 

2.8±0.3 roosts (range: 1 to 4), although the difference was 

not significant (Mann-Whitney U = 11.5, P = 0.91). We 

in the evening. We obtained locations of roosting sites using 

a handheld global positioning system (GPS) and recorded 

a description of the roost location. We took photographs 

and made graphical representations of roosting sites to aid 

in future identification. We attached uniquely numbered 

aluminum tree tags and high visibility flagging to tree roosts 

to aid in relocation. We recorded the species of tree, measured 

diameter at breast height (d.b.h.), estimated height of tree (m), 

noted condition of the tree (live, live-damaged, or snag), and 

the presence of vegetation layers surrounding the roost tree 

(canopy, subcanopy, and understory). These data were also 

taken on all trees within a plot surrounding the roost tree that 

were identified using a 10 basal area factor prism. Because 

this method is considered point sampling and not fixed-area 

sampling, the plots were not uniform in size. Rather, the 

“probability of a given tree being sampled is proportional to 

its size” (Avery and Burkhart 2002). Additionally, the plot 

radius factor is 2.75 feet, meaning “for each inch of dbh, a 

tree can be 2.75 feet from the point to still be included in the 

point’s tally” (Avery and Burkhart 2002).

In 2008, we selected 4 anthropogenic structures (cistern, 

building 764, house, building 104) used as roosting sites 

by C. rafinesquii for collection of temperature data. For the 

cistern, building 764, and the house, we placed one iButton® 

(Maxim Integrated Products, Sunnyvale, CA) where bats 

had been observed roosting and another on the north side 

of a neighboring tree to collect ambient temperatures. The 

cistern was approximately 5.2 by 1.5 by 1.8 m in size and 

contained water 0.5 m deep year round. Building 764 was 

an aboveground concrete outbuilding approximately 4.5 by 

4.5 by 3.0 m in size. The abandoned single-level, eight-room 

house overrun with vegetation, mostly wisteria (Wisteria sp.), 

was located off the military base. Because we discovered 

this roost on the last day of surveys in 2008, we placed 

the temperature data logger in a room adjacent to the one 

where bats were roosting to avoid disturbance. We placed 

temperature data loggers in three portions of building 104. 

This building roost was a large, old, three-story storage barn 

used for military training. Because bats had been observed 

roosting in all three portions of the building, we placed 

temperature data loggers in the attic, on the ground floor, 

and in the cinder block basement. We deployed iButtons® 

(programmed to record temperature every 2 hours) at the 

end of May, and we retrieved them on October 2, 2008. We 

checked structures periodically for bat use throughout the 

time that iButtons® were operating.

Landscape features such as distance to streams have been 

shown to be good predictors of roost selection by bats (Clark 

1990, Kurta and others 2002, Watrous and others 2006). 

Therefore, we used Mann-Whitney U tests to examine 

differences between roost types in distance to significant 

landscape features, e.g., water, roads, firebreaks. MannWhitney U tests were also used to compare differences in 
104

recorded 31 roost switches over 38 tracking days (1 bat 

tracked for 1 day) or 1 switch every 1.2 days. Bats moved 

an average of 2.5±2.9 km (n = 18, range: 0.06 to 8.73 km) 

between roosts. Distances moved by bats were either < 1 

km (n = 7), 1 to 2 km (n = 6), or 6 to 9 km (n = 5). Females 

moved greater distances than males (Mann-Whitney U = 12, 

P = 0.01), and pregnant females moved farther than lactating 

females (Mann-Whitney U = 30, P = 0.01). The number of 

bats observed in a roost ranged from 1 to 11. For many of the 

tree roosts, visual observation of bats was not possible due to 

small or nonexistent basal openings or because bats roosted 

above a bend in the tree and could not be seen. Counts of 

bats were taken in all structures except one building located 

on private property where we were denied access. However, 

an exit count conducted at this structure yielded seven bats. 

We attempted exit counts of tree roosts on Camp Mackall, 

but successful exit counts could not be completed due to 

the dense canopy. The roost housing the greatest number of 

bats (11 adults) was a tree that we netted in 2008, where 3 

of the 4 captured were previously banded. The next largest 

group of bats was located in 2009 and consisted of 10 bats 

(building 104: 5 adult females and 5 prevolant pups). Two 

of the five adults were recaptures from 2007. We banded the 

remaining eight bats, and one adult female was radio-tagged. 

Mean body mass of the adult females was 8.6 g, and mean 

body mass of young was 5.0 g, suggesting that females were 

carrying 58 percent of their body mass on average when 

transporting pups among roosts during flight. No bat was 

observed in the building the following day, and the radiotagged adult female was subsequently located in a roost tree 

that was 1.4 km from building 104. 

We successfully located radio-tagged bats 67 percent of the 

time. Bats used trees and buildings similarly (47 percent and 

53 percent, respectively; Mann-Whitney U = 55.0, P = 0.78). 

Of the 11 tree roosts, 9 were Nyssa spp. (6 N. aquatica, 

1 N. biflora, 1 N. sylvatica, 1 Nyssa sp.), and 2 were 

T. distichum. Mean d.b.h. for all trees was 83.0 ± 6.7 cm, 

but T. distichum used as roosts were larger in diameter than 

Nyssa spp. (Mann-Whitney U = 0, P = 0.04) (table 1). Of 

the 11 trees, 10 were live and possessed interior cavities, i.e., 

live-damaged. The one snag was a Nyssa spp. that contained 

an interior cavity. Of the nine anthropogenic structures, 

five were aboveground and four were underground. The 

aboveground roosts were abandoned buildings previously 

used for human lodging (n = 2) or animal shelters and 

storage of farm equipment (n = 3). Underground roosts 

were a cistern and a well that both contained water, a crawl 

space under a concrete slab that was previously the floor of a 

building, and a dry concrete culvert. 

All roost trees were in bottomland hardwood forest, as 

opposed to anthropogenic structures which were located 

in upland habitats, i.e., developed and cleared upland pine 

forest/savanna. Of the four landscape feature distances we 

Table 1—Characteristics of roost trees used by 

Corynorhinus rafinesquii and distances of roosts to 

selected landscape features on and around Camp 

Mackall, NC, 2006 to 2009

Roost characteristic Mean ± SD Minimum Maximum

Nyssa sp. (n = 9)

Diameter at breast 

height (cm) 75.1±5.1 56.5 104

 Height of tree (m) 19.3±0.7 17 21

Taxodium distichum 

(n = 2)

 Diameter at breast 

height (cm) 119±2.8 116 121

 Height of tree (m) 22.5±2.5 20 25

Diameter at breast height 

(cm)

 All other trees in plot 

(n = 152) 44.5±21.1 5.5 113

 All other Nyssa spp. 

(n = 61) 43.7±18.5 19.0 96.0

 All other T. distichum 

(n = 6) 63.6±35.2 16.5 112.5

All trees (m)

 Distance to capture site 938±199 60 1737

 Distance to paved road 643±119 51 1210

 Distance to firebreak 224±31.3 50 360

 Distance to Drowning 

Creek 71.9±15.3 0 139

Structures (m)

 Distance to capture site 1530±742 0 5965

 Distance to paved road 515±180 5 1420

 Distance to firebreak 415±385 10 3495

 Distance to Drowning 

Creek 1277±266 130 2960

SD = standard deviation.

measured, distance to capture site and distance to paved 

roads were not different between tree and anthropogenic 

structure roosts. However, tree roosts were closer than 

anthropogenic structures to firebreak roads (Mann-Whitney 

U = 87.0, P = 0.003) and Drowning Creek (Mann-Whitney 

U = 1.0, P < 0.0001).

Structures we selected for temperature monitoring housed 

at least one bat on at least one visit. The attic of building 

104 possessed the highest maximum, the lowest minimum, 

and the highest daily mean temperatures among all structure 

roosts sampled (table 2); each of these statistics was outside 
105

temperatures exceeding the 95-percent confidence limits 

was the cistern, which possessed the highest mean daily low 

temperatures recorded among the building roost sites.

Differences in temperatures among the three levels of 

building 104 were significant, and bat use varied with these 

temperature changes. During the day, the attic temperature 

was higher than the ground floor which in turn was higher 

than the basement temperature (fig. 1). An adult female 

(A0800) was observed using the attic of this roost while 

pregnant on May 27, 2008, where a maximum temperature 

of 46.0 °C and a minimum of 24.5 °C were recorded. On 

September 29, 2008, this individual, then postlactating, 

roosted in the basement of this building where the maximum 

temperature was only 23.0 °C and the minimum temperature 

was 20.5 °C. A comparison of all temperatures associated 

with the building in May showed a difference among 

levels (K = 7.12, df = 2, P = 0.03, n = 9) where the attic 

temperature was warmer than the basement (Bonferroni 

corrected significance level: 0.0167). In September, we 

observed a marginal difference among the temperatures in 

the three roosting areas of this building (K = 6.18, df = 2, 

P = 0.05, n = 21), where the attic temperature was warmer 

than the basement (Bonferroni corrected significance level: 

0.0167). The pattern across sampling seasons was similar, 

with the attic warmer than the other levels of the roost 

structure (fig. 2). On October 1, 2008, we found no bat 

present, and there was no difference in temperatures (K = 3.55, 

df = 2, P = 0.17, n = 21). 

Data for temperatures of two other structures (cistern and 

building 764) indicate that bats used these roosts without 

apparent association with roost temperatures. These two roosts 

Figure 1—Temperatures in roost building 104 on 4 calendar days when bats were using the roost in May 2008 on Camp Mackall, NC. 

Each line represents temperature data collected with one iButton® per level.

Table 2—Weekly maximum, minimum, and average 

temperatures of anthropogenic roosts of Corynorhinus 

rafinesquii from May 27 to October 1, 2008, on and around 

Camp Mackall, NC

Roosting site

Average 

weekly 

maximum 

(n =16)

Average 

weekly 

minimum 

(n =16)

Average 

for time 

period 

(n =1530)

Building 764 34.4±2.5b 21.9±2.5b 27.1±4b

Cistern 32.4±2.7b 22.7±1.9a 27.0±3.6b

House 28.7±2.5b 19.3±2.4b 24.3±3.3b

Building 104 attic 51.2±3.9a 18.3±2.9c 29.9±9.5a

Building 104 ground 31.6±2.6b 19.3±2.6b 25.4±3.8b

Building 104 basement 27.5±1.5b 21.2±1.7b 24.2±2.3b

a,b,c Within columns, means without common letters are significantly 

different (P < 0.05).

0

5

10

15

20

25

30

35

40

45

50

Temperature (°C)

attic

ground level

basement

28 May 08 29 May 08 30 May 08 31 May 08

the 95-percent confidence limits of temperature data for all 

structures combined. Temperatures in the attic of building 

104 spanned the greatest range (16 to 57.5 °C) among 

the buildings sampled. The basement of building 104 had 

the lowest range in temperatures (16 to 29.5 °C) of the 

building roost sites, suggesting it was the most thermally 

stable roosting location among the structures measured. 

The different temperature regimes within building 104 may 

provide important roost choices for bats at different times 

of the year. The only other building for which we recorded 
106

764 on the third day where there was no difference between 

the building temperature and the outside air (t = 0.72, P = 0.5), 

and a maximum temperature of 32.0 °C and a minimum of 

25.5 °C were recorded in the roost. The cistern was checked 

on 2 days during the summer, but no bat was observed on 

either day. There was no difference between the cistern and 

ambient temperatures on July 18, 2008 (t = 0.34, P = 0.75) 

or on July 22, 2008 (t = 0.39, P = 0.71).

DISCUSSION

During a 6-year study at Camp Mackall and Fort Bragg, we 

documented the presence of 10 bat species. We discovered 

a colony of C. rafinesquii only at Camp Mackall. Only a 

single C. rafinesquii was captured during extensive netting 

efforts within suitable habitat, with all other captures of this 

species made in or near roost sites. Monitoring population 

sizes of a highly mobile species that switches roosts often 

can be difficult (Clark 2000, Clark and others 1997, Gooding 

and Langford 2004, Lance and others 2001, Trousdale and 

others 2008). Relative to overall capture effort, however, our 

recapture rate was high, suggesting that the population of 

C. rafinesquii in the study area was small. The largest group 

we observed had 11 individuals; a small but not uncommon 

colony size across the range of the species (Barbour and 

Davis 1969, Jones and Suttkus 1975). The apparent local 

rarity of C. rafinesquii at Camp Mackall may be due to one 

or more factors including scarcity of food resources, higher 

rates of mortality, or limited roost availability. Future studies 

identifying availability of food resources and predation 

pressures would contribute to an understanding of the limits to 

the size of this population. We suggest that observations made 

in this study support the limited roost availability hypothesis. 

Several adult females were recaptured in multiple years, but no 

banded juvenile was identified after initial capture. Recapture 

of adults and not juveniles may indicate low survival rates 

or dispersal of juveniles out of the population. A study by 

Jones and Suttkus (1975) supports our conclusion of a small 

colony size at Camp Mackall by documenting recaptures of 

both adults and juveniles in larger colonies of C. rafinesquii in 

Louisiana and Mississippi.

Limited availability of natural roosts has been suggested as 

a reason for use of artificial roosts throughout the southern 

range of the species (Bennett and others 2008); however, it 

is likely that C. rafinesquii has used anthropogenic structures 

as long as structures have existed in the range of the species 

(Audubon 2003, Dalquest 1947, Handley 1959). Many 

buildings potentially used by bats were once scattered across 

Camp Mackall, as evidenced by the presence of numerous 

concrete foundations, but were removed after acquisition 

of the property by the military. In addition to the loss of 

anthropogenic roosts, many large trees were removed from the 

study area as part of the extensive timber harvests conducted 

were used by the same bat a few days apart and were checked 

on 2 days when no bats were present (table 3). On May 30, 

2008, one male (A0701) and one pregnant female (A0798) 

C. rafinesquii (both radio-tagged) were found roosting in the 

cistern when the average roost temperature was lower than the 

average ambient temperature (t = 3.2, P = 0.018) and where 

maximum and minimum temperatures of 27 and 19 °C were 

recorded in the roost, respectively. The cistern was again 

cooler than ambient the next day (t = 3.97, P = 0.007) where 

maximum and minimum roost temperatures of 29 and 22 °C 

were recorded, but only the male was present (the female had 

moved to the barn). The male then moved to concrete building 

May 2008

20

25

30

35

40

45

50

14:0116:0118:01

20:0122:01

Time

Temperature (°C)

attic

ground 

level

basement

ambient

September 2010

20

25

30

35

40

45

50

14:0116:0118:0120:0122:01

Time

Temperature (°C)

attic

ground 

level

basement

ambient

Figure 2—Temperature profiles associated with building 104 on days 

when a female Corynorhinus rafinesquii was roosting inside on Camp 

Mackall, NC. iButton® was placed at noon on May 27, 2008, so first 

hour of the top graph represents acclimation to the environment.
107

the species (Carver and Ashley 2008, Clark 1990, Clement 

and Castleberry 2008, Harvey and others 1999, Jones 1977, 

Lance and others 2001). The ratio of trees to structures used 

as roosts by C. rafinesquii in this study was 11 to 9, a ratio 

consistent with Trousdale and Beckett (2005) (14 trees to 

11 structures) but unlike those of any other reports cited. 

Furthermore, an area on Fort Bragg (Overhills) containing 

> 20 abandoned buildings adjacent to a reservoir bordered by 

very young stands of T. distichum (x d.b.h. ca. 21 cm) never 

housed C. rafinesquii during searches from 2004 to 2009. 

These observations along with other studies (Clark 1990, 

Lance and others 2001, Trousdale and Beckett 2005) support 

the hypothesis that anthropogenic structures are functional 

as roosts of C. rafinesquii only in association with natural 

roosting habitat.

Radio-tagged C. rafinesquii were not located on 33 percent 

of transmitter days, i.e., one transmitter active for one day, 

but signals were often heard following a period of absence. 

Bats may have used underground structures in upland 

habitats on days when a radio signal was not detected 

(England and others 1990, Hoffmeister and Goodpaster 

1963, Martin and others 2006). We found roosts for 

C. rafinesquii in four underground structures on the base. 

Cisterns and other underground structures that could be 

used by bats were widely scattered across the landscape and 

difficult to locate. The role that underground structures serve 

in the study area, as a component of the functionality of 

anthropogenic roost structures, is not fully understood and is 

a subject in need of further study.

Anthropogenic structures may offer similar temperature 

conditions to tree roosts (Rice 2009) but provide more space 

for maneuverability to escape predation (Clark 1990), greater 

roosting choices for thermoregulation within the same 

roost (Hoffmeister and Goodpaster 1963), and potential to 

switch thermal environments during day roosting without 

exposure to daytime predators. Regardless, temperature 

regimes of roost sites and the effect on roosting behavior of 

C. rafinesquii remain poorly understood. For example, two 

pregnant females during late May used two very different 

roosts with regards to temperature. Bat A0800 roosted in 

the hot attic of building 104 while bat A0798 used the much 

cooler cistern. The following day, bat A0798 moved to the 

barn where temperatures were probably more similar to 

building 104. We suggest this movement between thermally 

different roosts may have occurred to avoid prolonged torpor 

conditions. Similarly, C. rafinesquii may use the same roost 

throughout the year but use thermally different portions 

of the roost among seasons (Hoffmeister and Goodpaster 

1963, Hurst and Lacki 1999). Bat A0800 that roosted in 

the hot attic of building 104 demonstrated this behavior by 

choosing the cooler basement within the building later in 

in bottomland hardwood forests across the Southeastern 

United States (Tiner 1984). The forests on Camp Mackall 

were extensively logged up to the early 1980s.1

 The presence 

of large stumps throughout the area suggests that historical 

vegetation included large trees that likely provided more 

suitable roosts for C. rafinesquii. Roost trees used by this 

species at Camp Mackall were the largest trees measured. 

Trees in the current forest may just now be reaching sufficient 

size to develop cavities used as roosts by this species. Mean 

d.b.h. of roost trees were smaller than reported in some studies 

(129±7.3 cm, Carver and Ashley 2008; 120±3.5 cm, Gooding 

and Langford 2004) but similar to others (59 to 103 cm, 

Lance and others 2001; 81.9±25.4 cm, Rice 2009; 79.4 cm, 

Trousdale and Beckett 2005). The colony of C. rafinesquii at 

Camp Mackall may be either a recently established colony or 

a remnant population from a historically larger assemblage. 

Assuming the number and condition of anthropogenic 

structures remain the same and the forest continues to mature 

and additional roosts become available, a larger population of 

C. rafinesquii may be supported on Camp Mackall, especially 

if roost availability is the limiting factor to population size of 

this species in the area. 

Anthropogenic structures may be important for maintaining 

populations of C. rafinesquii where natural roost sites are 

severely limited. The ratio of natural to anthropogenic roosts 

used by C. rafinesquii varies considerably across the range of 

1

 Personal communication. 2010. Steve Riley, retired Forester, Ft. Bragg, 

NC 28310.

Table 3—Average daytime temperatures and SD (0800 

to 2000 hours; n = 7 readings) of selected roosts of 

Corynorhinus rafinesquii, with and without bats present, 

on, and around Camp Mackall, NC, 2008

Roost Date Bat Temperature (°C) P-value

Cistern Cistern Ambient

May 30, 

2008

Fa

, Mb 23.6±3.4 27.8±5.5 0.02

May 31, 

2008

M 25.7±3.1 30.2±4.9 0.01

July 18, 

2008

No bat 27.6±1.6 27.3±2.5 0.75

July 22, 

2008

No bat 31.2±3.2 32.1±6.1 0.71

Building 764 Building 764 Ambient

June 1, 

2008

M 28.9±2.3 31.0±7.1 0.50

a F = pregnant female; b M = adult male.
108

one female was documented transporting a pup exceeding 

50 percent of her body mass > 1 km to another roost. This is 

consistent with a report by England and others (1990) who 

observed that female C. rafinesquii transport large juveniles 

(5 g) when disturbed or to seek more favorable roost 

temperatures. 

Extensive habitat loss has placed bat populations at risk 

by reducing their population sizes to levels that will 

likely have difficulty resisting threats such as white-nose 

syndrome (Geomyces destructans) (Zimmerman 2009) 

and the rapidly growing use of wind turbines as an energy 

source (Baerwald and Barclay 2009, Cryan and Barclay 

2009, Johnson and others 2003). A better understanding of 

habitat requirements is essential for creating and applying 

more effective protection strategies for remaining bat 

populations. Forests provide food and shelter to many bat 

species, but in light of extensive logging practices and urban 

development throughout the range of C. rafinesquii in the 

last century (Marks and Marks 2006), management and 

preservation of anthropogenic structures and construction 

of artificial roosts will likely play an important role in the 

protection of populations of this species in human-altered 

environments. For example, bat houses specifically designed 

for C. rafinesquii erected near existing roost trees are used 

more readily than ones placed farther from known tree roosts 

(Bayless 2008). We found that bats moved farther from 

tree roosts and Drowning Creek to roost in anthropogenic 

structures on Camp Mackall and suggest that placing 

artificial roosts in the vicinity of known tree roosts may be 

beneficial in providing additional roosting habitat. Structure 

roosts alone, without a suitable forest component, are not 

likely to provide long-term support for the population of 

C. rafinesquii on Camp Mackall as demonstrated by the 

uninhabited buildings and unsuitable trees at Overhills on 

Fort Bragg. Due to the limited availability of bottomland 

hardwood forest at Camp Mackall, we encourage land 

managers to consider sustaining large (d.b.h. > 85 cm) 

hollow trees of appropriate species, such as T. distichum and 

Nyssa spp. We believe such an approach can be integrated 

into the management practices currently in use and will 

provide suitable roosting habitat needed to maintain future 

populations of C. rafinesquii on Camp Mackall. 

ACKNOWLEDGMENTS

We thank U.S. Department of Defense, Fort Bragg, for 

funding and support of this project. The Fort Bragg 

Endangered Species Branch, especially J. Britchard, J. 

Patten, and E. Evans, provided invaluable assistance and 

logistical support. This project would not have been possible 

without the dedication of the Copperhead Consulting field 

crew: C. Leftwich, J. Hawkins, J. Adams, E. Britzke, J. 

Hootman, D. Foster, G. Hurt, D. Pace, M. Gruen, and C. 

the year after her pup was presumably volant. Pregnancy 

is energetically expensive (Racey 1973), so this bat may 

have chosen the warmer roosting conditions to passively 

rewarm prior to exiting the roost to feed at night (Winchell 

1990). As with other species (Parkinson 2008), female C. 

rafinesquii may select warmer roosting conditions to avoid 

torpor when pregnant. Bats in torpor have a slower metabolic 

rate and, therefore, contribute fewer resources to a growing 

fetus under such conditions (Racey and Swift 1981). Later 

in the year, when the young are volant and the demands of 

reproduction have ceased, warmer roosts may be unnecessary 

or even counterproductive. Cooler roosts selected by bat 

A0800 later in the year may have provided an energy savings 

by permitting this bat to enter torpor during a period of lower 

temperatures when food availability was likely reduced. 

Although roost quality depends in part on temperature 

regime, distances to landscape features used as flight 

corridors or feeding and drinking sites are also important 

(Clark 1990, Kurta and others 2002, Watrous and others 

2006). Roost trees were located closer to Drowning Creek 

and firebreak roads than anthropogenic roost structures were 

to these features. This was due to buildings not being placed 

within the bottomland hardwood forest along Drowning 

Creek to avoid the potential of flooding. Nevertheless, 

proximity to permanent water has been suggested as an 

important habitat characteristic in selection of roosts 

by C. rafinesquii by enhancing access to food resources 

and drinking water (Clark 1990, Gooding and Langford 

2004). Permanent water in the form of creeks or rivers can 

also provide flyways for these bats. Firebreak roads may 

provide flight corridors for commuting between roosts 

and foraging areas. Thus, roosting closer to these features 

should be advantageous to these bats. We suggest that use 

of anthropogenic structures by C. rafinesquii on Camp 

Mackall, situated farther from water and firebreak roads, 

may offset these distance constraints through advantages 

in maneuverability inside roosts and access to diverse 

temperature regimes. 

We found distances that bats moved between roosts varied 

between sexes and reproductive condition classes. For 

example, males moved shorter distances between roosts than 

females. It is possible that males have fewer constraints and, 

thus, can use roosts that are less suitable for females. Roosts 

with lower temperatures may allow males to enter torpor 

and provide an energy savings advantage not available to 

reproductively active females that require warmer roosts for 

fetus development (Racey and Swift 1981). Thus, males may 

have more roosts available to them than females, and the 

need for longer movements is unnecessary. As documented 

in other species (Kurta and others 2002), lactating females 

moved shorter distances between roosts than pregnant 

females. Females with nonvolant young may move shorter 

distances due to the additional weight of the young. At least 
109

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111

it is unknown whether bats prefer one type of structure over 

the other or whether their preference varies seasonally. 

Some studies have examined year-round roost use by 

Rafinesque’s big-eared bats. In Louisiana and Mississippi, 

use of bridges as day roosts declines in winter (Ferrara 

and Leberg 2005b, Trousdale and Beckett 2004). Use of 

trees with basal openings or trees with basal and chimney 

openings also declines in winter in Louisiana, and bats 

appear to move to trees with chimney-only openings, 

particularly during periods of below freezing temperatures 

(Rice 2009). Trees with chimney-only openings have more 

stable temperatures, suggesting that thermal considerations 

may be important in selection of winter roost sites. Winter 

flooding may block the entrances to trees with basal 

openings, which may be another reason that the bats in 

winter select trees with chimney-only openings even though 

such trees provide less shelter from rain. 

Multiannual roost use is another important aspect of roosting 

ecology. Long-term use of tree roosts appears to be related 

to roost type (cavity/crevice versus bark) and decomposition 

state of the tree. For example, bats that roost between the 

bark and bole of snags are less likely to reuse roosts in 

subsequent years than bats that roost in crevices or cavities 

in live-damaged trees (Barclay and Brigham 2001, ChungMacCoubrey 2003, Lučan and others 2009, Willis and others 

INTRODUCTION

Day roosts are integral to the ecology and evolution of bats, 

and many aspects of roost use and selection have received 

attention over the past two decades (Barclay and Kurta 

2007, Carter and Menzel 2007, Kunz and Lumsden 2003). 

Studies have concentrated on habitat factors affecting roost 

site selection (Kalcounis-Ruppell and others 2005, Lacki and 

Baker 2003), effects of microclimate and parasites on roost 

selection (Kerth and others 2001, Reckardt and Kerth 2007, 

Willis and Brigham 2005), and roost fidelity (Gumbert and 

others 2002, Kurta and Murray 2002, Trousdale and others 

2008). However, most of these studies have been conducted 

during the summer, and, for most temperate and boreal bat 

species, little is known about use of tree roosts during other 

times of the year (although see Boyles and Robbins 2006, 

Hein and others 2005, Mormann and Robbins 2007).

Rafinesque’s big-eared bats (Corynorhinus rafinesquii) that 

inhabit bottomland hardwood forests and their environs 

roost in large hollow trees and anthropogenic structures 

such as buildings, bridges, and wells (Bennett and others 

2008; Carver and Ashley 2008; Gooding and Langford 2004; 

Lance and others 2001; Trousdale and Beckett 2004, 2005). 

Most studies have either examined use of anthropogenic 

structures or natural roosts, and few studies compare the use 

of anthropogenic and natural structures in a study area. Thus, 

SeaSONal aND mUlTIaNNUal ROOST USe by RafINeSqUe’S bIg-eaReD 

baTS IN The COaSTal PlaIN Of SOUTh CaROlINa

Susan C. loeb, Research Ecologist, U.S. Department of Agriculture Forest Service, 

Southern Research Station, Clemson, SC 29634

Stanley J. Zarnoch, Mathematical Statistician, U.S. Department of Agriculture Forest Service, 

Southern Research Station, Asheville, NC 28804

Abstract—Little is known about factors affecting year-round use of roosts by Rafinesque’s big-eared bats 

(Corynorhinus rafinesquii) or the long-term fidelity of this species to anthropogenic or natural roosts. The objectives 

of this study were to test whether seasonal use of roosts by Rafinesque’s big-eared bats varied with roost type and 

environmental conditions within and among seasons and to document multiannual use of natural and anthropogenic 

structures by this species. We inspected 4 bridges, 1 building, and 59 tree roosts possessing basal cavity openings; 

roosts were inspected at least once per week from May through October in every year from 2005 through 2008 and 

once a month from November through April in every year from 2005 through 2009. We found that use of anthropogenic 

roosts was significantly greater than the use of tree roosts in summer but that the use of structure types did not differ in 

other seasons. There was significant seasonal variation in use of anthropogenic and tree roosts. Anthropogenic roost use 

was higher in summer than in all other seasons. There was no significant difference in tree use among spring, summer, 

and fall, but use in winter was significantly lower in 2 years of the study. Overall use of anthropogenic and tree roosts 

was positively related to minimum temperature, but the relationship between use of roosts and minimum temperature 

varied among seasons. Bats showed multiannual fidelity (≥ 4 years) to all anthropogenic roosts and to some tree roosts, 

but fidelity of bats to anthropogenic roosts was greater and more consistent than to tree roosts. Our data indicate 

that Rafinesque’s big-eared bats responded differently to environmental conditions among seasons; thus, a variety of 

structure types and characteristics are necessary for conservation of these bats. We suggest long-term protection of roost 

structures of all types is necessary for conservation of Rafinesque’s big-eared bats in the southeast Coastal Plain.

Citation for proceedings: Loeb, Susan C.; Lacki, Michael J.; Miller, Darren A., eds. 2011. Conservation and management of eastern big-eared bats: 

a symposium. Gen. Tech. Rep. SRS-145. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 157 p.
112

We located roosts by inspecting trees with basal cavities 

in bottomland forests and the surrounding areas, bridges, 

and old buildings and by radiotelemetry. We found trees 

with basal cavities during systematic searches of areas 

that were likely to contain potential roosts, such as mature 

bottomland hardwood forests and cypress-tupelo swamps, and 

opportunistically while conducting radiotelemetry and habitat 

analyses. Mature bottomland hardwood forest and cypresstupelo swamp forests were located from forest maps, and all 

accessible trees within an area were examined, using a light 

and mirror, for the presence of Rafinesque’s big-eared bats. 

Bats that roosted under bridges were captured by hand or with 

hand nets. Bats in trees with basal openings were captured by 

placing a mist net over the cavity entrance and capturing the 

bats as they emerged at dusk. All captured Rafinesque’s bigeared bats were weighed, sexed, and aged and examined for 

parasites and injuries. We placed an aluminum lipped band 

(Lambournes Sophos Ltd., West Midlands, Birmingham, 

England) and a colored plastic split ring band (A.C. Hughes, 

Ltd., Middlesex, England) on the forearms of each bat. 

Various band placement and color combinations allowed us 

to determine the identity of bats when observed in a roost 

if the bands were visible. Capture and handling procedures 

followed guidelines established by the American Society of 

Mammalogists (Gannon and others 2007) and were approved 

by the Clemson University Institutional Animal Care and Use 

Committee (protocol numbers 50057 and ARC2008-027). 

To obtain additional roost locations, we attached radio 

transmitters (0.42 g; Holohil Systems Ltd, Ontario, Canada) 

to the dorsal surface of 49 bats with Skin Bond adhesive 

(Pfizer Hospital Products Group, Inc., Largo, FL). We held 

bats for ≥ 20 minutes before releasing them to ensure the 

transmitter was secure. On the following and subsequent 

days, we used three- or five-element Yagi antenna and 

receiver (Wildlife Materials, Inc., Murphysboro, IL) to 

track bats to day roosts. If the bat was tracked to a bridge 

or building, the bat’s relative location within the structure 

was recorded. If the bat was tracked to a tree, the tree 

was flagged, marked with a numbered aluminum tag, and 

identified to location with a global positioning system 

device. We treated tree roosts identified during random or 

systematic searches in the same manner. We verified that 

trees discovered using telemetry were the actual roost by 

visual inspection of the cavity with a light and mirror or by 

observing emergence of the bat from the cavity at dusk. 

After identifying roosts, we monitored them throughout the 

rest of the study with the exception of roosts with only an 

upper bole opening or those that could not be fully examined 

due to a bend in the tree or because the cavity entrance was 

too small. We examined each roost at least once a week 

from May through October and at least once a month from 

November through April, except in the winter of 2008 to 

2009 when we examined roosts at least once a week. The 

number of examined roosts varied throughout the study 

2003). Further, bats that roost in relatively permanent roosts 

such as caves or mines show greater fidelity to their roosts 

than bats that use relatively ephemeral roosts such as trees 

(Lewis 1995). While there are a few anecdotal accounts of 

multiannual use of anthropogenic roosts by Rafinesque’s 

big-eared bats (Clark 1990, Jones and Sutkus 1975), there 

are no quantitative data on long-term fidelity to either 

anthropogenic or tree roosts. 

The objectives of our study were to test whether seasonal use 

of roosts by Rafinesque’s big-eared bats varied with roost type 

(anthropogenic versus tree) and environmental conditions, 

both within and among seasons, and to document multiannual 

use of natural and anthropogenic structures by this species. We 

hypothesized that use of anthropogenic roosts and tree roosts 

with basal or basal-plus chimney openings would be positively 

related to ambient temperature and rainfall on an annual 

basis but would vary with season. We also hypothesized that 

multiannual use of anthropogenic structures would be greater 

than multiannual use of natural roosts.

meThODS

Our study was conducted from May 2005 through April 2009 

on the U.S. Department of Energy Savannah River Site (SRS) 

in Aiken and Barnwell Counties, SC. The SRS is a 78 000-

ha National Environmental Research Park in the sandhills 

and Upper Coastal Plain physiographic regions. The site is 

primarily forested in mid- to late-successional pine (Pinus

spp.), mixed pine-hardwood, and upland hardwood forests 

(Imm and McLeod 2005). However, approximately 20 percent 

of SRS is swamp and bottomland hardwood forest. SRS 

experienced extensive disturbance and land clearing from the 

mid-1800s to the early 1950s when the site became Federal 

property (White 2005). Chief disturbances to the swamp and 

along the major streams prior to and after 1950 were logging, 

damming, high flow rates, altered temperatures from reactor 

cooling waters, and changes in hydrology (Kolka and others 

2005). Bottomland hardwood forests consisted primarily of 

blackgum (Nyssa sylvatica), laurel oak (Quercus laurifolia), 

water oak (Q. nigra), red maple (Acer rubrum), American 

holly (Ilex opaca), sweetbay (Magnolia virginiana), redbay 

(Persea borbonia), ironwood (Carpinus caroliniana), and 

sweetgum (Liquidambar styraciflua); whereas major tree 

species in the swamps were water tupelo (N. aquatica), 

baldcypress (Taxodium distichum), and red maple. Average 

low and high temperatures from 1893 to 2008 ranged from 2.7 

and 14.4 °C in January to 21.0 and 33.2 °C in July (Southeast 

Regional Climate Center, http://www.sercc.com/cgi-bin/sercc/

cliMAIN.pl?sc0074). Average annual rainfall for the area was 

118.4 cm (Southeast Regional Climate Center, http://www.

sercc.com/cgi-bin/sercc/cliMAIN.pl?sc0074) but was below 

average in every year of the study (2005 to 2006, 58.3 cm; 

2006 to 2007, 101.3 cm; 2007 to 2008, 106.22 cm; 2008 to 

2009, 96.9 cm).
113

because new roosts were continually added to the sample of 

roost trees, and six tree roosts broke or fell during the course 

of the study. Some roosts were periodically inaccessible due 

to high water. Trees that could not be examined regularly 

were not included in the analyses. 

We defined seasons as spring (March and April), summer 

(May, June, July, and August), fall (September and October), 

and winter (November, December, January, and February) 

based on climatic conditions as well as the annual cycle of 

Rafinesque’s big-eared bats. For example, females in this 

area form maternity colonies and are visibly pregnant in 

May, and colonies begin to break up at the end of August. 

Thus, May was considered a summer month and September 

a fall month. Further, because November temperatures, 

particularly minimum temperatures, were more similar to 

December, January, and February than to October, November 

was considered a winter month (fig. 1). 

Temperature (°C), rainfall (mm), relative humidity (percent), 

and windspeed (m/second) were recorded hourly at a weather 

station maintained by other researchers on SRS (Coleman 

and others 2004). Daily maximum temperature (Tmax), 

minimum temperature (Tmin), average daily temperature 

(Tavg), minimum relative humidity (RHmin), average 

windspeed (WSavg), and total rainfall (Rainfall) were 

extracted for each day from mid-May 2005 through April 

2009. Because Tmax, Tmin, and Tavg were highly correlated 

(r > 0.70), only Tmin was used in statistical models. We 

selected Tmin because we were particularly interested in the 

effects of low temperatures on winter roost use. 

We used a split-split-plot approximation of a repeated 

measures model because both year and season were repeated 

in the model which presented a complex covariance 

structure. Under conditions of equal variances and equal 

pairwise correlations over time, the split-split plot is an 

optimal method of analysis (Littell and others 1998) and is 

valid under the Huynh-Feldt condition which is less stringent 

than equal variances and covariances. We used the PROC 

GLIMMIX procedure (Schabenberger 2005) in SAS (2003) 

to fit a generalized linear mixed model to the binary (absence 

= 0, presence = 1) data under the binomial distribution and 

logit link function, resulting in a logistic response model. 

A three-phased approach was used to analyze relationships 

between roost use (0, 1) and independent variables. In phase 

1, we analyzed roost use using a split-split-plot design to 

test fixed effects of roost type (main plot), year (split plot), 

and season (split-split plot) and their two- and three-way 

interactions. In phase 2, we tested the effects of season and 

year separately for each roost type using a split-plot design 

because we found strong interactions in the phase 1 analysis 

between roost type and season (P = 0.0239) and year and 

season (P = 0.0003). In phase 3, we modeled the effects 

of environmental parameters on roost use for each roost 

Figure 1—Long-term average (1893 to 2008) mean monthly 

maximum daily temperatures (Tmax), mean minimum daily 

temperatures (Tmin), and total rainfall (Rainfall) for the Savannah 

River Site, SC, and the mean maximum daily temperatures (Tmax), 

mean minimum daily temperatures (Tmin), and total rainfall (Rainfall) 

for each year of the study (2005 to 2009).
114

Anthropogenic roosts were four girder-type bridges and 

one barn. Tree roosts were in tupelos (N. aquatica and 

N. sylvatica), oaks (Q. laurifolia, Q. michauxii, Q. nigra, 

and Q. velutina), American beech (Fagus grandifolia), 

sweetbay, sweetgum, river birch (Betula nigra), yellowpoplar (Liriodendron tulipifera), baldcypress, and sycamore 

(Plantanus occidentalis). There were a total of 5,152 

roost inspections; the number of inspections per structure 

ranged from 2 to 195 for roost trees and 193 to 329 for 

anthropogenic roosts. The number of Rafinesque’s bigeared bats found in a roost ranged from zero to 9 for trees 

and from zero to 15 for anthropogenic roosts. 

Use of anthropogenic roosts was higher than tree roost use 

in every month except January 2008 and during most months 

in winter 2009 (fig. 2). Overall use of anthropogenic roosts 

was not significantly different from tree roost use based on 

the phase 1 analysis but there was a significant roost*season 

interaction (F = 3.19, P = 0.0239). Thus, we conducted 

pairwise comparisons between anthropogenic and tree roost 

use for each season. Anthropogenic roost use was higher 

than tree use in every season but the difference was only 

significant during summer (fig. 3). 

Use of both roost types was lowest in winter, particularly 

November to January, but higher in other seasons (fig. 2). 

Roost use in winter 2006 to 2007, particularly anthropogenic 

roosts, did not decline as much as in other years during 

the winter. Although Tmax was greater in November, 

December, and January 2006 to 2007 than the long-term 

average, it was also greater than the long-term average in 

type by testing the effects of year, season, year*season, and 

the environmental covariates consisting of Tmin, RHmin, 

WSavg, Rainfall, and their interaction with season (that 

is, season*Tmin, season*RHmin, season*WSavg, and 

season*Rainfall). Homogeneity of the slope parameter over 

season for each of the four environmental covariates was 

tested by inspection of the covariate*season interactions 

and then reducing the full model by deleting the most 

nonsignificant covariate*season interaction. The reduced 

model was then refitted, the remaining covariate*season 

interactions inspected and deleted sequentially until all 

remaining covariate*season interactions were significant at 

the 0.05 level. Then this model was reduced sequentially by 

deleting the most nonsignificant covariate and then refitting 

and testing the remaining covariates until all remaining 

covariates were significant at the 0.05 level. For each of the 

final reduced models, significant covariate interactions with 

season indicated that the covariate slopes differed among 

the seasons. We used contrasts to determine which slopes 

were significantly different. The Bonferroni correction for 

each set of six pairwise comparisons among the seasonal 

slopes set the rejection level at α = 0.0083 to ensure that the 

experimentwise error rate was maintained at 0.05 (Zarnoch 

2009). All other tests were evaluated at α = 0.05, and least 

square means ± 1 SE are presented. 

ReSUlTS

Fifty-nine roost trees with basal cavities and five 

anthropogenic roosts were examined during the study. 

Figure 2—Percent of roost checks in which at least one Rafinesque’s big-eared bat was observed in 

anthropogenic and tree roosts on the Savannah River Site, SC, May 2005 to April 2009.
115

was significantly greater in summer than in all other seasons 

in 2006 to 2007 and 2008 to 2009 and significantly greater 

in summer than in fall and winter in 2005 to 2006 and 2007 

to 2008 (table 1). Tree roost use did not vary significantly 

among seasons in 2005 to 2006 and 2006 to 2007 but was 

significantly lower in winter than all other seasons in 2007 

other years, and Tmin in 2006 to 2007 was similar to other 

years (fig. 1). The phase 2 analysis indicated that there 

was a significant interaction between year and season for 

both anthropogenic (F = 2.51, P = 0.0192) and tree roosts 

(F = 2.02, P = 0.0368). Thus, we examined seasonal use by 

year for each roost type. Use of anthropogenic structures 

Figure 3—Mean use of anthropogenic and tree roosts by season by Rafinesque’s big-eared bats 

on the Savannah River Site, SC, May 2005 to April 2009; means within a season with the same 

letter are not different (P > 0.05).

Table 1—mean proportional use (± Se) of anthropogenic and tree roosts by season 

and year of Rafinesque’s big-eared bats on the Savannah River Site, may 2005 to 

april 2009

Roost type 2005–06 2006–07 2007–08 2008–09

Anthropogenic roosts

Spring 0.78±0.19ab 0.36±0.23a 0.47±0.28ab 0.07±0.07a

Summer 0.76±0.18a 0.76±0.17b 0.75±0.18b 0.67±0.22b

Fall 0.47±0.24b 0.53±0.25a 0.40±0.24a 0.28±0.21a

Winter 0.40±0.25b 0.27±0.20a 0.07±0.07c 0.11±0.10a

Tree roosts

Spring 0.61±0.14a 0.26±0.09a 0.19±0.06a 0.11±0.03ab

Summer 0.58±0.33a 0.30±0.09a 0.27±0.06a 0.16±0.04b

Fall 0.43±0.16a 0.29±0.09a 0.21±0.05a 0.14±0.04b

Winter 0.35±0.16a 0.14±0.07a 0.02±0.0b 0.06±0.02a

a,b,c Proportions with the same letter within a year for a given roost type are not significantly different at 

the experimentwise error rate of 0.05 (Bonferroni correction, P = 0.0083).
116

(table 2), but the interaction between Tmin and season was 

also significant. Use of tree roosts was positively related 

to Tmin in fall and winter but negatively related to Tmin 

in summer (fig. 4B). The effect of Tmin was significantly 

different (P ≤ 0.0001) between summer and fall with use 

decreasing with increasing Tmin in summer and increasing 

with temperature in fall and winter. 

All five anthropogenic roosts were used in every year 

of study. Rafinesque’s big-eared bats were present in 

anthropogenic roosts during 56.7 to 88.6 percent of roost 

checks. Of the nine trees found in year one, four were used 

in all years, two were used in 3 years, and three in 2 years. 

One of the trees used in 3 years fell in year three, and the 

to 2008 and significantly lower in winter than summer and 

fall in 2008 to 2009.

The phase 3 full model revealed use of anthropogenic 

roosts was significantly related to Tmin and RHmin (table 

2). Anthropogenic roost use increased with increasing 

temperature and decreased with increasing RHmin. There 

was no effect of Rainfall or WSavg. However, examination 

of the reduced models revealed that the Tmin*season 

interaction was significant. The slope of use versus Tmin 

was significantly greater in winter than in fall (P = 0.0018) 

indicating that use was more sensitive to temperature in 

winter than in fall (fig. 4A). Overall, there was a significant 

and positive relationship between Tmin and use of tree roosts 

Table 2—Results of phase 3 generalized linear mixed models testing the effects of environmental variables on use of 

anthropogenic and tree roosts by Rafinesque’s big-eared bats on the Savannah River Site, SC, may 2005 through april 2009a

Anthropogenic roosts Tree roosts

Models Num. dfb Den. dfc F P Num. dfb Den. dfc F P

Full model

Year 3 12 2.90 0.0785 3 64 4.20 0.0089

Season 3 1199 0.13 0.9395 3 3660 3.48 0.0153

Year*Season 9 1199 2.27 0.0159 9 3660 1.52 0.1333

Tmind 1 1199 20.27 < 0.0001 1 3660 4.95 0.0261

Rainfall 1 1199 0.39 0.5336 1 3660 0.60 0.4385

RHmine 1 1199 12.13 0.0005 1 3660 0.23 0.6341

WSavgf 1 1199 2.05 0.1528 1 3660 0.21 0.6472

Tmin*Season 3 1199 4.19 0.0058 3 3660 5.57 0.0008

Rainfall*Season 3 1199 2.23 0.0828 3 3660 3.39 0.0172

RHmin*Season 3 1199 2.35 0.0712 3 3660 1.44 0.2302

WSavg*Season 3 1199 0.36 0.7808 3 3660 0.21 0.8915

Reduced model

Year 3 12 2.67 0.0948 3 64 4.78 0.0045

Season 3 1210 3.76 0.0105 3 3738 9.09 < 0.0001

Year*Season 9 1210 2.24 0.0176 9 3738 1.71 0.0803

Tmind 1 1210 16.73 < 0.0001 1 3738 5.19 0.0228

Tmin*Season 3 1210 3.71 0.0112 3 3738 5.69 0.0007

RHmine 1 1210 13.70 0.0002

a The full model and final reduced models are presented.

b

 Numerator degrees of freedom.

c Denominator degrees of freedom.

d

 Minimum temperature.

e

 Minimum relative humidity.

f

 Average windspeed.
117

2.4±0.18 for trees found in year two, and 1.7±0.10 for trees 

found in year three. There was considerable variation in 

tree roost use across time. For trees checked ≥ 20 times, 

bats were present an average of 17.6 percent with a range of 

1.0 to 89.2 percent.

Long-term use of roosts was accomplished by the same 

individual or group of individuals which was particularly 

other was used in 2005 to 2006, 2006 to 2007, and 2008 

to 2009. Of the nine trees found in year two, four were 

used for 3 years and five were used for 2 years; one of the 

trees used for 2 years fell during year four. Of the 24 trees 

found in year three, 15 were used in both years three and 

four, and 9 were only used in year three; 1 of these trees 

fell soon after it was discovered. The mean number of years 

trees were used was 3.1±0.31 for trees found in year one, 

A

B

Figure 4—The relationship between the proportion of (A) anthropogenic roosts 

and (B) tree roosts occupied and minimum temperature (Tmin) for each season 

based on a typical year (year = 2) and typical minimum relative humidity 

(RHmin = 40.3 for anthropogenic roosts and RHmin = 38.1 for tree roosts) on the 

Savannah River Site, SC, May 2005 to April 2009. The curve segment length for 

each season is based on the range of minimum temperatures observed for each 

season and roost structure. 
118

other tree structures. Our finding that use of anthropogenic 

roosts was significantly greater than use of trees in summer 

but not significantly different during other seasons suggests 

that bats indeed moved from trees to anthropogenic roosts 

during the warmest months. In Colorado, big brown bats 

(Eptesicus fuscus) that roost in buildings are more likely to 

shift to new roosts or new areas within the same roost during 

unusually hot periods (Ellison and others 2007). Because 

anthropogenic roosts are larger, there may be a greater 

variety of microclimates within each structure where bats can 

move to select the best microclimate (e.g., Clark 1990, Jones 

and Suttkus 1975). Rafinesque’s big-eared bats may also 

have moved to trees with chimney-only openings in summer. 

Rice (2009) found that cavity temperatures of roosts that 

have chimney-only entrances rise more slowly with increases 

in ambient temperature in summer and are more stable than 

those with basal cavities and basal-plus chimney openings.

While roost temperature may be an important factor 

governing differential use of anthropogenic and tree roosts 

during summer, other factors may also be important. 

Rafinesque’s big-eared bats that use bridges as day roosts 

in Louisiana select the warmest areas of the bridges even 

when temperatures are quite high (Ferrara and Leberg 

2005a). These areas are also the darkest portions of the 

bridges where bats are less likely to be detected by terrestrial 

predators. Although we did not measure light levels in trees 

and anthropogenic structures, it was often possible to spot 

bats under bridges and in the building without the aid of a 

light. It was never possible to see bats in trees without a light 

source. This suggests that bats were not using anthropogenic 

structures more often than trees due to light levels and that 

other features of anthropogenic structures may have reduced 

the risk of predation. For example, bats that used bridges 

often roosted in the middle of the bridge over water, putting 

them out of reach of snakes and raccoons, both of which 

were observed under bridges. 

Although use of anthropogenic structures was not lower in 

winter than in fall and spring, there was a general trend for 

use to decline in winter as in tree roosts. We were not able 

to survey trees with chimney-only openings due to logistical 

constraints. However, Rice (2009) found that Rafinesque’s 

big-eared bats in Louisiana often moved from trees with 

basal-only or basal-plus chimney openings to trees with 

chimney-only openings during winter. Therefore, it is likely 

that many of the bats that used anthropogenic roosts and 

trees with basal and basal-plus chimney openings during 

spring, summer, and fall moved to trees with chimney-only 

openings in winter. Lower use of roosts in winter may also 

be due to changes in clustering behavior. In summer, adult 

males usually roost by themselves, but during winter we 

have observed males roosting with large colonies as did Rice 

(2009) in Louisiana. Large aggregations of bats can increase 

the roost temperature by as much as 7 °C in summer (Willis 

evident for anthropogenic roosts. For example, orange 18 was 

captured and banded at bridge 603-01G in July 2003, prior to 

the initiation of this study, as a juvenile and was recaptured 

there in June 2005, July 2006, and August and October 2007. 

This bat was consistently observed roosting at this bridge 

throughout the 4-year study period and during periodic checks 

in summer 2009 after the study had concluded. Another 

example is green 22, an adult male, who was captured at 

bridge 603-02G in September 2004. He was observed at this 

bridge throughout the 4-year study period as well as summer 

2009. This bat also used tree 358 during summer and fall 

2006, summer and fall 2007, and winter and spring 2008 to 

2009. Bridge 603-03G was used throughout the study period 

by a maternity colony. The bats were first observed using 

this bridge in September 2004, and anywhere from 1 to 15 

individuals, including young, were observed at this bridge 

throughout the study, as well as in summer 2009. This colony 

also used two roost trees from summer 2007 through summer 

2009. Conversely, some roosts used for 3 to 4 years were 

used by a sequence of different individuals. For example, tree 

352 was used by orange 40, a juvenile male when banded, 

in fall 2005 and summer 2006; by green 28, an adult male, 

in summer and fall 2007; by pink 2, a juvenile male, in fall 

2007; and by blue 3, an adult male, in summer 2008. 

DISCUSSION

Decreased use of bridges and trees with basal cavities as 

day roosts by Rafinesque’s big-eared bats in winter has been 

previously documented in Louisiana (Ferrara and Leberg 

2005b, Rice 2009) and Mississippi (Trousdale and Beckett 

2004). We also found decreased use of anthropogenic and tree 

roosts by Rafinesque’s big-eared bats on the SRS in winter, 

but the seasonal patterns of use varied between types of 

roosts. Use of anthropogenic roosts peaked in summer but, in 

most years, there was no difference in use among fall, winter, 

and spring. In contrast, use of trees with basal cavities was 

similar during spring, summer, and fall but declined in winter, 

although the decline was only significant in the last 2 years 

of the study. Use of anthropogenic structures was also greater 

than use of tree roosts in summer but not in other seasons. 

Differential use of anthropogenic and tree roosts may be due 

to differences in the microclimate of the various structures. 

On an annual basis, use of both anthropogenic and tree 

roosts was positively related to Tmin. However, we found 

that the relationship between roost use and Tmin varied 

among roost types and seasons. Use of anthropogenic roosts 

was more strongly influenced, i.e., a steeper slope, by Tmin 

in winter than in fall, and use of tree roosts was positively 

related to Tmin in spring, fall, and winter but negatively 

related to Tmin in summer. During summer, some tree 

roosts with basal cavities may be too warm and bats may 

need to search out other types of roosts such as bridges or 
119

CONClUSIONS 

Our data suggest that factors affecting use of roosts by 

Rafinesque’s big-eared bats in bottomland hardwood forests 

may vary with roost type and season. Thus, conclusions 

based on data from anthropogenic roosts may not apply to 

tree roosts and vice versa. Our data also suggest that bats 

responded differently to environmental conditions among 

seasons and roost types. Because Rafinesque’s big-eared bats 

in the Coastal Plain are typically found in an area throughout 

the year (this study, Rice 2009, Trousdale and Beckett 

2004), studies of these bats should be conducted year round, 

when possible, to identify environmental and habitat factors 

affecting these populations. We encourage future studies 

of microclimate conditions within and between roost types 

to more fully understand roost selection by Rafinesque’s 

big-eared bats on an annual basis. The long-term use of both 

anthropogenic and tree roosts by these bats emphasizes the 

importance of such structures to the ecology of Rafinesque’s 

big-eared bats; when these are identified as used by these 

bats, we recommend that both types of structures be given 

long-term protection from disturbance and destruction. 

aCKNOWleDgmeNTS

Funding was provided by the U.S. Department of Energy, 

Savannah River Operations Office through the U.S. 

Department of Agriculture Forest Service, Savannah River 

under Interagency Agreement DE-IA09-00SR22188. We 

thank John Blake and Kim Wright for logistical support; Eric 

Winters, Kelley Kryshtalowych, Lindsey Wight, Matt Goode, 

Caitlin McCaw, Adrienne Debiase, Jennifer Gulbransen, 

and Charles Dachelet for assistance in the field; and Laura 

Krysinsky and Camille Warbington for assistance with 

weather data. We thank M. Lacki, M. Kalcounis-Rueppell, 

and an anonymous reviewer for comments on earlier drafts.

lITeRaTURe CITeD

Barclay, R.M.R.; Brigham, R.M. 2001. Year-to-year reuse of 

tree-roosts by California bats (Myotis californicus) in southern 

British Columbia. American Midland Naturalist. 146: 80-85.

Barclay, R.M.R.; Kurta, A. 2007. Ecology and behavior of bats 

roosting in tree cavities and under bark. In: Lacki, M.J.; Hayes, 

J.P.; Kurta, A., eds. Bats in forests: conservation and management. 

Baltimore, MD: Johns Hopkins University Press: 17-59.

Bennett, F.M.; Loeb, S.C.; Bunch, M.S.; Bowerman, W.W. 2008. 

Use and selection of bridges as day roosts by Rafinesque’s bigeared bats. American Midland Naturalist. 160: 386-399.

Boyles, J.G.; Robbins, L.W. 2006. Characteristics of summer and 

winter roost trees used by evening bats (Nycticeius humeralis) 

and Brigham 2007). Thus, bats may form larger aggregations 

in winter for thermoregulatory reasons, resulting in fewer 

roosts being used. 

There are few data on multiannual use of anthropogenic 

roosts by Rafinesque’s big-eared bats and even fewer data 

on multiannual use of tree roosts. Based on large guano 

accumulations in building roosts in North Carolina, Clark 

(1990) concluded that Rafinesque’s big-eared bats had 

used these roosts for many years. Jones and Sutkus (1975) 

reported on a big-eared bat colony that used a house roost 

over a 3-year period. Lewis (1995) predicted that bats will 

show greater fidelity to rare but stable roosts such as bridges 

and buildings than to more common and less stable roosts 

such as trees. Rafinesque’s big-eared bats in Mississippi 

show greater short-term fidelity to anthropogenic roosts 

than to tree roosts (Trousdale and others 2008), and our data 

suggest that longer term fidelity to anthropogenic roosts was 

also greater and more consistent than to tree roosts. All five 

anthropogenic roosts were used in all 4 years of the study. 

We also checked these structures prior to and after the study, 

and all were used for at least 6 years. In contrast, only four 

of nine tree roosts that were examined throughout the study 

were used in all 4 years. However, most roost trees we found 

were used for at least 2 years and many for 3 years. In some 

cases, multiannual use was by one bat or group of bats, and 

in some cases it was by a succession of bats. 

Multiannual use of crevice and cavity roosts has been found 

in several other bat species. For example, crevice roosts in 

ponderosa pine (P. ponderosa), alligator juniper (Juniperus 

deppeana), and pinyon (P. edulis) in New Mexico were 

reused by female long-eared myotis (Myotis evotis), fringed 

myotis (M. thysanodes), long-legged myotis (M. volans), 

and big brown bats during 75 percent of the summers they 

were monitored, 1 to 3 years postidentification (ChungMacCoubrey 2003). In Canada, 6 of 11 big brown bat cavity 

roosts in live trembling aspen (Populus tremuloides) were used 

in the 2 years following their identification as roosts (Willis 

and others 2003). Willis and others (2003) also checked some 

trees that had been identified as roosts during a previous study 

and found that some of those trees were used 8 to 10 years 

after they were first identified as roosts. We only observed tree 

roosts for 4 years, and observations of these trees over longer 

periods of time will be necessary to fully understand longterm roost use by Rafinesque’s big-eared bats. Nonetheless, 

our observations of multiannual use of anthropogenic and tree 

roosts suggest that long-term preservation of these roosts may 

be critical for long-term conservation of these bats, particularly 

in areas where roosts may be limiting. In addition, six tree 

roosts fell or broke during the 4 years of this study, suggesting 

the importance of recruiting new trees into the “roost tree 

population.” We suggest that trees with small cavities also be 

conserved as many of these are likely to become suitable roost 

trees in future years. 
120

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123

roosting sites by Rafinesque’s big-eared bats in southwestern 

Arkansas and discuss the importance of these wells in 

sustaining populations of this species in this region.

METHODS 

The study took place in Clark, Columbia, Lafayette, Nevada, 

Ouachita, and Sevier Counties in southwestern Arkansas, 

within the Tertiary Uplands of the southcentral Plains. 

Tertiary Upland sites are dominated by commercial shortleaf 

and loblolly pine plantations (Pinus echinata and P. taeda) 

that have replaced native oak-hickory-pine (Quercus spp.-

Carya spp.) forests except in narrow streamside zones. 

Forested tracts are interspersed with bayous and pasture 

for grazing cattle. Most of the large bottomland hardwood 

timber has been harvested at least once, with the majority of 

these acres converted to other resource areas. 

Because it was unclear how long wells would remain intact, 

we chose to survey for bats during the hibernation period 

when disturbance is normally to be avoided but when bats 

were most likely to be present for survey. Loss of structures 

used during the maternity period and a shortage of natural 

roosts such as large hollow trees suggested that local 

extirpation of populations in affected areas was possible, so 

we operated under the supposition that acquisition of winter 

natural history information was warranted because so little 

was known about Rafinesque’s big-eared bats in Arkansas.

We located wells by searching old home sites, often 

identified by large, residual, hardwood shade trees in areas 

INTRODUCTION

Rafinesque’s big-eared bat (Corynorhinus rafinesquii) has 

been documented from 42 of 75 Arkansas counties in the 

Mississippi River Alluvial Plain (commonly referred to as the 

Delta), the west Gulf Coastal Plain, and the Arkansas River 

Valley; the latter is a relatively narrow strip of land bordered 

to the south by the Ouachita Mountains and to the north by 

the Ozark Mountains (Fokidis and others 2005, Medlin and 

others 2006, Sasse and Saugey 2008). Historically these 

lowland areas were vegetated by bottomland hardwood forests 

where large hollow trees provided bat roosting sites that 

afforded protection from predators and provided stable internal 

environmental conditions. Changes in land use resulting in 

the draining of wetlands and the harvesting of potential roost 

trees have required Rafinesque’s big-eared bats to switch to 

humanmade structures for maternity sites, where bats use larger 

open spaces such as attics and rooms for roosting (Clark 1990). 

Abandoned houses and outbuildings, however, have relatively 

short life spans, often deteriorating quickly after sustaining 

roof damage, and are not reliable as maternity sites from year 

to year. In Arkansas, abandoned humanmade structures are 

usually associated with hand-dug water wells which are lined 

with concrete tile, brick, or stonework resulting in stable, 

long-lived structures that are commonly used by bats for winter 

hibernation (Blair 1939, England and Saugey 1999, Lowery 

1974, Saugey and others 1993, Tumlison and others 1992). 

We present data suggesting that water wells have allowed 

Rafinesque’s big-eared bats to persist throughout their range 

in Arkansas, despite conversion of most of the surrounding 

forested habitat and loss of natural tree roosts. In this paper we 

review over 20 years of data on use of water wells as winter 

WINTER ROOSTING BEHAVIOR OF RAFINESQUE’S BIG-EARED BAT 

IN SOUTHWESTERN ARKANSAS

D. Blake Sasse, Nongame Mammal Program Coordinator, Arkansas Game and Fish Commission, 

213A Highway 89 South, Mayflower AR 72106

David A. Saugey, Wildlife Biologist, U.S. Forest Service, 8607 Hwy 7 North, Jessieville, AR 71949

Daniel R. England, Professor of Biology, Southern Arkansas University, Box 253, Waldo, AR 71770

Abstract—We studied roosting behavior of Rafinesque’s big-eared bats (Corynorhinus rafinesquii) using water wells 

(n = 37 sites) in southwestern Arkansas from October through March, 1988 to 2009. Wells were lined with concrete, 

brick, or stone with a mean interior diameter of 74 cm (range: 51 to 78 cm). Most wells were used by < 20 bats, with 

colonies of > 40 bats observed in December, January, and February. Wells were used most often by females; however, as 

more bats moved to the wells in midwinter, sex ratios of bats in colonies tended toward a 50 to 50 ratio. Observed mass 

of Rafinesque’s big-eared bats was 9.6 g for females and 9.1 g for males, with females significantly heavier than males 

(P < 0.001). Mass increased for both sexes from October to November, declined in December, January, and February, 

then increased again in March (P = 0.026). Rafinesque’s big-eared bats were observed on 26 occasions to share wells 

with 1 to 12 southeastern bats (Myotis austroriparius) and were found roosting in a single well with 1 to 3 tri-colored bats 

(Perimyotis subflavus) 3 times. The number of wells available to Rafinesque’s big-eared bats for roosting decreased during 

the 21 years of study, as did the maximum winter colony size at 7 of 15 wells (46.6 percent), indicating that the abundance 

and distribution of Rafinesque’s big-eared bats in this region may be declining. 

Citation for proceedings: Loeb, Susan C.; Lacki, Michael J.; Miller, Darren A., eds. 2011. Conservation and management of eastern big-eared bats: 

a symposium. Gen. Tech. Rep. SRS-145. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 157 p.
124

among months of sampling was tested using a two-way 

analysis of variance. 

We used roosts containing ≥ 10 Rafinesque’s big-eared bats 

in calculating sex ratios of surveyed colonies. We estimated 

occupancy rates for all wells and for the 17 wells surveyed 

with a history of supporting ≥ 10 bats. We computed 

minimum winter colony size for 22 wells from 1990 to 

1996, based on the number of individual bats captured 

and banded at each site during the winter, and compared 

these data using linear regression analysis to the maximum 

number of bats captured or observed during any single 

survey at these wells during winter sampling. Trends in 

maximum winter population counts from 1991 to 2009 at 15 

wells with ≥ 4 years of data were analyzed using a MannKendall nonparametric test. This nonparametric statistical 

method is based upon annual positive or negative changes in 

population size and is useful when assumptions required for 

analysis using regression techniques cannot be met. This test 

determines whether the population is increasing or decreasing 

and does not take into account the magnitude of change 

(Hollander and Wolfe 1973, Thompson and others 1998).

RESULTS

We located water wells on upland sites in hardwood or pinehardwood stands and in the vicinity of small to midsized 

streams; wells were generally not adjacent to any large 

revegetated with pine plantations. Thirty-seven wells were 

identified in six counties as used by Rafinesque’s big-eared 

bats during winter months from 1988 to 2009. We were able 

to record interior dimensions and lining materials for only 

15 of these wells, as these measurements were not taken 

until late in the study and access to some wells was either no 

longer permitted or the wells had been destroyed. Wells were 

surveyed for use by bats irregularly when personnel were 

available and when the low temperature during the previous 

evening was < 4.4 °C. Thus, the number of wells visited 

each season and the number of times each well was surveyed 

within a season varied considerably. 

We recorded the total number of bats captured or visually 

counted at each visit. We captured bats from within wells 

using a device manufactured from a standard umbrella 

fitted with two control cords, two hardened edges, and 

from which the lock latch, normally used to maintain the 

umbrella in a rigid open position, was removed (fig. 1). The 

device was maneuvered underneath bats, and the hardened 

edges were used to gently lift bats off the wall of the well 

where they dropped into the umbrella (England and Saugey 

1999). We recorded sex, age, body mass (g), reproductive 

condition, and left forearm length (mm) of each bat 

captured. We banded a subset of bats to assess fidelity to 

hibernation sites, movement patterns among sites, and 

association with maternity roosts. We released all bats back 

into the well once they had fully aroused and were capable 

of flight. Variation in body mass between the sexes and 

Figure 1—Photograph of the sampling method used to extract bats from within water wells in southwestern 

Arkansas. (Photo by David A. Saugey)
125

males (n = 961), with females heavier than males (F = 234, 

P < 0.001). Mass increased for both sexes from October to 

November; declined in December, January, and February; 

and increased again in March (F = 2.55, P = 0.026) (table 1). 

We found sex ratios of colonies of bats during winter surveys 

(n = 61) varied by size of colony and month of sampling, with 

males becoming a larger proportion of colonies as winter 

progressed, only to decline again with the approach of spring. 

We found large colonies with > 40 bats to have more equal sex 

ratios compared to smaller colonies; 10 of 12 (83 percent) of 

these large colonies were observed in the months of December 

or January. The maximum count of Rafinesque’s big-eared 

bats at the majority (57 percent) of wells was < 20 bats, with 

24 percent of wells supporting a maximum count of 21 to 39 

bats, and only 19 percent of wells used by ≥ 40 bats. 

tracts of bottomland hardwood forest. We found wells that 

contained bats were lined with concrete, brick, or stone—

surfaces that provided good roosting substrates. Twelve wells 

were constructed of round concrete segments with a mean 

internal diameter of 72 cm (range: 51 to 78 cm), 2 bricklined wells were 77 and 83 cm in diameter, and 1 stone-lined 

well was 86 cm in diameter. The mean internal diameter of 

all wells we measured was 74 cm (SE = 2.1). A single well 

without lining was also used by Rafinesque’s big-eared bats, 

but we were unable to measure the internal dimensions. 

Wells lined with ceramic tiles had very smooth surfaces and 

were not used by bats. 

Observed mass of Rafinesque’s big-eared bats was 9.6 g 

(SE = 0.03) for females (n = 1,296) and 9.1 g (SE = 0.03) for 

Table 1—Monthly trends in occupancy rate, maximum bat counts, sex ratios, and mean body mass of Rafinesque’s 

big-eared bats using water wells as roosting sites in southwestern Arkansas, 1988 to 2009

October November December January February March

Occupancy rate

All wells 

Percent 94 100 94 97 92 86

 N 31 40 88 78 65 73

Of colonies consisting of >10 bats at wells known to contain large colonies 

Percent 24 33 38 45 39 31

 N 29 33 66 56 51 49

Maximum count

  n 50 38 89 88 103 65

 N 31 50 128 92 76 73

Percent female in large colonies (>10 bats)

Percent 67 54 50 45 70 60

 SD NA 13 14 11 19 33

 N 1 7 16 15 12 10

Mass (g)

Females

Mean 9.25 10.63 10.32 9.28 8.91 8.96

SE 0.08 0.07 0.05 0.05 0.04 0.05

 N 124 169 297 326 264 116

Males

Mean 8.69 9.77 9.63 8.81 8.19 8.41

SE 0.09 0.08 0.05 0.06 0.06 0.09

 N 90 130 278 289 126 48

N = sample size; SD = standard deviation; NA = not applicable; SE = standard error.
126

destroyed during the survey period, and we suspected other 

wells were also destroyed, but landowner permission to 

access was not granted in recent survey years to determine 

their status. Abandoned buildings, also serving as maternity 

sites of Rafinesque’s big-eared bats wintering in three of 

the wells studied, were destroyed late in the study possibly 

impacting the trends observed. 

We observed Rafinesque’s big-eared bats roosting in wells 

during the winter months with two other bat species. We 

found southeastern bats (Myotis austroriparius) roosting 

with Rafinesque’s big-eared bats on 26 occasions. Sixteen of 

the occurrences of joint use by southeastern and Rafinesque’s 

big-eared bats were observed in a single well where 1 to 12 

southeastern bats were seen. Six southeastern bats were in 

another well that was occupied by the largest group (n = 103) 

of Rafinesque’s big-eared bats observed during the study. 

Joint use was seen in nine other wells but only one or two 

southeastern bats were observed on these surveys. A single 

well was used by Rafinesque’s big-eared bats and tri-colored 

bats (Perimyotis subflavus) on three occasions with one 

The largest bat count (n = 103) we observed at any individual 

colony was on February 13, 2006, followed closely by 

maximum counts in December (n = 89) and January (n = 88). 

Wells with a history of use by Rafinesque’s big-eared bats 

were occupied by at least one bat 86 to 100 percent of the 

time during winter months. However, wells with a history of 

supporting ≥ 10 bats were occupied by groups of ≥ 10 bats on 

only 24 to 45 percent of surveys, with the greatest likelihood 

of encountering larger colony sizes in January (table 1). 

We found the total number of Rafinesque’s big-eared bats 

known to use a well each winter, based on bat banding 

events, to be linearly associated with the maximum number 

of bats observed in the well on any one survey (F = 564; 

P = < 0.001; R2 = 0.90) (fig. 2). Seven of fifteen (47 percent) 

wells we surveyed for at least 4 years had decreasing trends 

in maximum annual population counts; the remainder 

showed no trend. Of the seven wells surveyed for at least 10 

years, three (43 percent) had decreasing trends in maximum 

population counts. The remainder showed no trend. Four 

(11 percent) wells used by Rafinesque’s big-eared bats were 

Figure 2—Relationship of winter maximum observed population counts of Rafinesque’s big-eared bats to the minimum number of banded bats 

known to use water wells in southwestern Arkansas, 1990 to 1996. 

0

20

40

60

80

100

120

0 10 20 30 40 50 60 70 80 90 100

Maximum Observed Colony Size

Total Identified Bats
127

wells until the coldest period of winter. We suggest that 

male Rafinesque’s big-eared bats may be more tolerant of 

colder weather than females. Trousdale and Beckett (2004) 

often found solitary males roosting underneath bridges 

during the winter months in southern Mississippi. A colony 

of Rafinesque’s big-eared bats that roosted underneath 

ammunition bunkers in Louisiana was primarily comprised 

of males during winter months, though the small numbers of 

bats observed in these structures suggests that this complex 

may not have been conducive to the formation of large winter 

colonies (Jones and Suttkus 1975). 

The percentage of surveys where large colonies (> 10 bats) 

were observed in wells in our study (24 percent) was similar 

to the winter occupancy rates of tree cavities in Louisiana 

where only 18 percent of surveys found > 10 Rafinesque’s 

big-eared bats from November through February (Rice 

2009). In Mississippi, 6 of 14 (43 percent) trees used by 

Rafinesque’s big-eared bats during the winter were used by 

> 5 bats (Stevenson 2008). The strong relationship between 

the total number of bats known to use a well throughout the 

winter, based on banding data, and the highest bat count 

observed in winter indicates that population trends at wells 

can be monitored using visual counts without the need to 

capture bats during the coldest winter months (December, 

January, and February) when populations of Rafinesque’s 

big-eared bats in wells are usually highest. We hypothesize 

that water wells provide warm refugia during extreme cold 

weather, but data on internal and external temperatures 

associated with use of these wells by bats is needed to 

develop efficient long-term monitoring techniques. 

Results of our surveys are consistent with data reported 

elsewhere that demonstrate Rafinesque’s big-eared bats often 

cohabit roosting sites with southeastern bats and tri-colored 

bats in natural roosts, particularly live trees (Carver and 

Ashley 2008, Rice 2009, Stevenson 2008). This overlap in 

roosting preferences may confer an advantage in developing 

management strategies for roosting sites of these three 

species of bats in Southern U.S. forests. 

The closure of old water wells will remain a management 

issue for Rafinesque’s big-eared bats as many sites 

constitute pitfall dangers to humans and animals, 

particularly when the uppermost portion of the well casing 

is at or near ground level. This potential danger, along with 

concerns about potential impacts on water quality from 

using old wells as dump sites that could introduce pollution 

into the ground water, has resulted in the promulgation of 

State regulations requiring the closure of abandoned water 

wells as seen in our study. For Rafinesque’s big-eared 

bats this is unfortunate because wells appear to constitute 

important winter habitat, especially in areas devoid of large 

cavity trees, caves, mines, or other suitable winter roosting 

sites. The loss of wells previously known to be roosting sites 

bat observed on two occasions and three bats observed on 

another visit. 

DISCUSSION

Because water wells are primarily associated with human 

dwellings, it is not surprising that wells in this study were 

found in upland areas where houses are more likely to be 

built rather than in flood plain forests typically associated 

with natural roosting sites of Rafinesque’s big-eared bats. 

Rafinesque’s big-eared bats are often found roosting in 

abandoned houses in upland sites during summer months 

(Clark 1990, Mirowsky and others 2004), and males in South 

Carolina have been found foraging primarily in young pine 

stands in areas separate from extensive bottomland hardwood 

forest (Menzel and others 2001).

Mean monthly body mass of male and female Rafinesque’s 

big-eared bats was slightly higher than that observed in 

Mississippi, and lower than values reported for these bats 

in Louisiana, though the sample sizes in both studies were 

considerably smaller than in our study and did not reflect 

body condition of bats throughout the winter months (Jones 

and Suttkus 1975, Rice 2009). Nevertheless, our values 

are within the range expected in Arkansas and elsewhere 

throughout the distribution of the species (Jones 1977, 

Sealander and Heidt 1990). 

Prior to our study the only extensive report on winter use 

of water wells by Rafinesque’s big-eared bats was a cistern 

near Reelfoot Lake in western Tennessee (Hoffmeister and 

Goodpaster 1962). Though built of brick and stone, the inner 

face of the cistern was covered with cement, and bats were 

observed in it during the months of February, March, April, 

May, and September. Population counts ranged from 1 to 64 

bats and, similar to our study, banding and population count 

data indicated significant movement among roosting sites 

during winter months (Hoffmeister and Goodpaster 1962). The 

interior dimensions of the Tennessee cistern were not reported, 

but a diagram indicates the inside diameter was probably 

much larger than wells in our study, though the entrance may 

have been of similar width (Hoffmeister and Goodpaster 

1962). Other occurrences of this species in wells have been of 

individuals or small groups (Baker and Ward 1967, Blair 1939, 

Caire and others 1989, Steward and others 1986, Tumlison 

and others 1992). Stevenson (2008) examined the interior 

dimensions of Rafinesque’s big-eared bat roost trees and found 

that they averaged only 40 cm in width, much less than the 

water wells used by Rafinesque’s big-eared bats in our study. 

The increase in colony size and trend towards more equal 

sex ratios in midwinter indicates that during the early and 

late winter, male Rafinesque’s big-eared bats are more 

likely to use alternate roosting sites and do not move into 
128

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Louisiana bottomland hardwood forest streambed. Monroe, LA: 

University of Louisiana at Monroe. 117 p. M.S. thesis. 

Sasse, D.B.; Saugey, D.A. 2008. Rabies prevalence among and new 

distribution records of Arkansas bats. Journal of the Arkansas 

Academy of Science. 62: 159-160. 

Saugey, D.A.; England, D.R.; Chandler-Mozisek, L.R. [and 

others]. 1993. Arkansas range extensions of the eastern smallfooted bat, and northern long-eared bat and additional county 

records for the silver-haired bat, hoary bat, southeastern bat, 

and Rafinesque’s big-eared bat. Proceedings of the Arkansas 

Academy of Science. 47: 102-106.

Sealander, J.A.; Heidt, G.A. 1990. Arkansas mammals: their 

natural history, classification, and distribution. Fayetteville, AR: 

University of Arkansas Press. 308 p.

Stevenson, C.L. 2008. Availability and seasonal use of diurnal 

roosts by Rafinesque’s big-eared bat and southeastern myotis 

in bottomland hardwoods of Missisippi. Starkville, MS: 

Mississippi State University. 109 p. M.S. thesis. 

Steward, T.W.; McDaniel, V.R.; England, D.R. 1986. Additional 

records of distribution and hosts for the bat bug, Cimex

pilosellus, in Arkansas. Proceedings of the Arkansas Academy of 

Science. 40: 95-96.

Thompson, W.L.; White, G.C.; Gowan, C. 1998. Monitoring 

vertebrate populations. San Diego: Academic Press. 365 p.

Trousdale, A.W.; Beckett, D.C. 2004. Seasonal use of bridges 

by Rafinesque’s big-eared bat, Corynorhinus rafinesquii, in 

Mississippi. Southeastern Naturalist. 3: 103-112. 

Tumlison, R.; Karnes, M.; Clark, M. 1992. New records of 

vertebrates in southwestern Arkansas. Proceedings of the 

Arkansas Academy of Science. 46: 109-111.

of Rafinesque’s big-eared bats, coupled with the declining 

trend in maximum winter bat counts at remaining wells, 

indicates that this species may have difficulty maintaining 

population numbers across its distribution in Arkansas, at 

least outside of the remaining fragments of bottomland 

hardwood forest. 

LITERATURE CITED

Baker, R.J.; Ward, C.W. 1967. Distribution of bats in southeastern 

Arkansas. Journal of Mammalogy. 48: 130-132. 

Blair, W.F. 1939. Faunal relationships and geographic distribution 

of mammals in Oklahoma. American Midland Naturalist. 22: 

85-133.

Caire, W.; Tyler, J.D.; Glass, B.P. [and others]. 1989. Mammals of 

Oklahoma. Norman, OK: University of Oklahoma Press. 567 p. 

Carver, B.D.; Ashley, N. 2008. Roost tree use by sympatric 

Rafinesque’s big-eared bats (Corynorhinus rafinesquii) and 

southeastern myotis (Myotis austroriparius). American Midland 

Naturalist. 160: 364-373. 

Clark, M.A. 1990. Roosting ecology of the eastern big-eared bat, 

Plecotus rafinesquii, in North Carolina. Raleigh, NC: North 

Carolina State University. 112 p. M.S. thesis.

England, D.R.; Saugey, D.A. 1999. A safe and effective method to 

remove bats from abandoned water wells. Bat Research News. 

40: 38-39. 

Fokidis, H.B.; Brandebura, S.C.; Risch, T.S. 2005. Distribution 

of bats in bottomland hardwood forests of the Arkansas delta 

region. Journal of the Arkansas Academy of Science. 59: 51-56. 

Hoffmeister, D.F.; Goodpaster, W.W. 1962. Observations on a 

colony of big-eared bats, Plecotus rafinesquii. Transactions of 

the Illinois State Academy of Science. 55: 87-89.

Hollander, M.; Wolfe, D.A. 1973. Nonparametric statistical 

methods. New York: John Wiley. 503 p.

Jones, C. 1977. Plecotus rafinesquii. Mammalian Species. 69: 1-4. 

Jones, C.; Suttkus, R.D. 1975. Notes on the natural history of 

Plecotus rafinesquii. Occas. Pap. of the Museum of Zoology, 

Louisiana State University. 47: 1-13.

Lowery, G.H., Jr. 1974. The mammals of Louisiana and its adjacent 

waters. Baton Rouge, LA: Louisiana State University Press. 

565 p. 
129

habitat use concurrently. Further, the only published data 

on nocturnal habits of the species were collected in upland 

forests (Hurst and Lacki 1999, Menzel and others 2001) 

where habitat types differ from those available in bottomland 

hardwood forests. Nocturnal habitat use by bats is driven by 

prey availability and structure and composition of habitats 

(Hayes and Loeb 2007, Lacki and others 2007). Thus, even 

though dietary studies have shown Rafinesque’s big-eared 

bat to be a moth specialist (Hurst and Lacki 1997, Lacki 

and LaDeur 2001, Lacki and others 2007), it is not known 

whether habitat structure or moth availability imparts a larger 

influence on nocturnal habitat use in this species. The goal 

of our study was to examine foraging and roosting habits 

of adult female and male Rafinesque’s big-eared bats in a 

landscape dominated by bottomland hardwood forests in 

western Kentucky.

MATERIALS AND METHODS

Study Area

Our study took place on Ballard and Boatwright Wildlife 

Management Areas (WMAs) in Ballard County, KY 

(37.091°N, 89.091°W). The management areas were part of 

the Ohio River flood plain and contain more than 8 000 ha 

of seasonally flooded forests, lakes, and agricultural land. 

The WMAs consist of several disconnected land parcels 

distributed across the western edge of Ballard County. 

Dominant tree species include baldcypress, water tupelo, 

INTRODUCTION

Studies examining foraging and roosting habits of North 

American bat species have increased in the past two decades 

in response to technological advancements in miniature radio 

transmitters and ultrasonic bat detectors (Barclay and Kurta 

2007, Lacki and others 2007). While much has been learned 

of the diet, nocturnal habitat use, and day-roosting habits of 

North American bats, research suggests that these behaviors 

can vary geographically within species (Lacki and others 

2010), highlighting the need for regional studies examining 

requirements and preference for each species. Rafinesque’s 

big-eared bat (Corynorhinus rafinesquii) is considered 

vulnerable throughout its range (NatureServe 2010) and has 

been the focus of several studies aimed at identifying habitat 

features important to day roosting. However, most of this 

research has investigated day roosting in the southern portion 

of the range (Bennett and others 2008; Clark 1990; Clark 

and others 1998; Cochran 1999; Gooding and Langford 

2004; Lance and others 2001; Mirowsky and others 2004; 

Rice 2009; Stevenson 2008; Trousdale and Beckett 2004, 

2005; Trousdale and others 2008) with few studies (Carver 

and Ashley 2008, Hurst and Lacki 1999) conducted near the 

northern edge of the range. 

While day-roosting habitat of Rafinesque’s big-eared bat 

has received attention, only three studies have collected 

data on home range or nocturnal habitat use (Clark and 

others 1998, Hurst and Lacki 1999, Menzel and others 

2001), and no study has examined diurnal and nocturnal 

FORAGING AND ROOSTING ECOLOGY OF RAFINESQUE’S BIG-EARED BAT 

AT THE NORTHERN EDGE OF THE RANGE

Joseph S. Johnson, Research Associate, University of Kentucky, Department of Forestry, 

Lexington, KY 40546

Michael J. Lacki, Professor, University of Kentucky, Department of Forestry, Lexington, KY 40546

Abstract—Limited data exist on foraging and roosting habits of Rafinesque’s big-eared bat (Corynorhinus rafinesquii) 

at the northern edge of the species’ range, where habitat use may differ from that reported for southern portions of the 

distribution. To provide land managers with regional data on habitat use of Rafinesque’s big-eared bat, we radio-tagged 15 

adult bats to document diurnal and nocturnal habitat use in western Kentucky during June and July 2009. We tracked 12 

females (7 lactating, 5 postlactating) and 2 males to 35 day roosts, including 29 baldcypress (Taxodium distichum), 4 water 

tupelo (Nyssa aquatica), 1 sweetgum (Liquidambar styraciflua), and 1 concrete bridge. Roost trees consisted of a basal 

entrance to the roost cavity (n = 2, 5.9 percent), a basal and top entrance (n = 15, 44.1 percent), a top entrance (n = 14, 

41.2 percent), and entrances located in the mid-section of the bole (n = 3, 8.8 percent). Males switched roosts every 

1.3±0.04 days, lactating females every 2.2±0.3 days, and postlactating females every 2.7±0.7 days. Home range estimates 

did not differ between lactating (178.5±103.4 ha, n = 6) and postlactating females (231.7±66.7 ha, n = 6; P = 0.17). 

Second-order habitat use by females (n = 11) was nonrandom (P < 0.001), with home ranges closest to forested and 

herbaceous wetlands and upland deciduous forests and farthest from agriculture and open fields. Third-order habitat use for 

females (n = 11) did not differ from random (P = 0.47). Our data indicate importance of a variety of roost types, wetlands, 

and upland forests to Rafinesque’s big-eared bat in western Kentucky.

Citation for proceedings: Loeb, Susan C.; Lacki, Michael J.; Miller, Darren A., eds. 2011. Conservation and management of eastern big-eared bats: 

a symposium. Gen. Tech. Rep. SRS-145. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 157 p.
130

continuous residency (days), roost diversity (H ́ ), distances 

traveled between consecutive roosts, and distances between 

roosts and capture sites for lactating and postlactating 

females were compared using Wilcoxon tests (SAS Institute 

2001), with all tests based on a significance level of 0.05. 

Males were not included in the analysis due to low sample 

size (n = 2), but mean values are reported.

We measured habitat characteristics of the roost tree and 

forested stands for each day-roost tree following Baker 

and Lacki (2006). Habitat characteristics of roost trees 

included tree species, diameter at breast height (d.b.h.) or 

above any basal swell, roost tree height, number of cavities, 

maximum cavity height inside the tree, minimum cavity 

height inside the tree, height of entrance to the main cavity, 

entrance dimension (length, width, and height), presence 

of basal cavity entrances, presence of a “top” cavity 

entrance (broken tree tops, hollow knots, or other cavities), 

presence of entrances along the tree bole (broken tree tops, 

hollow knots, or woodpecker cavities), dimensions of basal 

entrances, and whether or not the roost tree was alive or 

dead. Stand-level habitat characteristics included canopy 

height, canopy cover (percent), and distance to the nearest 

cavity tree. Distances were measured with meter tapes 

or laser rangefinders (Opti-Logic Corp., Tullahoma, TN) 

for distances > 25 m; heights were measured with a laser 

hypsometer (Opti-Logic Corp., Tullahoma, TN); diameters 

were measured with a d.b.h. tape (Forestry Suppliers, Inc., 

Jackson, MS), and canopy cover was visually estimated. 

Because many roost trees were in standing water, trees 

were measured in August when water level was near the 

summer minimum. Roost trees were categorized into roost 

types based on the location of entrances to the main cavity 

following Rice (2009), with the addition of a fourth roost 

type. Roost trees were classified as type I if possessing only 

a basal entrance to the main cavity, type II if possessing 

basal and top entrances, type III if possessing a top but 

not a basal entrance, and type IV if possessing only bole 

entrances to the main cavity. Habitat values for day roosts 

used by lactating and postlactating females were compared 

using Wilcoxon tests (SAS Institute 2001). Habitat values 

were also compared among the four roost types using 

Kruskal-Wallis tests; all tests were based on a significance 

level of 0.05. Day roosts used by males were not included 

in analysis due to low sample size of radio-tagged males (n

= 2), but mean values are reported. 

We counted the number of bats inhabiting each roost through 

emergence counts, visual inspection of trees with large basal 

openings, or by taking digital photographs of tree cavities 

when possible. Emergence counts were conducted from 

15 minutes prior to sunset to ca. 1 hour after sunset with the 

assistance of night-vision goggles (ATN Corp., San Francisco, 

CA). We compared estimates of roosting bats among roost tree 

types based on the maximum count for each roost known to be 

oak species (Quercus spp.), and hickories (Carya spp.). 

Topography is predominantly flat and ranges from 280 

to 350 m asl. Mean monthly rainfall in the area is 8.5 to 

13.4 cm between April and September (National Oceanic 

and Atmospheric Administration 2002). Mean monthly 

temperatures measured with HOBO data loggers (model 

U23-002, Onset Computer Corp., Pocasset, MA) were 22.6 

to 27.8 °C between June and September 2009.

Capture and Radio-tagging

We employed capture, handling, and radiotelemetry 

techniques consistent with the American Society of 

Mammalogists’ guidelines (Gannon and others 2007) 

and approved by the University of Kentucky, Institutional 

Animal Care and Use Committee (IACUC no. A3336-

01). We captured bats at 12 locations across 19 nights of 

sampling in 38-mm diameter polyester mist nets (Avinet, 

Inc., Dryden, NY) placed over forest roads, lake edges, 

in an old campground, and outside entrances to known 

Rafinesque’s big-eared bat roost trees. Nets ranged in 

size from 2.6 to 7.8 m high and 2.6 to 18 m wide. We 

recorded age, sex, reproductive condition, body mass, and 

right forearm length for all bats. We aged bats as adult 

or juvenile by examining ephiphyseal-diaphyseal fusions 

(calcification) of long bones in the wing (Anthony 1988). 

We classified females as nonreproductive, pregnant, or 

lactating based on the presence of a fetus or teat condition 

(Racey 1988) and classified males as nonreproductive or 

scrotal based on swelling of the epididymides (Krutzsch 

2000, Racey 1988). We fitted adult males and reproductive 

adult females with 0.42-g (model LB-2N or LB-2NT; 

Holohil Systems Ltd., Carp, Ontario, Canada) radio 

transmitters attached between the shoulder blades using 

surgical adhesive (Torbot Group, Inc., Cranston, RI). 

Radio-tagged bats were visually monitored after release 

to ensure their flight capabilities had not been noticeably 

affected, and briefly monitored with telemetry equipment to 

ensure that bats continued to fly after passing out of sight.

Day Roosting

We tracked radio-tagged bats to their day roosts each 

day using TRX-1000S telemetry receivers (Wildlife 

Materials, Inc., Murphysboro, IL) and three-element 

Yagi antennas (Advanced Telemetry Systems, Inc., 

Isanti, MN). We recorded day-roost locations using a 

Garmin 60CSx handheld Global Positioning System 

(Garmin International, Inc., Olathe, KS) and recorded a 

chronological account of each bat’s day-roost locations. 

We examined roost switching using two methods: dividing 

number of roost days observed for individual bats by the 

number of times that bat switched roosts, i.e., length of 

continuous residency; and calculating roost diversity (H ́ ) 

for each individual (Trousdale and others 2008). Length of 
131

home range estimates was used as the minimum number 

of locations required to include a home range estimate 

for further analysis. We compared 95-percent home range 

estimates for lactating and postlactating females using a 

Wilcoxon test (SAS Institute 2001) and a significance level 

of 0.05. Male home range was not analyzed due to low 

sample size (n = 1). 

Nocturnal habitat use was analyzed at the second- and thirdorder levels defined by Johnson (1980) using the Euclidean 

distance method (Conner and Plowman 2001, Conner and 

others 2003). In this approach, second-order habitat use refers 

to placement of home ranges on the landscape, while thirdorder use refers to use of habitats within home ranges. We 

chose the Euclidean distance method because it inherently 

considers telemetry error in its calculations, takes patch size 

and shape into account, has a lower type I error rate, and 

does not require a defined study area for third-order analysis 

(Bingham and Brennan 2004, Conner and others 2003). For 

second-order analysis, we defined the study area by creating a 

minimum convex polygon surrounding all bat locations using 

the Animal Movement extension (Hooge and Eichenlaub 

1997) and then buffering this polygon by the greatest distance 

any bat was observed traveling in a single night (4334 m). 

We selected five habitats for analysis based on the 2001 

National Land Cover Database (NLCD, available at http://

kygeonet.ky.gov, see Homer and others 2004): (1) forested and 

herbaceous wetlands (23.6 percent of study area), (2) upland 

deciduous forests (14.5 percent), (3) agricultural and open 

fields (45.9 percent), (4) edges of fields and upland forested 

areas, and (5) edges of lakes and forested wetlands. Lakes 

composed 12.9 percent of the study area; thus, we considered 

this habitat to be lake edge because habitat structure, including 

edges, has been shown to influence habitat use in big-eared 

bats, and because big-eared bats are less likely to forage over 

open water (Lacki and Dodd 2011). Developed areas were 

not included in the analysis because they composed a small 

portion of the study area (3.1 percent) and, thus, were likely to 

be found avoided in the analysis simply because these habitats 

were scarce on the landscape. We verified the NLCD by 

comparing habitat polygons to 2008 aerial photographs (http://

kygeonet.ky.gov) and by driving and walking the study area. 

Only nocturnal locations of bats with the minimum number 

of locations to generate home range estimates were used 

for analysis. Due to low sample size of bats, we combined 

lactating and postlactating females for analysis. For secondand third-order analyses, mean distances of random and bat 

locations to available habitats were compared using a multiple 

analysis of variance to determine if use differed from random 

(SAS Institute 2001). Where habitat use was nonrandom, 

habitats were ranked from closest to farthest from bat locations 

using t-tests (SAS Institute 2001), with tests based on a 

significance level of 0.05 (Conner and Plowman 2001, Conner 

and others 2003).

used by reproductive females using Kruskal-Wallis tests, with 

tests based on a significance level of 0.05.

Home Range and Nocturnal Habitat Use

Nocturnal locations of radio-tagged bats were triangulated 

during the first 5 hours of the evening to generate home 

range estimates and analyze habitat use. Two field personnel 

communicating with hand-held radios took simultaneous 

bearings on radio-tagged bats at 2-minute intervals, 

following an individual bat for no more than five consecutive 

bearings (10 minutes) to reduce autocorrelation among 

locations (Swihart and Slade 1985). Because some bats 

foraged in the vicinity of their roost for the first hour after 

emergence and then flew several km to a different foraging 

area, we distributed tracking efforts for each bat as evenly 

as possible across the 5-hour period to ensure representation 

of all activity areas used during the tracking period. Because 

the study area was predominately flat, radio signals from 

transmitters were never detected from distances > 1 km 

from the signal source during daytime tracking efforts. As 

a result, personnel tracking bats at night could not establish 

permanent telemetry stations from which bearings could 

be taken on several bats throughout the night (Johnson 

and others 2007). Instead, personnel tracked bats from 

vehicles, moving to locations where a selected bat was 

known to forage to take bearings before shifting locations to 

track a new bat. We ensured that each bat could be located 

throughout the tracking period by following bats to various 

foraging areas as the night progressed. A dense network of 

roads in the study area facilitated this approach and allowed 

personnel to select temporary tracking stations situated close 

to the signal source, eliminating the need for a third person to 

ground truth estimated locations (Johnson and others 2007). 

Bearings were triangulated in Locate III (Nams 2006) and 

imported into ArcView ver. 3.2 (Esri Corporation 1999). 

Triangulated locations were reviewed, and locations 

triangulated > 1 km away from either observer’s location 

were discarded because daytime tracking efforts found this 

to be the maximum effective transmitter range in the local 

topography. Remaining locations were used to calculate 

95-percent home ranges using the fixed kernel method 

(Seaman and Powell 1996, Seaman and others 1999), using 

least square cross-validation (Worton 1989) and the Animal 

Movement extension (Hooge and Eichenlaub 1997). Dayroost locations were used in home range calculations, with 

a roost used as a single location regardless of the number of 

days a bat occupied the roost. We determined the minimum 

number of nocturnal locations necessary to obtain stable 

home range estimates (Aebischer and others 1993) by 

calculating estimates for bats in five-location increments. We 

graphed the change in home range estimates and determined 

when the graph reached an asymptote or oscillated about 

the mean. The mean number of locations needed to stabilize 
132

water, further preventing accurate measurement of entrance 

dimensions. Twelve day roosts were used by more than one 

radio-tagged bat; three of which were used by both lactating 

and postlactating females and two by males and lactating 

females. No habitat characteristic differed among trees 

used by lactating and postlactating females (table 2). The 

majority of roost trees were type II (44.1 percent) and type 

III (41.2 percent) trees (table 3). Type II trees were shorter 

in height (KW = 8.3 df = 3, P = 0.04) than type I trees, 

reflecting that many type II trees had top entrances because 

of broken tree boles (minimum tree height was 4.7 m).

Roosting bats were counted during emergence on 21 roost 

days and by taking digital photographs on 77 roost days. 

While males were tracked to 2-day roosts known to be used 

by reproductive females, the maximum number of bats 

counted emerging from a roost while a male was known to 

be present was two. Roost counts ranged from 1 to 96, with 

colonies of ≥ 20 bats counted at all 4 roost types (table 4). 

No difference in maximum roost count was detected among 

roost types.

The minimum number required for home range estimates to 

stabilize was 26.3±2.1 locations. This minimum was collected 

for 11 females and 1 male bat (x = 42.1±2.8 locations) 

tracked during 3.3±0.30 nights. No difference was detected 

in home range estimates between lactating (178.5 ± 103.4 

ha, range = 23.1 to 689) and postlactating (231.7±60.7 ha, 

range = 83.5 to 454) females (P = 0.17). The only male 

home range estimated was 8.1 ha. Second-order habitat 

use by females was nonrandom (Wilk’s lambda = 0.003, 

F = 365, P < 0.001). Home ranges were closer to forested 

and herbaceous wetlands (t = 42.5, P < 0.001), upland 

deciduous forests (t = 19.3, P < 0.001), and edges of lakes 

and forested wetlands (t = 13.5, P < 0.0001) than expected, 

and farther from edges of fields and upland forests (t = 2.33, 

P = 0.04) and agriculture and open fields (t = 2.68, P = 0.02) 

than expected. Home ranges were composed of 52.7 percent 

RESULTS

We captured 23 adult (20 females, 2 males, and 1 of 

unknown sex) and 5 juvenile (4 females and 1 male) 

Rafinesque’s big-eared bats between June 9 and July 10, 

2009. We captured 61 percent (n = 17) over road corridors 

and in a forest gap created by an abandoned campground. 

The remaining 11 bats were captured emerging from 2 

known roost trees. Females were already lactating at the 

time the first Rafinesque’s big-eared bat was captured; the 

first volant juvenile was captured on July 1. We radio-tagged 

13 adult females (8 lactating and 5 postlactating) and 2 

adult male bats (1 with the epididymides beginning to swell 

and a second with no sign of swelling). Radio transmitters 

increased wing loading of radio-tagged bats by a maximum 

4.9 percent [x = 4.4±0.1 (SE) percent] of body mass. 

We successfully tracked 14 of 15 radio-tagged bats on 147 

of 151 (97.4 percent) potential roost days before radio 

transmitters were shed (x = 10.8 ± 0.8 days). One lactating 

female was not relocated during the day despite radio signals 

being detected during evening foraging bouts. No difference 

was found in length of continuous residency (P = 0.75), roost 

diversity (P = 0.52), distances traveled between consecutive 

roosts (P = 0.19), and distances between roosts and capture 

sites (P = 0.52) for lactating and postlactating females (table 1).

Radio-tagged bats were tracked to 34 day-roost trees, 

consisting of tree cavities in 29 baldcypress, 4 water 

tupelo, and 1 sweetgum. One concrete bridge was regularly 

used by a radio-tagged male. Roost trees were located in 

flooded forests and along lake edges, with 30 of 34 tree 

roosts (88.2 percent) standing in 0.2 to 1.1 m of water at 

the time of discovery. Basal entrances often consisted of 

irregular cracks and fissures in the tree bole, and accurate 

measurements of basal openings could not be acquired on 

a consistent basis. Additionally, 15 (83.3 percent) of the 

roost trees with basal entrances were partially submerged in 

Table 1—Summary of roost-switching behaviors of Rafinesque’s big-eared bats during June and July 2009, Ballard 

County, KYa

Roost-switching behaviors Lactating females Postlactating females Males

Number of radio-tagged bats 7 5 2

Number of days tracked 11.3±1.3 (7–18) 9.6±1.0 (7–13) 12.0±3.0 (9–15)

Length of residency (days) 2.2±0.3 (1–6) 2.7±0.7 (1–8) 1.3±0.04 (1–8)

Roost diversity (H ́) 0.62±0.09 (0.41–1.0) 0.53±0.10 (0.22–0.75) 0.91±0.09 (0.82–1.0)

Distance to next roost (m) 321±214 (15.1–3389) 655±178 (16.3–1107) 457±334 (69.0–1473)

Distance from capture site (m) 490±201 (60.4–3342) 570±167 (62.1–1139) 297±169 (65.2–1417)

a Data are presented as mean ± SE and range. 
133

Table 2—Mean ± SE of habitat characteristics of day roosts of Rafinesque’s big-eared bats during 

June and July 2009, Ballard County, KY

Habitat characteristics Lactating female Postlactating female Male

Number of roost trees 24 10 5

Diameter (cm) 150.5±7.65 135.4±11.8 150.6±14.8

Tree height (m) 17.5±1.2 17.9±2.1 20.5±3.3

Tree height – canopy height (m)a 0.04±1.0 −0.9±2.3 −0.2±0.4

Canopy cover (percent) 27.7±5.4 26.5±8.8 20.0±9.1

Type I trees (percent of total) 0.0 10.0 20.0

Type II trees (percent of total) 41.7 60.0 40.0

Type III trees (percent of total) 45.8 20.0 40.0

Type IV trees (percent of total) 12.5 10.0 0.0

 Alive (percent of total) 83.3 60.0 100.0

Cavity height (m)b 13.5±2.0 10.7±1.6 13.1±4.6

Number of cavity entrances 4.9±0.77 7.0±1.9 10.2±4.7

Distance to nearest cavity tree (m) 33.0±8.9 61.0±28.9 20.8±8.9

a

 Measure of the difference between the tree height and the height of the surrounding canopy.

b

 Cavity heights could not be measured for type III and type IV roosts, reducing sample sizes to 10 for lactating females, 8 

for postlactating females, and 3 for males. 

Table 3—Mean ± SE of habitat characteristics of day roosts of Rafinesque’s big-eared bats by roost type 

during June and July 2009, Ballard County, KY

Habitat characteristics Type I Type II Type III Type IV

Number of roost trees 2 15 14 3

Diameter (cm) 98.2±9.6 137.9±7.2 155.5±11.5 159.3±10.6

Tree height (m) 29.7±2.5 16.1±1.5 17.7±1.3 22.9±3.3

Tree height – canopy height (m) 0.0±0.0 −2.9±1.7 1.5±1.2 4.4±3.4

Canopy cover (percent) 37.5±12.5 27.3±7.3 32.9±7.5 13.3±6.0

Alive (percent of total) 50.0 66.7 100 100

Cavity height (m)a 8.1±2.5 13.0±1.6 — —

Number of cavity entrances 1.0±0.0 7.4±1.7 5.0±1.3 6.0±1.7

Distance to nearest cavity tree (m) 20.2±7.2 49.1±19.7 29.0±12.9 65.2±37.6

a Cavity heights could not be measured for type III and type IV roosts.
134

Rafinesque’s big-eared bats reported is 79.4 cm (Trousdale 

and Beckett 2005) and is often > 100 cm (Carver and 

Ashley 2008, Gooding and Langford 2004, Rice 2009). 

Large diameter cavity trees may benefit Rafinesque’s 

big-eared bats by providing large amounts of space for 

roosting bats, allowing for larger potential colony sizes, 

or may exhibit more favorable microclimates. Rice (2009) 

found that diameter and inside cavity height were positively 

correlated, with cavity height influencing the number of 

days roost trees were used. While we did not compare 

roost trees to random trees, the large overall mean diameter 

(146.5 cm) of roost trees located in this study supports 

previous research demonstrating the importance of large 

diameter trees. We did not measure cavity height for 

type III and type IV roost trees. Regardless, mean cavity 

height for type I and II roosts was greater than heights 

reported elsewhere, likely because our sample of day 

roosts consisted of a larger number of completely hollow 

cypress trees than were present in other studies (Rice 

2009, Stevenson 2008). Additional work comparing used 

and unused trees is needed to determine if cavity height is 

significant in roost tree selection by Rafinesque’s big-eared 

bats in western Kentucky.

Although we found limited tree species diversity in day 

roosts used by Rafinesque’s big-eared bats, day roosts were 

diverse in terms of roost type. This is in agreement with two 

recent studies (Rice 2009, Trousdale and Beckett 2005) that 

had a larger focus on radiotelemetry than previous studies 

(Clark 1990, Gooding and Langford 2004, Mirowsky and 

others 2004). Rice (2009) documented a decrease in use 

of type I and II roosts from summer to winter and that 

these roost types had less stable microclimates during the 

summer and winter than type III roosts. Rice (2009) visually 

confirmed use of type III roosts during the summer through 

emergence counts and during winter using radiotelemetry, 

but variation in seasonal use of type III roosts was not 

quantified. Regardless, type III roosts were used exclusively 

by radio-tagged bats during an exceptionally cold period. 

Trousdale and Beckett (2005) also found use of 3 roost types 

during the summer months, locating 12 type IV roosts (85.7 

percent), 1 type I roost (7.1 percent), and 1 (7.1 percent) 

tree with a basal and bole entrance (most similar to a type II 

roost). Not all telemetry studies have tracked Rafinesque’s 

big-eared bats to a diversity of roost types. Carver and 

Ashley (2008) reported 96 percent (n = 24) of day roosts 

were type I trees; Lance and others (2001) reported 100 

percent (n = 4) type I trees, and Stevenson (2008) reported 

only roosts with basal cavities (type I or II, n = 49). 

Our data were limited to two summer months within 1 

year, and it is uncertain whether or not seasonal variation in 

use of roost types exists or how these data compare to day 

roosting behavior of adult females during the remainder of 

the year. Additionally, the number of day roosts we located 

herbaceous and forested wetlands, 22.0 percent upland 

deciduous forests, 15.7 percent agriculture and open fields, 

8.0 percent lakes, and 1.6 percent developed areas. Thirdorder habitat use by females did not differ from random 

(Wilk’s lambda = 0.54, F = 1.0, P = 0.47). 

DISCUSSION

Use of large tree hollows as day roosts by Rafinesque’s 

big-eared bats in bottomland hardwood forests is well 

documented (Carver and Ashley 2008, Clark 1990, Gooding 

and Langford 2004, Lance and others 2001, Mirowsky and 

others 2004, Rice 2009, Stevenson 2008, Trousdale and 

Beckett 2005). Rafinesque’s big-eared bats primarily day 

roosted in hollow baldcypress trees (85.3 percent of all 

tree roosts), similar to results from eastcentral Mississippi 

(Stevenson 2008) where baldcypress was among the most 

common tree species used despite constituting 4 percent 

of available cavity trees. In northeastern Louisiana, Rice 

(2009) found Rafinesque’s big-eared bats roosting in only 

two baldcypress trees, but this represented 66.7 percent of 

available cypress trees. Other studies of Rafinesque’s bigeared bats have reported roost trees consisting primarily of 

a single species, usually water tupelo (Carver and Ashley 

2008, Gooding and Langford 2004, Rice 2009). Studies 

from eastcentral Mississippi (Stevenson 2008), southern 

Mississippi (Trousdale and Beckett 2005), and westcentral 

Louisiana (Lance and others 2001), however, found use 

of a wide variety of tree species as day roosts, including 

baldcypress, water tupelo, black tupelo (N. sylvatica), 

magnolia species (Magnolia spp.), sweetgum, oak species, 

American sycamore (Platanus occidentalis), and hickories.

While most studies have not compared roosts to random 

trees, the smallest mean diameter of roost trees of 

Table 4—Summary of roost counts at day roosts of 

Rafinesque’s big-eared bats by roost type during June 

and July 2009, Ballard County, KY

Summary of roost 

counts Type I Type II Type III Type IV

Number of roosts 

counted

2 12 9 2

Total number of nights 

counted

37a 43 9 3

Mean number of bats 5.5 23.5 5.9 27.7

Maximum number of 

bats

25 96 20 33

a

 One male roost was counted 31 times, with a maximum count of 1 

individual.
135

forested systems (Hurst and Lacki 1999, Menzel and others 

2001) is of limited value. 

We found that establishment of home ranges by reproductive 

female Rafinesque’s big-eared bats was nonrandom and 

that they were located closest to forested and emergent 

wetlands and farthest from agriculture and open fields. 

These results are at least partly driven by the importance of 

forested wetlands for day roosting; Ballard and Boatwright 

WMAs provided these bats with an “island” of conserved 

bottomland hardwood forest in a largely agricultural 

landscape. Because home ranges consisted primarily of 

wetlands and upland deciduous forests, with agriculture and 

open fields comprising a small percent of home ranges, our 

results confirm that bats spent more time foraging in forested 

habitats than in agricultural habitats. Hurst and Lacki (1999) 

found these bats preferred to forage in oak and oak-hickory 

stands over other forested stands. Hurst and Lacki (1999) 

noted that more than half of noctuid moths in the genus 

Catocala, important prey items of Rafinesque’s big-eared 

bats (Hurst and Lacki 1997), feed on oaks and hickories 

in their larval stages, suggesting a partial explanation for 

the selection of oak and oak-hickory stands for foraging 

by Rafinesque’s big-eared bats. Additional studies of 

moth families commonly eaten by big-eared bats have 

found that the preferred prey species are more positively 

associated with riparian or upland forests than open 

habitats and forest edges (Burford and others 1999, Dodd 

and others 2008). Regardless, numerous studies have 

demonstrated the use of habitats with edges or vertical 

structure for foraging by Corynorhinus bats (reviewed 

in Lacki and Dodd 2011), including Rafinesque’s bigeared bats (Hurst and Lacki 1999), suggesting some 

interplay between habitat use by a gleaning species of 

bat and predator avoidance by moths (Lacki and Dodd 

2011). We suggest that Rafinesque’s big-eared bats in 

western Kentucky concentrated their foraging efforts in 

and adjacent to wetland and upland deciduous forests in 

response to localized abundance of preferred moth prey 

in these habitats. Insect sampling and dietary analysis 

are needed to confirm this prediction and determine the 

potential role of other factors, such as structural benefits 

of foraging habitat, in nocturnal habitat use. 

Our data highlight the importance of bottomland hardwood 

forests for foraging and roosting in Rafinesque’s bigeared bats. While larger sample sizes for various sexes 

and reproductive classes and research earlier and later in 

the growing season are still needed, our data indicate that 

use of type III and IV day roosts during the summer is 

potentially underestimated in studies using cavity search 

methods and shows that open habitats, while used, are of 

lesser importance compared to upland and forested wetlands 

as foraging habitats. We recommend studies examine roost 

microclimates and thermoregulation throughout the year 

was limited, especially among type I and IV trees, while 

variability in habitat characteristics of trees within each roost 

type was often substantial. For example, type II trees ranged 

from 4.7 to 25.3 m in height, including trees with snapped 

tops above the surrounding canopy and old trees in advanced 

stages of deterioration. Thus, more research is needed to 

locate and characterize day-roost trees. Regardless, findings 

of Rice (2009) suggest that thermal properties of cavities 

differ among roost types and vary seasonally within roost 

types. Intuitively, thermal properties of cavities are likely 

influenced by the number and location of cavity entrances 

and that a diversity of roost types aids Rafinesque’s bigeared bats in enduring variable environmental conditions 

throughout the year. Regardless, we recommend that 

future work examine not only seasonal variation in 

cavity temperatures among roost types but also focus on 

thermoregulatory strategies among sexes and reproductive 

classes of bats using these roost types.

Our observations of roost switching in Rafinesque’s big-eared 

bats are similar to other findings from bottomland hardwood 

forests. In northeastern Louisiana, Rice (2009) found that 

radio-tagged females switched roosts every 2.8 days from 

September through November, similar to our results for 

lactating and postlactating females. In South Carolina, Lucas 

(2009) observed a lactating female and two juvenile males 

switching roosts every 1.3 days, while we observed lactating 

females switching every 2.2 days. Both Rice (2009) and Lucas 

(2009) reported males switching roosts less frequently, but our 

sample size for males was too small to compare to females. 

Trousdale and others (2008) reported switching every 2.6±2.0 

days (pooling data from all bats), and Stevenson (2008) 

reported that 10 males and 4 females (ages and reproductive 

condition not reported) switched roosts an average of 3 times 

(range = 1 to 9) during tracking sessions. We observed a range 

and mean of distances traveled between sequential roosts 

similar to those reported by Trousdale and others (2008) 

(x ̄= 573 ± 640 m, range = 120 to 4000) during the summer. 

Distances reported by Rice (2009) were somewhat smaller 

than our results, ranging from 0 to 778 m (x ̄= 177) for males 

and 0 to 1726 m (x ̄= 291) for females.

Our data represent the first published account of home 

range size and habitat use of Rafinesque’s big-eared bats 

in bottomland hardwood forests. While we did not detect 

differences in the size of home ranges between lactating and 

postlactating females, our sample sizes were small, and we 

observed large variation in home range size. This variation 

indicates a larger sample size is necessary to accurately 

characterize home range sizes and to test for differences 

among sexes and reproductive classes; thus, our inability to 

detect differences should be treated with caution. Further, 

because no other data on home range sizes of Rafinesque’s 

big-eared bats have been collected in bottomland hardwood 

forests, comparison with home range estimates from other 
136

southeastern myotis (Myotis austroriparius). American Midland 

Naturalist. 160: 364-373.

Clark, M.K. 1990. Roosting ecology of the eastern big-eared bat, 

Plecotus rafinesquii, in North Carolina. Raleigh, NC: North 

Carolina State University. 121 p. M.S. thesis.

Clark, M.K.; Black, A.; Kiser, M. 1998. Roosting and foraging 

activities of Corynorhinus rafinesquii and Myotis austroriparius

within the Francis Beidler Forest, South Carolina. Raleigh, 

NC: North Carolina Museum of Natural Sciences; draft report 

C7745.11. [Number of pages unknown.]

Cochran, S.M. 1999. Roosting and habitat use by Rafinesque’s 

big-eared bat and other species in a bottomland hardwood forest 

ecosystem. Jonesboro, AR: Arkansas State University. 109 p. 

M.S. thesis.

Conner, L.M.; Plowman, B.W. 2001. Using Euclidean distances 

to assess nonrandom habitat use. In: Millspaugh, J.; Marzluff, 

J., eds. Radio telemetry and animal populations. San Diego: 

Academic Press: 275-290. 

Conner, L.M.; Smith, M.D.; Burger, L.W. 2003. A comparison of 

distance-based and classification-based analyses of habitat use. 

Ecology. 84: 526-531.

Dodd, L.E.; Lacki, M.J.; Rieske, L.K. 2008. Variation in moth 

occurrence and implications for foraging habitat of Ozark bigeared bats. Forest Ecology and Management. 255: 3866-3872.

Esri Corporation. 1999. ArcView GIS. Version 3.2. Redlands, CA: 

Environmental Systems Research Institute, Inc. 

Gannon, W.L.; Sikes, R.S.; Animal Care and Use Committee of 

the America Society of Mammalogists. 2007. Guidelines of 

the American Society of Mammalogists for the use of wild 

mammals in research. Journal of Mammalogy. 88: 809-823. 

Gooding, G.; Langford, J.R. 2004. Characteristics of tree roosts of 

Rafinesque’s big-eared bat and southeastern bat in northeastern 

Louisiana. Southwestern Naturalist. 49: 61-67.

Hayes, J.P.; Loeb, S.C. 2007. The influence of forest management 

on bats in North America. In: Lacki, M.J.; Hayes, J.P.; Kurta, A., 

eds. Bats in forests: conservation and management. Baltimore, 

MD: The Johns Hopkins University Press: 207-236.

Homer, C.; Huang, C.; Yang, L. [and others]. 2004. Development 

of a 2001 national land-cover database for the United States. 

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bat in southeastern Kentucky. Journal of Mammalogy. 78: 

525-528.

to elucidate the advantages, if any, of various roost types. 

We also encourage simultaneously examining diurnal and 

nocturnal behaviors of Rafinesque’s big-eared bats to link use 

with availability and to make more sound recommendations 

on how to protect and enhance habitat for this species.

ACKNOWLEDGMENTS

Funding for this project was provided by the Kentucky 

Division of Fish and Wildlife Resources (KDFWR) and the 

University of Kentucky, College of Agriculture. We thank G. 

Langlois and D. Fraser for their hard work in the field. We 

also thank B. Slack, J. MacGregor, D. Baxley, and R. Colvis 

of the KDFWR for their help, without which this project 

would not have been possible. Protocols for handling and 

tracking bats were approved by the University of Kentucky, 

Institutional Animal Care and Use Committee (IACUC no. 

A3336-01). This investigation is connected with a project of 

the Kentucky Agricultural Experiment Station (KAES no. 

10-09-044) and is published with the approval of the director.

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139

STUDY AREA AND METHODS

The study was located in the Ridge and Valley Province near 

the town of Upper Tract, Pendleton County, WV (fig. 1). The 

study area was centered on Cave Mountain Cave on Cave 

Mountain and included the area within an 11.3-km radius 

INTRODUCTION

The Virginia big-eared bat (Corynorhinus townsendii 

virginianus) was one of two subspecies of C. townsendii

listed as federally endangered in 1979 (U.S. Fish and 

Wildlife Service 1979). The listing package noted that 

increased disturbance of cave roosts from speleological 

recreation was resulting in population declines. In the 

early 1980s, most important C. t. virginianus caves in West 

Virginia were closed to recreational human traffic, either 

seasonally or year round, to reduce disturbance to maternity 

colonies and hibernating concentrations. Many of these 

caves were protected with fences or gates to control human 

entry. These management activities resulted in an increase in 

C. t. virginianus numbers in these caves (Stihler 2011).

In the late 1980s, biologists in Virginia and West Virginia began 

to determine the habitat needs of C. t. virginianus outside 

of their cave roosts. Of particular concern at the time was 

the continuing spread of the exotic gypsy moth (Lymantria 

dispar) into the range of C. t. virginianus in West Virginia 

and the potential impacts of both forest defoliation and gypsy 

moth control measures on the food base of C. t. virginianus

which consists largely of moths (Dalton and others 1986, 

Lacki and Dodd 2011). Light-tagging studies were conducted 

cooperatively between these States to obtain information 

on foraging habitats and behaviors, but most of the bats 

were lost from sight shortly after release. In 1991, I initiated 

a radiotelemetry study in West Virginia to obtain better 

information on habitats used by C. t. virginianus during the 

summer and distances the bats traveled to forage from the cave 

roosts.

RADIOTELEMETRY STUDIES OF FEMALE VIRGINIA BIG-EARED BATS 

(CORYNORHINUS TOWNSENDII VIRGINIANUS) IN PENDLETON COUNTY, 

WEST VIRGINIA

Craig W. Stihler, Wildlife Biologist, West Virginia Division of Natural Resources, Elkins, WV 26241

Abstract­—Virginia big-eared bats (Corynorhinus townsendii virginianus) have benefited from the protection of important 

cave roosts, but understanding habitat use outside of caves will allow land managers to manage foraging habitats as well. 

Thus, I conducted a radiotelemetry study at Cave Mountain Cave, a maternity colony cave in Pendleton County, WV, 

between 1991 and 1998. Forty-five female C. t. virginianus were radio-tagged and tracked during four 2-week sessions 

from mid-May through late August. To minimize disturbance, only one session was conducted in any year. Bats were 

tracked from the time they left the roost in the evening until they returned to day roost in the cave the next morning. Bats 

traveled up to 11.3 km from the cave to forage and used a variety of habitats including deciduous forest, mixed deciduous/

coniferous forest, old fields, hayfields, and corn fields. Foraging areas contained significantly more open habitat and had 

a greater habitat interspersion index (interspersion of open and forest habitats) than random plots. The bats often night 

roosted near foraging areas; most night roosts were buildings, but one State highway bridge was used during all four 

tracking sessions. To date, most conservation measures for this bat have focused on cave protection, but land managers can 

provide noncave habitats by maintaining a mosaic of forested and open habitats around cave roosts and retaining structures 

that provide night roosts. 

Figure 1—Location of the Corynorhinus townsendii virginianus 

radiotelemetry study area centered on Cave Mountain Cave, 

Pendleton County, WV.

Pennsylvania

3HQQV\OYDQLD

Ohio

Maryland

Virginia

Kentucky

Citation for proceedings: Loeb, Susan C.; Lacki, Michael J.; Miller, Darren A., eds. 2011. Conservation and management of eastern big-eared bats: 

a symposium. Gen. Tech. Rep. SRS-145. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 157 p.
140

were tracked at any time. Because only a small amount of 

adhesive was used in an attempt to minimize weight and to 

allow the transmitters to fall off the bats after a relatively 

short time, some of the transmitters remained on the bats 

only a few days. Transmitter loss in August seemed to be 

related to hair loss associated with molting. When this 

occurred, additional bats were captured during a second 

trapping effort and tracked for the remainder of the session. 

Bats were trapped at one of the cave entrances using one 

or more harp traps (0.91 m by 0.91 m); during the trapping 

effort, the other entrances to the cave were blocked with 

tarps. Only female C. t. virginianus were radio-tagged. After 

trimming the fur in the area where the transmitter was to 

be attached, each transmitter (Holohil Systems Ltd., Carp, 

Ontario, Canada) was affixed to the bat between the scapulae 

using Skin-Bond surgical adhesive (Smith & Nephew 

United, Inc., Largo, FL). The smallest transmitters available 

when each tracking session took place were used (0.51 to 

0.65 g). Transmitter weight represented 5.25±0.55 percent of 

body mass.

Bats were tracked each night from the time they emerged 

from the cave in the evening until they returned to the cave in 

the morning. If a bat was not observed returning to the cave, 

tracking was terminated when it was light enough that the bat 

was no longer likely to return to the cave. Bats were located 

using Wildlife Materials, Inc. (Murphysboro, IL) model 

TRX-2000S or Advanced Telemetry Systems, Inc. (Isanti, 

MN) model R4000 receivers and three-element directional 

Yagi antennae and vehicle-mounted omnidirectional 

antennae. Citizens’ Band radios and low-band State radios 

were used by observers to communicate with each other, 

but because of the rugged terrain, communication was 

sometimes difficult. Four to ten observers collected data each 

night. At emergence, at least one observer was positioned 

to monitor bats exiting the cave and alert other observers 

when each bat had emerged. Other observers were stationed 

on high points throughout the study area and tracked each 

of the cave entrances, the greatest distance we tracked a bat 

from the cave. This area is east of, and in the rain shadow 

of, the Allegheny Front, the Eastern Continental Divide. The 

area around the cave is rugged and contains steep slopes 

and numerous rock outcrops. The study area was mostly 

second- or third-growth forests (82 percent forested) and 

was largely undeveloped (table 1). Forests in the study area 

were dominated by oaks (Quercus spp.), sometimes mixed 

with or dominated by pines (Pinus spp.) on ridge tops and 

dry slopes. Cove hardwood forests occurred in the ravines. 

The South Branch of the Potomac River and North Fork of 

the South Branch of the Potomac River ran through the study 

area; the flood plains of the rivers contained concentrations 

of agricultural lands, i.e., hayfields, row crops, and pasture. 

Cave Mountain Cave is within the Monongahela National 

Forest, and much of the study area was located within The 

Nature Conservancy’s designated Smoke Hole Canyon-North 

Fork Mountain Bioreserve.

Cave Mountain Cave housed a maternity colony of > 600 

C. t. virginianus during the summer and a small number of 

hibernating C .t. virginianus in the winter. The cave was 

gated and closed to human entry during the maternity period 

(April 1 to September 15). This cave has multiple entrances 

located in a limestone cliff approximately 128 m above the 

South Branch of the Potomac River.

Bats were tracked during four 14-night tracking sessions; 

to minimize disturbance to the colony, only one session 

was carried out in any year. The four sessions corresponded 

roughly to four life stages (table 2): (1) after the bats 

arrived at the maternity site, but before parturition; (2) early 

lactation; (3) late lactation; and (4) after young became 

volant and left the cave in the evening. Ten to fourteen bats 

were tracked each session; however, no more than eight bats 

Table 1—Land cover type composition of the 

Corynorhinus townsendii virginianus radiotelemetry 

study area (401 ha) centered on Cave Mountain Cave, 

Pendleton County, WV

Land cover type Study area

percent

Deciduous forest 73.07

Mixed coniferous/deciduous forest 9.04

Agricultural/open 17.03

Urban 0.40

Open water 0.45

Wetlands < 0.01

Total 100.00

Table 2—Corynorhinus townsendii virginianus

radiotelemetry sessions conducted at Cave Mountain 

Cave, Pendleton County, WV, and number of bats tagged 

each session, 1991 to 1998

Session Year Dates Total number of 

bats tagged

1 1991 May 13–June 1 10

2 1994 June 25–July 9 14

3 1992 July 11–July 25 10

4 1998 August 9–August 22 11
141

categories: forest (mainly deciduous forest) and open (mainly 

field, pasture, and row crops) (fig. 2). NLCD01 classes—

developed open space, shrub/scrub, grassland/herbaceous, 

pasture/hay, cultivated crops, and emergent herbaceous 

wetlands—were reclassified as open habitat. Deciduous 

forest, evergreen forest, mixed forest, and woody wetlands 

classes were reclassified as forest habitat. All remaining 

classes (open water, developed low, medium, high intensity, 

and barren) were reclassified to “no data.”

To examine the interspersion of open and forested habitats 

across the landscape and in high-use areas, an interspersion 

index was created using the ESRI Spatial Analyst focal 

variety tool (Environmental Systems Resource Institute 

2009). An index of interspersion was assigned to each 

NLCD01 30-m pixel in the forest/open cover type dataset. A 

5-pixel diameter circle was created centered on each pixel, 

and, if the circle contained only one cover type, that pixel 

was assigned a value of one; if it contained two cover types, 

i.e., both open and forest, it was assigned a value of two. 

These data were then combined to create an interspersion 

map for the study area.

To provide a measure of habitat availability in the study areas 

as a whole, a set of 5,000 random points was established 

within the study area, and 500-m radius circular plots were 

created centered on each random point. For each high-use 

area and random plot the proportion of open habitat and 

mean interspersion index were calculated using ESRI Spatial 

bat as it traveled to a foraging area. Readings were taken by 

multiple observers every other minute on the even-numbered 

minutes. If more than one bat was being tracked, locations 

were recorded on odd-numbered minutes for one bat and 

on even-numbered minutes for the other bat. Once a bat 

was tracked to a foraging area, observers coordinated their 

observations to best delineate the area where that particular 

bat was foraging. Night roosts were also recorded; when a 

bat appeared to night roost, i.e., steady signal suggesting 

the bat was not flying, the roost was confirmed by quietly 

approaching the roost to determine the bat’s location. 

For each reading taken, the observer recorded the observer’s 

location, time (watches synchronized beforehand), receiver 

used, transmitter frequency, azimuth (uncorrected for 

declination), whether or not the signal was variable, and 

whether or not an attenuator was used when taking the 

reading. Signal strength and receiver gain setting were also 

recorded. Although these last two items were subjective, 

observers attempted to standardize these ratings among each 

other. Observers also noted when a reading was attempted 

but no signal was detected.

Because the study area was rugged and contained numerous 

steep slopes and outcroppings, signal bounce was a problem 

that could lead to misinterpretation of the data. To minimize 

this error, locations for each minute were plotted, and the 

data were reviewed to determine if the plotted locations 

“made sense.” For example, if two readings suggested the bat 

was near a third observer, but that observer could not pick 

up a signal from the bat, the data point was discarded. Or, 

if the readings positioned the bat much closer to observer 

one than observer two, but observer one’s signal was much 

weaker, the data were again suspect and discarded. After the 

“clean” data for an individual bat were plotted, areas of high 

use were delineated for each bat. Areas of high use were 

defined as areas where a bat spent > 30 minutes actively 

flying. I assumed that the high-use areas were foraging areas 

because the bats were active in relatively small areas for 

extended periods of time. In addition, the signals received 

from the bats’ transmitters while in these areas varied greatly 

in intensity suggesting the bats were flying erratically or in 

loops, as expected of foraging insectivorous bats.

Telemetry points and high-use areas were plotted on 

U.S. Geological Survey 7.5-minute topographic maps. 

High-use areas for each bat were digitized using ArcMap 

(Environmental Systems Resource Institute 2009). Habitat 

use was analyzed using the National Land Cover Dataset 

2001 (NLCD01, http://www.epa.gov/mrlc/nlcd-2001.html). 

Although this dataset was created after the telemetry project 

was completed, land use in this area changed little during 

and shortly after the study, and it is representative of the 

land cover type distribution during the project period. For 

the analyses, land cover types were combined into two broad 

Open

Forest

Figure 2—Map of the Pendleton County, WV, Corynorhinus 

townsendii virginianus radiotelemetry study area showing land 

cover types grouped into two broad categories: open (light gray) and 

forested (dark gray).
142

3, and 7.4 km in session 4 (fig. 3). Thus, maximum distances 

traveled were greatest early in spring, before parturition, 

and least in mid- to late July, during late lactation. A similar 

seasonal pattern was observed for the mean distances to 

high-use area centroids. The mean distances to the centroids 

of high-use areas were: session 1, 6.5 km; session 2, 4.1 km; 

session 3, 3.5 km; and session 4, 6.0 km. Mean distance 

was significantly less (P < 0.1) in session 3 (late lactation) 

than in session 1 (prelactation) or session 4 (postlactation). 

There was no significant difference between early and late 

lactation. 

As expected, most of the foraging habitat used by the 

bats was considerably closer to the cave than the greatest 

Analyst. These data were analyzed using the nonparametric 

Kruskal-Wallis chi-square test. To examine distance to 

foraging areas, the distance from the centroid of each highuse area was measured using ESRI Spatial Analyst, and the 

mean distances during each session were compared using 

Tukey’s Honestly Significant Difference test. Statistical tests 

were run using R (R Development Core Team 2010).

RESULTS

Distances Traveled from Cave

The greatest distances bats traveled from the cave were 

11.3 km in session 1, 10.8 km in session 2, 6.5 km in session 

Figure 3—Map of high-use (foraging) areas used by female Corynorhinus townsendii virginianus from the Cave 

Mountain Cave maternity colony, Pendleton County, WV, during four radio tracking sessions: session 1, May 13 to 

June 1; session 2, June 25 to July 9; session 3, July 11 to July 25; and session 4, August 9 to August 22.
143

Although the cover-type data lumped many habitat types into 

broad categories, foraging areas were visited during the study 

to provide greater detail on the habitat types used by the 

bats. Most of the open habitats were either hayfields or old 

fields. Grazed lands were rarely used by the bats, although 

distances traveled. Although the bats traveled up to 11.3 km 

from the cave, 59.5 percent of the foraging habitat occurred 

within 5 km of the cave, and 80.5 percent of the foraging 

habitat occurred within 6 km of the cave (fig. 4).

Habitat Use

The high-use areas for all bats during each radio tracking 

session are shown in figure 3. The amount of open habitat in 

the high-use areas was significantly greater (Kruskal-Wallis 

χ2 = 23.838, P < 0.001) than in the random plots (fig. 5). On 

average, high-use areas contained 35.02±0.35 percent open 

habitat compared to 16.85±0.20 percent open habitat in the 

random plots. There were no significant seasonal differences 

in the amount of open habitat in the high-use areas (KruskalWallis χ2

 = 3.11, P = 0.375). Although not statistically 

significant, the amount of open habitat in the foraging areas 

was greatest (54.0 percent) during session 4. Percent open 

habitat observed in other sessions was 28.9 percent in session 

1, 30.3 percent in session 2, and 33.2 percent in session 3. 

High-use areas also had a significantly greater amount of 

habitat interspersion than the random plots (Kruskal-Wallis 

χ2

 = 24.349, P < 0.001) (fig. 6). High-use areas had a mean 

interspersion value of 1.65±0.32, while the random plots 

had a mean value of 1.46±0.32. There were no significant 

seasonal differences in the amount of habitat interspersion in 

the high-use areas (Kruskal-Wallis χ2 = 1.607, P = 0.658). High Use Random 0.0 0.2 0.4 0.6 0.8 1.0 Habitat Fraction Open

Figure 5—Box plot comparing proportion of habitat classified as open 

in Corynorhinus townsendii virginianus high-use areas in Pendleton 

County, WV, and random plots within the study area. Dark bar 

indicates median value.

123 456 7 8 9 10 11 12

Kilometers from Cave

Cumulative Area (percent)

0 20 40 60 80 100

Figure 4—Cumulative percent of Corynorhinus townsendii virginianus 

foraging habitat contained in consecutive 1-km wide rings centered on 

the entrance of Cave Mountain Cave, Pendleton County, WV.

High Use Random

1.0 1.2 1.4 1.6 1.8 2.0

Forest−Open Interspersion Index

Figure 6—Box plot comparing interspersion indices of Corynorhinus 

townsendii virginianus high-use areas in Pendleton County, WV, and 

random plots within the study area. Dark bar indicates median value.
144

within hollows enclosed by cliffs” (Adam and others 1994). 

Although clearings were uncommon in the Kentucky study 

area, no radio-tagged bats were tracked to openings that were 

available. However, using echolocation call monitoring to 

examine habitat use on the DBNF, Burford and Lacki (1995) 

documented significantly greater C. t. virginianus activity 

(passes per minute) in old field habitats than in forest or cliff 

top habitats. 

Female C. t. ingens in Oklahoma use open habitat in 

proportion to its availability in early lactation, late lactation, 

and fall (August through October) but avoid it during 

midlactation (Clark and others 1993, Wethington and others 

1996). Open habitat made up 29.7 percent of the available 

habitat in Oklahoma. However, at the West Virginia site, 

where open habitat made up 17.0 percent of the available 

habitat, areas with greater percentage of open habitats were 

selected as foraging sites throughout the summer. During 

the present study, C. t. virginianus foraged in corn fields 

in August (session 4), a habitat not used in earlier tracking 

sessions. High use of corn fields in August is probably the 

reason the proportion of open habitat was highest during 

session 4. Use of corn fields could be related to the second 

generation peak flights of corn earworm (Helicoverpa zea), 

European corn borer (Ostrinia nubilalis), or fall armyworm 

(Spodoptera frugiperda).2

Other than corn fields during session 4, most of the open 

areas used by C. t. virginianus were hayfields or old fields. 

Similar results were found during light-tagging studies in 

West Virginia where no C. t. virginianus foraged in a grazed 

pasture located approximately 400 m from the cave roost, 

even though both hayfields and forest in the same general 

area were used (Stihler and others 1996). Although insect 

abundance at these sites was not measured, it seems likely 

that insect abundance was low in the grazed areas because 

vegetative structure was low (mostly short grass). The only 

pasture used by the bats did have some vegetative structure 

in an abundance of thistles and riparian vegetation along a 

small stream. Only one bat appeared to forage over water, 

but this bat may have been foraging around young sycamore 

(Plantanus occidentalis) trees growing on the banks of and 

on a small island in the South Branch. In addition, the bats 

never appeared to go to the river to drink after emerging from 

the cave in the evening.

Foraging areas used by C. t. virginianus exhibited a higher 

degree of habitat interspersion than random plots, suggesting 

that forest edges may be important. Indeed, C. t. ingens in 

Oklahoma use edges more than expected based on their 

availability (Clark and others 1993). However, neither the 

2

 Personal communication. 2010. Sherri Hutchinson and Laura Miller, 

West Virginia Department of Agriculture, Plant Industries Division, 

1900 Kanawha Blvd., East, Charleston, WV 25305.

two bats during tracking session 2 foraged in a lightly grazed 

pasture with numerous thistles, scattered trees, and riparian 

vegetation along a small stream flowing through the pasture.

There was little overlap of high-use areas among seasons. 

Overlap in foraging areas ranged from < 1.0 percent between 

session 3 and session 4 to 5.6 percent between session 2 and 

session 3, i.e., early and late lactation. 

Night Roosts

Bats often used night roosts near the foraging areas 

during sessions 1, 3, and 4. Most of the night roosts were 

anthropogenic structures including barns, a chicken coop, 

various outbuildings, the porch of an abandoned house, and 

a concrete bridge (three-span continuous steel beam bridge 

with a composite concrete deck). This bridge was used as 

a night roost during all four tracking sessions, and multiple 

bats were observed roosting under the bridge at one time. 

In addition, after one bat appeared to be night roosting on a 

forested hillside, the site was visited the next day, and a large 

rock outcrop was found at the site. During session 2 (early 

lactation) the bats returned to the cave up to three times during 

the night and rarely used night roosts. Bats rarely returned to 

the cave during the night during the other sessions.

Other Observations

One bat tracked during session 1 switched cave roosts and 

moved to a maternity colony in Schoolhouse Cave located on 

the west side of North Fork Mountain approximately 9.2 km 

from Cave Mountain Cave. Each evening this bat crossed the 

mountain to forage on the east side of North Fork Mountain. 

On two occasions during session 3 and one occasion during 

session 2, a bat did not return to the cave roost before 

morning; in all three cases, the bat returned to the cave early 

the following evening.

DISCUSSION

C. t. virginianus at the Cave Mountain Cave study site 

foraged in areas with a mixture of forested and open habitats 

but selected areas that contained a significantly larger 

proportion of open habitat than found in random plots. Data 

from light-tagging studies of C. t. virginianus in Virginia and 

West Virginia (Stihler and others 1996)1 also documented the 

use of both open (hay, alfalfa, and corn fields) and forested 

habitats. In contrast, radio-tagged male and female C. t. 

virginianus on the Daniel Boone National Forest (DBNF) 

in Kentucky “foraged along cliffs and in forest habitat 

1

 Dalton, V.M.; Brack, V.W., Jr.; Williams, C. 1989. Foraging ecology of 

the Virginia big-eared bat: performance report. Richmond, VA: Virginia 

Department of Game and Inland Fisheries. Unpublished report. 14 p.
145

areas. The total population of C. t. ingens in Oklahoma 

maternity colonies was approximately 650 bats (U.S. Fish 

and Wildlife Service 1995), while the colony in Cave 

Mountain Cave numbered between 637 and 826 bats during 

the study period, and the 6 maternity colonies within the 

study area contained a total of more than 2,000 bats. 

As observed in C. t. ingens (Clark and others 1993), the 

females returned to the roost up to three times a night during 

early lactation, and the number of returns decreased as 

lactation progressed. Before parturition and after the young 

became volant, most bats left the cave in the evening and did 

not return until morning. The number of feeding bouts per 

night probably did not change over the summer, but between 

bouts the bats night roosted closer to their foraging areas and 

away from the cave outside of the lactation period. Most of 

the night roosts used were buildings. The use of buildings as 

night roosts was also observed in C. t. virginianus in Virginia 

(see footnote 1).

CONCLUSIONS

In the largely forested landscape around a maternity 

colony cave in West Virginia, female C. t. virginianus

used foraging areas that contained more open habitat and 

had a greater interspersion of open and forested habitats 

than was expected based on availability. Land managers 

may be able to improve or maintain foraging habitats for 

C. t. virginianus by creating or maintaining open fields 

in the vicinity of summer roosts. Because open habitats 

are often the areas most suitable for future development, 

these habitats may be lost to development. Further, open 

habitats may return to forests without active management, 

e.g., burning, mowing, and herbicides. The creation of a 

mosaic of open and forested habitat types may provide 

foraging bats a more diverse prey base where they can 

switch foraging habitats from night to night or throughout 

the night depending on prey availability. During this study, 

female bats traveled up to 11.3 km from the cave to forage. 

However, 80.5 percent of the foraging habitat used during 

the four tracking sessions occurred within 6.0 km of the 

cave. Efforts to maintain or create foraging habitat would 

be most effective when done within 6.0 km of the maternity 

colony roost. Although most foraging activity occurred in 

forests, old fields, and hayfields, corn fields were used in 

August, and agricultural use of pesticides could pose a risk 

to foraging bats and their pups. 

Because C. t. virginianus usually night roosted near their 

foraging areas in uninhabited structures such as barns and 

abandoned houses, maintenance or creation of suitable roost 

structures near foraging habitats should benefit them. Bridges 

may also provide important night roosts, and bridge designs, 

such as the steel beam/concrete deck bridge used during 

telemetry data nor the light-tagging studies conducted in 

West Virginia support this assumption. On several occasions 

multiple observers tracked bats foraging in an open field 

from positions along the edges, and bats never seemed to 

be foraging along the field edge. Similar observations were 

made for bats foraging in small woodlots. These results are 

further corroborated by observations during light-tagging 

studies in Pendleton County (Stihler and others 1996). 

Bats foraged low over hayfields and in and above the forest 

canopy, and when foraging around trees, bats appeared 

to follow the surface contours of the tree canopies. While 

this could include edge habitat, especially when the bats 

foraged around a single tree or small group of trees, the bats 

generally foraged in the woods away from the forest/field 

edge. The selection of areas with high habitat interspersion 

may be related to the availability of a variety of food items 

throughout the night in areas offering a mix of foraging 

habitats (Lacki and Dodd 2011). For example, one bat 

tracked all night for 7 nights between May 23 and June 1 

foraged in hayfields early in the evening, night roosted for 

approximately 55 minutes, and then foraged in wooded 

habitats for the remainder of the night. The bat never foraged 

along the forest edge but was always either in the field or 

in the woods. This suggests that the mix of habitats and 

associated feeding opportunities were the driving force in 

selecting foraging areas with high interspersion, not the 

availability of edge.

The greatest distance traveled from the maternity cave 

(11.3 km) and the greatest mean distance to all high-use 

areas (6.5 km) occurred in the spring (session 1) before 

the females had given birth; during lactation the greatest 

distance bats traveled was 10.8 km, but the mean distances 

to foraging areas were 4.1 km in early lactation and 3.5 

km in late lactation. Following lactation, the bats again 

increased the distances they traveled with a maximum 

distance of 7.4 km and a mean distance to high-use areas 

of 6.0 km. These data suggest that female C. t. virginianus

forage closer to the roost during lactation when they 

also return to the cave during the night to nurse their 

pups. Distances observed during the present study are 

considerably greater than those observed at other study 

sites. At a maternity roost in Kentucky, the greatest distance 

a C. t. virginianus was tracked from the maternity roost was 

3.65 km which was recorded in August (Adam and others 

1994). The greatest distance to a foraging area recorded 

for C. t. ingens in Oklahoma was 7.0 km and occurred 

during the late lactation; during early lactation the greatest 

distance observed was 2.0 km (Clark and others 1993). In 

August, the greatest distance to a foraging area recorded 

for C. t. ingens in Oklahoma was 5.5 km (Wethington and 

others 1996). These differences may be due to the larger 

number of big-eared bats in the West Virginia study area 

and the need for these bats to disperse over a larger area to 

reduce interspecific competition for food and/or foraging 
146

Dalton, V.M.; Brack, V.W., Jr.; McTeer, P.M. 1986. Food habits of 

the big-eared bat, Plecotus townsendii virginianus, in Virginia. 

Virginia Journal of Science. 37(4): 248-254.

Environmental Systems Resource Institute. 2009. ArcMap. Version 

9.3.1. Redlands, CA.

Lacki, M.J.; Dodd, L.E. 2011. Diet and foraging behavior of 

Corynorhinus in Eastern North America. In: Loeb, S.C.; Lacki, 

M.J.; Miller, D.A., eds. Conservation and management of 

eastern big-eared bats: a symposium. Gen. Tech. Rep. SRS-145. 

Asheville, NC: U.S. Department of Agriculture Forest Service, 

Southern Research Station: 39-52. 

R Development Core Team. 2010. R: a language and environment 

for statistical computing. Vienna, Austria: R Foundation for 

Statistical Computing. [ISBN 3-900051-07-0].

Stihler, C.W. 2011. Status of the Virginia big-eared bat 

(Corynorhinus townsendii virginianus) in West Virginia: 

twenty-seven years of monitoring cave roosts. In: Loeb, S.C.; 

Lacki, M.J.; Miller, D.A., eds. Conservation and management of 

eastern big-eared bats: a symposium. Gen. Tech. Rep. SRS-145. 

Asheville, NC: U.S. Department of Agriculture Forest Service, 

Southern Research Station: 75-84. 

Stihler, C.W.; Dalton, V.M.; Wallace, J.L.; Brack, V., Jr. 1996. Radio 

telemetry and light-tagging studies of Corynorhinus townsendii 

virginianus: preliminary results [Abstract]. Bat Research News. 

37(4): 152.

U.S. Fish and Wildlife Service. 1979. Endangered and threatened 

wildlife and plants: listing of Virginia and Ozark big-eared bats 

as endangered species, and critical habitat determination. 50 

CFR Part 17. Federal Register. 44(232): 69,206-69,208.

U.S. Fish and Wildlife Service. 1995. Ozark big-eared bat (Plecotus 

townsendii ingens (Handley)) revised recovery plan. Tulsa, OK. 

51 p. 

Wethington, T.A.; Leslie, D.M., Jr.; Gregory, M.S. 1996. 

Prehibernation habitat use and foraging activity by endangered 

Ozark big-eared bats (Plecotus townsendii ingens). The 

American Midland Naturalist. 135(2): 218-230.

all four sessions, could be employed to provide additional 

roosting opportunities within the forage areas of maternity 

colonies, although more research is needed to determine the 

best design for creating night roosts. 

ACKNOWLEDGMENTS

The author expresses his appreciation to the Monongahela 

National Forest for granting access to Cave Mountain Cave 

and for partial funding for this project, the U.S. Fish and 

Wildlife Service for providing additional funding, and the 

numerous people who contributed to the West Virginia 

Nongame Wildlife Fund which also funded much of this 

work. This project would not have been possible without 

the access provided by numerous landowners within the 

project area and the hard work and dedication of several 

West Virginia Department of Natural Resources (WVDNR) 

employees, especially Jack Wallace, Donna Mitchell, Bill 

Roody, and Jeff Hajenga, who spent many long nights 

tracking bats and long days contacting landowners. The 

assistance of numerous volunteers contributed to the success 

of this effort. The assistance of WVDNR technical support 

staff with the analysis of the data, especially Michael 

Dougherty and Jeremy Rowan, was greatly appreciated. The 

author also expresses his gratitude to Dave Dalton, Ginny 

Dalton, The Nature Conservancy, Steve Kimble, and Thorn 

Spring Park for their assistance and support.

LITERATURE CITED

Adam, M.D.; Lacki, M.J.; Barnes, T.G. 1994. Foraging areas and 

habitat use of the Virginia big-eared bat in Kentucky. Journal of 

Wildlife Management. 53(3): 462-469.

Burford, L.S.; Lacki, M.J. 1995. Habitat use by Corynorhinus 

townsendii virginianus in the Daniel Boone National Forest. The 

American Midland Naturalist. 134: 340-345.

Clark, B.S.; Leslie, D.M., Jr.; Carter, T.S. 1993. Foraging activity of 

adult female Ozark big-eared bats (Plecotus townsendii ingens) 

in summer. Journal of Mammalogy. 74(2): 422-427.
147

relatively high capture rates for Rafinesque’s big-eared bats 

(Medlin and Risch 2008). Several studies have dealt with the 

reported difficulty by netting at known roosts (Carver and 

Ashley 2008, Lance and others 2001, Trousdale and Beckett 

2005) or conducting visual surveys of potential roosts 

(Bennett and others 2008, Gooding and Langford 2004). 

A second challenge to studying Rafinesque’s big-eared bats 

is that they are “whispering bats” that echolocate at low 

intensity (Griffin 1958). This fact has limited the use of 

ultrasonic detectors for Rafinesque’s big-eared bat surveys. 

Several acoustic surveys of bat communities within the range 

of Rafinesque’s big-eared bats have reported that they are 

virtually undetectable using bat detectors (Ford and others 

2006, Loeb and O’Keefe 2006, Menzel and others 2005, 

Murray and others 1999). O’Farrell and Gannon (1999) were 

able to acoustically detect only one Townsend’s big-eared bat 

(C. townsendii), a congener, at 57 recording sites. In contrast, 

Burford and Lacki (1995) reported acoustically detecting 

Virginia big-eared bats (C. t. virginianus) in every habitat 

sampled.

We compared the effectiveness of mist nets, bat detectors, 

and visual surveys of potential roosts in detecting 

Rafinesque’s big-eared bats in bottomland forests in the 

Coastal Plain of Georgia. Specifically, we investigated (1) 

the hourly rates of detection for each method in areas where 

Rafinesque’s big-eared bats were known to be abundant, and 

(2) the cost per detection for each method in areas where 

Rafinesque’s big-eared bats were known to be abundant.

INTRODUCTION

Rafinesque’s big-eared bat (Corynorhinus rafinesquii) is a 

small, insectivorous bat found in the Southeastern United 

States (Jones 1977) and is considered uncommon throughout 

its range (Harvey and others 1999). While it is found under 

bridges and in abandoned buildings (Bennett and others 

2008, Menzel and others 2001), its natural roosts are 

primarily caves in karst regions (Barbour and Davis 1969) 

and hollow trees in bottomland forests in the Coastal Plain 

(Carver and Ashley 2008, Gooding and Langford 2004). 

Rafinesque’s big-eared bat is of particular interest because 

bottomland forests have been reduced dramatically in size 

since the precolonial period (Fredrickson 1997).

Rafinesque’s big-eared bat has been designated a species 

of concern by the U.S. Fish and Wildlife Service and State 

wildlife agencies and, therefore, has been the target of recent 

research efforts (e.g., Bennett and others 2008, Carver and 

Ashley 2008, Medlin and Risch 2008, Piaggio and others 

2009). Unfortunately, there is evidence that Rafinesque’s 

big-eared bat is unusually difficult to survey using 

standard techniques. Several investigators have reported 

that Rafinesque’s big-eared bats are difficult to capture in 

mist nets (Hurst and Lacki 1999, Lance and Garrett 1997, 

Mirowsky and others 2004, Trousdale and Beckett 2002, 

Trousdale and others 2008). This has been attributed to their 

low wing loading and low aspect ratio (Jones and Suttkus 

1971) which allow them to be extremely maneuverable in 

flight (Norberg 1990). However, a study in Arkansas reported 

COMPARISON OF SURVEY METHODS FOR RAFINESQUE’S BIG-EARED BATS 

Matthew J. Clement, Ph.D. candidate, University of Georgia, D.B. Warnell School of Forestry 

and Natural Resources, Athens, GA 30602

Steven B. Castleberry, Professor, University of Georgia, D.B. Warnell School of Forestry 

and Natural Resources, Athens, GA 30602

Abstract—Rafinesque’s big-eared bat (Corynorhinus rafinesquii) is designated a species of concern by the U.S. Fish and 

Wildlife Service and therefore has been a focus of recent research. Relative to other North American bats, the species is 

reported to be difficult to survey using mist nets and bat detectors. However, it is unclear if low detection is due to difficulties 

in detecting Rafinesque’s big-eared bat or low bat abundance. We employed mist nets and bat detectors and visually surveyed 

potential roosts at sites with known Rafinesque’s big-eared bat populations to determine if detection rates were low even when 

bats were abundant and estimated the hourly cost per detection of each technique. We mist netted for 39 nights and captured 

51 Rafinesque’s big-eared bats, yielding a capture rate of 0.99 bats per hour. Captures were higher in summer (1.10 captures 

per hour) than during winter (0.75 captures per hour), and during summer captures per hour were higher in sloughs (1.53) 

than on roads (0.54). We acoustically surveyed bat activity on 85 nights and detected 54 Rafinesque’s big-eared bat passes, 

yielding a detection rate of 0.07 bat passes per hour. Detections per hour were higher in sloughs (0.60) than along roads 

(0.04). We visually surveyed 1,606 potential roost sites and made 178 roost observations, yielding an observation rate of 0.28 

per hour. Although mist nets had the highest hourly capture rate, roost searches were the most cost-effective method, costing 

$50.49 per detection, followed by mist nets and bat detectors. In addition to costs, project goals must also be considered when 

selecting survey methods.

Citation for proceedings: Loeb, Susan C.; Lacki, Michael J.; Miller, Darren A., eds. 2011. Conservation and management of eastern big-eared bats: 

a symposium. Gen. Tech. Rep. SRS-145. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 157 p.
148

Acoustic Survey

We performed acoustic surveys during the summer of 

2007 at Moody Forest Natural Area, Ocmulgee WMA, and 

Tuckahoe WMA. Each bat detector (AR125, Binary Acoustic 

Technology, Tucson, AZ) was housed in a piece of PVC pipe, 

mounted on a tripod, positioned 1.5 m above the ground and 

aimed downward at a 45-degree angle at a sheet of plexiglass. 

Calls were recorded on a laptop computer (model NX570X, 

Gateway, Inc., Irvine, CA) connected to each detector. The 

AR125 uses a direct digital conversion technology so that 

recordings are wideband, full spectrum, and realtime, in 

contrast to frequency division or time division detectors 

(Parsons and others 2000). Detectors were turned on before 

sunset and retrieved after sunrise. We use the term “call” to 

describe an individual pulse of echolocation and the term “bat 

pass” to describe a sequence of one or more calls separated by 

less than one second (Hayes 1997). 

We recorded bat calls at sites along roads at both upland 

and bottomland sites within each field site. Recording sites 

were not the same as mist-net sites. We identified potential 

recording locations using ArcMap, ver. 9.2 (Esri, Redlands, 

CA) and 30- by 30-m resolution 44-class land cover type 

data obtained from the University of Georgia, Natural 

Resources Spatial Analysis Laboratory. We located all 

unpaved roads in the Georgia Department of Transportation’s 

Road Characteristics inventory on each field site. We then 

randomly selected an equal number of roadside recording 

points that were either in (1) stands of baldcypress-gum 

swamp and/or bottomland hardwoods and > 90 m from a 

different stand type or (2) stands of loblolly-shortleaf pine, 

loblolly-slash pine, and/or longleaf pine and > 90 m from a 

different stand type. Recording sites were ≥ 250 m apart. We 

selected 14 pairs of roadside locations (1 bottomland and 1 

upland pine) and recorded each pair simultaneously with a 

bat detector at each location. Each pair was surveyed on 3 

nights over 2 months. We selected six additional recording 

sites in baldcypress-gum swamp and/or bottomland 

hardwoods and > 90 m from a different stand type, but in 

sloughs instead of beside roads. Each of these sites was 

surveyed on 1 night in late July or early August.

We recorded voucher calls outside six known Rafinesque’s 

big-eared bat roosts during evening emergence to aid in 

identifying calls of Rafinesque’s big-eared bat. Emergence 

calls are not an ideal source of voucher calls because calls 

emitted during emergence may differ from calls emitted 

during commuting or foraging (Berger-Tal and others 

2007). However, given the low intensity of Rafinesque’s 

big-eared bat echolocation, we judged that recording during 

emergence was the only feasible way to obtain numerous 

voucher calls (O’Farrell and Gannon 1999). Therefore, we 

treated emergence calls as representative of their repertoire. 

We analyzed all calls with SCAN’R (Binary Acoustic 

STUDY AREA

We conducted our study at eight sites in the Coastal Plain 

physiographic region of Georgia, USA, that were known 

to contain Rafinesque’s big-eared bats. All study sites 

were State managed (owned or leased by the State) and 

located within a major river flood plain with baldcypress 

(Taxodium distichum)-gum (Nyssa spp.) swamps and 

bottomland hardwoods as major habitat components. We 

conducted field work in Beaverdam Wildlife Management 

Area (WMA), Chickasawhatchee WMA, Clayhole Swamp 

WMA, Little Satilla WMA, Moody Forest Natural Area, 

Ocmulgee WMA, Riverbend WMA, and Tuckahoe WMA. 

Habitat composition varied across study sites but generally 

consisted of large areas of loblolly pine (Pinus taeda) with 

smaller areas of slash pine (P. elliottii), shortleaf pine (P. 

echinata), and hardwoods on upland sites and baldcypressgum swamps and bottomland hardwoods in areas bordering 

each river. At most sites, upland forests were almost 

entirely < 80 years old, while bottomland forests were often 

older. 

METHODS

Mist Netting

We captured bats in mist nets (Avinet, Inc., Dryden, NY) 

during the summers (mid-May to mid-August) of 2007 and 

2008 on all eight field sites and during the winter (February 

and March) of 2010 at Riverbend WMA only. We placed 

one to three single-high nets in potential flyways such as 

roads and over water sources such as sloughs and puddles 

(Kunz and others 2009). All winter netting was conducted 

over roads due to very deep water in sloughs. Netting sites 

were selected on an ad hoc basis with the goal of maximizing 

captures of Rafinesque’s big-eared bat. We selected one to 

five (mean = 3.2) netting locations at each field site. We tried 

to separate netting locations in space to avoid conditioning 

bats to netting locations (Kunz and Brock 1975). As a 

separate technique, we targeted bats exiting known roosts 

because Rafinesque’s big-eared bats frequently have been 

reported to be more difficult to capture in mist nets than 

other bats (Hurst and Lacki 1999, Lance and Garrett 1997, 

Mirowsky and others 2004, Trousdale and Beckett 2002, 

Trousdale and others 2008). When we targeted a known 

roost, we placed a mist net approximately 0.5 m from a basal 

opening of the roost tree. Because this research was part of 

a larger study, we generally constrained mist netting to 1 to 

2 hours per night. We often closed the nets as soon as we 

captured bats to avoid capturing more bats than needed for 

a concurrent radiotelemetry study. We measured mist-net 

success rate for each technique (flyways and water sources or 

targeting known roosts) by calculating bat captures per hour 

(CPH). 
149

bat passes were very long with modulated frequencies. We 

suspect these were social calls and excluded them from the 

call library. We quantified the variation in voucher calls 

of Rafinesque’s big-eared bats for the following acoustic 

parameters: maximum frequency, minimum frequency, 

dominant frequency, bandwidth, and curvature. We assessed 

the comprehensiveness of our library by examining the 

cumulative variation in the measured parameters (Duffy 

and others 2000). We randomly sorted the reference calls in 

our library 20 times and tracked the change in the range of 

Technology, Tucson, AZ) with the following settings: pop 

filter on, fit restriction high, trigger level 20 dB, minimum 

frequency cutoff 15 kHz, peak power 13 dB, minimum 

duration 1 millisecond. The first two settings restrict the 

number of fragmented and partial calls which cannot be used 

to identify bats. The remaining settings are permissive and 

intended to maximize the number of calls, given they meet 

the fit restriction. Most calls recorded during emergence had 

the short duration, high frequency, and downward sweep 

typical of vespertilionid echolocation, but nine calls in three 

Figure 1—Characteristics of 997 echolocation calls of Rafinesque’s 

big-eared bats (Corynorhinus rafinesquii) recorded as bats exited 

roosts at 3 study sites in the Coastal Plain of Georgia, 2007; (A) 

minimum frequency, (B) maximum frequency, (C) bandwidth, (D) 

dominant frequency, and (E) curvature. Solid lines indicate the call 

parameters used to filter potential Rafinesque big-eared bat calls. 

20

25

30

35

40

45

50

0 2 4 6 8

Duration

Frequency

A

30

35

40

45

50

55

0 2 4 6 8

Duration

Frequency

B

0

5

10

15

20

25

30

0 2 4 6 8

Duration

Frequency

C

20

25

30

35

40

45

50

0 2 4 6 8

Duration

Frequency

D

-2

-1.5

-1

-0.5

0

0.5

1

0 2 4 6 8

Duration

Curvature 

E
150

in a tree during a survey, this counted as one observation, 

regardless of the number of bats present. If a tree was 

observed to be occupied during multiple surveys this counted 

as multiple observations. In repeat surveys all trees were 

rechecked, regardless of their previous occupancy status. The 

three surveys were not independent because we searched the 

same trees each time, and trees that were occupied during 

the first survey were often occupied in later surveys. While 

this type of pseudoreplication would increase type I error in 

many statistical tests, it does not affect the calculation of an 

average. We measured roost search success by calculating bat 

roost observations per hour (OPH). 

Cost Efficiency

We compared the relative cost of mist-net surveys and acoustic 

surveys on our field sites by calculating the hourly cost of 

each method and dividing by detections per hour to get cost 

per detection. We divided survey costs into fixed costs, such 

as equipment purchases, and variable costs, such as field labor 

and analysis labor. The hourly price of a fixed cost declines 

with increasing survey hours, while hourly price of a variable 

cost is relatively constant as number of survey hours changes. 

We calculated cost estimates with and without equipment 

costs for use when equipment is available and does not need to 

be purchased. For bat detector surveys, necessary equipment 

included a bat detector, computer, weather protection unit, 

tripod, marine battery, power inverter, and call analysis 

software. Field labor included travel time and equipment setup 

and takedown time for one worker. Analysis labor included 

separating bat calls from insect noise, extracting parameter 

values, manually screening calls for errors, an initial scan 

to identify potential calls, and a second scan to identify 

probable calls. We assumed that a call library had already been 

constructed. If not, additional field work and analysis would 

be required. For mist-net surveys, equipment included four 

sets of poles and eight nets of various lengths, stakes, and bat 

bags. Field labor included transportation, equipment setup and 

takedown, and time spent monitoring nets for two workers. 

No analysis labor was required. For roost searches, equipment 

included five 1-million candle watt spotlights and two mirrors. 

Field labor included transportation, setting up transects, 

labeling trees, and searching for bats. No analysis labor was 

required. Field labor was paid $7.00 per hour, and analysis 

labor was paid $22.36 per hour, standard rates for a forestry 

worker I and a PhD student at the Warnell School of Forestry 

and Natural Resources at the University of Georgia. 

RESULTS

Mist Netting

Combining all sites and seasons but excluding nights when 

we targeted known roosts, we used mist nets on 39 nights 

for 51.6 hours. We captured a total of 61 bats, for a rate 

values as call number increased. We assumed an asymptote 

indicated a comprehensive library. 

In analyzing calls from unknown bats, we used the same 

SCAN’R settings and used the parameters from our library 

to create a simple quantitative filter that selected only those 

calls that fell within the variation found in the voucher calls 

(fig. 1). We then reviewed the entire bat pass containing 

the selected calls and eliminated those that were part of a 

sequence of calls dissimilar to our voucher calls. We divided 

the remaining calls into “probable Rafinesque’s big-eared 

bat” if the call sequence had ≥ 4 calls or if a second harmonic 

was visible and “possible Rafinesque’s big-eared bat” 

otherwise. We measured bat detector success by calculating 

bat pass detections per detector per hour (DPH). 

We captured few bats of other species and, therefore, did not 

obtain original voucher calls for any other species. However, 

without information on call characteristics of other species, 

we cannot distinguish between their calls and Rafinesque’s 

big-eared bat calls. Sympatric species include the tri-colored 

bat (Perimyotis subflavus), evening bat (Nycticeius humeralis), 

southeastern myotis (Myotis austroriparius), Brazilian freetailed bat (Tadarida brasiliensis), big brown bat (Eptesicus 

fuscus), eastern red bat (Lasiurus borealis), Seminole bat 

(L. seminolus), hoary bat (L. cinereus), and possibly the silverhaired bat (Lasionycteris noctivagans; Menzel and others 

2000). Based on our experience, species with echolocation 

calls that might overlap the frequency range of Rafinesque’s 

big-eared bat were the evening bat, big brown bat, hoary bat, 

and silver-haired bat. We used information from the published 

literature (Betts 1998, Murray and others 2001, O’Farrell and 

others 2000, Surlykke and Moss 2000) on bat echolocation 

calls to distinguish Rafinesque’s big-eared bat passes from 

these four bat species. 

Roost Searches

We conducted visual surveys of hollow trees with basal 

cavity openings in forested wetlands at all eight field sites 

during the summers of 2007 and 2008. We used the U.S. 

Fish and Wildlife Service’s National Wetland Inventory to 

identify forested wetlands that were either seasonally flooded 

or semipermanently flooded (Cowardin and others 1979). 

Seasonally flooded wetlands have surface water early in the 

growing season, while semipermanently flooded wetlands 

have surface water during the entire growing season. Because 

wetland areas generally were linear, we created 500-m long 

by 30-m wide transects along the approximate center of all 

wetland areas using ArcMap, ver. 9.2. We randomly selected 

transects to survey at each site. We conducted roost searches 

by searching for trees with basal hollows within 15 m of the 

center of the transect during daylight hours. When we located 

a hollow tree, we visually inspected the cavity for bats using 

a spotlight and mirror. We searched each transect three times 

during the same summer field season. If bats were present 
151

gradually (fig. 2), indicating our library was nearly 

comprehensive. 

We discarded 5 nights of recording due to equipment 

malfunction, leaving us with 85 recording nights. In 

total, we recorded 13,551 bat passes or 17.71 DPH. Our 

quantitative filter based on call parameters identified 458 

unique bat passes that contained potential Rafinesque’s bigeared bat calls. Our assessment of the entire call sequences 

eliminated 385 bat passes from further consideration. 

Eliminated calls were either part of a feeding buzz of 

a different bat species or a fragmented call and bore 

no resemblance to a typical Rafinesque’s big-eared bat 

call (fig. 3). We divided the retained bat passes into 54 

“probable” and 19 “possible” Rafinesque’s big-eared bat 

passes. Considering only probable calls, DPH was 0.07. 

Once again, we had higher success in sloughs with 0.60 

DPH in sloughs and 0.04 DPH along roads. We recorded a 

probable bat pass at 16 of 34 recording sites (47 percent) 

and on 19 of 85 nights (22 percent).

Roost Searches

We searched 97 seasonally flooded or semipermanently 

flooded transects containing 1,606 hollow trees 3 times each. 

The roost searches took approximately 640 hours and yielded 

215 observations of roosting bats for a rate of 0.34 roost 

OPH. Rafinesque’s big-eared bat was the most commonly 

observed species with 178 observations of 109 unique roosts 

(0.28 OPH). 

of 1.18 CPH. Our most commonly captured species was 

Rafinesque’s big-eared bat, with 51 captures, for a rate 

of 0.99 CPH. We also captured five southeastern myotis 

(0.10 CPH), four eastern red bats (0.08 CPH), and one big 

brown bat (0.02 CPH). We captured bats of any species on 

22 nights (56 percent) and Rafinesque’s big-eared bat on 18 

nights (46 percent). Netting in sloughs appeared to be more 

productive than netting along roads. During the summer, we 

captured 9 Rafinesque’s big-eared bats (0.54 CPH) along 

roads during 16.7 hours over 14 nights and 30 bats (1.53 

CPH) in sloughs during 19.6 hours over 17 nights. During 

the winter, all netting was along roads at Riverbend WMA, 

and we captured 12 Rafinesque’s big-eared bats (0.75 CPH) 

during 16.1 hours of netting over 9 nights. During the 

summer, we recorded 1.50 CPH at Riverbend WMA and 1.10 

CPH at all eight sites combined. We targeted 23 Rafinesque’s 

big-eared bat roosts with nets set 0.5 m from the roost for a 

total of 16.6 hours. We captured 36 (2.17 CPH) Rafinesque’s 

big-eared bats at 18 of the 23 roosts (78 percent). 

Acoustic Survey

Using SCAN’R, we identified 997 calls in 130 bat passes 

that we recorded outside known Rafinesque’s big-eared bat 

roosts, which we used as our reference library. Minimum 

and maximum values of call parameters varied with call 

duration, which we incorporated into the filter used to 

identify potential Rafinesque’s big-eared bat calls (fig. 

1). The cumulative variation of all call parameters rose 

dramatically for the first 100 calls and then increased 

Reference calls

Bandwidth

Dominant frequency

Minimum frequency

Maximum frequency

Duration

Curvature

Range

Figure 2—Variation in call parameters of Rafinesque’s big-eared bats (Corynorhinus rafinesquii) as a 

function of number of reference calls recorded as bats exited roosts at three study sites in the Coastal Plain 

of Georgia, 2007. Values for duration and curvature are shown on right axis.
152

being almost twice as expensive and bat detector surveys 

being more than three times as expensive. Roost searches 

had by far the lowest hourly equipment costs of any method, 

followed by bat detectors and mist nets. Because of the low 

equipment costs, roost searches had the lowest total cost 

per observation, followed closely by mist netting, with bat 

detectors being over three times as expensive.

Cost Efficiency

Following our protocols, bat detector surveys had the lowest 

hourly labor cost of any method, followed by roost searches 

and mist netting (table 1). However, the capture rate with 

mist nets was so much higher than the other methods that 

it had the lowest labor cost per capture, with roost searches 

Figure 3—Examples of bat calls recorded at three study sites in the Coastal Plain of Georgia, 2007. Silent 

periods between calls have been reduced to better present call details. (A) Typical Rafinesque’s big-eared 

bat (Corynorhinus rafinesquii) bat pass; (B) fragmented call that a quantitative filter identified as a potential 

Rafinesque’s big-eared bat call (circle), but was discarded based on additional portions of the same call 

(arrow); (C) feeding buzz call that a quantitative filter identified as a potential Rafinesque’s big-eared bat 

call (circle), but was discarded due to dissimilarity of preceding calls (arrows). 

Table 1—Labor cost and total cost per detection of Rafinesque’s big-eared bat 

(Corynorhinus rafinesquii) using three different survey techniques

Costs Bat detector Mist net Roost search

Variable costs

 Field labor per night

 Analysis labor per night

 Hours per night

 Hourly cost

Fixed costs

Equipment

Nights

 Hours per night

 Hourly cost

Hourly detection rate

Labor cost per detection

Total cost per detection

$8.75

$48.45

9.0

$6.36

$2,197

45

9.0

$5.42

0.07

$90.79

$168.29

$36.01

$0.00

1.3

$27.28

$1,514

39

1.3

$29.86

0.99

$27.59

$57.78

$70.00

$0.00

5.0

$14.00

$110

162

5.0

$0.14

0.28

$50.00

$50.49
153

more easily survey multiple sites simultaneously, allowing 

for better statistical control of temporal variation in data 

(Hayes 1997). Ultimately, it is necessary to consider the 

research question, field conditions, and available resources 

to select a survey method, but our analysis can be useful for 

informing the decision-making process.

In contrast to previously published reports (Hurst and 

Lacki 1999, Lance and Garrett 1997, Mirowsky and others 

2004, Trousdale and Beckett 2002, Trousdale and others 

2008), we found that Rafinesque’s big-eared bats were not 

prohibitively difficult to capture in mist nets in areas where 

they were known to roost. Comparison with some readily 

available studies from other sites in the southeastern Coastal 

Plain (Miller 2003, Trousdale and Beckett 2002, Vindigni 

and others 2009) or with some highly cited studies from 

other regions (Johnson and others 2004, Kunz 1973, Kunz 

and Brock 1975, Kurta and Teramino 1992, Zielinski and 

Gellman 1999) indicates that our Rafinesque’s big-eared bat 

CPH of 0.99 was higher than nearly all reported CPH. In 

those studies, only 3 of 46 species’ CPH were higher than 

0.99. While it is difficult to compare CPH across different 

studies due to confounding factors including abundance of 

bats, habitat structures that concentrate bat activity, duration 

of netting, season, and placement of mist nets (Mallory and 

others 2004), the high CPH in this study is not consistent 

with the claim that Rafinesque’s big-eared bats are unusually 

difficult to capture in mist nets. Another recent study also 

demonstrated the feasibility of mist netting Rafinesque’s 

big-eared bats by capturing 67 bats (0.19 CPH) during 72 

nights of mist netting (Medlin and Risch 2008). In contrast to 

our result that sloughs were the most productive area, Medlin 

and Risch (2008) captured more bats over land corridors than 

over water corridors and recommended surveying over land, 

not water. Given the disagreement in results, future projects 

should consider mist netting at a variety of sites. The lack of 

capture success in previous studies could be due to a factor 

other than an inherent difficulty in capturing Rafinesque’s 

big-eared bats, such as small populations or a lack of habitat 

structures that concentrate activity (Mallory and others 

2004). We cannot definitively state which factors were 

responsible for our relatively high CPH, but we can conclude 

that when our techniques were applied to several sites known 

to harbor Rafinesque’s big-eared bat roosts, we were able, on 

average, to capture a bat with 1 hour of mist netting.

Rafinesque’s big-eared bats are reported to be exceptionally 

difficult to detect with bat detectors (Ford and others 2006, 

Loeb and O’Keefe 2006, Menzel and others 2005, Murray 

and others 1999). Only one study has reported high success 

in detecting a congener, Virginia big-eared bat, with bat 

detectors (Burford and Lacki 1995). However, calls in 

that study were identified by listening to tape recordings 

made with a heterodyne detector, so they may have been 

recording other species as well. While more time and 

Cost efficiency was affected by the survey protocol. When 

mist netting in sloughs, CPH increased to 1.53. If we had 

maintained this higher capture rate for the entire study, the 

total cost per detection would have dropped to $37.35 which 

would be more cost effective than roost searches. During our 

limited acoustic surveys of sloughs, DPH was 0.60. If we had 

maintained this higher detection rate for the entire study, the 

total cost per detection would have been the lowest overall at 

$15.11 per detection.

DISCUSSION

Overall, we found that roost searches were the most costeffective technique considering labor and equipment costs, 

but mist netting had the highest capture rate and was most 

cost effective if we considered only labor costs. In addition 

to the cost differences, each survey technique measured 

a different component of bat ecology. Roost searches 

recorded day roost observations; mist-net surveys recorded 

captures of commuting and foraging bats; and bat detector 

surveys recorded bat echolocation activity. While we 

identified the most cost-effective methods when following 

our protocols, different protocols could affect calculations. 

For example, mist netting for more hours could reduce the 

hourly labor cost because the fixed labor cost of erecting 

and collapsing nets would become a smaller portion of 

labor costs. However, mist netting for more hours could 

also lower CPH because bat captures are usually highest 

early in the evening (Kunz and Brock 1975). Other protocol 

changes could also affect cost estimates. 

Although we identified cost-effective methods for conducting 

Rafinesque’s big-eared bat surveys, project goals must be 

considered in selecting a survey method. Roost searches 

locate bat roosts as well as large numbers of bats. The 109 

unique roosts found with this technique held approximately 

409 total bats based on counts of visible bats. However, 

roosts found with this technique are limited to those with 

basal hollows, which might not be representative of all 

roosts. Using mist nets to survey bats eliminates uncertainty 

about species identification and allows collection of 

additional data, such as sex, age, and reproductive condition. 

Additionally, if bats are required for radio tracking, mist 

netting would be a more efficient survey method. Locating 

roosts by radio tracking bats captured in mist nets would 

eliminate the bias towards trees with basal hollows but 

would incur additional labor and equipment costs. Despite 

the costs and difficulty of assembling a call library, there 

are advantages to using bat detectors. Mist nets typically 

are ineffective in open areas (Kunz and others 2009), and 

it may be more practical to randomly assign survey points 

with detectors than with mist nets. Bat detectors can be left 

unattended at night, allowing workers to collect data day and 

night with analysis completed at a later date. Detectors can 
154

(Murray and others 2001) which is not consistent with 

Rafinesque’s big-eared bat calls. Therefore, all species with 

a minimum call frequency similar to that for Rafinesque’s 

big-eared bats generally differ in another characteristic, such 

as duration, curvature, or maximum frequency.

Because our library did not include any other bat species we 

cannot provide estimates of error rates. To calculate DPH, we 

assumed that we had no identification error, but this may not 

be true. For any future projects that attempt more extensive 

acoustic surveys, we would recommend using a call library 

that includes sympatric bat species so that error rates can be 

estimated.

Our mist-net and bat detector results gave radically different 

impressions of the bat community in bottomland forests in 

Georgia. Nearly 84 percent of bats captured when netting 

away from known roosts, but only 0.4 percent of our acoustic 

detections, were probable Rafinesque’s big-eared bats. 

Researchers have long recognized that both mist netting and 

acoustic surveys yield biased estimates of bat communities, 

with some species being more capture resistant (Thomas 

and West 1989). Several studies investigating these biases 

also found that whispering bats were a larger percentage of 

captures when mist netting than when recording, although 

differences were not as dramatic as in the current study 

(Duffy and others 2000, Loeb and O’Keefe 2006, O’Farrell 

and Gannon 1999). We concur with previous conclusions that 

mist nets and bat detectors are each biased against certain 

species and recommend using both methods in combination 

as well as careful interpretation of results (Murray and others 

1999, O’Farrell and Gannon 1999). 

Compared to other surveys in Coastal Plain bottomlands 

(Medlin and Risch 2008, Trousdale and Beckett 2002, 

Vindigni and others 2009), Rafinesque’s big-eared bats were 

an unusually large component of captures. This may be due 

to the community of bats present, the goals of the study, or 

the availability of sites for mist netting. The fact that roost 

searches yielded few southeastern myotis roosts may explain 

the relative rarity of that species among mist-net captures 

relative to other studies (e.g., Medlin and Risch 2008). 

Additionally, our goal was to survey for Rafinesque’s bigeared bats, so we focused netting in sloughs supporting large 

diameter trees, while some studies targeted other rare species 

in addition to Rafinesque’s big-eared bats (e.g., Trousdale 

and Beckett 2002). Other study sites had landscape features, 

such as heliponds, that were lacking on our sites, which 

could affect trapping success (Vindigni and others 2009). 

Given the results of our acoustic surveys, it is obvious that 

many other bats share bottomland habitats with Rafinesque’s 

big-eared bats. However, some factor in their ecology or our 

protocol prevented us from capturing them, whether it was 

related to foraging habits, commuting paths, or ability to 

avoid mist nets.

expense was required to detect Rafinesque’s big-eared bats, 

we found that acoustic surveys have potential as a technique 

in areas with sufficient numbers of bats. We detected 

Rafinesque’s big-eared bats at 47 percent of recording sites, 

including upland pine sites where no bats were detected 

by the other two methods. Comparison with some readily 

available studies from other sites in the southeastern 

Coastal Plain (Menzel and others 2002, Vindigni and others 

2009) or with some frequently cited studies from other 

regions (Gannon and others 2003, Gehrt and Chelsvig 

2004, Hayes 1997, Humes and others 1999) indicates that 

our Rafinesque’s big-eared bat DPH of 0.07 was not the 

lowest reported DPH. In those studies, 9 of 33 species’ 

DPH were lower than 0.07. It is difficult to compare DPH 

across studies due to differences in placement of detectors 

(Weller and Zabel 2002), technology employed (Johnson 

and others 2002), suite of species on a field site (Duffy 

and others 2000), forest structure (Patriquin and others 

2003), season (Hayes 1997), and the definition of bat passes 

(Gannon and others 2003). Despite the caveats, our results 

suggest that Rafinesque’s big-eared bats are difficult but not 

impossible to survey with bat detectors. 

We are confident that we identified bat passes correctly, 

although such self-assessment may be inaccurate (Betts 

1998). Our literature review suggested that the 54 probable 

Rafinesque’s big-eared bat passes were unlikely to have 

come from other bat species. Although minimum frequencies 

were similar in some cases, the echolocation calls differed 

in other characteristics. Big brown bats have a minimum 

call frequency near 25 kHz, but call duration is over 

10 milliseconds (Surlykke and Moss 2000), longer than any 

of our probable Rafinesque’s big-eared bat calls. Although 

big brown bat call duration falls to < 5 milliseconds during 

feeding buzzes, frequency also falls below 20 kHz and 

interpulse interval falls to 10 milliseconds (Surlykke and 

Moss 2000), neither of which was consistent with our 

probable Rafinesque’s big-eared bat calls. Typical hoary bat 

calls are both longer duration and have a lower characteristic 

frequency than the voucher Rafinesque’s big-eared bat 

calls, but their repertoire includes some shorter and higher 

calls that could overlap with Rafinesque’s big-eared bats 

(O’Farrell and others 2000). However, if these calls were 

fragments or part of a feeding buzz, then our inspection 

of the entire call sequence should have identified them as 

hoary bat calls (fig. 3). With a mean minimum frequency of 

27 kHz, silver-haired bat calls overlap with Rafinesque’s bigeared bats, but mean call duration is longer, and this species 

is known for a pronounced bend in its call which would 

distinguish it from Rafinesque’s big-eared bats (Betts 1998). 

With an average around 37 kHz, evening bat echolocation 

minimum frequency is only consistent with Rafinesque’s 

big-eared bat calls with a duration < 2 milliseconds (fig. 1). 

However, evening bat calls have an average duration of 

5 milliseconds and a maximum frequency over 50 kHz 
155

Betts, B.J. 1998. Effects of interindividual variation in echolocation 

calls on identification of big brown and silver-haired bats. 

Journal of Wildlife Management. 62(3): 1003-1010.

Burford, L.S.; Lacki, M.J. 1995. Habitat use by Corynorhinus 

townsendii virginianus in the Daniel Boone National Forest. 

American Midland Naturalist. 134(2): 340-345.

Carver, B.D.; Ashley, N. 2008. Roost tree use by sympatric 

Rafinesque’s big-eared bats (Corynorhinus rafinesquii) and 

southeastern myotis (Myotis austroriparius). American Midland 

Naturalist. 160(2): 364-373.

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Raptors and bats - threats and opportunities. Animal Behaviour. 

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Ford, W.M.; Menzel, J.M.; Menzel, M.A. [and others]. 2006. 

Presence and absence of bats across habitat scales in the 

upper Coastal Plain of South Carolina. Journal of Wildlife 

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of articulating assumptions when conducting acoustic studies of 

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Gehrt, S.D.; Chelsvig, J.E. 2004. Species-specific patterns of bat 

activity in an urban landscape. Ecological Applications. 14(2): 

625-635.

Gooding, G.; Langford, J.R. 2004. Characteristics of tree roosts of 

Rafinesque’s big-eared bat and southeastern bat in northeastern 

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63 p.

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Our finding that call parameter variation increased 

dramatically through 100 calls implies that some previous 

studies may have suffered from inadequate call libraries. 

O’Farrell and others (2000) found that hoary bat call 

variation and an inadequate call library led to erroneous 

conclusions. Calls recorded during our field surveys fell 

within the range of reference calls but tended to be flatter 

and have less downward curvature and in a few cases were 

longer than any reference calls. This trend in our recordings 

indicated that calls of emerging bats were biased, with 

shorter and steeper calls. Although the bias was undesirable, 

we do not believe it impaired our ability to identify 

Rafinesque’s big-eared bat calls because they still fell within 

the range of reference calls, apart from duration in a small 

number of cases. 

We were able to catch Rafinesque’s big-eared bats almost as 

frequently over sloughs (59 percent of nights) as when we 

netted at known roosts (78 percent of nights). Traditional 

mist netting may have rivaled netting at known roosts 

because more bats use certain sloughs than a single roost 

or because bats are more vigilant as they exit their roosts. 

Higher vigilance during emergence may be due to the threat 

of predators at that time (Fenton and others 1994). While the 

best mist-netting technique depends on local conditions and 

the research question, we found that mist netting in sloughs 

was an effective strategy in our study area and may be the 

best course if researchers do not want to disturb bats at 

their roosts.

ACkNOwLEDGMENTS

We thank J. Adams and C. Carpenter for field assistance. 

The Nature Conservancy provided access to Moody Forest 

Natural Area and onsite housing. The Georgia Department of 

Natural Resources provided access and housing at all other 

sites. Funding was provided by the Georgia Department 

of Natural Resources, Wildlife Resources Division and the 

Daniel B. Warnell School of Forestry and Natural Resources 

at the University of Georgia.

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Big-eared bats (genus Corynorhinus) in the Eastern United States are species 

of special conservation concern. These species are at risk due to many factors, 

including lack of knowledge about their basic biology, population numbers or trends, 

and distribution. This volume contains five synthesis papers on the status, ecology, 

and conservation of eastern big-eared bats and nine papers that present new data on 

the status, roosting and foraging ecology, and methodology for inventorying bigeared bats in the Eastern United States. These papers were presented at a symposium 

held at the University of Georgia in March 2010. 

Keywords: Big-eared bats, bottomland hardwood forest, caves, conservation, 

Corynorhinus, endangered species.
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