Proceedings of the Marsh Bird

Monitoring Workshop

U.S. Fish & Wildlife Service

U.S. Geological Survey
Proceedings of the Marsh Bird

Monitoring Workshop

U. S. Fish and Wildlife Service

Patuxent Research Refuge

National Wildlife Visitor Center

Laurel, Maryland

26-28 April 1998

April 1999

Compiled by:

Christine A. Ribic, U. S. Geological Survey (USGS)–Biological Resources Division (BRD), Wisconsin

Cooperative Wildlife Research Unit, University of Wisconsin, 1630 Linden Drive, 226 Russell Labs,

University of Wisconsin, Madison, WI 53706-1598

Stephen J. Lewis, U. S. Fish and Wildlife Service (USFWS), Bishop Henry Whipple Federal Building, 1

Federal Drive, Fort Snelling, MN 55111-4056

Scott Melvin, Massachusetts Division of Fisheries and Wildlife, Westboro, MA 01581

Jon Bart, USGS–BRD, Snake River Field Station, 970 Lusk Street, Boise, ID 83706

Bruce Peterjohn, USGS–BRD, Patuxent Wildlife Research Center, Breeding Bird Survey, 12100 Beech

Forest Road, Laurel, MD 20708-4038

Workshop Steering Committee:

Christine Ribic (Chair), USGS–BRD, Wisconsin Coop. Wildlife Research Unit, Madison, WI

David Dolton, USFWS, Office of Migratory Bird Management, Denver, CO

Sam Droege, USGS–BRD, Patuxent Wildlife Research Center, Laurel, MD

Marshall Howe, USGS–BRD, Patuxent Wildlife Research Center, Laurel, MD

Stephen J. Lewis, USFWS, Fort Snelling, MN

Scott Melvin, Massachusetts Division of Fisheries and Wildlife, Westboro, MA

For additional copies of this report contact:

David Dolton

U.S. Fish and Wildlife Service/MBMO

PO Box 25486 DFC

Denver, CO 80225-0486

U.S. Fish & Wildlife Service

U.S. Geological Survey
Proceedings of the Marsh Bird Monitoring Workshop iii

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Need for a Workshop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Scope of the Monitoring Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Workshop Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Objective 1: Review Current Monitoring and Research Efforts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Objective 2: Develop Standardized Protocols for Monitoring Marsh Birds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Report from Group 1: Field protocols for marsh bird monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Preliminary recommendations for survey protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Objective 3: Develop Sampling Schemes at Multiple Scales. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Report from Group 2: Statistical design and sampling considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Report from Group 3: Implementing a Marsh Bird Monitoring Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Information Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Topics Needing Further Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Objective 4: Enhance Communication Among Biologists and Managers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Letters of Support (USGS-BRD and USFWS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Literature Cited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Appendix 1. List of Participants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Appendix 2. Topics for the Discussion Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Appendix 3. Common and Latin Names of Bird Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Appendix 4. Abstracts of Invited Presentations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Table of Contents
The Workshop Steering Committee would like to

thank all of the participants of the workshop for

their enthusiasm and willingness to help in

developing a Marsh Bird Monitoring Program. We

also thank Deb Ziebarth, Department of Wildlife

Ecology, University of Wisconsin-Madison, and

Linda Lee, U. S. Fish and Wildlife Service, Office of

Migratory Bird Management, for administrative

support. The U. S. Fish and Wildlife Service’s Office

of Migratory Bird Management and U. S. Geological

Survey’s Biological Resources Division provided

financial support for the workshop.

iv

Acknowledgments
A Marsh Bird Monitoring Workshop was held at the

National Wildlife Visitor Center located on the

Patuxent Research Refuge in Laurel, Maryland, in

April 1998, to discuss strategies for monitoring

populations of wetland-dependent bird species.

Inconspicuous marsh birds (e.g., rails, bitterns,

moorhens, gallinules, snipe and coots) include both

game and nongame species. These birds are sought

by hunters and birders alike. Some (black and

yellow rails and American and least bitterns) are U.

S. Fish and Wildlife Service species of management

concern because they are thought to be rare or

declining, and many are included on state lists of

rare or endangered species. However, inconspicuous

marsh birds are difficult to detect and inhabit areas

that are often not readily accessible. Therefore, they

are poorly surveyed by the Breeding Bird Survey

and other existing monitoring programs.

The workshop brought together experts actively

working on marsh bird monitoring issues. The

workshop reviewed current monitoring and research

efforts related to marsh bird population assessment,

initiated development of standardized protocols for

monitoring marsh birds, identified information

needs necessary for developing protocols and

sampling schemes for monitoring marsh birds at

national, regional, and local scales, and established a

Steering Committee to continue the development of

a Marsh Bird Monitoring Program.

Priority information needs identified by the

participants are to understand statistical issues and

potential biases of call-playback techniques and how

to choose habitats for sampling. Secondary

information needs are to evaluate: current wetland

databases, how to accommodate habitat change over

time, what habitat variables to collect, whether

counts should be made in the morning or evening,

how the index is linked to population size, and

geographical differences in the timing of the

breeding season. A tertiary information need relates

to data quality issues, such as the use of volunteers.

Several topics were identified as needing further

discussion. These include the geographic scale of the

program, what trend changes will be acceptable to

fulfill differing objectives, and how monitoring of

local management impacts might be evaluated by

the program.

A new Steering Committee composed of

representatives from U. S. Federal and state

agencies and Canadian organizations was

constituted to further develop a Marsh Bird

Monitoring Program. Activities of this committee

will be communicated at the following web site:

http://www.mp1-pwrc.usgs.gov/marshbird/ 

1

Executive Summary
Inconspicuous marsh birds (e.g., rails, bitterns,

moorhens, and gallinules) are important components

of the biodiversity of wetland ecosystems and

include both game and nongame species. These

birds are sought by hunters and birders alike, and

some (black and yellow rails and American and least

bitterns) are U. S. Fish and Wildlife Service

(Service) species of management concern because

they are thought to be rare or declining. These

species also appear on many state agency lists of

threatened and endangered species; they and their

habitats are afforded varying levels of state

regulatory protection. Many units of the National

Wildlife Refuge System provide important habitat

for these species, and the birds have undoubtedly

benefitted from wetland restoration activities

undertaken through the Service’s Partners for

Wildlife and the North American Waterfowl

Management Plan programs. However, little is

known about the abundance, population trends, or

management needs of these species.

Inconspicuous marsh birds are difficult to detect and

inhabit areas that are often not readily accessible.

Therefore, they are poorly surveyed by the North

American Breeding Bird Survey and other existing

monitoring programs. A number of efforts have

been made to standardize marsh bird surveys using

taped playback response. Notable among these is

the work by Gibbs and Melvin (1993), Bird Studies

Canada’s (formerly Long Point Bird Observatory)

Marsh Monitoring Program, and the USGS

Biological Resource Division’s (BRD) listserver

discussion group on marsh bird monitoring. The

Service’s Office of Migratory Bird Management

(MBMO), through its Webless Migratory Game Bird

Research Program, is currently funding a number of

studies across the country that are aimed at

developing marsh bird monitoring techniques and

determining the relationship between indices

derived from call-response surveys and other

measures of abundance. Finally, a number of

national wildlife refuges have monitored marsh

birds using a variety of approaches with a wide

range of scientific rigor.

There are several factors that limit the utility of

data obtained from current marsh bird monitoring

efforts. First, protocols are not standardized,

making it difficult to compare results from different

surveys. Second, a statistically based sampling

framework for conducting these surveys has not

been developed. A variety of sampling schemes is

needed because monitoring is desired at several

levels, specifically, large-scale monitoring to

determine a species’ range-wide or regional status

and to set hunting regulations on a flyway basis,

local monitoring on refuges and similar areas to

determine presence, habitat associations, and

responses to management, and nonrandom

monitoring of special sites like the Great Lakes

Areas of Concern that are the focus of Bird Study

Canada’s Marsh Monitoring Program. Finally, it is

not known what the relationship is between indices

obtained in call-response surveys and actual

population levels of the target species.

To address the aforementioned needs, a workshop

was held at the National Wildlife Visitor Center,

Laurel, Maryland, in April 1998, to bring together

biologists who are actively working on marsh bird

monitoring issues. Invited speakers presented

overviews of their work and then the group, through

a facilitated discussion, attempted to reach

consensus on standardized protocols and sampling

schemes for monitoring marsh birds, and to

prioritize research needs. Workshop participants are

listed in Appendix 1.

Objectives

The workshop objectives were to:

1) Review current monitoring and research efforts

related to marsh bird population assessment,

focusing primarily on rails, bitterns, pied-billed

grebes, common moorhens, and American coots.

2) Develop standardized protocols for monitoring

marsh birds.

3) Develop sampling schemes for monitoring marsh

birds at national, regional, and local scales.

4) Enhance communication among biologists and

managers interested in marsh bird monitoring

issues.

3

Need for a Workshop
Objective 1 was met by presentations of current

research (summarized below). To answer Objectives

2–4, the workshop participants divided themselves

up into three working groups: Field Protocols for

Marsh Bird Monitoring, Statistical Design and

Sampling Considerations, and Implementation of a

Marsh Bird Monitoring Program. The charges for

each group are in Appendix 2. Each group was free

to modify the questions posed and a group report

was made to the assembled scientists. These reports

are summarized below.

Scope of the Monitoring Program

The participants defined the primary species of

interest as those species that are marsh- dependent

and not well covered by existing monitoring

programs. The primary species are grebes, rails,

bitterns, moorhens, gallinules, snipe, and coots.

Secondary species are herons, black and Forster’s

terns, sedge and marsh wrens, red-winged and

yellow-headed blackbirds, Franklin’s gull, sharptailed and LeConte’s sparrows, common

yellowthroat, willow and alder flycatchers, cranes,

and belted kingfisher. See Appendix 3 for Latin

names.

The participants further agreed to limit the program

to the breeding season. It was noted that migration

routes and wintering ground monitoring would be

important but, at this time, beyond the scope of the

workshop. The participants further agreed that

trend information at the continental or rangewide,

national, regional/provincial, and state levels should

be considered in the discussion groups.

4 Proceedings of the Marsh Bird Monitoring Workshop
Objective 1: Review current monitoring and research

efforts related to marsh bird population assessment,

focusing primarily on rails and bitterns

Researchers and agency biologists presented

current work related to marsh bird monitoring. The

presentations are summarized here by common

themes. Abstracts of the presentations can be found

in Appendix 4.

The first speaker, Sam Droege, set the development

of a Marsh Bird Monitoring Program in perspective

by reviewing general approaches to developing

monitoring programs. Pertinent points made

included the need to define what species are going to

be covered by a new program, what magnitude of

change is to be detected, and how often a program is

going to be wrong in finding a change when there

isn’t one. Mr. Droege argued that a monitoring

program, by its nature, should be willing to say

there is a change before the decline is obvious, if the

program is to serve as an early warning system.

Otherwise the monitoring program merely

documents that species have declined. He also

pointed out that any program is vulnerable if there

is no evidence that the index being used in the

program actually reflects the population levels of the

target species. Finally, a set of constituents that

need to know or care about marsh birds were

discussed, including hunting regulators, refuge

managers (due to the Refuge Organic Act),

conservationists, citizens, hunters, and anti-hunters.

The majority of speakers dealt with Field

Methodology issues (Downs and Anderson; Gibbs,

Melvin, and Crowley; Haramis and Kearns; Kirsch;

Legare, Eddleman, Buckley, and Kelly; Monahan

and Faulk; Paine; Skoloda and Ribic; Slack and

Mizell; Therres, Brinker, and Tango; Vogel,

Helmers, Fredrickson, and Humburg; Walther and

Hohman) (Table 1). Most of the speakers dealt with

rails; six of the eight presented information on sora

and Virginia rail. Most of the presentations included

information gleaned from point-count or transect

surveys coupled with call-playback surveys, leading

to information on multiple species. A few studies

used other techniques to try to understand the

relationship of call-playback surveys to species

numbers. Some information was presented on rails

during the non-breeding seasons.

Another set of speakers (Adamcik; Francis and

Weeber; Gibbs and Melvin; Sauer; Shieldcastle;

Weeber, McCracken, and Francis) dealt with the

development of Marsh Bird Monitoring Programs.

Current monitoring programs and their drawbacks

were discussed. Site selection was a critical issue.

Issues of the number of samples needed to detect

certain trends with specified Type I error and power

were presented. Typically, the number of routes may

look high enough to detect trends but the number of

routes on which specific species are actually

detected can be low. These problems are not atypical

when dealing with multiple species, leading to the

recommendation that surveys need to be planned

using the most variable species. Data needs for

developing a monitoring program were presented.

Problems with implementation were discussed. One

issue was the use of refuges in such a program and

that addressing refuge needs in the program would

be critical in eliciting the participation of refuges.

The last speaker, Paul Adamus, presented

information on the movement of the U.S.

Environmental Protection Agency to develop an

Index of Biotic Integrity for wetlands using marsh

birds. This program is currently in development but

gives another indication that marsh birds are of

interest to other Federal agencies not typically

considered to be concerned with this group of birds.

Objective 2: Develop standardized protocols for

monitoring marsh birds

Report from Group 1: Field protocols for marsh bird

monitoring

The group discussed issues related to standardizing

field protocols for use in a Marsh Bird Monitoring

Program.

1. Priority species

There was general agreement that priority species

in a Marsh Bird Monitoring Program should include

all rails, American and least bittern, common snipe,

and pied-billed grebe. American coot, common

5

Workshop Results
moorhen, and purple gallinule could also be included

in areas where they occur at low to moderate

densities. However, in some regions these three

species may be adequately monitored through

existing programs that track populations of breeding

waterfowl. Participants recognized that marsh bird

surveys will likely yield detection rates that are

significantly higher for many other species than

those obtained on Breeding Bird Survey routes.

2. Chronology of surveys

It was agreed that first priority should be to develop

monitoring programs for marsh birds on the

breeding grounds. However, participants recognized

that there may be interest in developing monitoring

programs on wintering grounds or in migration

areas for some species. Subsequent discussions

focused primarily on field protocols for monitoring

on the breeding grounds.

3. Use of playbacks

The issue of whether broadcasts of taped

vocalizations (playback surveys) should be used to

increase detection rates of some species of marsh

birds received considerable discussion and was one

of the major unresolved issues of the workshop.

Participants identified the following benefits of using

playbacks:

a. They significantly increase detection rates for

some species over passive listening. Table 2

summarizes participants’ species-specific

recommendations regarding improvements in

detection rates with playbacks.

b. They probably reduce variance in mean detections

per survey station or per mini-route (multiple

stations), by reducing numbers of “0” counts. This

may be especially important in regions where

target species occur at low to moderate densities,

for example, in northeastern North America, and

where marsh birds may be presented with fewer

intraspecific stimuli to vocalize than in other

regions (i.e., few calling individuals per wetland).

c. They probably increase proficiency of field staff.

By repeatedly playing tapes and eliciting more

responses from target species, field staff become

more familiar with marsh bird vocalizations.

d. They probably increase long-term interest of field

staff, especially volunteers. Playbacks

significantly increase detections of several target

species. It may be difficult to maintain the interest

of volunteers if they seldom detect target species

during surveys that consist only of passive

observations.

e. Cooperators will likely want to use playbacks for

intensive local surveys, to monitor patterns of

distribution or habitat use, determine presence or

absence of protected rare species, or monitor

effectiveness of habitat management. It may be

inefficient to conduct intensive local surveys with

playbacks and extensive regional surveys without

playbacks.

6 Proceedings of the Marsh Bird Monitoring Workshop

Table 1. Number of studies, by species, season studied, and techniques used, for presentations made in the

Field Methodology section of the Marsh Bird Monitoring Workshop. 

(Abstracts are in Appendix 4. Primary and secondary species were defined by the participants. Latin names of species

mentioned are in Appendix 3.)

Primary Species Secondary Species

Rails Bitterns Moorhens Grebes Snipe Coots/

Gallinules

Season and Technique

Breeding

Playback or Passive

Surveys 843412 4

Telemetry 2

Trapping 1

Nest Monitoring 111111 1

Visual Observation 1 1

Other 1 1

Migration

Playback 2 1 1 1

Telemetry 1

Wintering

Telemetry 1
However, participants also recognized potential

disadvantages of using playbacks as part of

extensive regional or continental monitoring efforts:

a. Playbacks introduce an additional source of bias.

It would be necessary to standardize, as nearly as

possible, playback equipment, tapes, and how they

are used (for example, volume, distance from

observer).

b. It may not be feasible to expect that all

participants will be willing to purchase adequate

playback equipment. On the other hand,

volunteers that conduct Breeding Bird Surveys

are expected to use binoculars, which are often 

2–3X more expensive than adequate playback

equipment.

Table 2. Summary of recommendations as to whether

playback surveys can increase detection rates of

marsh birds on the breeding grounds. 

(Latin names of species are in Appendix 3.)

Are detection 

rates improved

Species with playback surveys? 

Virginia rail Yes

Sora Yes

King rail Yesa

Clapper rail Yesa

Black rail Yes

Yellow rail Probably no

American bittern Uncertain

Least bittern Probably

Common moorhen Yes

Purple gallinule Uncertain

American coot Probably yes at low 

breeding densities

Pied-billed grebe Probably yes at low 

breeding densities

Other grebes No

a King and clapper rails may respond well enough to each other’s

vocalizations that only one or the other need be included in a

playback survey protocol.

Participants agreed that a research priority should

be to determine detection rates for target species

both with and without use of playbacks. Power

analysis should then be used to estimate differences

in species-specific sample size requirements for

monitoring programs using playback versus passive

observations only. Data sets already exist for a few

species, for example, sora and Virginia rail, but for

most species, additional research will be required.

The prime determinant of whether or not to use

playbacks will be whether sample sizes adequate to

monitor population trends can be obtained for target

species in all or most regions using only passive

surveys.

If playbacks are to be used, additional research is

needed to support development of standardized

methods, including which calls to broadcast,

sequence of calls, sound levels, and types of

equipment to use.

Participants generally agreed upon interim

guidelines for playback survey methodology. At each

survey station, the following sequence of playback

and passive observation/listening was

recommended:

a. Begin with an initial passive listening period of 3-5

minutes.

b.Broadcast approximately 1 minute of vocalizations

for each species. For each species, broadcast the

type of call that is most likely to elicit a response

(e.g., the “whinny” call for soras, the “grunt” call

for Virginia rails).

c. Insert 30 seconds of silence after each minute of

vocalizations for each species.

d. Broadcast vocalizations of the least intrusive

species first, for example least bittern or black rail

before American bittern and pied-billed grebe.

e. At each station, end the series of broadcasts with

a “post-playback” listening period of

approximately 1 minute.

Playback vocalizations should be broadcast in all

directions over suitable wetland habitats (i.e., the

playback arc should be 360 degrees from the

observer). However, playback arc may be as little as

180 degrees at some survey stations along the edge

of wetlands or along dikes.

4. Spacing of survey points

Spacing of survey points will be a compromise

between spacing large enough to minimize doublecounting of loudest species and smaller spacing that

reduces travel time between stations and maximizes

the number of points that will fit in a given wetland.

Participants recommended a minimum spacing of

200-300 m between survey stations.

5. Seasonal timing of monitoring

Participants recognized that peak vocalizations

occur in late spring and early summer. Regional

differences in breeding phenology may exist and

may be of sufficient magnitude to require regional

differences in timing of surveys.

Proceedings of the Marsh Bird Monitoring Workshop 7
Participants recommended that marsh bird

monitoring on the breeding grounds should take

place during a 6-8 week period that is consistent

over as large a region as possible (e.g., 15 May to 30

June). Sampling each survey station 2-3 times per

season will likely reduce effects of annual variation

in phenology. However, the relative benefits of

reducing bias associated with annual variation in

phenology should be compared to the cost of

reduced sample size that will occur if points are

sampled multiple times in a year.

6. Time of day

Most participants believed that detection rates of

most species are highest in early morning, from

approximately 1/2 h before sunrise to 4 h after

sunrise. The logistics of accessing and returning

from relatively large or remote wetlands are easier

in early morning than in early evening or at night.

Detection rates of secondary species, for example

wetland passerines, may be highest in early

morning, and wind speeds may be less in early

morning than in late afternoon or early evening.

Both of these assumptions need to be tested.

Bird Studies Canada already has in place a

relatively large volunteer program based on

monitoring between 6 and 9 p.m. This protocol

results in only 2-4 stations per day, versus > 10 that

can be done between 1/2 hour before to 4 hours after

sunrise. However, if a regional monitoring program

is based on volunteers, more volunteers may be

available and willing to participate in early evening

than in early morning.

7. Should surveys be done on foot or by canoe?

It was agreed that, when possible, surveys by canoe

are preferable because they are quieter, often faster,

and place the observer at the interface between

water and emergent vegetation where many target

species are most likely to be detected. However,

there was also agreement that surveys by canoe are

often not practical or necessary, for example, at

remote palustrine wetlands where canoe access is

not possible, at relatively small or narrow wetlands,

and where easy foot access is possible to points at

the edge of representative portions of the wetland

being sampled.

8. Weather

Participants agreed that the Breeding Bird Survey

weather standards should be observed for marsh

birds surveys (i.e., no surveys during periods of

sustained precipitation or when winds exceed 20

kph).

9. Habitat data collection

Participants agreed that collection of data on habitat

conditions at survey stations or for entire wetlands

where surveys are conducted is desirable, to be able

to relate trends in habitat conditions to patterns and

trends in marsh bird abundance and distribution.

Participants agreed this topic needs further

discussion.

10. Training

Participants agreed that some form of training is

desirable for individuals that will be conducting

marsh bird surveys. This is especially true when

monitoring will be done by large groups of

volunteers. This subject needs further discussion.

The group did recommend that training should focus

on primary target species.

Preliminary Recommendations for Survey Protocol 

The recommendations of Group 1 were discussed

with the larger group and the following preliminary

protocol was agreed upon. We note that this protocol

will change as more research is conducted and a

Marsh Bird Monitoring Program is developed.

a. Surveys can be conducted in the morning (1/2 h

before sunrise to 4 h after sunrise). Note that

detection rate for snipe may be lower on morning

surveys. Evening surveys are recommended if

snipe is of primary concern. Field protocol for

common snipe can be found in the abstract by

Downs and Anderson (Appendix 4).

b. Surveys should be done when there is no steady

precipitation and low wind (less than 20 knots).

Use the Breeding Bird Survey recommendations

for further weather restrictions.

c. Survey points should be a minimum of 200 m

apart. Distances up to 800m may be appropriate

in certain wetland types such as tidal marshes

(due to the probability that birds will be heard at

much longer distances in these marshes

compared to other wetland types). Use some

type of marking or mapping system so that the

point can be found again for repeated surveys

(e.g., a sketch map, marking of the point, use of

Global Positioning System).

d. At a point, a 5-minute passive count should be

made first, followed by tape playback, and then 1

minute of passive listening. For tape playback, 5-

15 seconds of a species’ call should be repeated 3

times with 5 seconds of silence between repeats

for a total of 30-60 seconds per species. Thirty

seconds of silence should be used before

8 Proceedings of the Marsh Bird Monitoring Workshop
beginning another species’ call. Use the call most

likely to elicit a response (Table 3).

We suggest using the Cornell Laboratory of

Ornithology’s Library of Natural Sounds as a

source for recordings of vocalizations. The order

of calls on the tapes should be from the least

intrusive to the most intrusive calls. An example

of this ordering would be the calls of black rail,

followed by least bittern, other rails, American

bittern, and, lastly, pied-billed grebe. How loud to

play the tape was not discussed though it was

noted that quality of the tape and equipment

would impact the quality of the sound if the

volume was turned up to the maximum. Also,

having the tape played too loudly could drown

out some responses or inhibit nearby birds from

vocalizing.

e. The number of surveys to be done at a survey

point depends on the objectives of the survey. For

a monitoring program, 1 survey may be

adequate. For local information, we recommend

at least 2 surveys during a 6-week period during

the breeding season; surveys should be made at

least 1 week apart. Three surveys per season

may be necessary to accurately determine

presence/absence of some species. Local

information sources should be used to define the

breeding season for a specific location.

f. The number of survey points to be done depends

on the objectives of the study, size of wetlands,

and spacing between points. No general number

can be given. For example, the number of points

per route for a regional monitoring program is

still in need of research.

g. Use an arc that encompasses all wetland habitat

adjacent to the survey station.

h. The habitat focus of the survey should be on

emergent vegetation.

i. Points should be as close to or as far into the

wetland as possible/feasible. Canoeing or walking

into the wetland to place points are preferred.

Doing surveys along a dike or along a shoreline

are permissible where the preferred options are

not possible/feasible.

j. The survey point should consist of a 100 m fixedradius half-or whole-circle and then an area of

unlimited radius. Birds should be noted as being

within the 100 m radius or outside of the fixed

radius.

k. Collect information on the major habitat within

the fixed radius and beyond (where possible).

Some suggested habitat information includes:

area and percent coverage of sedge/grass or

cattail/bulrush, open water, aquatic bed (from

Cowardin et al. 1979), shrubs, scrub, flooded

timber; overall wetland area.

l. All participants should be trained in species

identification (in the lab as well as in the field),

estimation of distance, habitat assessment,

establishment of points, and the mechanics of

running a survey.

Table 3. Suggested calls to use in a playback survey.

Species Call

Sora Whinny

Virginia rail Grunt

King/clapper rail Mating call

Black rail Kic-kic-kerr call

Common moorhen/Gallinule Primary advertising call

Bitterns Advertising call

American coot Advertising call

Objective 3: Develop sampling schemes for

monitoring marsh birds at national, regional, and

local scales

Report from Group 2: Statistical design and

sampling considerations

The group discussed issues of scale, sampling frame,

sampling design, and field protocols, and reached

the following conclusions:

1. Scale of the survey.

A strong consensus existed that the marsh bird

survey should be multi-scale, responding to both

local and regional needs. National needs could then

be addressed by combining results from different

regions.

2. Sampling framework.

There was a consensus that the sampling program

should be based on sampling wetlands (i.e., habitatbased) and that the development of a sampling

frame is a necessary prerequisite to developing a

sampling design. There was uncertainty about what

information is available to develop a list of habitats

(i.e., sampling frame). Information from which a list

of habitats could be constructed may already exist

for many local and regional (e.g., statewide) areas.

At the national level, no habitat-based frame

currently exists. An alternative approach would be

an “area-based” frame from which smaller areas

could be selected—for example squares 10 km on a

Proceedings of the Marsh Bird Monitoring Workshop 9
side—and sampling would then be conducted within

such areas. More information is needed on the

current and imminent availability of habitat-based

frames, especially at the national level, and on the

relative utility of habitat-based and area-based

frames, especially at the regional and national level.

A first step using either approach should be to

identify all areas that should definitely be sampled

(e.g., Federal refuges, state wildlife management

areas, waterfowl production areas), and these should

be designated as comprising a separate stratum

which would be sampled with 100% selection

probabilities (i.e., all units in this stratum would be

selected). This step is appropriate from a statistical

standpoint and will insure that high-interest areas

are included in the monitoring program.

3. Sampling plan to choose sites.

The group agreed that a sampling plan to develop

strategies for choosing sites and stations (including

geographical distribution) needs investigation. Such

factors as specific objectives, costs, and results from

simulations should be used to develop specific

sampling plans. We did not feel that blanket

statistical recommendations could usefully be made

at this early stage in the development of monitoring

programs. Some of the related issues that need

consideration are the relative need for, and difficulty

of, sampling edge vs. interior areas, the role of

volunteers in selecting survey locations, and

whether surveys can include both whole and half

circles around the observer.

4. Field protocols.

The group discussed statistical issues related to field

methods, identifying factors that affect detectability,

and factors that might cause biases in average

detectability through time or across other domains

of interest (e.g., regions, habitats). The possibility

that such biases might occur will be one of the most

serious problems in interpreting results from the

survey unless analysts can be sure that any such

biases are substantially smaller than observed

trends (otherwise observed trends might be due

entirely to changes in detectability). The group

agreed that this issue warrants careful study to

determine how factors such as density, habitat,

timing, and playbacks affect detectability.

Studying effects of playbacks will be important

considering the popularity of using this technique

and the fact that the use of playbacks in a

monitoring program was recommended by the Field

Methodology Discussion Group (see above). There

are many issues. Only a few are discussed here. One

important question concerns playback response and

population density. Specifically, is there a nonlinear

relationship between the number of calls from

playback and density (i.e., does the number of calls

level off when density is high?). Another issue is the

possible movement of birds towards the observer.

This means that one cannot census a plot of known

size (i.e., densities or indices cannot be calculated;

only presence/absence information is obtained) and

that this movement may depend on the habitat and

density of the species (it cannot be assumed that

there is a standard movement towards the observer

across all habitats and densities). Such information

would lead to guidelines for how field methods

should be standardized.

In conclusion, the group targeted investigating

sampling frames, sample selection designs based on

them, and studying detectability as issues of

importance from a statistical standpoint.

Report from Group 3: Implementing a Marsh Bird

Monitoring Program

This discussion group initially attempted to identify

the important needs that might be addressed by the

implementation of an operational Marsh Bird

Monitoring Program. These needs are summarized

in order of importance as evaluated by the group:

1. Estimates of annual population trends.

Many aspects of the biology of marsh birds remain

relatively poorly known as compared with other

groups of birds. Even fairly basic information such

as distribution during the breeding and winter

seasons, timing and status of migrants, and specific

habitat preferences throughout the year are poorly

documented in the literature in many geographic

areas. While obtaining these data may not be the

primary purpose of a marsh bird monitoring

program, some monitoring data may be helpful in

“filling the gaps” of our knowledge of these species.

The ability to obtain basic population trend

estimates for marsh birds is very important because

existing surveys do not adequately sample most

species. Trend estimates would be needed at various

geographic scales, particularly state/provincial,

regional, and continental estimates. While local

trends of marsh birds may be of interest to land

managers, these survey methods probably lack

sufficient precision to reliably estimate local

population trends. Ideally, marsh bird surveys

conducted at the state/provincial scale would

contribute to trend estimates at larger geographic

scales. The adoption of consistent survey

methodologies is critical to accomplish this goal.

However, sample sizes and survey designs necessary

to obtain trend estimates at the state/provincial

10 Proceedings of the Marsh Bird Monitoring Workshop
scale may be different from those of regional and

continental surveys. Greater sampling effort would

be needed to obtain reasonable trend estimates at

smaller geographic scales, and the distribution of

survey points may be different to meet the specific

needs of the states/provinces conducting the

surveys. However, the participants agreed that

these specific sample designs could probably be

accommodated within the framework of sample

designs for the regional/continental surveys.

In addition to the basic need to obtain population

trend estimates, this monitoring program would be

important for the following purposes:

■ To obtain adequate population trend data for

establishing hunting regulations for hunted marsh

bird species.

■ To better understand the population trends of rare

or declining marsh bird species at the Federal and

state/provincial levels, and to better ascertain the

status of species of management concern before

they require formal listing as threatened or

endangered.

■ To help state agencies develop information on

population trends, distribution, and effects of

management as a basis for regulatory protection for

species of marsh birds already listed as endangered,

threatened, or of special concern under state laws.

■ To meet various Federal legislative requirements

pertaining to the need for monitoring bird

populations, including the Migratory Bird Treaty

Act, Fish and Wildlife Conservation Act, and

National Wildlife Refuge System Improvement Act.

■ To focus research and management activities for

the benefit of marsh bird species.

2. Habitat assessment.

To better understand the overall importance of

population trend estimates, trends must be placed

within the context of changes occurring within the

wetland habitats occupied by these species. Hence,

there is a need to:

■ Obtain information on the habitat associations of

the various marsh birds. Since bird- habitat

associations can vary geographically, this

information is needed throughout the ranges of

these species.

■ Obtain information on the trends of these habitats.

As was true for the population trend estimates,

habitat trend estimates will also be needed at

various geographic scales.

3. Monitor the effectiveness of management actions.

At the local scale of individual wildlife refuges or

similar management areas, there is a need to

understand how marsh birds respond to

management activities. Projects studying the effects

of management activities on marsh birds require

knowledge of population levels within the area of

interest, knowledge of the specific bird-habitat

associations of the region, and possibly some

demographic data to understand the factors

responsible for the observed changes in population

levels. Additionally, the survey design and allocation

of survey points would reflect the specific questions

being addressed at each area, and may be very

different from the survey design used to collect

large-scale population trend data.

The group participants recognized the need to

include a variety of stakeholders in monitoring

efforts for marsh birds, expanding beyond the

agencies and participants present at the workshop.

Various governmental and non-governmental

organizations, private industry, researchers, and the

general birding public will need to be involved in

various aspects of this program for these monitoring

efforts to be successful. Additionally, marsh bird

monitoring efforts have to focus beyond the goal of

simply obtaining population trend estimates; they

must also relate to wetland habitat management,

development of regional conservation plans for

birds, research, and actions devoted to the recovery

of declining species.

The group participants recognized that the three

needs listed above cannot be accomplished with a

single survey design. Hence, a tiered approach

should be considered that would allow managers to

collect the desired data according to their needs.

The first tier of data collection consists of the survey

design and methodology needed to estimate the

population trends of marsh birds. A consistent

methodology should be followed at all locations, and

the survey design should allow for the estimation of

population trends at several geographic scales.

The other tiers of data collection would be optional

and depend upon the needs of the local habitat

manager or the state/province coordinating the

survey efforts. The second tier of data collection

would emphasize the habitat characteristics at the

survey sites. While the complexity of these habitat

data depends upon the specific management or

research questions under study, in general, these

data should be fairly easy to obtain by the survey

participants and should not interfere with the bird

population surveys. A recommended set of habitat

parameters and survey methods should be

developed to promote the consistent collection of

Proceedings of the Marsh Bird Monitoring Workshop 11
habitat data across sites. The third tier of data

collection would relate to specific management

issues that require additional study. While the

nature of these surveys would vary from site to site

depending upon the management questions under

study, these surveys should try to adopt the survey

methodology used to estimate population trends

while allocating samples to meet specific needs, such

as to compare treatment with control sites. In this

way, some data could contribute to the first-tier

surveys that estimate population trends, while all of

the data would be available to address the specific

management questions.

Uncertainties

The group participants identified a number of

questions that need to be addressed prior to the

actual implementation of an operational Marsh Bird

Monitoring Program. The answers to these

questions will significantly influence the direction

and success of these monitoring efforts.

1. Observer-related issues.

Recruiting and retaining qualified observers to

conduct marsh bird surveys is fundamental to the

success of the program. Paying biologists to conduct

every survey is probably not a realistic option for a

continental monitoring program, because the costs

would greatly exceed the available funds, and

coordinating the logistics of many field crews

scattered across the continent would be a very timeconsuming task for the agency responsible for the

monitoring program. Hence, a volunteer-based

effort comparable to the Breeding Bird Survey

(BBS) is a more realistic approach for a continental

Marsh Bird Monitoring Program. However, there

also are several problems associated with the use of

volunteers to conduct these surveys:

■ The expertise in bird identification required to

conduct these surveys will dictate the number of

potential volunteers in an area. If the marsh bird

surveys are restricted to a relatively small number

of species, then the potential pool of qualified

volunteers will be larger since it may be possible to

provide the necessary training to people with more

limited bird identification skills so they can

participate in these surveys. Conversely, marsh bird

surveys that require the identification by voice of all

species present in the wetland would require a much

greater level of bird identification skills, comparable

to those required for the BBS, and would reduce the

pool of qualified volunteers to a relatively small

proportion of the birders living in an area.

■ Volunteers will not be evenly distributed across

the landscape, but will tend to be concentrated near

urban areas. Hence, rural areas may have few

potential volunteers so that some volunteers may

have to drive considerable distances to conduct

marsh bird surveys. A survey method that requires

multiple visits to each site may discourage regular

coverage of distant locations.

■ The availability of volunteers to conduct marsh

bird surveys may be a limiting factor since many

qualified birders also participate in other bird

monitoring programs. This problem may be

compounded by survey methods for marsh birds

that require relatively greater effort on the part of

the volunteer, either to conduct multiple surveys or

to gain access to survey sites, for example.

While any Marsh Bird Monitoring Program will

require volunteers to collect data, this program may

also have to rely on paid biologists to participate in

order to achieve consistent coverage across the

continent. Hence, cooperation with Federal, state, or

other agency biologists will be important to obtain

coverage at some managed sites that may not be

easily accessed by volunteers. In more remote areas

where volunteers and agency biologists are scarce,

some paid field crews may be necessary to conduct

these surveys.

2. Access/logistic issues.

The methods and survey design implemented for

this marsh bird monitoring program will play an

important role in the long-term success of these

efforts. The methods should be kept as simple as

possible to collect accurate data but not impose

hardships on the volunteers collecting the data.

These methods should also minimize the logistical

considerations of the agency managing the

monitoring program. For example, the use of tape

playbacks may increase detection rates for some

species but would require the development of

region-specific tapes, and the necessity to routinely

provide the participants with new copies of the tapes

and broadcast equipment so that the same methods

are uniformly applied at each site. Considerable

resources would be necessary to provide the tapes

and broadcast equipment to observers scattered

across a continent.

The survey design should try to select sites that

have relatively easy access, either near roads or on

public lands, rather than a strictly random process.

Factors such as requirements for multiple visits

each year, the need to use boats to conduct surveys,

obtaining permission to visit sites on private

property, and crossing difficult terrain in darkness

would discourage participation by volunteers and

reduce the number of surveys conducted each year.

Incorporating off-road sites into the sampling

12 Proceedings of the Marsh Bird Monitoring Workshop
scheme may complicate the ability of some Federal

and state biologists to participate on surveys located

on private property. Such factors should be

implemented in the monitoring program only if

there are no acceptable alternatives.

3. Funding issues.

Questions regarding how to obtain the necessary

funding for a Marsh Bird Monitoring Program were

largely beyond the realm of this discussion group.

Some source of consistent funding will be required

to implement and operate this monitoring program,

but whether these funds are derived from additions

to base budgets or the redirection of existing funds

would have to be decided by others. However, the

coordinating agency(ies) should develop

partnerships with a broad spectrum of

governmental and non-governmental groups to

assist in the development and implementation of

these monitoring efforts. These partnerships may

reduce some of the funding requirements for both

the initiation and long-term operation of marsh bird

monitoring.

4. Coordination role.

Questions regarding who will coordinate the

development and operation of the marsh bird

monitoring program were also beyond the realm of

this discussion group, although the group

participants felt strongly that a Federal agency

should take the lead in this process. Since the trend

data for some species would be used in the

establishment of annual hunting regulations, the

U.S. Fish and Wildlife Service will want to be closely

involved with most aspects of this program;

coordination by a non-governmental agency may not

be appropriate. Since USGS Biological Resources

Division has a mandate to monitor the continental

wildlife resources and has considerable expertise in

monitoring non-game bird populations at large

geographic scales, this agency should also be

involved in various aspects of any Marsh Bird

Monitoring Program.

Regardless of which agency takes the lead

coordination role for marsh bird monitoring,

operating this monitoring program will require a

sizable commitment of resources. Unless large

amounts of new funding are available, one possibility

would be to have one agency coordinate the

operational aspects of the monitoring efforts, while

another agency would manage the data and

coordinate additional research studies.

Programmatic responsibilities could be shared

through other means, but various options should be

explored to reduce the amount of funding required

by a single agency to initiate marsh bird monitoring

efforts.

5. Habitat information.

Many uncertainties surround the collection of

habitat data. For example, which parameters to

measure, how to measure them, and to what

distance from the sample point should habitat data

be collected are some of the topics that remain

controversial. These issues need to be resolved

before a habitat component can be incorporated into

the marsh bird monitoring program and sampling

methodologies can be developed that would be

consistent across sites. Whatever methods are

developed, they should be as simple as possible since

adding a detailed habitat component to the

monitoring protocol would increase the cost of

training/supervision to prepare volunteers to collect

habitat data and increase difficulty of recruiting and

retaining qualified volunteers by adding additional

work.

Habitat data will also be needed at large geographic

scales in addition to the site-specific information.

Defining wetland physiographic strata at regional

scales may be important in any analysis of

population trends. Understanding regional trends in

habitats may be valuable in identifying factors

influencing marsh bird populations. Wetland

habitats at large geographic scales are currently

classified by the National Wetlands Inventory

(NWI), but additional information and ground

truthing may be needed to more precisely establish

the distribution and abundance of wetlands at the

landscape level.

6. Outreach/public education.

The group participants recognized an important

need to broaden the base of support for marsh bird

monitoring efforts and the conservation of these

species. The desirability of creating partnerships

with a variety of governmental and nongovernmental agencies to promote the marsh bird

monitoring program is described above.

Additionally, marsh birds need to receive a higher

level of recognition in ongoing bird conservation

efforts, such as the conservation planning processes

underway within Partners in Flight, the North

American Waterfowl Management Plan (NAWMP),

and the U. S.Shorebird Conservation Plan. Given

that marsh birds occupy the same habitats as

waterfowl, there is a natural linkage to include all

marsh-inhabiting birds within the NAWMP.

Increasing the visibility of marsh birds within these

planning processes will be necessary to obtain and

maintain the necessary funding to implement an

operational Marsh Bird Monitoring Program.

Proceedings of the Marsh Bird Monitoring Workshop 13
Recommendations

After discussing these topics, the group participants

developed the following list of recommendations

concerning the implementation of a Marsh Bird

Monitoring Program:

1. Overall coordination of the marsh bird monitoring

program should be at the level of the Federal

government in the United States and at a national

level within Canada, with assistance provided by

non-governmental organizations, states, and

provinces.

a. A central database should be created for this

program, which should be managed by the

Federal government.

b. The BBS should be used as a model for

establishing a coordination network of volunteers

willing to conduct these surveys.

2. Coordination between the U.S. Fish and Wildlife

Service and USGS Biological Resources Division

will be required to develop the budget initiatives and

necessary institutional support to implement marsh

bird monitoring across North America. These

agencies cannot be successful by themselves, but

will have to develop partnerships with a variety of

governmental and non-governmental agencies to

support these efforts. For example, the

International Association of Fish and Wildlife

Agencies and Waterfowl Flyway Councils should be

enlisted to elevate the priority of marsh bird

monitoring efforts within the states and provinces.

These activities also should be coordinated with the

Partners in Flight, NAWMP and shorebird

conservation planning activities.

3. The survey methods should be as simple as

possible but still collect adequate data for estimating

population trends at various geographic scales. The

survey design should consider the accessibility of

sites during the site-selection process. Feasibility of

the program may mean the use of boats and use of

sites far removed from roads may have to be

minimized. Volunteers will be required to collect

much of the survey data, and their long-term

participation in marsh bird monitoring efforts will

be directly related to the amount of time and effort

required to conduct these surveys.

4. A combination of volunteers, agency biologists,

and personnel paid to specifically conduct marsh

bird surveys will probably be needed to implement a

continental monitoring program. The paid personnel

may be needed in the more remote areas where few

qualified volunteers are available, but their use

should be kept to a minimum. Training materials will

have to be developed for the volunteers, to ensure

that the methodology is consistently followed across

sites. These materials may also be helpful to recruit

new volunteers who may currently lack the

necessary expertise to conduct marsh bird surveys.

The necessity for use of tape playbacks should be

carefully considered, because many significant

logistical problems would be associated with

providing tapes and broadcast equipment to the

survey participants.

5. To associate marsh bird population data with

habitat changes, wetland habitat databases should

be developed for relatively large geographic scales.

Available sources such as the National Wetlands

Inventory and GAP projects will provide the initial

information for these databases, but the reliability of

these data for the regional monitoring of habitats

remains uncertain. Resources may be necessary for

ground-truthing of available habitat data or to

obtain data from other sources.

6. Outreach and communication strategies should be

developed at the same time as the marshbird

monitoring program is being developed. Marsh

birds are currently overlooked members of

communities in many areas, and their visibility

within bird conservation and monitoring efforts has

to improve in order to develop all of the financial and

volunteer resources needed to implement a

continental Marsh Bird Monitoring Program.

Information Needs 

The workshop participants agreed that specific

research should be undertaken as soon as possible to

further the development of a Marsh Bird Monitoring

Program. The following topics were identified by the

participants as being important to the success of a

Marsh Bird Monitoring Program and ranked

according to priority of which should be done first

(Table 4).

First Priority

1. Statistical issues using call-playback techniques.

The Field Protocol Group recommended using callplayback techniques because of the belief that using

call-playbacks would increase detectability of certain

species, leading to a reduced number of zero counts

and an assumed decrease in variance. However, the

Statistical Design group argued that call-playbacks

should not be used because an unknown area is

being sampled, birds most likely move into an area

in response to the call-playback, and bird movement

is dependent on a variety of currently unknown

habitat (e.g. size of marsh, vegetation type) and

biological factors (e.g. bird density). Some members

14 Proceedings of the Marsh Bird Monitoring Workshop
of the Statistical Design Group argued that callplaybacks could lead to an increase in variance

rather than a decrease. Therefore, an information

need identified was the following: In comparing

passive and call-playback observations, (a) is there

an improvement of detectability with call-playback?

(b) is there a change in the variance and in what

direction? If there is a reduction, how much of a

reduction is seen? and (c) What are the implications

for required sample sizes in a power analysis?

2. Evaluation of a sampling frame/scheme.

The workshop participants agreed that local

protected areas such as refuges and state protected

areas could form their own stratum and be

completely or almost completely sampled without

impact to the validity of the Program. The major

concern was how to pick samples from the nonprotected/non-priority sites. Two suggested schemes

were proposed though there is no reason to think

there are only these two alternatives. The first

alternative was a habitat-based approach that is

dependent on existing maps for choosing wetlands

according to some statistically-based scheme. A

second alternative is an area-based approach where

areas are picked by some statistically-based scheme,

these areas are evaluated for the existence of

wetlands, and then those wetlands are sampled by

some statistically-based scheme. The workshop

participants agreed that a high priority research

need is to evaluate different sampling schemes for

use in a Marsh Bird Monitoring Program.

Second Priority

3. Development of habitat information.

The workshop participants agreed that the habitat

classification of Cowardin et al. (1979) should be used

for site selection. An alternative, the

hydrogeomorphic scheme, may be useful at

individual points. But it was acknowledged that a

status review of current databases was needed.

Some databases to consider are the National

Wetlands Inventory and GAP databases. Concerns

were raised about how current the databases were

and at what scale(s) they would be helpful. There

was no information on potential Canadian databases

nor what databases were currently being developed.

Another aspect to investigate is how well the habitat

of priority species would be covered by the existing

databases. There was some debate about whether or

not this would be covered under the Evaluation of a

Sampling Frame/Scheme. This need may or may not

be met, depending on the scope of the proposed

sampling frame project.

4. Documenting habitat change over time (including

what type of habitat data should be collected).

An acknowledged difficulty was the fact that

wetlands change over time. This means that habitat

information needs to be collected at the survey

points as well as documenting the existence of the

wetland (which may disappear due to development

or succession). This information will be important in

understanding trends seen in the data as well as

impacting the design of the program (e.g., fixed

points versus new points every year versus some

kind of mixture). So the information need is to

determine how wetland/habitat change will be

accommodated in the program. Some of these issues

may be addressed in the Evaluation of a Sampling

Frame/Scheme, depending on the proposed project.

5. Timing of counts (a.m. versus p.m.).

An issue that was brought up was the timing of the

counts from a biological point of view and from an

operational point of view. Some of the priority

species are not detected during morning surveys

while timing may not make a difference for other

priority species. Secondary species, though, may be

detected at much lower rates during evening

surveys. An operational problem is that if the

Proceedings of the Marsh Bird Monitoring Workshop 15

Table 4. Information needs and importance as ranked by participants in the Marsh Bird Monitoring Workshop. 

(Not all information needs were ranked by all participants, therefore, row sums will not be equal.)

Information need Very Important Secondary Importance Can be done later

Statistical issues using call-playback techniques 31 8 0

Evaluation of a sampling frame/scheme 31 6 1

Development of habitat information 16 15 6

Documenting habitat change over time 11 18 8

Timing of counts (morning vs. evening) 14 16 7

Assessing what the index means 13 15 9

Phenology or geographical differences that 11 15 9

influence the timing of surveys

Data quality issues 5 13 19
program is to be volunteer-based and volunteers are

only available during the evenings, then should an

evening survey period be used? Some workshop

participants indicated they thought that the data

probably exist to answer the biological questions

and that all that needs to be done is to evaluate this

information.

6. Assessing what the index means.

The issue of what the index means in terms of

population density or size is a critical one and is an

issue for all monitoring programs. Most of the

programs that are considered weak are those whose

index cannot be linked to some measure of

population size. However, trying to answer this

question will be difficult to study.

7. Phenology or geographical differences that

influence the timing of surveys.

When to do the surveys will vary by region and the

workshop participants discussed the need to

understand these differences to provide guidance to

the monitoring program. There was some

agreement that the databases exist to answer this

question and that the information just needs to be

evaluated. One participant suggested a national

team could be used to do this.

Third Priority

8. Data quality issues.

The participants agreed that evaluating the quality

of the data collected by any program is important.

In particular, we need to understand the costs,

benefits, and trade-offs between using volunteers

(which can include professional biologists) and using

a dedicated set of technicians to collect the

monitoring data. Other issues, such as hearing

ability and song identification, were also discussed.

Topics Needing Further Discussion

Scale of the program.

Though the participants agreed that the program

should focus on trends at multiple geographic scales,

there was little discussion in the breakout groups

about the implications of multi-scale monitoring on

the design and objectives of the program. The

Statistical Design Group explicitly suggested a

multi-scale program at local and regional scales,

noting that national trends would come from the

regional programs. However, other than pulling the

local protected areas out as an individual stratum,

little was done to address design at multiple-scales.

Another suggestion was to consider all scales

suitable to establish hunting regulations, assess

threatened and endangered species and species of

management concern, and to address other

legislative requirements. Clearly, more discussion is

needed on the objectives and scale of the program.

2. What trend and other details.

One aspect of the program that was not discussed in

detail was the time-scale over which true changes

needed to be detected. One group suggested that

detecting differences in trend on an annual basis

was necessary. But there was little discussion in the

other groups. Most concurred that, at this stage, one

scenario was unrealistic and that research could

address different scenarios of trend/Type I error/

power that would be helpful in setting realistic goals.

3. Evaluation of habitat relationships/management

impacts.

Though identified as one of the goals of a program,

no discussion of how these questions might be

addressed in a monitoring program was made.

Clearly, specific local goals and how they might

interact with a monitoring program need further

discussion and development.

16 Proceedings of the Marsh Bird Monitoring Workshop
Objective 4: Enhance communication among

biologists and managers interested in marsh bird

monitoring issues

This workshop was the first step in forming a

network of professionals interested in marsh birds

and monitoring. It was recognized that this was only

the first step.

It was agreed that the research priorities identified

in the workshop should be used to keep the

momentum going in the development of the Marsh

Bird Monitoring Program. The participants also

agreed that a pilot program building on Bird Studies

Canada’s Marsh Monitoring Program, and having a

heavy research emphasis, is needed. However, longterm strategies are needed for obtaining

institutional support for such a program. The U.S.

Fish and Wildlife Service and the USGS Biological

Resources Division were identified as the

appropriate agencies for developing a strategy for a

Marsh Bird Monitoring Program. A new Steering

Committee composed of representatives from U.S.

Federal and state agencies, and Canadian

organizations was established to go forward with the

development of a Marsh Bird Monitoring Program.

The Committee consists of the following people:

Marshall Howe, USGS-BRD (Chair)

Robert Blohm, USFWS, Office of Migratory Bird

Management

Peter Blancher, Canadian Wildlife Service

Russell Weeber, Bird Studies Canada

Scott Melvin, Massachusetts Division of Fisheries

and Wildlife (representing the International

Association of Fish and Wildlife Agencies)

Bruce Peterjohn, USGS-BRD

Jon Bart, USGS-BRD.

Activities of this committee will be communicated at

the following web site:

http://www.mp1-pwrc.usgs.gov/marshbird/

Proceedings of the Marsh Bird Monitoring Workshop 17
Statement of Support from the Deputy Chief Biologist,

USGS Biological Resources Division

August 12, 1998

The Biological Resources Division (BRD) of USGS

recognizes secretive marsh birds as one of several

guilds of North American birds whose populations

are not effectively monitored by existing methods.

The April 1998 marsh bird workshop, co-sponsored

by the US Fish and Wildlife Service (FWS) and

USGS, has successfully summarized the existing

state of knowledge about marsh bird populations

and has defined the information and research needs

that will enable a marsh bird monitoring program to

be implemented. USGS is fortunate to have a

considerable body of expertise in sampling design

and in development of population monitoring

protocols. USGS also places a high priority on

achievement of these goals for marsh birds and is

committed to contributing its expertise accordingly.

We propose to incorporate eventual databases

derived from a monitoring program into the national

bird population data center being developed at

Patuxent Wildlife Research Center. We look forward

to working cooperatively with the FWS and other

entities working for marsh birds in reaching these

goals.

Susan D. Haseltine

Deputy Chief Biologist for Science

Biological Resources Division

Statement of Support from the Assistant Director,

Refuges and Wildlife, U.S. Fish and Wildlife Service

The U.S. Fish and Wildlife Service acknowledges

secretive marsh birds as an integral component of

North America’s avifauna. Yet, little is known about

their abundance, distribution, and population status.

The Service considers the acquisition of scientific

information to enhance management decisions

extremely important to its mission and fully

supports research, monitoring and management

efforts to remedy these limitations. Consequently,

high priority will be placed on development of

standardized survey protocols for monitoring marsh

birds, through future budget initiatives and other

opportunities for cooperative support. The Service

looks forward to working with the Biological

Resources Division of the U.S. Geological Survey,

States, and other agencies and organizations to

share research and management expertise and

improve our collective ability to manage this

historically-overlooked group of birds.

Daniel W. Ashe

Assistant Director—Refuges and Wildlife

18

Letters of Support
Cowardin, L.M., V. Carter, F.C. Golet, and E.T.

LaRoe. 1979. Classification of wetlands and

deepwater habitats of the United States. U.S. Fish

and Wildlife Service FWS/OBS-79/31.

Gibbs, J. P. and S. M. Melvin. 1993. Call-response

surveys for monitoring breeding waterbirds.

Journal of Wildlife Management 57: 27-34.

19

Literature Cited
Bob Adamcik

U.S. Fish and Wildlife Service (USFWS)

Division of Refuges

Room 670

4401 N Fairfax Drive

Arlington, VA 22203

Phone: 703-3587-2359

Fax: 703-358-1826

bob_adamcik@mail.fws.gov

Paul Adamus

Department of Fisheries and Wildlife

Oregon State University

Corvallis, OR 97330

Phone: 541-745-7092

Fax: 541-753-4507

adamusp@ucs.orst.edu

Stanley Anderson

Wyoming Cooperative Fish 

and Wildlife Research Unit

University of Wyoming

Biological Science Bldg

Room 419 Box 3166

Laramie, WY 82071-3166

Phone: 307-766-5415

Fax: 307-766-5400

anderson@uwyo.edu

Jon Bart

U.S. Geological Survey (USGS), Biological

Resources Division (BRD)

Snake River Field Station

970 Lusk Street

Boise, ID 83706

Phone: 208-331-5216

Fax: 208-331-5210

jbart@eagle.idbsu.edu

Robert Blohm

USFWS

Office of Migratory Bird Management

634 Arlington Square

4401 N Fairfax Drive

Arlington, VA 22203

Phone: 703-358-1966

Fax: 703-358-2217

robert_blohm@mail.fws.gov

David Brinker

Maryland Department of Natural Resources

1200 Frederick Rd.

Catonsville, MD 21228

Phone: 410-744-8939

Fax: 410-260-8596

dbrinker@dnr.state.md.us

John Bruggink

USFWS

Office of Migratory Bird Management

11500 American Holly Drive

Laurel, MD 20708-4016

Phone: 301-497-5627

Fax: 301-497-5871

john_bruggink@mail.fws.gov

Mike Cadman

Canadian Wildlife Service

75 Farquhar St.

Guelph, Ontario

CANADA N1H 3N4

Phone: 519-826-2094

Fax: 519-826-2113

Mike.Cadman@ec.gc.ca

Jennifer Casey

Lake Umbagog National Wildlife Refuge

Route 16, PO Box 240

Errol, NH 03579

Phone: 603-482-3415

Fax: 603-482-3308

jennifer_casey@mail.fws.gov

Courtney Conway

Division of Biological Sciences and

Montana Cooperative Wildlife Research Unit

University of Montana

Missoula, MT 59812

Phone: 406-243-5137

Fax: 406-243-6064

CONWAY@selway.UMT.edu

20

Appendix 1. Participant List for the 

Marsh Bird Monitoring Workshop

National Wildlife Visitor Center, Laurel, Maryland, 26-28 April 1998.
David Dolton

USFWS

Office of Migratory Bird Management

PO Box 25486 DFC

Denver, CO 80225-0486

Phone: 303-275-2388

Fax: 303-275-2384

david_dolton@mail.fws.gov

Kevin Downs

Wyoming Cooperative Fish 

and Wildlife Research Unit

University of Wyoming

Biological Science Bldg.

Room 419 Box 3166

Laramie, WY 82071

Phone: 307-766-4515

Fax: 307-766-5400

downsk@uwyo.edu

Sam Droege

USGS, BRD

Patuxent Wildlife Research Center

12100 Beech Forest Drive

Laurel, MD 20708

Phone: 301-497-5840

Fax: 301-497-5784

FROG@usgs.gov

Erica Dunn

Canadian Wildlife Service

National Wildlife Research Centre

100 Gamelin Blvd.

Hull, Quebec

CANADA K1A 0H3

Phone: 819-994-0182

Fax: 819-9543-6612

Erica.Dunn@ec.gc.ca

William Eddleman

Department of Biology-MS6200

Southeast Missouri State University

Cape Girardeau, MO 63701-4799

Phone: 573-651-2364

Fax: 573-651-2223

weddlema@biology.semo.edu

Charles Francis

Bird Studies Canada

PO Box 160

Port Rowan, Ontario

CANADA N0E 1M0

Phone: 519-586-3531

Fax: 519-586-3532

cfrancis@bsc-eoc.org

James Gibbs

State University of New York

College of Environ. Science and Forestry

350 Illick Hall

1 Forestry Drive

Syracuse, NY 13210

Phone: 315-470-6764

Fax: 315-470-6934

jpgibbs@syr.edu

Michael Haramis

USGS, BRD

Patuxent Wildlife Research Center

11410 American Holly Drive

Laurel, MD 20708-4015

Phone: 301-497-5651

Fax: 301-497-5624

Michael_Haramis@usgs.gov

Douglas Helmers

USDA, National Conservation Service (NRCS)

601 Business Loop I-70W

Parkade Center, Suite 250

Columbia, MO 65203

Phone: 573-876-0900

Fax: 573-876-0914

doug.helmers@mo.nrcs.usda.gov

William Hohman

USDA, NRCS

Iowa State University

124 Science II

Ames, IA 50011-3221

Phone: 515-294-8591

Fax: 515-294-2234

Whohman@iastate.edu

Marshall Howe

USGS, BRD

Patuxent Wildlife Research Center

12100 Beech Forest Drive

Laurel, MD 20708

Phone: 301-497-5858

Fax: 301-497-5784

Marshall_howe@usgs.gov

Douglas Johnson

USGS, BRD

Northern Prairie Wildlife Research Center

Route 1, Box 96C

Jamestown, ND 58401

Phone: 701-253-5539

Fax: 701-253-5553

Douglas_H_Johnson@usgs.gov

Proceedings of the Marsh Bird Monitoring Workshop 21
Greg Kearns

Patuxent River Park

1600 Croom Airport Road

Upper Marlboro, MD 20772

Phone: 301-627-6074

Fax: 301-952-9754

Eileen Kirsch

USGS, BRD

Upper Mississippi Science Center

2630 Fanta Reed Rd.

P O Box 818

LaCrosse, WI 54602-0818

Phone: 608-783-6451 Ext. 226

Fax: 608-783-6066

Eileen_Kirsch@usgs.gov

David Klute

Pennsylvania Cooperative Fish and Wildlife

Research Unit

Pennsylvania State University

107 Merkle Building

University Park, PA 16802

Phone: 814-865-3972

Fax: 814-863-4710

dsk5@psu.edu

Hal Laskowski

USFWS

2145 Key Wallace Drive

Cambridge, MD 21613

Phone: 410-221-1836

Fax: 410-228-3261

Hal_Laskowski@mail.fws.gov

Steve Lewis

USFWS

Bishop Henry Whipple Federal Bldg

1 Federal Drive

Fort Snelling, MN 55111-4056

Phone: 612-713-5473

Fax: 612-713-5286

steve_j_lewis@mail.fws.gov

Soch Lor

Cornell University

Department of Natural Resources

Fernow Hall

Ithaca, NY 14853-0188

Phone: 607-255-2606

Fax: 607-255-1895

SKl11@cornell.edu

Richard Malecki

USGS, BRD

New York Cooperative Fish 

and Wildlife Research Unit

Fernow Hall, Room 202

Cornell University

Ithaca, NY 14853-0188

Phone: 607-255-2839

Fax: 607-255-1895

RAM26@cornell.edu

Jim Mattsson

C/o Mark Twain NWR

1704 N. 24th Street

Quincy, IL 62301

Phone: 217-224-8580

Fax: 217-224-8583

Jim_mattsson@mail.fws.gov

Scott Melvin

Massachusetts Division of Fisheries and Wildlife

Westboro, MA 01581

Phone: 508-792-7270 ext. 150

Fax: 508-792-7275

scott.melvin@state.ma.us

Kelly Mizell

Department of Wildlife and Fisheries Sciences

Texas A & M University

College Station, TX 77843-2258

Phone: 409-845-5777

Fax: 409-845-3786

Michael Monahan

Co-Director of Environmental Science

University of Denver

Denver, CO 80208

Phone: 303-871-3540

Fax: 303-871-3471

mmonahan@du.edu

Charles Paine

Max McGraw Wildlife Foundation

PO Box 9

Dundee, IL 60118

Phone: 847-428-6331

Fax: 847-428-8157

CRPaine@aol.com

Bruce Peterjohn

USGS, BRD

Patuxent Wildlife Research Center

12100 Beech Forest Road

Laurel, MD 20708-4037

Phone: 301-497-5841

Fax: 301-497-5784

Bruce_Peterjohn@usgs.gov

22 Proceedings of the Marsh Bird Monitoring Workshop
Dan Petit

USFWS

Office of Migratory Bird Management

4401 N Fairfax Drive

Arlington, VA 22203

Phone: 703-358-1824

Fax: 703-358-2272

daniel_petit@mail.fws.gov

Christine Ribic

USGS, BRD

Wisconsin Cooperative Wildlife Research Unit

University of Wisconsin

Department of Wildlife Ecology

226 Russell Labs

1630 Linden Drive

Madison, WI 53706-1598

Phone: 608-263-6556

Fax: 608-263-4519

caribic@facstaff.wisc.edu

John Sauer

USGS, BRD

Patuxent Wildlife Research Center

11510 American Holly Drive

Laurel, MD 20708-4017

Phone: 301-497-5662

Fax: 301-497-5666

John_R_Sauer@usgs.gov

Mark Shieldcastle

Crane Creek Wildlife Research Station

Ohio Division of Wildlife

13229 W St., Rt. 2

Oak Harbor, OH 43449

Phone: 419-898-0960

Fax: 419-898-4017

Mark.shieldcastle@dnr.state.oh.us

David Shuford

Point Reyes Bird Observatory

4990 Shoreline Highway

Stinson Beach, CA 94970

Phone: 415-868-1221, Ext. 14

Fax: 415-868-1946

dshuford@prbo.org

Jennifer Skoloda

University of Wisconsin

Department of Wildlife Ecology

226 Russell Labs

1630 Linden Drive

Madison, WI 53706-1598

Phone: 608-263-7595

Fax: 608-262-6099

jskoloda@students.wisc.edu

Graham Smith

USFWS

Office of Migratory Bird Management

11500 American Holly Drive

Laurel, MD 20708-4016

Phone: 301-497-5860

Fax: 301-497-5871

graham_smith@mail.fws.gov

Kelli Stone

USFWS

Midcontinent Ecological Science Center

4512 McMurray Avenue

Fort Collins, CO 80525-3400

Phone: 970-226-9408

Fax: 970-226-9230

kelli_stone@mail.fws.gov

Glenn Therres

Maryland Department of Natural Resources

Wildlife and Heritage Division

580 Taylor Avenue, E-1

Annapolis, MD 21401

Phone: 410-260-8572

Fax: 410-260-8596

gtherres@dnr.state.md.us

John Trapp

USFWS

Office of Migratory Bird Management

4404 N. Fairfax Drive ARLSQ-634

Arlington, VA 22203

Phone: 703-358-1821

Fax: 703-358-2217

john_trapp@mail.fws.gov

Cecilia Walther

Louisiana State University

227 Forestry-Wildlife-Fisheries Bldg.

Baton Rouge, LA 70803-6202

Phone: 504-388-4131

Fax: 504-388-4227

cwalthe@tiger.lsu.edu

Russ Weeber

Bird Studies Canada

PO Box 160

Port Rowan, Ontario

CANADA N0E 1M0

Phone: 519-586-3531

Fax: 519-586-3532

rweeber@bsc-eoc.org

Proceedings of the Marsh Bird Monitoring Workshop 23
Discussion Group I: 

Field Protocols for Marshbird Monitoring

Leader: Scott Melvin

Recorder: Marshall Howe

(a) Develop a list of species (or groups of species)

covered by marsh monitoring. Describe any

techniques or protocols already in place for specific

species or species groups.

(b) What time of day should surveys be conducted?

The participants may want to come up with a list of

species or species groups that should be monitored

at dawn, dusk, day, or at night, and any species or

groups that could be monitored at a variety of

times).

(c) What weather restrictions are there for doing

surveys?

(d) Where should the sampling points be located? On

roads, off roads by walking into the habitat, in the

water done by boat? This will bring in practicality

issues. The group may want to discuss the optimum

location but consider the implications if the optimum

cannot be reached. Are the alternatives acceptable?

One of the criticisms of the BBS is that the surveys

are all done from roads. Can this criticism be

avoided at the outset? Is it an important

consideration?

(e) For call-playback surveys, what quality, loudness,

length, and order of play should tapes be?

(f) Can multiple survey methodologies be combined

into one survey? What are the implications of doing

that? What are the drawbacks? What are the

benefits?

(g) Consider logistical restrictions when sampling at

a refuge level, on a statewide level, and on a rangewide level that might impact recommended

protocols.

(h) Should habitat information be collected every

time a survey is done? If so, what habitat variables

should be measured and what protocols should be

used?

(i) What are the highest priority research needs in

the area of field protocols, e.g. where should we be

putting our limited research dollars?

Discussion Group II: 

Statistical Design and Sampling Considerations

Leader: Jon Bart

Recorder: Chris Ribic

(a) How would design and sampling change for

surveys done at various spatial scales:

1. Local (e.g., refuge) need information on

presence, abundance (maybe in just a gross

sense), habitat associations, and responses to

management.

2. State need information on abundance and trends,

especially for state-protected rare species. For

hunted species, also need information for setting

hunting seasons.

3. National need information on status and

landscape relationships. For hunted species, also

need information for setting hunting seasons.

4. North America (e.g. rangewide) need

information on status, trends and landscape

relationships.

(b) What are the implications for the sampling unit

when monitoring at these different scales?

(c) Would stratification be an important tool to

consider? What would be some possible stratification

variables?

(d) What data are necessary to do a power analysis

for a multi-species monitoring program at the

different scales?

(e) For call playback surveys, what is the

relationship of call-count indices to true population

levels?

(f) What are the highest priority research needs in

the area of sampling and statistical considerations

(e.g., where should we be putting our limited

research dollars)?

24

Appendix 2. Topics for the Discussion Groups at

the Marsh Bird Monitoring Workshop.
Discussion Group III: 

Implementation of a Marshbird Monitoring Program

Leader: Bruce Peterjohn

Recorder: Glen Therres

(a) What species and geographic areas (e.g., refuge,

states, U.S.) should be focused on?

(b) What are the agencies’ needs?

(c) What role should each agency and organizations

(e.g., states, FWS, BRD, Flyway Councils,

NGOs) play in monitoring marshbirds?

(d) Is a central database desirable? If so, can BRD

oversee this?

(e) To what degree can volunteers be used in

implementing a monitoring program?

Proceedings of the Marsh Bird Monitoring Workshop 25
Group/Species Latin Name

Grebes Family Podicipedidae

Bitterns and herons Family Ardeidae

Rails, gallinules, moorhens, coots Family Rallidae

Cranes Family Gruidae

Snipe Order Charadriiformes

Pied-billed grebe Podilymbus podiceps

American bittern Botaurus lentiginosus

Least bittern Ixobrychus exilis

Yellow rail Coturnicops noveboracensis

Black rail Laterallus jamaicensis

Clapper rail Rallus longirostris

King rail Rallus elegans

Virginia rail Rallus limicola

Sora Porzana carolina

Purple gallinule Porphyrula martinica

Common moorhen Gallinula chloropus

American coot Fulica americana

Common snipe Gallinago gallinago

Franklin’s gull Larus pipixcan

Forster’s tern Sterna forsteri

Black tern Chlidonias niger

Belted kingfisher Ceryle alcyon

Alder flycatcher Empidonax alnorum

Willow flycatcher Empidonax traillii

Sedge wren Cistothorus platensis

Marsh wren Cistothorus palustris

Common yellowthroat Geothlypis trichas

Red-winged blackbird Aegelaius phoeniceus

Yellow-headed blackbird Xanthocephalus xanthocephalus

LeConte’s sparrow Ammodramus leconteii

Saltmarsh sharp-tailed sparrow Ammodramus caudacutus

American Ornithologists’ Union (AOU). 1998. Check-list of North American birds, 7th ed. Allen Press, Lawrence, KS.

26

Appendix 3. Common and Latin Names of Bird

Groups and Species in Report. 

Latin names are taken from AOU (1998).
Considerations Regarding Refuge Participation in 

Landscape Scale Monitoring

Robert S. Adamcik, Division of Refuges, U.S. Fish and Wildlife Service, 

4401 N. Fairfax Drive, Arlington, VA 22203

The National Wildlife Refuge System includes the single most extensive network of wetland reserves in the

United States. Hence, continental, national, or regional marshbird monitoring initiatives will likely include

refuges as sampling units. Gaining the participation of refuges in such initiatives requires a firm

understanding of the ecological and administrative context in which refuges function, the factors driving

refuge survey activities, and the manner in which refuge managers choose those surveys in which to

participate. Surveys on refuges can contribute to biological objectives at three spatial scales: (1) refugespecific surveys driven by specific refuge objectives, such as assessment of management activities; (2)

landscape scale surveys that address issues relevant to both the refuge and surrounding landowners; and

(3) regional, national, or continental monitoring programs. Refuge priorities are focused on Category 1,

which are derived from specific management objectives for each refuge. These surveys often provide critical

information for adaptive management. Refuge participation in the other two categories may be related to

relevance of the project to the refuge, as well as availability of funding and staff.

Recruitment of refuges into broader geographic monitoring initiatives will depend heavily upon whether the

data gathered are relevant to ongoing or proposed refuge management, and whether the sampling

technique and intensity are simple enough that a manager will not have to forego other management

priorities.

27

Appendix 4. Abstracts of Invited Presentations 

at the Marsh Bird Monitoring Workshop

26-28 April, 1998.
Proposed Applications of Data from a Marshbird Monitoring Network

Paul R. Adamus, Department of Fisheries and Wildlife, 

Nash Hall, Oregon State University, Corvallis, OR 97330

If implemented, a continental or regional marshbird monitoring program would serve mainly to detect

temporal trends in populations of individual species. However, with modification such a program could also

analyze spatial trends in collected data to identify areas where the biological integrity of wetlands and their

associated landscapes is being degraded. Especially when used with data from monitoring of other taxa,

knowledge gained from a marshbird monitoring program could form a basis for remedial action, such as

selection of particular wetland sites for restoration or implementation of watershed management plans.

Conceptually, one tool for interpreting and presenting the data from a marshbird monitoring program might

be the “Index of Biotic Integrity” (IBI). Aquatic biologists have developed and validated IBI’s regionally,

using fish and macroinvertebrates, to indicate the condition of streams and lakes. Developing and applying

wetland bird IBI’s probably would require identification of all bird species at each monitoring site, and

assignment of the species to guilds or assemblages known to be sensitive to pollution and other human

disturbance (as distinct from extreme naturally-occurring conditions). Pilot projects in riparian habitats in

Pennsylvania, Maryland, the mid-Atlantic highlands, and the Southwest have supported the usefulness of

bird communities as indicators of landscape disturbance, so continued development and validation of bird

IBI’s is warranted. Further research should focus on (1) defining the domain of regions, landscapes, wetland

types, and disturbance types over which wetland bird IBI’s can provide accurate information on

environmental impairment, (2) identifying which wetland bird assemblages are most sensitive to humancaused disturbances, and (3) identifying the metrics (combinations of variables) most able to separate

human-related from natural, macroscale spatial variation in bird community structure.

Since 1996 the USEPA has sponsored a Biological Assessment of Wetlands Work Group (BAWWG),

consisting of scientists from state and federal agencies and universities, to organize and communicate

information on protocols for monitoring and analyzing data on wetland birds, amphibians,

macroinvertebrates, algae, and plants. BAWWG has recently prepared information for state agencies to use

in developing and testing bird IBI’s in wetland and riparian habitats.

28 Proceedings of the Marsh Bird Monitoring Workshop
Evaluation and Development of Survey Techniques for Common Snipe

Kevin D. Downs and Stanley H. Anderson, Wyoming Cooperative Fish and Wildlife Research Unit,

University of Wyoming, Box 3166, University Station, Laramie, WY 82071

Common snipe (Gallinago gallinago delicata) numbers in North America are unknown. No survey

technique to monitor their numbers has been developed and doubts exist about using the Breeding Bird

Survey (BBS) to monitor snipe trends. In order to help solve these problems, this research project focused

on four major objectives: (1) evaluate existing labor intensive techniques such as tape playback, territorial

mapping, territorial/spot mapping, flush counts and nest searches; (2) develop and evaluate indices (call,

winnow and call/winnow counts) that could monitor snipe numbers on a continental scale; (3) identify

important habitat characteristics; (4) evaluate the effectiveness of the BBS for common snipe. Four labor

intensive techniques were evaluated for effectively estimating the number of snipe or territories. Territorial/

spot mapping was found to be the most effective technique because the results obtained accurately

represented the number of territories present. Flush counts were the second best technique because they

did not accurately estimate the number of snipe present in all snipe habitats. Flush counts worked best in

long narrow strip habitats that could be easily covered by a few people. In large continuous habitats flush

counts did not accurately estimate snipe numbers because snipe were harder to flush. Tape playback

territorial mapping and nest searches did not accurately estimate snipe numbers due to varying snipe

responses and difficulty in finding nests. An index that counts the number of different calling and winnowing

snipe heard most accurately monitored snipe numbers because the probability of detection, percentage of

snipe detected and the estimate of snipe numbers was the greatest, most consistent and most accurate. The

index should be conducted during the 20 day time period before snipe begin to incubate and after the arrival

of females. This 20 day time period usually falls after the full moon in April and before the first quarter in

May. Transects should be established in the habitat with points spaced 1 km apart. minimum of seven points

should be used to conducts surveys from in order to obtain good results. The survey is conducted at dusk

approximately 5 minutes after most of the snipe become active and should be discontinued when snipe cease

or decrease activity. The survey period is short (only usually lasts 30-45 minutes), so only 3 points or less

may be surveyed in one night. Each point should be visited at least 3 times during the 20 day time period.

There are six factors (season, time of day, lunar cycle, wind speed, solar radiation, and temperature) that

effect snipe winnowing and calling and should be considered or at least measured when conducting snipe

surveys. Driving roads the season prior to actual surveying will help identify possible snipe areas. Those

areas should also be searched for snipe nests the season prior to surveying, in order to have good

phenological information about the snipe area in question, which will help identify appropriate survey times

the following season. Surveyors should be standardized prior to conducting actual surveys if more than one

surveyor is used. For more detailed information about surveying for snipe refer to Downs (1998). From our

results, we identified four important characteristics (distance to nearest shrubby cover, water depth, soil

moisture, the dominance of sedges and sedge heights) and used them to construct a ranking criteria for

categorizing snipe habitats. We found the BBS is not conducted at the right time of day nor does it consider

the variables (season, lunar phase, solar radiation and temperature) that affect snipe activity to be effective

in detecting snipe trends. As a result, the numbers of snipe the BBS detects is low and the snipe activity

detected could be related to nest success more than abundance. A final report by Masters candidate Kevin

D. Downs will be completed during the spring of 1998. These results are from the last year of a 3-year study

funded by the 1995 Webless Migratory Game Bird Research Program (U.S. Fish and Wildlife Service and

the U.S. Geological Survey-Biological Resources Division), U.S. Fish and Wildlife Service (Migratory Bird

Management Office), Wyoming Game and Fish Department and the Wyoming Cooperative Fish and Wildlife

Research Unit.

Downs, K. D. 1998. Common snipe surveys, habitat and evaluation of the breeding bird survey. M.S. thesis,

University of Wyoming, Laramie. 91pp.

Proceedings of the Marsh Bird Monitoring Workshop 29
A 12-Step Program for Creating a Monitoring Program: 

An Extended Abstract Written in the Everyday Language of the Wildlife Biologist

Sam Droege, U.S. Geological Survey, Patuxent Wildlife Research Center, 11410 American Holly Drive,

Laurel, MD 20708-4015

The traditional approach to designing a new program is to pick the technique your buddies use, put in as

many samples as looks good on a map, locate those samples so that you get to hang out in your favorite

habitats, and hope that 20 years down the road someone will analyze and interpret it all for you.

In this document I propose an alternative model, one hopefully superior to that of the traditional one. For

those of you still captivated by the traditional approach, consider this a 12-step plan to freedom. When

examples are needed they will be for the situation of setting up a monitoring program for marsh inhabiting

birds.

Step 1.

First comes the question of which species are being targeting for monitoring. All birds that live in and

around marshes? Some ranking of primary species, secondary species, and collateral? What of things like

frogs, toads, and other non-birds too?

Step 2.

Over what time periods do you want your monitoring program to report on trends of marshbirds?

2, 3, 5, 10, 25, 100?

Step 3.

What MINIMUM magnitude of change or trend in marshbirds should this program be able to detect over

the time period stated in Step 2?

10%, 50%, 100%, ....- 3% per year, 5% per year?

Step 4.

Over what geographic region do you want to talk about changes in marshbird populations?

A refuge? A province? A country? A continent? Now we need to work through the whole notion of how

precisely you might want to talk about these trends.

Step 5.

Please designate your willingness to cry wolf, done via the setting of alpha (Type I error)

levels. That is, how often are you willing to claim that a significant population trend has occurred when, in

actuality, none has. For example, alpha (Type I error) can be 5%, 10%, or 20%. Hint: It is better to cry wolf

20% of the time and spend a little bit of time following up false leads than it is to set you alpha level so small

that populations have all gone to Hell while you waited for everything to be extremely statistically

significant.

Step 6.

Designate what proportion of the time the monitoring program should detect a trend if one

was really going on. This is known as setting the power of the program. For example, power can be 80%,

90%, 95%, or even, 100%. Hint: Detecting trends is the whole point of a monitoring program;. No?, so set

your power high.

Now we come to the phase of inspecting the monitoring technique you propose to use track population

trends and ask the question: Can it really deliver the goods?

WARNING: Pilot data required.

30 Proceedings of the Marsh Bird Monitoring Workshop
Step 7.

Either find someone who has used the methodology you are considering for your monitoring program (and

is willing to share their data with you) or go out and collect some pilot data on your own.

Step 8.

Ask your pilot data the following questions (Hint: These are simple calculations of means and sample

standard deviations and you can do them in any spreadsheet program).

What are the mean counts on plots or routes that get your target species? Low mean counts (<10) are

undesirable because the smaller the mean the greater your likelihood of getting a slug of zeros on a

significant number of your counts. Because the existence of negative birds is still a hotly debated topic

among biostatisticians (they really should spend more time out in the field) you have effectively run into a

wall with your monitoring program (that is, once your reach zero birds, no more information is available

regarding status) and the mathematics become difficult.

What is the spatial variation, that is, how variable are counts geographically (among plots or routes) for each

species?

How many completely zero plots or routes turn up (that is, plots that never get the species) when you set

your samples out? Sites that do not have the target species obviously tell you nothing about the trend in that

species, so, when you estimate how many samples you need to monitor a species you must adjust the sample

size upwards to account for the fact that a certain proportion of those plots will be always be zero.

How variable are counts for each species at a single site? The best way to answer this question is by looking

at long-term datasets, so that you can look at how the numbers vary over a period of years. If you only have

one year to collect pilot data and no existing datasets are available to mine, then you can take repeated

counts at a single site to get some minimum idea about sampling variation. However, be warned that

repeated counts WITHIN a year underestimate the overall count variation which must account for within

and among year variation in counts (this captures the variation due to the slop in your technique AND due

to normal fluctuations in numbers of critters among years).

Step 9.

Can a poorly performing technique be saved by covariates? If you find an ungodly amount of variation in

your counts, it may be possible that you can account for some of that noise (and decrease your needed

number of samples while increasing your power to detect trends) by accounting for the effects that

phenology, weather, and observers have on your system.

Step 10.

So that is all well and good, now how do I figure out how many samples I need?

What follows is a simple recipe for calculating that sample size. First go to the power analysis cookbook web

site at:

http://WWW.MP1-PWRC.USGS.GOV/powcase/powcase.html

(note: the occurrence of the letter one in the domain name, that is not the letter L)

And download the MONITOR.EXE sample size ez-baker and read over the enclosed directions for proper

use of this product. Then add the following ingredients into the MONITOR.EXE program:

■ Take the mean and standard deviations of counts and make some CVs.

■ Calculate the proportion of zero routes.

■ Mix well with your targets for:

■ Length and steepness of trend.

■ Precision of the estimates targets.

■ Bake your worst species CV first.

■ Double the number of samples to make sure that you have enough.

Now we come to the very hardest part of the process, the part where most of us fall from grace.

Proceedings of the Marsh Bird Monitoring Workshop 31
Step 11.

Prove that the method you are using yields an unbiased view of trends in the critters you are monitoring.

Several paths are open to you, pilgrim.

High Road:

Empirically prove that there is a relationship between the index you propose and the real number of birds

out there.

Road to Nowhere:

Heuristically prove that the likelihood of bias affecting the counts or affecting the sign of the slope is low to

nil.

See http://WWW.MP1-PWRC.USGS.GOV/.... for an example using counts of frogs and toads.

Road to Ruin:

This would be the attitude expounded by Baron Ernest Rutherford: “If your result needs a statistician then

you should design a better experiment”

In general, discovering the effects of bias is a difficult and expensive path to travel upon. But by avoiding

that path you take the risk of your program painting a false picture of the trends in your target animals. At

minimum, an attempt should be made to use the technique in conjunction with a set of mark-recapture

populations to investigate the relationships between count and population over several potentially biasing

situations.

Step 12.

Ok, now that you have reached sainthood by passing through the previous 11 steps you are ready to figure

out where you are going to put out your samples. Keep in mind the following: All things being equal all

things should be equal, that is, plot and route placement should be random or systematic. However,

completely random placement of plots is rarely efficient and you will likely need to think about setting up a

set of decision rules (e.g., only wetlands near roads will be surveyed) along with some stratification rules

(e.g., we will put in a higher density of samples in these areas because they are more important or they have

more potential observers).

Congratulations, you have made it through the 12 Step Monitoring Program. Now go check in with your

neighborhood statistician and have him check under the hood of your sampling design just to make sure you

have really been cured of your old habits.

32 Proceedings of the Marsh Bird Monitoring Workshop
Statistical Issues Related to Monitoring Marsh Birds

Charles M. Francis and Russ C. Weeber, Bird Studies Canada, 

P.O. Box 160, Port Rowan, Ontario N0E 1M0, Canada

We examined a number of statistical issues related to monitoring marsh birds that arose from a scientific

evaluation of the Marsh Monitoring Program (MMP) that has been run in the Great Lakes basin by Bird

Studies Canada (Long Point Bird Observatory) in collaboration with Environment Canada since 1995. Some

of these issues are discussed in the companion presentation by Weeber et al. Here, we focus on three

themes: route selection, sampling intensity (number of surveys per year), and power for trend detection.

1. Route Selection

The MMP was developed to sample marsh habitats throughout the Great Lakes basin, with particular

emphasis on marshes in “Areas of Concern” (AOC’s). The sampling procedure for AOC’s is different from

that outside of these areas. Within AOC’s, the survey goal has been to sample every marsh. Although this

has not been completely achieved, all AOC’s and most marshes within them are covered by at least one

route. As such, to the extent that stations are suitably positioned along these routes, the routes should

provide a fairly good sampling of AOC marshes (although sampling intensity is generally not adequate to

characterize individual AOC’s well). Outside of AOC’s, routes have been primarily picked by volunteers, and

we can be much less confident that they are representative of non-AOC marshes within the survey area (the

Great Lakes basin).

There are many challenges to developing a more representative (i.e. stratified randomized) sample of

marshes with a volunteer-based survey such as this one. One approach would be to select marshes based

upon a GIS database of all marshes/wetlands in the region. Selection could be based on strata determined

by criteria such as marsh characteristics (e.g. size, adjacent land use), ecoregions, and location (e.g. distance

from potential sources of surveyors). This method could provide known sampling probabilities for all

marshes in the study area, but has several potential difficulties. In practice, the sampling would have to be

further constrained by accessibility (not too far from a road and accessible by foot or possibly by canoe).

Discrete marshes are not necessarily easy to delineate. Problems could arise if the database is incomplete

(e.g. if some types or sizes of marshes are inadequately represented), if it does not accurately differentiate

all marshes from other types of wetlands, or if accessibility cannot readily be determined from the database.

At present, sampling for the whole Great Lakes Basin would require GIS databases from several sources

that probably differ in their characteristics.

An alternative sampling procedure would be to select random positions in the landscape, with appropriate

stratification, in a similar fashion to route selection for the Breeding Bird Survey, then survey the nearest

accessible marsh. This approach would be cheaper and easier to implement (GIS technology not required),

but will not lead to equal selection probability for all marshes: marshes with few neighboring marshes will

have a higher probability of being selected than marshes with many neighbors, and large marshes will be

more likely to be picked than small marshes. Stratification of the landscape by marsh density (if suitable

data are available to do this) could reduce but not eliminate this problem.

Regardless of the selection procedure, there are further constraints associated with matching routes and

volunteers. If routes are pre-selected, and volunteers allowed to choose from among the selected routes,

then the sample will no longer be strictly random if any of the selected routes are not covered—those

farthest from population centers or least accessible may be less likely to be picked. If routes are selected

upon demand for each volunteer, selections will need to be constrained to within a reasonable radius from

the volunteer’s home base. Furthermore, regardless of initial assignments, volunteers may be less likely to

continue surveying routes that are difficult or otherwise unattractive.

In view of the preceding limitations, it is quite possible that population trends on our volunteer-picked

routes will not be any less representative of the basin as a whole than those on randomly picked routes. For

this reason, we are currently encouraging volunteers to continue to survey existing routes, to ensure

adequate continuity for trend analysis using route regression. However, we plan to adopt some sort of

randomization procedure for selection of new routes as they are required in the future.

Proceedings of the Marsh Bird Monitoring Workshop 33
2. Number of Surveys

The MMP protocol for sampling birds requests two surveys per year on each route, at least 10 days apart

between May 20 and July 5 each year. Two surveys were chosen to reduce the effects of seasonal variation in

detectability of some species, and to increase the number of species detected at each station. However,

because the second survey carries a cost of reduced total numbers of routes surveyed, it is appropriate to

consider in some detail the actual benefits of two surveys based upon data from 1995-97. In each year, 70-

80% of stations were surveyed twice within the desired time frame. Of these, a mean of 0.5-1.1 (depending

upon the year) more species were detected on the first survey (mean date June 5) than on the second survey

(mean date June 25). On average, only 40% of species were detected on both surveys—the second survey

increased the number of species detected at each station from a mean of 17 to a mean of 24. Considering only

marsh nesting birds detected at 10 or more stations each year (22 species), 11 species were significantly

more likely to be detected on the first survey, but 4 species were more likely to be detected on the second

survey, highlighting the fact that the optimal survey time differs among species. For 4 of these species, there

were significant (p <0.05) differences among the three years in the relative value of the first and second

survey. This indicates that a single survey might confound annual variation in seasonal detectability

(possibly due to variation in vegetation phenology) with annual variation in populations. Thus the second

survey clearly does have benefits especially for evaluation of individual routes. From the perspective of

trend estimation, we do not know how many additional routes volunteers might be able to run if only a

single survey were required each year (it would probably be much less than double), and hence whether this

would outweigh the benefits of the second survey.

3. Survey Power for Estimating Trends.

We estimated the power of the survey to detect long-term population trends in mean numbers of 11 species

of marsh-nesting birds considered of particular conservation concern. We assumed analysis using log-linear

route regression models, and extrapolated variance estimates from changes on routes run in both 1995 and

1996. For 10 of the 11 species, a sample of 100 routes per year (on which the species was detected) was

estimated to be sufficient to detect a consistent annual change of 1-3% over 10 years (at p <0.05, power =

0.80). However, of 91 routes run in both years, most of the target species were detected on fewer than half of

the routes. Thus, for some of these species, the survey with its current sampling intensity could not be

expected to detect changes less than 4% per year over a 10-year period.

34 Proceedings of the Marsh Bird Monitoring Workshop
Techniques for Monitoring Inconspicuous Waterbirds: 

Results from Studies in Maine and Massachusetts

James P. Gibbs, College of Environmental Science and Forestry, State University of New York,

1 Forestry Drive, Syracuse, NY 13210

Scott M. Melvin, Massachusetts Div.of Fisheries & Wildlife, Rte. 135, Westborough, MA 01581

Shawn K. Crowley, Department of Forestry and Wildlife Management, Holdsworth Hall, 

University of Massachusetts, Amherst, MA 01003

We broadcast vocalizations of pied-billed grebe (Podilymbus podiceps), American bittern (Botaurus

lentiginosus), least bittern (Ixobrychus exilis), Virginia rail (Rallus limicola), and sora (Porzana carolina)

at 60 wetlands in Maine in 1989 and 1990 to derive standardized methods to monitor breeding populations of

these species. All wetlands contained 0.1-125.0 ha of emergent vegetation. Broadcasts of tape-recorded calls

at 1-10 stations per wetland between 1 May and 15 July improved detectability for all species by 93 to 1,320%

over 15-min passive observation periods at the edge of each wetland. Detection rates at wetlands where

target species were known to occur ranged between 0.56 (least bittern) and 0.86 (pied-billed grebe) per

survey visit. Three visits to a wetland were adequate to determine presence or absence of all species with

90% certainty. Least bitterns, soras, and Virginia rails were detected primarily within 50 m of observers,

while pied-billed grebes and American bitterns were detected up to 500 m away. Most detections were of

birds heard and not seen. Responsiveness of each species varied in relation to seasonal chronology, time of

day, wind, precipitation, and cloud cover.

We surveyed 123 emergent wetlands in Massachusetts and Maine during the 1991 and 1992 breeding seasons

to determine if broadcasts of tape-recorded calls increased detection rates of pied-billed grebes, American

bitterns, least bitterns, green herons (Butorides striatus), Virginia rails, and soras. Following a 3-minute

passive listening period at each station, we broadcast 1 minute of calls for each species at 1-10 survey

stations per wetland. Detection rates of Virginia rails and soras were greater during the conspecific call

portion of the broadcast sequence than during passive listening periods. In addition, both rails exhibited a

peak of response within the broadcast sequence during broadcast of conspecific calls. In contrast, both

green heron and American bittern had higher detection rates during passive listening periods than during

broadcasts of calls. However, due to small sample size and potential bias, we recommend further study of

responses of American bitterns to broadcasts of taped vocalizations. Sample sizes of pied-billed grebe and

least bittern were too small for analysis.

We suggest that regional populations of marsh birds can be monitored using standardized surveys along

mini-routes comprised of 10-15 point-count stations per route. From 10-15 survey points can be done in a

morning, either within 1 large or several smaller wetlands. In the northeastern United States, we

recommend that broadcasts of tape-recorded vocalizations be used to increase detection rates of pied-billed

grebes, least bitterns, Virginia rails, soras, and, perhaps, American bitterns. Except for wetlands that are

small and easily accessible, surveys should be conducted by canoe. Surveys should be conducted between

0430 and 1000 h on days with calm or light winds and no steady precipitation. Randomly stratifying sampling

effort between large, species-rich wetlands and wetlands that are small, of marginal habitat quality, were

historically occupied by target species, or have been recently created, for example by beavers, may be

desirable. This design would balance the need to maximize detection rates while surveying populations over

a representative sample of available habitats. Finally, monitoring habitat changes along mini-routes would

be important for interpreting population trends of marsh birds.

Proceedings of the Marsh Bird Monitoring Workshop 35
Designing Effective Regional Monitoring Programs for Marshbirds

James P. Gibbs, State University of New York, College of Environmental Science and Forestry, 

350 Illick Hall, Syracuse, NY 13210

Scott M. Melvin, Massachusetts Division of Fisheries and Wildlife, Field Headquarters, 

Westborough, Massachusetts 01581

In developing regional monitoring programs, biologists should retain a focus on the major challenge that we

face: to devise sampling methods that permit unbiased and statistically powerful surveys of marshbird

populations in a logistically feasible manner. Clear articulation of monitoring objectives (time frame, trend

strength sought for detection, alpha, and beta) is the first step in this process. Based on a decade of

experience with marshbird monitoring in Maine and Massachusetts, we highlight several considerations for

the effective design of regional marshbird monitoring programs. These include whether call-response

surveys adequately “index” marshbird abundance, use of waterbird mini-routes’ as the unit for sampling

marshbird populations, and tools for estimating the trade-offs between survey effort and power to detect

trends in marshbird populations.

36 Proceedings of the Marsh Bird Monitoring Workshop
Sora Rail Studies on the Patuxent River, Maryland

Michael Haramis, U.S. Geological Survey, Patuxent Wildlife Research Center, 11410 American Holly

Drive, Laurel, MD 20708-4015

Gregory D. Kearns, Maryland National-Capital Park and Planning Commission, Patuxent River Park,

16000 Croom Airport Road, Upper Marlboro, MD 20772-8395

The freshwater marshes of the tidal Patuxent River are well known for their annual fall concentration of

migrant soras (Porzana carolina) and were formerly the most famous rail hunting grounds in the

Chesapeake Bay region. Because of concern over the apparent long-term decline in number of soras and the

decline in the quality of the Patuxent marshes, especially the loss of wild rice (Zizania aquatica), the

Maryland National-Capital Park and Planning Commission (MNCPPC), co-steward of the Jug Bay National

Estuarine Research Reserve, sponsored rail-related research beginning in 1987. Past efforts focused on

developing efficient trapping techniques, age and sex criteria, and monitoring body mass dynamics. Noted

progress was made in developing digital playback systems and trap improvements to enhance sora captures.

These improvements increased capture success by over an order of magnitude and resulted in capture of

2,315 soras and 276 Virginia rails (Rallus limicola) in the 5 year period, 1993-97. Although these methods

demonstrate the efficacy of banding large numbers of soras on migration and possibly winter concentration

areas, captures at the Patuxent River site have been 70-90% hatching-year birds and recoveries and

recaptures have been virtually nonexistent. With the present effort, this outcome precludes population

parameter estimation using traditional capture-recapture or recovery model methodologies.

In 1996, studies were initiated to employ radio telemetry methods to investigate length of stay, habitat use,

survival, and migration characteristics of fall migrant soras. These studies are ongoing and will be continued

through 1998 with a grant from the U.S. Fish and Wildlife Service’s Webless Migratory Game Bird

Research Program and support from the U.S. Geological Survey’s Patuxent Wildlife Research Center.

Supplemental funding has also been provided by MNCPPC, FWS Region 5, the Maryland Ornithological

Society, Quail Unlimited, and Prince Georges Community College.

During 1996-97 we developed a successful radio transmitter attachment technique to secure 1.8g radio

transmitters over the synsacrum of migrant soras. We modified Rappole and Tipton’s (1991) leg-loop

attachment method by addition of a waist loop to prevent soras from slipping transmitters over their short

tails. Thin gauge (0.6mm) elastic thread proved ideal for attachment and allowed for girth expansion

associated with fattening during stopover. Sixty instrumented soras have been monitored in two years of

study from early September until early November. Only a single mortality was recorded and 41 (68%) were

confirmed and another 13 (total 90%) were believed to have migrated from the study area. Only a single bird

slipped a radio transmitter. Most birds demonstrated a sedentary nature in the marsh throughout stopover.

Average length of stay was 44 days in 1997 (n = 29) with peak departure occurring 20-24 October.

Departing migrants were detected using a receiver/data-logger monitoring system placed 4 miles down

river from the study site. Thirty-six of 37 (97%) soras departed in a 2-hour window of time, beginning 1 hour

after sunset. Departure was synchronized with cold fronts on clear, starlit nights. Twenty-five soras were

monitored on migration from 8 km to as far away as 770 km. Findings indicate migration flight speeds of 40

to 50mph and a direct southward orientation from the study site at least until contact with the Atlantic

Ocean west of Cape Lookout, North Carolina. We also attempted to monitor passage of migrant soras radio

tagged at Iroquois National Wildlife Refuge in western New York by biologist Soch Lor. None were

recorded passing a monitoring unit at Haldeman Island in the middle of the Susquehanna River 10 miles

north of Harrisburg, Pennsylvania. This further corroborates our findings that when migrating overland,

soras move in a direct southward orientation and are not following land features such as major rivers. We

will attempt to expand our tracking effort of migrant soras especially in the deep South in fall 1998.

In 1997 we further examined the effect of our audio lure on the age, sex, and capture rate of soras. We

alternated 5 trap lines with and 5 lines without playback every 2 days for a period of about 5 weeks. The

results indicated a 2 x capture rate with playback (p <0.001), with no effect related to age (p >0.1), or sex

among AHY birds (p >0.9). Sex effect among HY birds was less conclusive because of sexing error. Using

DNA finger printing techniques on a grab sample of 81 HY soras, we determined our sexing error to be

about 13% in favor of males. Applying this correction, our test was marginally significant (p = 0.06, n = 622).

The DNA sexing results indicate that it is unlikely that HY soras can be sexed at a confidence level of 90%

or better. This finding is preliminary and we intend to reexamine this issue in 1998.

Proceedings of the Marsh Bird Monitoring Workshop 37
Comparison of Point Count and Play Back Survey: 

Techniques for Detecting Breeding Wetland Birds

Eileen Kirsch, Upper Mississippi Science Center, 

2630 Fanta Reed Rd. PO Box 818, LaCrosse, WI 54602-0818

Tape play back can be effective for detecting inconspicuous wetland birds. However, in a broader study

focusing on breeding passerines, I wanted to determine if playing the tape affected detectability of wetland

passerines, and if tape play back could increase detectability of the inconspicuous species although the

survey design was not optimal for them. Therefore, both survey types were conducted consecutively during

a single visit at each point. Within a 50 m radius of an observer, neither survey method was better than the

other (paired t-test) for detecting total numbers of birds, numbers of species, and individuals of most

species. The exception was that more Virginia rail (Rallus limicola) were detected with play back than point

count. At an unlimited distance, however, more birds, species, and individual Marsh Wrens (Cistothorus

palustris), Song Sparrows (Melospiza melodia), Swamp Sparrows (M. georgiana), Willow Flycatchers

(Empidonax trailii), Yellow Warblers (Dendroica petechia), and Red-winged Blackbirds (Agelaius

phoeniceus) were detected with point counts. At an unlimited distance, play back was more effective for

detecting Virginia Rails and Soras (Porzana carolina), but not Least Bitterns (Ixobrychus exilis), Common

Moorhens (Gallinula chloropus), and Pied-billed Grebes (Podilymbus podiceps). Survey order did not

affect comparisons between the 2 methods for either distance. If all wetland birds are the target for study or

monitoring, an unlimited detection distance is desired, and only a single visit to survey sites is possible, both

methods should be used.

38 Proceedings of the Marsh Bird Monitoring Workshop
Vocalization Behavior and Response of Black Rails

Michael L. Legare, Dynamac Corporation, DYN-2, Kennedy Space Center, FL 32899

William R. Eddleman, Department of Biology, MS6200, Southeast Missouri State University, 

Cape Girardeau, MO 63701

P. A. Buckley, U.S. Geological Survey, Patuxent Wildlife Research Center,

11410 American Holly Drive, Laurel, MD 20708-4015

Colleen Kelly, Department of Mathematics, San Diego State University, 

5500 Campanile Drive, San Diego, CA 92182-7720

We measured the vocal responses and movements of radio-tagged black rails (Laterallus jamaicensis) (n =

43, 26 males, 17 females) to playback of vocalizations at 2 sites in Florida during the breeding seasons of

1992-95. We used regression coefficients from logistic regression equations to model the probability of a

response conditional to the birds’ sex, nesting status, distance to playback source, and the time of survey.

With a probability of 0.811, non-nesting male black rails were most likely to respond to playback, while

nesting females were the least likely to respond (probability = 0.189). Linear regression was used to

determine daily, monthly, and annual variation in response from weekly playback surveys along a fixed route

during the breeding seasons of 1993-95. Significant sources of variation in the linear regression model were

month (F = 3.89, df = 3, p = 0.0140), year (F = 9.37, df = 2, p = 0.0003), temperature (F = 5.44, df=1, p =

0.0236), and month*year (F = 2.69, df = 5, p = 0.0311). The model was highly significant (p <0.0001) and

explained 53% of the variation of mean response per survey period (R2 = 0.5353). Response probability data

obtained from the radio-tagged black rails and data from the weekly playback survey route were combined

to provide a density estimate of 0.25 birds/ha for the St. Johns National Wildlife Refuge.

Density estimates for black rails may be obtained from playback surveys, and fixed radius circular plots.

Circular plots should be considered as having a radius of 80 m and be located so the plot centers are 150 m

apart. Playback tapes should contain one series of Kic-kic-kerr and Growl vocalizations recorded within the

same geographic region as the study area. Surveys should be conducted from 0-2 hours after sunrise or 0-2

hours before sunset, during the pre-nesting season, and when wind velocity is <20 kph. Observers should

listen for 3-4 minutes after playing the survey tape and record responses heard during that time. Observers

should be trained to identify black rail vocalizations and should have acceptable hearing ability.

Given the number of variables that may have large effects on the response behavior of black rails to tape

playback, we recommend that future studies using playback surveys should be cautious when presenting

estimates of “absolute” density. Though results did account for variation in response behavior, we believe

that additional variation in vocal response between sites, with breeding status, and bird density remains in

question. Playback surveys along fixed routes providing a simple index of abundance would be useful to

monitor populations over large geographic areas, and over time. Considering the limitations of most agency

resources for webless waterbirds, index surveys may be more appropriate. Future telemetry studies of this

type on other species and at other sites would be useful to calibrate information obtained from playback

surveys whether reporting an index of abundance or density estimate.

Proceedings of the Marsh Bird Monitoring Workshop 39
Avian Community Structure of Front Range Wetlands: 

Effects of Area, Shape, Hydrology and Vegetation

Michael W. Monahan, Department of Biological Sciences, University of Denver, Denver, CO 80208

Steven T. Faulk, Foster Wheeler Environmental, Lakewood, CO 80228

This study explored the factors shaping avian use of 36-closed canopy, cattail wetlands on the Colorado

Piedmont. Six species (sora and Virginia rail, red-winged and yellow-headed blackbird, yellowthroat, and

song sparrow) were censused on three dates by one of three methods, song playback for rails, visual

scanning for blackbirds, and line transects for yellowthroats and song sparrows. The presence and breeding

status of other bird species (principally waterfowl species but also mourning dove, common grackle, and

American coot) were recorded while censusing the six “target” species. Wetland shape, size and edge

density were determined from aerial photographs. Transect sampling was used to quantify hydrologic and

vegetation features (floristics and physiognomy) of each wetland. Objectives of the study were to identify

habitat correlates of avian species richness and densities of individual wetland residents.

Breeding bird richness on individual wetlands varied from 1 to 13 with a modal value of 5 to 6 species. In

general, the species makeup of individual communities was a function of community size. Thus, redwings

were the only species to appear alone, yellowthroats typically joining redwings in two-species communities,

song sparrows or Virginia rails being the third member of 3-species communities, and so on. In effect, the

species tended to form a “nested series,” implying that the resource needs of the habitat specialists were

subsumed under those of the habitat generalists. Soras and yellow-headed blackbirds were uncommon

members of these communities (12 and 4 sites, respectively) and only occurred on sites that also had other

members of the breeding bird community.

Roughly half the variance (R2 of 52%) in avian species richness across sites was accounted for variation in

wetland size (range, 0.5 to 5.0 ha). Using stepwise regression analysis, within site diversity in water depth

accounted for the next largest fraction of the variance in avian species richness (R2 of 73% for the twovariable model). The various measures of plant floristics and physiognomy showed little or no associations

with avian species richness after wetland size and hydrology were taken into account. Likewise, wetland

shape, as measured by edge length relative to wetland area, had little or no measurable effect on avian

species richness. Results were similar when wetlands were compared for variation in richness of individual

bird taxons (6 species of songbirds, 3 species of rails, and 5 species of waterfowl.

Variation in wetland size was the single strongest correlate of resident population size for song sparrows

(R2 of 36%), red-winged blackbirds (R2 of 49%), Virginia rails (R2 of 49%), and yellowthroats (R2 of 68%).

Sora numbers correlated most strongly with area of wetland containing standing water (R2 of 64%). When

subjected to stepwise regression analysis, models incorporating wetland size and hydrology accounted for

most of the explained variation in population sizes of these 6 resident species.

For closed canopy, cattail wetlands on the Colorado Piedmont, avian species richness in the breeding season

is likely to be highest on sites that are large, spatially diverse in depth of standing water, and settled by

soras and/or yellow-headed blackbirds. Soras and Virginia rails were the only two wetland specialists among

webless species in these breeding bird communities. For purposes of estimating resident population size of

these two rail species, the present results point to area of measurable water as a reliable indicator.

40 Proceedings of the Marsh Bird Monitoring Workshop
Effectiveness of Marsh Bird Monitoring Methods

Charles R. Paine, Max McGraw Wildlife Foundation, P.O. Box 9, Dundee, IL 60118

Standard survey methods that rely on passive observation are ineffective for many wetland bird species

because individuals vocalize infrequently and are difficult to observe in dense wetland habitats. Biologists

have been using playbacks of pre-recorded calls to increase detection rates of rails and other marsh birds

for more than 20 years, but few studies have evaluated the effectiveness of the method and its possible

biases. Variation resulting from differences in observers, weather, time of day, date, and other factors

complicates analyses of large scale bird population surveys and sometimes makes results difficult to

interpret. Use of broadcast calls in population surveys further complicates this situation by introducing an

array of potential new sources of variation including 1) the number of species included in broadcasts, 2) the

number of repetitions of each call, 3) the type of calls that are used, 4) the order of recorded calls, 5) the

length of the silent period between calls, and 6) the volume of broadcasts. The more species that are

included in broadcasts, the greater the problems. It is important that we weigh the relative costs and

benefits of using call broadcasts in population surveys and understand the biases associated with their use

before designing a national scheme for monitoring marsh birds.

In 1995, the Max McGraw Wildlife Foundation initiated a project to develop multi-species survey techniques

to estimate abundance and nesting productivity of wetland birds. Point counts using playbacks of prerecorded calls were conducted on 11 northeastern Illinois marshes once every two weeks from mid-April

through July, 1995 –1997. Points were placed at least 25 m from the edge of wetlands in a rough 200 m grid.

Counts were conducted from dawn until five hours after dawn. During each point count, 8 minutes of passive

observation was followed by playback of 8 minutes of recorded calls. Tapes including calls of 4 or 11 wetland

bird species were played at alternating points. Wetlands were searched for nests once every two weeks and

nests were re-visited once a week to determine their fate.

Thirty-four wetland associated species were detected 10 or more times during 910 point counts. Both passive

observation and playbacks proved effective in monitoring wetland bird populations. More birds were first

detected during the initial 8-minute passive observation period than during the subsequent 8-minute

playback period in four of the eight common species included in playbacks (p <0.010, American coot, least

bittern, green heron, and marsh wren). No difference in the number of birds first detected during the

passive and playback periods could be found in two species (common moorhen and pied-billed grebe). Only

Virginia rails and soras were detected more frequently (p <0.033) during playback than passive

observation. However, the preceding analysis assumed a 1:1 expected ratio between the number of

detections in the first and second half of a 16-minute observation period. This assumption proved wrong.

New detections declined steadily from minute one through eight of the passive observation period and likely

would have continued to decline through an additional eight minutes of passive observation. Further

analyses that accounted for declines in the rate of new detection with time spent at a point indicated that

playback during observation minutes 9-16 increased detection rates over predicted values for passive

observation by 13.0 times for Virginia rail, 6.3 times for common moorhen, 2.2 times for sora, 2.0 times for

American coot, 1.9 times for green heron, and 1.6 times for pied-billed grebe (p < 0.027). Playbacks could not

be shown to increase detection rates in least bitterns or marsh wrens (p >0.100).

The number of species included in broadcasts, which species are included, the length of broadcast for each

species, and the overall length of the observation period all potentially impact

the number of individuals detected during a point count. It is impossible to standardize all of these factors

simultaneously across multiple studies and regions with different species compositions.

However, length of nonspecific call broadcasts may influence detection rates less than the other factors

listed above. We found broadcast of calls of four versus eleven species (120 s and 45 s of calls per species,

respectively) had no impact (p >0.200) on effectiveness of playbacks in three of the four species included on

both tapes (sora, Virginia rail, and common moorhen). The 4-species tape was more effective (p = 0.026) in

eliciting responses from American coots, suggesting a longer sequence of calls may improve detection rates

in coots.

Proceedings of the Marsh Bird Monitoring Workshop 41
We also located and monitored over 900 nests of 13 wetland species from 1995-1997. Nest location and status

information was used to identify point counts conducted near active nests. To evaluate survey effectiveness,

we determined whether or not adult birds were detected near nests for all point counts conducted within

75m of active nests. In red-winged blackbirds, marsh wrens, and yellow-headed blackbirds, at least one

adult was detected within 50m of active nests during 89-94% of counts. Common moorhen, sora, and Virginia

rail adults were detected within 75m of active nests during 53-68% of point counts. Adults were detected in

the vicinity of active nests less frequently in pied-billed grebes (33% of 15 counts), least bitterns (28% of 43

counts) and American coots (40% of 5 counts).

Mayfield nest success for years combined was 38% in red-winged blackbirds (n = 377), 42% in least bitterns

(n = 60), 73% in yellow-headed blackbirds (n = 102), 30% in marsh wrens (n = 64), 33% in common grackles

(n = 48), 78% in common moorhens (n = 34), 73% in pied-billed grebes (n = 17), 32% in sora (n =17), 52% in

Virginia rail (n = 17), and 83% in black terns (n = 39). Nest success for most species was at or above values

that have been reported in the literature, and monitoring methods appeared to have no dramatic impact on

nest success.

42 Proceedings of the Marsh Bird Monitoring Workshop
Marsh Birds and the North American Breeding Bird Survey: 

Judging the Value of a Landscape Level Survey for Habitat 

Specialist Species with Low Detection Rates

John R. Sauer, USGS BRD, Patuxent Wildlife Research Center, Laurel, MD 20708

The North American Breeding Bird Survey was started in 1966, and provides information on population

change for >400 species of birds. It covers the continental United States, Canada, and Alaska, and is

conducted once each year, in June, by volunteer observers. A 39.4 km roadside survey route is driven

starting 30 min before sunrise, and a 3 min point count is conducted at each of 50 stops spaced every 0.8 km.

Existing analyses of the data are internet-based (http://www.mbr-pwrc.usgs.gov/bbs/bbs.html), and include

maps of relative abundance, estimates of population change including trends (%/yr), composite annual

indices (pattern in time), and maps of population trend (pattern in space).

At least 36 species of marsh birds are encountered on the BBS, and the survey provides estimates with

greatly varying levels of efficiency for the species. It is often difficult to understand how well the BBS

surveys a species. Often, efficiency is judged by estimating trend and its variance for a species, then by

calculating power and needed samples to detect a prespecified trend over some time period (e.g., a 2%/yr

trend over 31 yr). Unfortunately, this approach is not always valid, as estimated trends and variances can be

of little use if the population is poorly sampled. Lurking concerns with BBS data include (1) incomplete

coverage of species range; (2) undersampling of habitats; and (3) low and variable visibility of birds during

point counts. It is difficult to evaluate these concerns, because known populations do not exist for

comparison with counts, and detection rates are time-consuming and costly to estimate.

I evaluated the efficiency of the BBS for selected rails (Rallidae) and snipes (Scolopacidae), presenting

estimates of population trend over 1966-1996 (T), power to detect 2%/yr trend over 31 yr, needed samples to

achieve power of 0.75 with alpha= 0.1, number of survey routes with data for the species (N), average

abundance on survey routes (RA), and maps of relative abundance. Examples include Yellow Rail

(Coturnicops noveboracensis) (T=12 %/yr; P= 0.0085; N=28; routes; RA=0.05; Power=0.37; Needed

samples=85), Black Rail (Laterallus jamaicensis) (No trend data or power information available, N=8),

Clapper Rail (Rallus longirostris) (T=1.9%/yr; P=0.55; N=64; RA=0.31; Power=0.35; Needed

samples=590), King Rail (Rallus elegans) (T=-4.2 %/yr; P= 0.03; N=76; Power=0.41; Needed

samples=159), Sora (Porzana carolina) (T=0.98 %/yr; P= 0.24; N=720; RA= 0.92; Power=0.69; Needed

samples= 377), and Common Snipe (Gallinago gallinago) (T=-0.24 %/yr; P= 0.54; N=1412; RA= 2.19;

Power=0.98; Needed samples=205).

With regard to quality of BBS data, marsh birds fall into 3 categories: (1) almost never encountered on BBS

routes; (2) encountered at extremely low abundances on BBS routes; and (3) probably fairly well sampled by

BBS roadside counts. BBS data can provide useful information for many marsh bird species, but users

should be aware of the limitations of the BBS sample for monitoring species that have low visibility from

point counts and prefer habitats not often encountered on roadsides.

Proceedings of the Marsh Bird Monitoring Workshop 43
The Ohio Breeding Bird Survey

Mark C. Shieldcastle, Ohio Division of Wildlife, Crane Creek Wildlife Research Station,

13229 W. S.R. 2, Oak Harbor, OH 43449

The Ohio Division of Wildlife Strategic Plan, Ohio Partners in Flight and the Lower Great Lakes Joint

Venture of the North American Waterfowl Management Plan all point out that severe wetland habitat loss

has most likely resulted in population reduction of wetland birds. A survey designed to establish wetland

breeding bird abundance was initiated in 1990 by the Ohio Division of Wildlife (ODOW) and Ohio

Cooperative Wildlife Research Unit (OCWRU). The Research Unit was contracted by the ODOW, to first

determine what species in Ohio are not adequately covered by the Federal BBS and to secondly, develop a

survey that would fill this gap in knowledge. Species inadequately monitored were predominately wetland

species but also included forest patch specialist, nocturnal and relatively non-vocal species (Andres, 1990;

Earnst and Andres, 1996).

An experimental wetland breeding bird survey (WBBS) has been conducted since 1991. Volunteers are

utilized for the survey and data was compiled by the OCWRU until 1994 and since by the Wetland Research

Station of the ODOW. Approximately 40 survey routes were initiated by volunteers on wetlands familiar to

them. Study design is composed of a series of stops conducted on pre-determined routes from May 15 to

June 10 (Andres 1991). All birds seen or heard in a five minute period within an arc of 100 yards of the

observer are recorded. During the five minute period, a tape is played containing calls of the American

bittern, least bittern, sora, Virginia rail, and king rail. Any birds flushed from the survey zone upon

approach, or flying through the zone, are counted. Each route is to start 2 hour before sunrise, and continue

for three hours, or until the route is completed. Selected species are recorded.

Several points stand out that need to be dealt with to have a useable survey for statewide wetland breeding

bird trends. There is considerable concern with the method of wetland selection. Nearly half of the sites are

located in the Lake Erie marsh region which is substantially different from the rest of the state. The Lake

Erie wetlands are all control level marshes that may have very different water regimes and associated birds

from year to year. Inland wetlands are most often located along roads and were chosen by volunteers

because of birding interest. These wetlands tend to be small and highly variable in quality, It is unknown as

to the representation these wetlands have to Ohio’s wetland habitat base. A patchwork of data collection has

been a result of volunteers having only mornings available to conduct surveys. Often a volunteer has only

one or two opportunities to complete their survey.

ODOW has initiated a graduate level study to investigate both survey timing and to evaluate the quantity

and location of various wetland habitats throughout Ohio. Survey timing will look at the feasibility of

utilizing evening surveys to increase volunteer participation and compliance in survey needs. Wetland

habitats in Ohio will be stratified by GIS analysis of the wetland inventory completed in Ohio and wetlands

will be systematically chosen for inclusion in the long term study design. Wetlands in the Lake Erie marsh

region will be stratified between drawdown and water units and individual points will shift between these

strata from year to year depending on land management.

Objectives of the Ohio survey are to develop a long term wetland breeding bird monitoring program

representative of Ohio wetlands with adequate sample size and consistent coverage to evaluate population

health at state wide and habitat type levels.

44 Proceedings of the Marsh Bird Monitoring Workshop
Density Indices for Sora and Virginia Rails

Jennifer Skoloda and Christine A. Ribic, USGS BRD Wisconsin Cooperative Wildlife Research Unit, 

Dept. of Wildlife Ecology, University of Wisconsin, Madison WI 53706

Recently, interest in developing standardized monitoring techniques for inconspicuous marsh birds has

grown. In order to develop standard protocols more information is needed about the meaning of callplayback surveys in relation to population size. In addition, designing surveys for rails at the refuge level

has been hampered due to lack of long-term baseline data. We report on (1) a comparison of call playback

surveys to a population index based on live trapping and (2) evaluating survey effort and timing in a refugewide monitoring program based on 11 years of past survey data. Each one will be discussed separately

below.

Comparison of vocalization and trapping indices

Call-playback surveys and live-trapping surveys were conducted at 10 sites at Horicon National Wildlife

Refuge (NWR), Wisconsin, during the breeding season (May to July) in 1996 and 1997. Trap sites were 50 m

radius circles (0.88 ha), randomly placed along dikes throughout the refuge. At each site there were two

modified cloverleaf traps, a drift fence, and a center platform with a sound system. Call-playback surveys

were done at the trap sites the day before trapping or as close to the corresponding trapping date as

weather permitted. We surveyed and live-trapped each site at dawn, bi-weekly until 15 July. Call-playback

indices were the average number of birds detected per site.

We originally planned on doing a mark-recapture estimate based on trapping. However, recapture rates

within and between years were too low (no soras and only two Virginia rails were recaptured within a

season; none of either species was recaptured between years). Therefore we developed a population index

based on trapping of adults. Trapping indices were the average number of adults caught per site.

Trap sites were classified as breeding and non-breeding based on whether or not juveniles were trapped at

the site before 15 July. We plotted vocalization indices against trapping indices. Correlations of the indices

were calculated using Spearman’s rank correlation coefficient. Tests for significant positive correlation were

made using an a of 0.05.

Sora vocalization and trapping indices showed a significant positive correlation in 1996. This correlation was

strongly influenced by two points. In 1997 the sora indices were not significantly correlated and there were

no influential points. Vocalization and trapping indices for the Virginia rail had a significant positive

correlation in 1996. This correlation was even stronger when one influential point was removed. There was

no significant correlation between vocalization and trapping indices for Virginia rails in 1997. Removal of an

influential point did not change this.

More work is needed to understand the relationship between both indices and population size for sora and

Virginia rail. Vocalization surveys should be used until trapping can be investigated more thoroughly.

Evaluating refuge-level survey design using 11 years of survey data

Horicon NWR has surveyed rails using call-playback surveys in the spring and summer 1983-1986 and 1990-

1996. Each year 16 to 18 survey points were established along refuge roads. Location and number of the

sites varied from year to year depending on habitat and water conditions. Survey points were semicircles of

one hectare in size (80 m diameter). These sites were surveyed weekly, usually for 10 weeks (late April

through mid June) using call-playback point counts. When designing a survey for rails, questions arise

about how many sites to survey and when to do them. We use subsets of the 11 years of survey data to

determine when surveys should be done and how many sites should be surveyed in order to adequately

track population trends on a refuge scale.

Proceedings of the Marsh Bird Monitoring Workshop 45
We averaged results from sites and weeks within years to get yearly indices for the 11 years for both sora

and Virginia rail. This was assumed to be a true representation of the population trend over time at Horicon

NWR and we refer to this as the true trend. We then created random subsets of weeks and sites and

compared results from these subsets to the true trend using Pearson’s correlation coefficient; significance

was assessed at an a of 0.05.

We wanted to determine if conducting a single annual survey would result in a trend similar to the true

trend and what the optimum timing for a single annual survey would be. First we compared trends obtained

from all single-week indices (averages of all sites within a single week) to the true trend. All trends resulting

from the single-week subsets were significantly similar to the true trend. For data on sora, the median

correlation was between 0.76 and 0.81. For data on Virginia rail, the median correlation was between 0.88

and 0.92.

Given that any week would be suitable for doing a single annual survey we chose two

weeks, the second week in May and the second week in June, to test random subsets of reduced number of

sites. These weeks were chosen specifically to test for differences in sora call rates; in June, sora typically do

not respond to call-playback tapes. There is no such major refractory period for Virginia rail. For each of the

two weeks we took subsets of sites by randomly selecting 10, 20, 30, 40, 50, 60, 70, 80, and 90% of the sites.

This random selection was repeated 20 times for each percentage level. If surveys were done in the second

week of May, at least 40-50% of the sites would need to be surveyed to have correlations of greater than 0.6

with the true trend for both sora and Virginia rails. If the surveys were done in the second week of June at

least 70% of the sites would need to be surveyed to obtain these same correlations with the true trend for

both species.

Because it is unrealistic to assume that a refuge biologists will be able to survey in a given week every year,

we wanted to investigate what would happen to the trend if the biologist could do the survey in one out of

three chosen weeks with a fixed subset of random sites. To do this we randomly selected the week within a

three week window (the second, third and forth weeks of May) in one of three ways. Weeks were selected

using either a uniform random distribution, normal random distribution with a standard deviation of a half a

week, or normal random distribution with a standard deviation of one week. We ran this simulation

assuming 16 sites would be surveyed. We ran 30 trials for each of the 3 methods of randomly selecting a

week. We found that consistent surveying in one week was important; trends from the normal random

distribution methods were more likely to have correlations greater than 0.70, regardless of species.

At the refuge scale less effort is needed to maintain sufficient monitoring. Subsets from the 11 years of

Horicon data show that we can do single annual surveys with fewer sites and still obtain results similar to

those obtained using more effort. Surveys done in May require less effort when covering both rail species

than when done in June. We suggest that, at the refuge level, it would be beneficial to do a pilot study to

locate areas where rails are heard and use these sites to choose a random subsample for future monitoring.

46 Proceedings of the Marsh Bird Monitoring Workshop
Monitoring King and Yellow Rails in Texas

R. Douglas Slack and Kelly L. Mizell, Department of Wildlife and Fisheries Sciences, Texas A&M

University, College Station, Texas 77843

Texas coastal wetlands serve as wintering or breeding grounds for 6 species of rails. King rails (Rallus

elegans), clapper rails (Rallus longirostris), and black rails (Laterallus jamaicensis) are known to breed

and winter in Texas, whereas yellow rails (Coturnicops noveboracensis), soras (Porzana carolina), and

Virginia rails (Rallus limicola) are winter residents only. These rails inhabit coastal marshes throughout the

western gulf coast as well as freshwater wetlands associated with rice agricultural fields.

Rails are almost entirely associated with wetlands and therefore are likely important indicators of wetland

ecosystem quality. Coastal wetlands in Texas have declined by more than 52% during the last 200 years.

Remaining wetlands have been fragmented and degraded. Declining rail numbers on wintering grounds are

likely related to habitat loss, but also may be an indication of degradation in quality of remaining wetlands.

Although the nature of wetland degradation is not fully known; factors which may contribute to changes in

wetland quality include: nonpoint source pollution, alterations of hydrology, and declines in food availability.

We report on efforts to monitor local populations on two national wildlife refuges, primarily designed to

determine presence, habitat associations and responses to management. We have chosen to focus on king

and yellow rails studied at the Attwater Prairie Chicken National Wildlife Refuge and Anahuac National

Wildlife Refuge. These two species were selected because of differing periods of residency in Texas. Because

the king rail breeds and winters in Texas coastal freshwater marshes, we used both audio techniques and

radio telemetry to determine habitat associations. Responses of king rails to taped calls were recorded most

frequently from early spring to the onset of summer in freshwater marshes associated with nearby rice

agriculture. Audio techniques were supplemented by use of radio-telemetry during the non- breeding

season. On the other hand, the yellow rail presents a significant monitoring challenge. Because the yellow

rail only winters in Texas, attempts to elicit vocal responses to audio techniques were unsuccessful.

Therefore, we used radio-telemetry with a geographic positioning system to determine habitat associations

and home range sizes of yellow rails.

Radio telemetry requires capture of individuals and successful attachment of appropriate radio

transmitters. Attempts to capture king rails included the unsuccessful use of cloverleaf and havahart traps.

We were successful using drop nets in capturing individual king rails foraging in irrigation canals. Backpack harnesses were used for attachment of transmitters to king rails. Unsuccessful attempts to capture

yellow rails included drift lines with funnel traps and mist nets. We were successful in capturing yellow rails

by pulling weighted drag lines through the marsh to flush individuals at night. Flushed birds were captured

using hand nets. Transmitters were affixed to the bird using a modified synsacrum attachment. This

attachment placed the weight of the transmitter in the pelvic region and was used on 38 yellow rails during

the winters of 1997 and 1998. Transmitters attached in the scapular region were unsuccessful.

Data from these studies indicated that while present in Texas these species exhibited different habitat

associations. King rails were found in freshwater coastal marshes and inland wetlands, including those

associated with rice agriculture. King rails were located in marshes with relatively dense vegetation and

water ranging in depth from 3-10 cm. Yellow rails were found in marshes characterized by >50% vegetative

cover and at sites with <2.5 cm water depth. In addition, yellow rails have been reported to inhabit dry,

mature rice fields. In addition, king and yellow rails were associated with marshes receiving burning and

grazing management regimes.

Few studies have been documented on king and yellow rail populations along the western Gulf coast and

little is know about their current status. Studying king and yellow rails require large investments of effort.

Therefore, it is our opinion that future studies should use available monitoring techniques and investigate

new methods. Rails are characteristic of Texas coastal wetlands and are indicative of the condition of these

wetlands.

Proceedings of the Marsh Bird Monitoring Workshop 47
Evaluation of a Tape Playback Survey Method for Nocturnal 

Marshbirds in Maryland

Glenn D. Therres, David F. Brinker, and Peter J. Tango, Maryland Department of Natural Resources, 

580 Taylor Avenue, Annapolis, MD 21401

The tidal marshes of the Chesapeake Bay support a high diversity of breeding marshbirds, including five

species of rails, both American and Least bitterns, Pied-billed Grebe and Common Moorhen. No reliable

estimates of breeding populations of these obligate wetland birds were known for Maryland. Since

marshbirds are inconspicuous and not easily surveyed by traditional breeding bird surveys, special survey

methodology is needed for these species. The use of tape playback techniques have been used for

marshbirds elsewhere with success. This study was initiated to evaluate the use of tape playback techniques

for surveying marshbirds in Maryland.

To evaluate the playback methodology, two study sites were selected. These sites were selected to represent

different tidal marsh communities in the Maryland portion of the Chesapeake Bay. At these sites tape

playback surveys were conducted weekly in 1990 and biweekly in 1991 to determine seasonal, daily,

environmental and others effects on marshbird response rates. At each study site, four sample points were

surveyed during each visit. The survey protocol used consisted of 5 minutes of listening for spontaneously

calling birds, followed by broadcasting the calls of the nine target species, and concluding with another 5

minutes of listening without playbacks. During the broadcast portion of this protocol, vocalizations of each

species were broadcast for 2 minutes each followed by 2 minutes of listening without broadcasted

vocalizations then repeated again with the next species. Surveys were initiated just prior to sunset and

continued until after sunrise.

Seasonal patterns of response indicated that the period May 15 through July 15 was the optimum period for

surveying breeding marshbirds in Maryland. Highest daily responses occurred during the dawn survey

period. Probability of detection, defined as the probability of detecting a given species during a single visit,

ranged from 0.11 for Black Rail to 1.00 for Common Moorhen. Effective distances of detection for most

species surveyed were to 200 m.

Of particular interest during this study were the effects of marshbird responses to the lead species

broadcasted on the tape and the effects of the sequence of species broadcasted. Four different lead species

vocalizations were tested. Analysis of responses to the different tape sequences found no differences,

indicating that the sequence of species vocalizations did not influence the overall responsiveness of each

species. This is important for multiple species surveys. The use of tape playback increased the

responsiveness of two of four species tested, namely King Rail and Virginia Rail. Probabilities of detection

for the rare species also seemed enhanced by the use of tape playback.

Recommendations for designing a survey the marshbirds include: (1) use tape playback methodology to

enhance marshbird responses, (2) for multiple species surveys in the Chesapeake Bay broadcast

vocalizations of Black Rail, Clapper Rail, Virginia Rail and Common Moorhen at a minimum, (3) broadcast

rare species first, (4) conduct breeding surveys in the Chesapeake Bay area between May 15 and July 15, (5)

initiate surveys 2-3 hours before sunrise and continue 1-2 hours after sunrise, (5) conduct each survey at

least three times during the season, (6) space survey points at least 800 m apart, and (7) avoid surveying on

windy days or days with precipitation.

48 Proceedings of the Marsh Bird Monitoring Workshop
Migration Chronology and Habitat Use of Webless Migratory Game Birds in the

Lower Missouri River Floodplain

John Vogel, University of Missouri, 112 Stephens Hall, Columbia, MO 65211

Douglas L. Helmers, U.S. Department of Agriculture, Natural Resources Conservation Service, 

601 Business Loop 70, Columbia, MO 65203

Leigh Fredrickson, Gaylord Memorial Laboratory, Puxico, MO 63960

Dale Humburg, Missouri Department of Conservation, 1110 S. College Ave., Columbia, MO 65201

This study focuses on webless migratory game birds such as rails, coots, and snipe in relation to their

habitat use within the Missouri River floodplain. This group of birds primarily uses the lower Missouri River

as a corridor for migration between wintering and breeding habitats. Some breeding by rails probably

occurs within the study area but the location and extent of nesting is poorly documented. In order to develop

management strategies for intensively managed areas and restoration projects in the Missouri River

floodplain, additional information is needed on chronology of use, relative densities of birds, and habitat use.

Because this group uses diverse wetland habitats from open water to shallowly flooded dense robust

emergents, the physical and biological conditions within different wetland types is essential in the

development of sound wetland management. Migration chronology, relative densities of migrating and

breeding birds, microhabitat conditions, and landscape features associated with wetland type, size, and

distribution are included in the study objectives.

A total of 6 floodplain wetland types (remnant, managed moist-soil impoundment, connected scour, nonconnected scour, farmed temporary wetland, and unfarmed temporary wetland) were studied in 1996 and

1997. Four sites from each type were selected for this study. The field season was separated into two

different sampling periods, spring and fall. The spring season was from late March until mid-June and

consisted of visual surveys, flush counts, and call response surveys. The fall season was from mid-August

until mid-October and consisted of visual surveys and flush counts.

Information on the chronology of use, densities of birds, and habitat use of webless migratory game birds is

incomplete for lower Missouri River floodplain wetlands. The objectives of this study are to: (1) determine

the chronology of use and determine densities of webless game birds using floodplain wetlands; (2) compare

the microhabitat characteristics of sites that are used by webless game birds; and (3) compare the

macrohabitat characteristics among the different wetland types. Visual surveys of open water and mud flat

areas and flush counts through vegetated areas were conducted weekly on each site. Call response surveys

were also used in the spring to detect king rails, Virginia rails, and sora. Flush counts and call response

surveys were compared to determine if either of the techniques proved more effective in detecting birds.

Preliminary analysis of the data showed no significant difference in detecting rail species. Survey data from

both years show high numbers of American coot and common snipe using several sites. Significant numbers

of sora were detected in many sites. Small numbers of Virginia rails were detected and no king rails were

detected. Preliminary analyses of the survey data show that webless game bird use was highest in managed

moist-soil impoundments and remnant wetlands. There was moderate use of temporary wetlands, and

virtually no use of scoured basins. All 24 sites were mapped with a Global Positioning System (GPS) unit in

1996 and 1997. These data will be analyzed to determine the relationships between bird use and

macrohabitat availability.

These are results from a 2-year study funded by the 1995 Webless Migratory Game Bird Research Program

(U.S. Fish and Wildlife Service and U.S. Geological Survey-Biological Resources Division), Missouri

Department of Conservation, and University of Missouri.

Proceedings of the Marsh Bird Monitoring Workshop 49
Factors Affecting Vocalization Rates of Common Moorhens

Cecilia R. Walther, School of Forestry, Wildlife, and Fisheries, Louisiana State University, Baton Rouge, LA

70803

William L. Hohman, U.S. Department of Agriculture, National Resource Conservation Service, Department

of Animal Ecology, Iowa State University, 124 Science II, Ames, IA 50011

Reliable, standardized population survey methods are lacking for Common Moorhens (Gallinula

chloropus). In response to this important management need, we examined the effect of month, time of day,

sex, and taped calls on vocalization rates of Common Moorhens.

This study was conducted in southwestern Louisiana from April to June 1997. We located birds visually

during morning (to 3 hours after sunrise), evening (3 hours before sunset), and midday (3 hours after

sunrise to 3 hours before sunset). We recorded spontaneous vocalizations made by selected Common

Moorhens for 5 minutes after which we played a one minute tape with clucks, purrs and primary advertising

calls. Common Moorhen vocalizations were recorded from initiation of the tape to 3 minutes after the tape.

Two additional sets of one minute taped calls were then played, each followed by 3 minutes of vocalization

monitoring. Vocalizations made by other Common Moorhens while observing the individual were also

recorded. A subset of birds was collected and necropsied to determine sex.

Time of day and month did not significantly affect Common Moorhen vocalization rates. Males vocalize

significantly more (p = 0.01) than females. Common Moorhens vocalized more in response to taped calls

than spontaneously, with an increase in the number of vocalized responses while the tape played and for the

first minute after the taped calls stopped. During the next 2 minutes, vocalization rates were similar to

spontaneous rates.

This project was made possible by support from the USFWS Office of Migratory Bird Management,

Louisiana Department of Wildlife and Fisheries Fur and Refuge Divisions Rockefeller State Wildlife

Refuge, Louisiana State University—Louisiana Cooperative Fish and Wildlife Research Unit, Cameron

Prairie National Wildlife Refuge, USGS/BRD National Wetlands Research Center, and Miami Corporation.

50 Proceedings of the Marsh Bird Monitoring Workshop
The Marsh Monitoring Program of Bird Studies Canada 

(Long Point Bird Observatory)

Russ C. Weeber, Jon D. McCracken, and Charles M. Francis, Bird Studies Canada, 

P.O. Box 160, Port Rowan, Ontario N0E 1M0

The Marsh Monitoring Program (MMP) was initiated in 1994 by Long Point Bird Observatory (now Bird

Studies Canada) and Environment Canada in response to a recognized need for information on the status

and trends of marsh breeding amphibian and bird populations, particularly in some highly impacted Great

Lakes coastal wetlands (Areas of Concern). The MMP is an international, volunteer-based program focused

on surveying birds and calling frogs and toads in coastal and inland marsh habitats in the Great Lakes

basin. The program’s main objectives are to: monitor populations of marsh birds and amphibians, both

spatially and temporally; investigate habitat associations of marsh birds and amphibians; contribute to

assessments of Areas of Concern; and to disseminate results and conclusions to the public and the scientific

community.

Several aspects of alternative protocols were explored in 1993, including: fixed-distance and unlimited

distance survey methods; morning and evening surveys; mid-season (late June) and late-season (mid-July)

visits; survey durations from 5 to 20 minutes; and detection rates prior to and after broadcasts of taped bird

calls. The selected protocol was tested in Ontario in 1994 and expanded to the whole basin in 1995.

Under the current MMP protocol, participants select survey routes consisting of one to eight stations.

Routes must be surveyed within a single evening, by a single surveyor. Stations are 100 m radius semicircles, positioned along the wetland edge and containing marsh vegetation (i.e. non-woody, emergent

plants). Stations surveyed for birds must be at least 250 m apart and those sampled for amphibians must be

at least 500 m apart. Participants are free to conduct surveys for marsh birds, amphibians, or both groups

but are encouraged to commit to bird surveys only if they can correctly identify at least 50 common bird

species, with particular emphasis on those associated with wetlands. All volunteers receive a Training Kit

containing: a protocol booklet; data forms; a broadcast tape used to elicit calls from the more inconspicuous

marsh bird species; and an instructional tape with examples of the songs and calls of marsh birds and

amphibians most likely to be encountered in the Great Lakes basin. The protocol booklet contains

instructions for establishing survey routes, conducting surveys for amphibians and marsh birds, and

summarizing wetland habitat characteristics. The broadcast tape includes calls of Virginia Rail (Rallis

limicola), Sora (Porzana carolina), Least Bittern (Ixobrychus exilis), Pied-billed Grebe (Podilymbus

podiceps), and the paired calls of Common Moorhen (Gallinula chloropus) and American Coot (Fulica

americana), with the call of each species separated on the tape by a silent listening period. Marsh

Monitoring Program participants also receive an annual newsletter that summarizes survey results and

includes articles on marsh ecology, amphibians and marsh birds.

Each station surveyed for marsh birds is visited twice each year between May 20 and July 5, no less than 10

days apart, in the early evening, with surveys ending at or before sunset. Each station is surveyed for 10

minutes, with the 5-minute broadcast tape played during the first half of the survey. All birds observed or

heard within a 100 m radius semi-circular sample area are counted, and birds detected flying over or outside

the station area are tallied separately.

Marsh Monitoring Program participants also describe general habitat characteristics of their survey

stations between May and early June. Within the station area, volunteers classify the percent cover of five

major habitat types (e.g. herbaceous emergent vegetation or open water/submergents), of submergent

plants within open water areas, and of the four dominant plant genera within the emergent vegetation

zones. Participants are also asked to classify the wetland size and adjacent upland land use, and to note

obvious human influences such as dykes or channels.

Proceedings of the Marsh Bird Monitoring Workshop 51
Marsh Monitoring Program routes are distributed throughout the Great Lakes basin, in Ontario and in each

of the Great Lakes states. Between 1995 and 1997, 425 routes have been surveyed during at least one of

these years. Almost 40% of these routes have been surveyed for both amphibians and marsh birds, with the

remaining routes split about equally between amphibian routes and bird routes. Of routes established in

1995, 49% have been monitored in three years, 11% in 1995 and 1996 only, 6% in 1995 and 1997 only, and 34%

were surveyed in 1995 only. Of those routes established in 1996, approximately half were surveyed again in

1997.

Guided by a formal scientific evaluation of the program and the survey protocols, and incorporating lessons

learned during four years of administering and conducting the surveys, we are currently considering a

variety of refinements to the program design. Issues concerning route allocation, survey intensity and

statistical power are discussed in a companion paper (Francis and Weeber), others are presented here. Of

particular concern is a clear definition of the sampling objectives of the survey, which has implications for

both the selection of survey routes and selection of stations along routes. Should the survey be intended to

sample a particular wetland type (i.e. dominated by a specific vegetation assemblage) or a particular

vegetation assemblage within aquatic systems in general (e.g. herbaceous emergents in wetlands or along

lake edges)? If station selection is based on particular vegetation characteristics, how should the protocol

address temporal changes in plant composition and density within the station area? Ideally, survey stations

would be randomly allocated within selected strata (e.g. within wetland or vegetation types). How should

station allocation strategies for volunteer-based, long-term programs integrate constraints such as those

imposed by a required minimum distance between stations (i.e. to avoid overlapping counts); differing

accessibility to potential stations; and limitations in surveyor motivation and knowledge of the waterbody

surveyed? Similarly, how can assessments of wetland habitat characteristics and landscape context measure

the habitat attributes actually involved in marsh bird habitat selection most effectively, and at appropriate

spatial and temporal scales? Unfortunately, habitat selection criteria are not well understood for marsh bird

communities, and the design of these assessments can be further constrained by surveyor’s motivation and

knowledge of wetland habitat measures, and by access to information ranging from wetland nutrient status

through regional land use patterns.

Stimulated by a concern for wetlands and wetland dependent wildlife, interest in marsh bird monitoring

appears to be increasing, as shown by the terms of reference for this workshop. Bird Studies Canada is

interested in exploring the need and practicality of developing an expanded version of the MMP, applicable

across Canada as well as the Great Lakes basin. Implementation of any such expanded program will be

contingent on sufficient interest and funding.

52 Proceedings of the Marsh Bird Monitoring Workshop
Front Cover Photos

Left column from top

Least bittern, USFWS photo by Jill Parker

Clapper rail, photo by Gregory Kearns

Common moorhen, USFWS photo by G. Gentry

Horned grebe, USFWS photo by E. McLaury

Center column from top

King rail, photo by Gregory Kearns

Virginia rail, photo by Jack Bartholmai

Yellow rail, USFWS photo by Hollingsworth

Sora, photo by Gregory Kearns

Right column from top

Common snipe, photo by Travis Olson

Red-necked grebe, USFWS photo by J. Nickles

American bittern, USFWS photo by Hollingsworth
June 1999