Northern Prairie Wildlife Research Center— 

Celebrating 50 Years of Science

50

Circular 1434

U.S. Department of the Interior

U.S. Geological Survey
B

C

D

E

G F

H

I

A

Cover. A, Female blue-winged teal ready for release after attaching a back-pack radio-transmitter. B, John Shoesmith 

holds an Erlenmeyer flask up to a laboratory instrument. C, An old military jeep is used to drag a cable-chain and locate duck 

nests in a grassland in early spring. D, Early photograph of Northern Prairie Wildlife Research Center’s main administration 

building, 1970. E, Waist deep in waters of the Upper Mississippi River, a technician pulls up a mass of aquatic vegetation 

while a second technician stands nearby holding a galvanized tub. F, A technician bands a hen mallard. G, From a grassy 

hill overlooking a wetland, a technician locates radio-marked ducks using a yagi antenna and receiver. H, Tom Eagle 

removes an American mink from its den and hands it to Todd Arnold. I, Early photograph of the Woodworth Field Station. All 

photographs, maps, and illustrations used in this publication were produced or taken by former or current personnel of the 

U.S. Fish and Wildlife Service or U.S. Geological Survey and are in the public domain.
Northern Prairie Wildlife Research 

Center—Celebrating 50 Years of Science

By Jane E. Austin, Terry L. Shaffer, Lawrence D. Igl, Douglas H. Johnson, 

Gary L. Krapu, Diane L. Larson, L. David Mech, David M. Mushet, and 

Marsha A. Sovada

An aerial view of the Northern Prairie Wildlife Research Center near Jamestown, North Dakota.

Circular 1434

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

RYAN K. ZINKE, Secretary

U.S. Geological Survey

William H. Werkheiser, Acting Director

U.S. Geological Survey, Reston, Virginia: 2017

For more information on the USGS—the Federal source for science about the Earth, its natural and living 

resources, natural hazards, and the environment—visit https://www.usgs.gov/ or call 1–888–ASK–USGS.

For an overview of USGS information products, including maps, imagery, and publications, 

visit https://store.usgs.gov.

Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials 

as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

Suggested citation:

Austin, J.E., Shaffer, T.L., Igl, L.D., Johnson, D.H., Krapu, G.L., Larson, D.L., Mech, L.D., Mushet, D.M., and Sovada, 

M.A., 2017, Northern Prairie Wildlife Research Center—Celebrating 50 years of science: U.S. Geological Survey 

Circular 1434, 27 p., https://doi.org/10.3133/cir1434.

ISSN 1067-084X (print)

ISSN 2330-5703 (online)

ISBN 978-1-4113-4169-2
iii

Acknowledgments

We thank the many staff and alumni for sharing their knowledge and insights of the Northern 

Prairie Wildlife Research Center’s history as we developed this document. Patricia J. Heglund, 

Michael A. Johnson, and David L. Trauger provided valuable comments on earlier drafts to help 

us provide a balanced and accurate story of our history. Lynn Hill provided a compilation of 

Center publications, which served as the basis for the publication list associated with this history. Images came from the Center’s archives and Center staff. We also acknowledge with pride, 

friendship, and gratitude the many people who worked and partnered with the Northern Prairie 

Wildlife Research Center during its first 50 years and beyond.

A technician holds a hen mallard while a second technician applies an aluminum leg band to 

her right leg.

v

Contents

Acknowledgments........................................................................................................................................iii

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................2

Foundation and Background of the Center ...............................................................................................4

Waterfowl........................................................................................................................................................6

Other Birds....................................................................................................................................................17

Sandhill Cranes ...................................................................................................................................17

Nongame Birds....................................................................................................................................18

Imperiled Species........................................................................................................................................20

Large Mammals............................................................................................................................................22

Wetlands .......................................................................................................................................................23

Cottonwood Lake Study Area ...........................................................................................................23

Other Wetland Research ...................................................................................................................24

Invasive Species and Restoration Ecology .............................................................................................25

Landscape Ecology......................................................................................................................................26

Research Techniques and Information Transfer....................................................................................27

Looking to the Future...................................................................................................................................29

References....................................................................................................................................................29

Conversion Factors

U.S. customary units to International System of Units

Multiply By To obtain

Length

mile (mi) 1.609 kilometer (km)

acre 0.4047 hectare (ha)

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2) 

Facing page: Trumpeter swans and other waterfowl on a wetland at Lacreek National Wildlife 

Refuge, South Dakota.
vi

Abbreviations

CAP Cropland Adjustment Program

CRP Conservation Reserve Program

DNC dense nesting cover

DOI Department of the Interior

EMAP Environmental Monitoring and Assessment Program

FWS U.S. Fish and Wildlife Service

GAP Gap Analysis Program

GIS geographic information system

HAPET Habitat and Population Evaluation Team

ILM Integrated Landscape Management

MCP Midcontintent Population

NGO nongovernment organization

NPAM Native Prairie Adaptive Management

NPWRC Northern Prairie Wildlife Research Center

NWR national wildlife refuge

PPJV Prairie Pothole Joint Venture

PPR Prairie Pothole Region

SUMP Small-Unit Management Project

USDA U.S. Department of Agriculture

USGS U.S. Geological Survey
Northern Prairie Wildlife Research Center—Celebrating 

50 Years of Science

By Jane E. Austin, Terry L. Shaffer, Lawrence D. Igl, Douglas H. Johnson, Gary L. Krapu, Diane L. Larson, 

L. David Mech, David M. Mushet, and Marsha A. Sovada

Abstract

The Northern Prairie Wildlife Research Center (NPWRC) 

celebrated its 50-year anniversary in 2015. This report is 

written in support of that observance. We document why and 

how the NPWRC came to be and describe some of its many 

accomplishments and the influence the Center’s research 

program has had on natural resource management. The history 

is organized by major research themes, proceeds somewhat 

chronologically within each theme, and covers the Center’s 

first 50 years of research. During that period, Center scientists 

authored more than 1,700 publications and reports. More than 

1,000 seasonal or temporary field personnel, and more than 

100 graduate students, contributed to the Center’s success; 

many went on to have exemplary careers in natural resource 

management, conservation, and education. The mission of 

the Northern Prairie Wildlife Research Center today remains 

true to the original vision: to provide the knowledge needed 

to understand, conserve, and manage the Nation’s natural 

resources for current and future generations, with an emphasis 

on species and ecosystems of the northern Great Plains. The 

Center’s first 50 years of applied biological research provides 

a deep scientific foundation on 

which to address emerging issues 

for the natural resources in the 

northern Great Plains and beyond.

Dedication brochure (right) and 

ceremony (below) for the Center, 

September 18, 1965.
2 Northern Prairie Wildlife Research Center—Celebrating 50 Years of Science

Introduction

The Northern Prairie Wildlife Research Center (hereafter 

the Center) celebrated its 50-year anniversary in 2015. This 

report is written in support of that observance, documents why 

and how the NPWRC came to be, and describes some of its 

many accomplishments and the effect the Center’s research 

program has had on natural resource management. The history 

is organized by major research themes, proceeds somewhat 

chronologically within each theme, and covers some ongoing 

projects as well as past work. Because NPWRC scientists have 

authored more than 1,700 publications and reports covering 

a broad range of important topics during the 50 years, deciding what to highlight was no easy task (all references for the 

studies mentioned in this report are listed in U.S. Geological Survey 2017). As with most histories, this one invariably 

reflects the perspectives and experiences of the writers: six 

long-term employees and three retirees, collectively representing 276 years with the Center. 

Although scientific achievements and the scientists 

behind them are the focus of this document, it is important to 

recognize the invaluable roles of the many staff and technicians who supported the work and made the science possible. 

Every member of the Northern Prairie team, from administrative staff to maintenance personnel to information technology 

specialists and statisticians, has contributed to the effort in 

some essential way. A cadre of highly talented and dedicated 

biological support staff, including long-term and shortterm employees, has been critical to the Center’s success. 

The number of seasonal and temporary field personnel who 

collected the data is unknown but surely would number in the 

thousands. More than 100 graduate students have contributed 

to the scientific accomplishments of the Center. Numerous 

partnerships with other agencies and organizations have been 

integral to the success of the Center’s research program. 

Scientific leadership has been provided by Center Directors 

Harvey K. Nelson (1964–74), W. Reid Goforth (1974–80), 

Rey C. Stendell (1979–89), Susan D. Haseltine (1989–92), 

Ronald E. Kirby (1993–2001), Jay B. Hestbeck (2001–06), 

Janine E. Powell (2007–08), and Robert A. Gleason 

(2010–present). 

The many collaborations and partnerships with other 

institutions and organizations, from local to international, have 

been fundamental to the Center’s success. These cooperative 

efforts emerged from strong relationships at both organizational and personal levels. Many examples are presented in 

this publication but they cannot fully capture the breadth and 

depth of such affiliations across 50 years. Among the strongest 

partnerships throughout the years have been with the U.S. Fish 

and Wildlife Service (FWS; National Wildlife Refuges 

[NWRs], Migratory Bird Program, Habitat and Population 

Evaluation Team [HAPET]), flyways, joint ventures, and State 

wildlife agencies, especially the North Dakota Game and Fish 

Department. These partnerships reflect the Center’s original 

mission focusing on waterfowl and other migratory birds 

and its more recent charge of supporting U.S. Department of 

Interior (DOI) agencies. Collaboration with the USGS Water 

Sciences staff in Lakewood, Colorado, began in the 1960s and 

The Center, 1970.
Introduction 3

remains a key element of ongoing research. With the Center’s 

broadened mission under USGS, Center scientists have 

increased and expanded collaborations with the National Park 

Service, U.S. Department of Agriculture (USDA), U.S. Army 

Corps of Engineers, State and Provincial agencies, various 

universities and nongovernment organizations (NGOs), and 

others. Partners and collaborators contribute valuable skills, 

expertise, and resources that complement those at the Center 

and lead to stronger science capability. Close affiliations with 

management agencies have been central to the Center’s focus 

on applied research that contributes to scientifically based 

decision-making and conservation actions.

The Center takes tremendous pride in the impact its many 

alumni have had on natural resource management, conservation, and education. During these 50 years, thousands of dedicated individuals began their professional careers at the Center 

as temporary, seasonal, or term hires, students, contractors, or 

volunteers. These talented individuals were instrumental in 

collecting data in the field, often under challenging conditions, 

or working in the bird pens, laboratories, or office. They were 

trained and mentored by Center staff and by one another, and 

carried their training and experiences on to productive careers 

as biologists, managers, researchers, educators, or policy 

makers. More than 100 graduate students have contributed 

directly to the Center’s science through their studies; some 

became permanent staff at NPWRC or at other USGS research 

centers. Many of these students have gone on to exemplary 

careers in natural resource management. During the 1980–90s, 

three of four FWS flyway representatives had begun their 

careers at NPWRC. The network of Center alumni, and in turn 

the Center’s impact, spans Federal, State, local, and NGOs 

across the Nation. 

Harvey K. Nelson 

(1964–74)

W. Reid Goforth 

(1974–80)

Rey C. Stendell 

(1979–89)

Susan D. Haseltine 

(1989–92)

Ronald E. Kirby 

(1993–2001)

Jay B. Hestbeck 

(2001–06)

Janine E. Powell 

(2007–08)

Robert A. Gleason 

(2010–present)

Scientific leadership has been provided by eight Center Directors over its 50-year history.
4 Northern Prairie Wildlife Research Center—Celebrating 50 Years of Science

Foundation and Background of the Center

The 1950s and 1960s were a period of major change in 

the Prairie Pothole Region (PPR). The Federal Government 

subsidized the drainage of potholes, which led to widespread wetland loss and, together with continuing conversion 

of native prairie to cropland, threatened the future of the 

continent’s primary duck production area. Federal and State 

waterfowl managers, alarmed by loss of waterfowl habitat 

and supported by waterfowl hunters, succeeded in moving 

Congress to amend the Duck Stamp Act in 1958 to fund the 

Small Wetlands Acquisition Program in an attempt to slow 

the loss of breeding habitat for waterfowl. Resource managers also recognized that remaining waterfowl habitat would 

need to be more productive if duck populations were to be 

maintained at levels adequate to satisfy the growing interest 

in waterfowl hunting. Making waterfowl breeding habitat 

more productive and sustainable over the long term would 

require increased knowledge of the breeding ecology of 

prairie-nesting ducks, waterfowl predators, wetland ecology, 

and an understanding of waterfowl-land-use relationships. 

In the early 1960s, long-time waterfowl managers began 

to develop a research facility to address key information 

needs for increasing duck production. Named the Northern Prairie Wildlife Research Center, it was administered 

by the Bureau of Sport Fisheries and Wildlife (later the 

FWS). The Center’s mission was to produce information that 

110° 100° 90°

50°

45°

0 150 300 MILES

Base from U.S. Geological Survey digital data, 0 150 300 KILOMETERS

various scales, variously dated

Universal Transverse Mercator projection, zone 14

North American Datum of 1983

MANITOBA

SASKATCHEWAN

ALBERTA ONTARIO

MONTANA

NORTH

DAKOTA MINNESOTA

IOWA

CANADA

UNITED STATES

SOUTH

DAKOTA

Prairie Pothole Region

Location of the Prairie Pothole Region in the United States and 

Canada (Mann, 1974).

Aerial view of the Prairie Pothole Region.
Foundation and Background of the Center 5

would improve management of waterfowl breeding habitats. 

Dr. I. G. Bue, former Commissioner of the North Dakota 

Game and Fish Department, was charged with locating a 

suitable site for the Center and an associated field research 

station, designing and developing plans for the buildings, 

and managing construction contracts. Bue chose to locate 

this new research facility at Jamestown, North Dakota, in the 

heart of the PPR. Bue died of a heart attack while hunting 

in October 1963 before construction of the Center began. 

Harvey K. Nelson, who also played a major role in planning 

for the Center, moved from Region 3 (FWS) headquarters in 

Minneapolis to Jamestown in the summer of 1964 to become 

the Center’s first Director. The Center at Jamestown officially 

opened on September 18, 1965. The 1,230-hectare Woodworth 

Study Area was purchased as a waterfowl production area in 

1963 with funds from the Federal Migratory Bird Hunting 

and Conservation Stamp (duck stamp dollars); the study area, 

located 72 kilometers (45 miles) from the Jamestown headquarters, served as an important research area for the Center 

into the late 1980s. 

Developing a broad-based research program required 

teams of scientists from several disciplines to work together. 

The transfer and hiring of staff began several years before 

the Center was officially dedicated. Harvey Nelson brought 

together a cadre of highly skilled and experienced biologists 

and managers who understood prairie habitats and waterfowl 

to lead the new research program. In 1993, biological research 

staff and functions from several agencies in the DOI, including NPWRC, were consolidated into the short-lived National 

Biological Survey (later National Biological Service) and in 

1997 transferred into the U.S. Geological Survey (USGS), 

where they remain today.

Facilities at the Woodworth Study Area in the early 1970s.

0 200 400 600 800 1,000 MILES

0 100 200 300 400 1,000 KILOMETERS

120° 110° 100° 90° 80° 70°

40°

30°

Dixon Field Station

Arcata Field Station

Cottonwood Lake

Study Area

Columbia Field Station

La Crosse

Field Station

Woodworth Field Station

Northern Prairie Wildlife Research Center

NORTH

DAKOTA

WISCONSIN

MISSOURI CALIFORNIA

Base from U.S. Geological Survey digital data, 2014, 1:100,000

Shaded relief from Tom Patterson, National Park Service

Albers Equal-Area Conic projection

Standard parallels 29°30’N and 45°30’N, central meridian -96°00’W

North American Datum of 1983

Minneapolis Research Station

MINNESOTA

Bear River

Research Station

Hot Springs Research Station

UTAH

SOUTH

DAKOTA

Ely Research Station

NEBRASKA

ARKANSAS

Lincoln Field Station

Fayetteville Field Station

EXPLANATION

Current field or research station

Past field or research station

Locations of the Center, field and research stations, Woodworth Study Area, 

and Cottonwood Lake Study Area.
6 Northern Prairie Wildlife Research Center—Celebrating 50 Years of Science

Waterfowl

Research planners recognized the need for a balanced, 

long-term scientific research program to provide information about factors regulating waterfowl populations, which 

required improved insights into the ecology of breeding waterfowl to better understand the complex relations controlling 

reproduction and determining populations. Among potential 

benefits of the research program was an increased capacity 

to manage lands more effectively for duck production. Initial 

investigations focused primarily on gathering baseline data on 

waterfowl breeding biology, wetland habitats, and estimating 

duck nest success rates. Some of the Center’s earliest work 

on these topics was by Jerome (Jerry) H. Stoudt, who, prior to 

joining the NPWRC in 1963, had initiated a 12-year study of 

breeding canvasbacks (Aythya valisineria) near Minnedosa, 

Manitoba, Canada. Also in 1961, Horatio (Ray) W. Murdy 

initiated work on waterfowl and wetlands on the Yellowknife 

Study Area, located along the north shore of Great Slave 

Lake, Northwest Territories. Other work started in the early 

1960s and continued as Center projects, including baseline 

waterfowl and wetland studies near Woodworth, N. Dak., 

by Robert (Bob) E. Stewart, Sr.; Harold (Hal) A. Kantrud; 

Keith D. Bayha; and David L. Trauger. 

A founding mission of the Center was to learn how to 

make the FWS’s national wildlife refuges and waterfowl 

production areas more productive for waterfowl. This mission 

led to the early formation of a research team charged with 

investigating wildlife-land-use relationships. Studies were 

carried out at the Woodworth Study Area and other grassland 

landscapes in the PPR. Leo M. Kirsch, an experienced FWS 

Refuge manager and biologist, managed the Woodworth Study 

Area and its research program during 1964–79, later followed 

by Kenneth (Ken) F. Higgins (1979–86) and Michael (Mike) 

Callow (1986–89). Early studies by this team focused on 

differences in duck use and nesting success among various 

wetland types and cover types, and the roles of prescribed fire, 

grazing, and various cover plantings in influencing duck nest 

success. Work by Harvey W. Miller, Kirsch, Higgins, Harold 

F. Duebbert, Albert (Tom) T. Klett, John T. Lokemoen, and 

Arnold (Arnie) D. Kruse, with assistance from James (Jim) L. 

Piehl, Robert (Bob or Woody) O. Woodward, and hundreds of 

summer students, provided valuable information about nesting 

ducks and grassland management. By 1974, the Center had 

become a renowned source of information on prairie-nesting 

ducks and the importance of grassland management for waterfowl production. Researchers and managers came from all 

over North America and the world to learn about prairie ducks, 

grassland management, and how to improve duck production. 

At the Woodworth Study Area, biological surveys of 

various kinds, including nest searches and repeated counts of 

ponds, duck breeding pairs, and duck broods, were carried 

out annually and led to an extensive, long-term database that 

was the foundation for a monograph by Ken Higgins and 

others about waterfowl production. Kirsch’s use of prescribed 

burning and grazing to manage the area’s upland habitats 

spurred interest in these methods for managing grasslands for 

wildlife. By the 1970s, workshops, presentations, and publications by Kruse, Higgins, and Kirsch established the Center as 

a primary resource for information about prescribed fire for 

prairie management.

Through the early 1960s, searching for waterfowl nests 

in herbaceous vegetation was a time-consuming effort that 

had largely been accomplished by pulling a rope between two 

people, beating the vegetation with sticks, or using dogs. Nest 

searching was greatly facilitated by pulling a combination 

cable and chain between two motor vehicles, a development 

made by Higgins, Kirsch, and I. Joseph (Joe) Ball. The cablechain drag made it possible to efficiently locate large numbers 

of duck nests and paved the way for numerous duck-nesting 

A Center biologist carries a wooden box containing ducks 

captured in drive-trap nets in a wetland near Minnedosa, 

Manitoba, Canada, 1978.

Researchers monitor a burning fire break at Arrowwood National 

Wildlife Refuge, North Dakota, 1984. 
Waterfowl 7

Leo Kirsch (left) and Ken Higgins (right) setting up a cable-chain 

drag for nests.

studies through the 1980s by NPWRC scientists and cooperators and for monitoring programs throughout the United States 

and Canada. In 1986, Klett, Duebbert, Craig A. Faanes, and 

Higgins authored a techniques publication, including data 

forms, for conducting duck-nesting studies. This publication 

led to greater implementation of this detailed protocol by 

refuge staff and others for finding and monitoring waterfowl 

nests. The nest-drag method was later modified to locate nests 

of passerines and other ground-nesting grassland birds. The 

nest-drag technique remains a critical tool for monitoring a 

large variety of grassland-nesting birds. 

In the early 1970s, Harvey Miller and Douglas (Doug) H. 

Johnson coordinated an analysis of nesting data collected in 

North Dakota and South Dakota. From this mass of data came 

the then-surprising result: nests found later in development 

were more likely to be successful than those found earlier. 

Researchers soon discovered that Harold F. Mayfield had 

made a similar observation and had developed a method to 

address the bias. Doug Johnson went on to develop a variance 

estimator for Mayfield’s method and a series of methods to 

estimate nest success under a variety of circumstances. These 

methods were widely adopted for nesting studies and were 

extended by Terry L. Shaffer in 2004 for more detailed analysis of factors affecting nest success. 

The extensive studies of duck nesting by NPWRC staff 

and collaborators led to an enormous collection of nesting 

data and the development of a data repository, curated since 

1992 by Thomas K. [Tom] Buhl. By 2015, the Center nest 

file included more than 143,000 records from 11 States and 

3 Provinces and encompassed 54 species. In 1988, Klett, 

Terry Shaffer, and Doug Johnson published results of a 

detailed analysis of data from the Center nest file that provided 

compelling evidence that duck nest success in the U.S. PPR 

was below levels needed to maintain populations of most 

species. These are but a few of many efforts that helped establish the NPWRC as a leader in generating information on duck 

recruitment. 

The many studies of upland-nesting waterfowl also led 

to the growing recognition of the importance of tall, dense 

cover to nesting ducks. Kirsch observed higher nest success 

and density in idled (no management treatment) compared to 

grazed grasslands and recommended that lands managed for 

waterfowl production be periodically idled to maximize their 

return for waterfowl. Harold Duebbert and John Lokemoen 

noted the high duck nest densities and apparent nest success 

in grasslands established on retired cropland. Harold Duebbert promoted dense nesting cover (DNC)—a mixture of tall, 

robust grasses and legumes planted to benefit duck production. 

DNC produced dense residual cover for nesting waterfowl 

and had higher nest densities than other vegetative cover, such 

as native prairie or smooth brome (Bromus inermis). DNC 

became the preferred nesting cover planted on most public 

lands managed for waterfowl production.

Howard Thornsberry (left) with Forrest Lee (right) checking an 

artificial nesting structure for waterfowl.

Cartoon illustrating the need for dense nesting cover for ducks. 

Illustration by Mavis Meyer.
8 Northern Prairie Wildlife Research Center—Celebrating 50 Years of Science

Meanwhile, other Center researchers focused their 

efforts on filling crucial information gaps about duck breeding 

biology. By the late 1960s, NPWRC biologists had established 

study sites across the PPR in the United States and Canada, 

into forested regions of Minnesota, and northward to the 

subarctic of Canada. NPWRC had one of the first wildlife 

disease specialists, Gary L. Pearson (Doctor of Veterinary 

Medicine), contributing to waterfowl research related to 

disease and mortality and also had a disease staff based at the 

Bear River Research Station located at Brigham City, Utah, 

(1969–72) to study avian botulism. Food habit studies were 

breaking new ground in understanding how wetland dynamics influenced waterfowl productivity. Existing knowledge in 

the 1950s and 1960s led to the widely held conclusion that 

ducks feed mostly on plants, which was based on examination of gizzard contents. George Swanson suspected gizzards 

did not accurately reflect foods consumed by ducks in prairie 

wetlands. By comparing food habits of blue-winged teal 

(Spatula discors) based on food items present in esophagi and 

gizzards, Swanson, working with James (Jim) C. Bartonek, 

determined that gizzard samples strongly underrepresented 

invertebrate consumption. His finding provided an impetus 

for further investigations that would lead to the discovery that 

macroinvertebrates served a vital role in fueling reproduction 

in prairie ducks.

Gary L. Krapu hypothesized that female dabbling ducks 

select animal foods because of their high protein requirements 

during egg production. Focusing on food habits of female 

northern pintails (Anas acuta), he showed that macroinvertebrates dominated the diet during the rapid follicular development and laying stages. Selection of animal foods during egg 

production was further substantiated in studies of gadwalls 

(Mareca strepera) by Jerome (Jerry) R. Serie and mallards 

(Anas platyrhynchos) by George Swanson and others. Jan L. 

Eldridge and Krapu followed up with an experimental study 

that showed that a diet consisting solely of plants resulted 

in reductions in clutch size, egg size, laying rate, number 

of nesting attempts, and total eggs laid. Based on studies in 

NPWRC’s experimental ponds and sampling invertebrates 

in the field, Swanson determined that shallow wetlands, after 

being drawn down and then re-flooded, produced exceptional 

blooms of macroinvertebrates of the types sought by prairie 

waterfowl during reproduction. Together, the body of knowledge identifying dietary needs of prairie-nesting waterfowl and 

the role of shallow wetlands in supplying these needs became 

the impetus for expanded research on wetland-waterfowl relations and led to support for wetland conservation policies in 

the PPR, across North America, and elsewhere in the world.

The finding that prairie ducks require a nutrient-rich diet 

during breeding also shed light on factors affecting distribution patterns of ducks at the landscape level in the PPR. Gary 

Krapu, Tom Klett, and Dennis G. Jorde used the North American May waterfowl population and pond surveys to show that 

mallard pair density was correlated with pond density, which 

varied with numbers of seasonal and temporary ponds present. 

John Lokemoen, Harold Duebbert, and David (Dave) E. Sharp 

Bruce Hanson sieves aquatic invertebrates from a plexiglass 

invertebrate sampler at the edge of a wetland.

Harold Duebbert and Leo Kirsch prepare to mark a duck nest with 

a willow stick.
Waterfowl 9

Dave Sharp and Harold Duebbert examine a banded blue-winged 

teal hen.

concluded that settling patterns also were influenced by 

nesting history; female mallards and gadwalls that had nested 

successfully at a site during the previous year were more 

likely to return to nest at the same site the following year. This 

finding had important implications to mallard and gadwall 

management because the potential existed for building high 

pair and nest densities. Such a situation was reported by 

Duebbert, Lokemoen, and Dave Sharp for a 4.5-hectare island 

in Miller Lake, N. Dak., in 1977, where nest success was 

high and the wetland base was sufficient to meet needs of 

nesting waterfowl. In 1987, a multifaceted follow-up study, 

the Small Unit Management Project, was initiated to test this 

hypothesis. The study involved many Center researchers and 

its experimental design centered on the use of predator-proof 

exclosures and predator control to provide secure blocks of 

cover for nesting ducks. Although the study was cut short by 

extreme drought in the early 1990s, it provided a pathway 

for many important findings highlighted elsewhere in this 

document.

In related work, Doug Johnson compared settling patterns 

of waterfowl breeding in the midcontinent region by analyzing 

May pair and pond count data collected during 1955–81 and 

identified important differences in species’ settling patterns 

linked to favored types of wetland habitats. Homing generally 

was more pronounced among species living in landscapes with 

wetland types that hold water in most years, such as redhead 

(Aythya americana), canvasback, lesser scaup (Aythya affinis), 

mallard, gadwall, and northern shoveler (Spatula clypeata). 

In contrast, there was opportunistic settling in species such as 

blue-winged teal and northern pintail, which are prone to shift 

their distribution between years to take advantage of newly 

flooded, shallow wetlands in landscapes with limited stable 

water. Together, NPWRC studies indicated wetland conditions and available wetland types strongly influence distributions of all prairie-nesting ducks, but settling strategies differ 

Drawing illustrating the Small Unit Management Project.

Technicians take morphological measurements of a hen mallard 

in preparation for radio-marking.

John Lokemoen candles a duck egg to determine incubation 

stage.
10 Northern Prairie Wildlife Research Center—Celebrating 50 Years of Science

widely among species. This knowledge is now widely considered by waterfowl managers when interpreting the results of 

May pair and pond counts, targeting management practices 

toward certain species or groups of species, and guiding 

conservation planning.

In several species of ducks, reproductive rate was noted 

to vary by hen age. David Trauger studied lesser scaup in 

the subarctic Yellowknife study area and determined that 

brood:hen ratios varied with age of the hen. Jerry Serie, David 

Trauger, and Jane E. Austin concluded that re-nesting effort, 

success, and return rate of canvasback hens breeding on the 

Minnedosa Study Area in southwestern Manitoba increased 

with hen age. Several NPWRC studies reported that younger 

and less experienced female mallards were less likely to breed 

initially or to re-nest. For example, John Lokemoen, Harold 

Duebbert, and Dave Sharp reported mallards and gadwalls 

were less likely to breed under very crowded conditions. 

These findings underscore the major influence of hen age on 

reproductive success in several species of prairie waterfowl 

and have implications for waterfowl management.

Early-nesting waterfowl such as mallards and northern 

pintails arrive and begin nesting before foods become plentiful in prairie wetlands. Studies of mallards by Gary Krapu in 

North Dakota and of canvasbacks by Jerry Serie and Dave 

Sharp in southwestern Manitoba determined that females 

acquire large fat reserves prior to nesting and channel a major 

part of their fat reserves into producing eggs, which makes 

it possible for early-nesting females to lay large clutches. 

Lewis M. (Lew) Cowardin led a study using radio-telemetry 

to examine factors influencing mallard recruitment in agricultural landscapes in North Dakota. He determined that 

the probability that female mallards produced eggs and the 

number of eggs laid were greater among females in better 

condition. Center research on fat reserve dynamics relative 

to egg production also served as a major impetus for research 

addressing cross-seasonal effects on waterfowl body condition and production. Studies in Nebraska’s Rainwater Basin 

by Krapu, Robert (Bobby) R. Cox, Jr., and Aaron T. Pearse 

demonstrated the importance of this spring staging area for fat 

acquisition by greater white-fronted geese (Anser albifrons), 

snow geese (Anser caerulescens), and northern pintails. Aaron 

Pearse, collaborating with Ray Alisauskas (Canadian Wildlife 

Service), concluded that amount of fat stored by white-fronted 

geese at spring stopovers in Saskatchewan increased from the 

1970s to the 1990s but was insufficient to fully compensate 

for the lost opportunity to store fat in the Rainwater Basin; as 

a result, pairs fledged fewer young. Pearse and Cox identified 

increased human activity in the Rainwater Basin during the 

annual spring conservation hunt of snow geese and declining availability of waste corn as important factors in changing fat acquisition in the Rainwater Basin. These findings 

have important implications to waterfowl populations that 

rely primarily on corn to acquire fat in preparation for reproduction. In the Rainwater Basin, Federal, State, and private 

waterfowl managers have undertaken a major wetland restoration effort, in part to broaden the distribution of spring staging 

waterfowl to help limit food shortages. These studies relating 

acquisition and use of nutrient reserves for reproduction have 

led to a more holistic approach to waterfowl management that 

takes into account habitat 

needs across seasons 

and have been used to 

support habitat conservation efforts on important 

wintering grounds and 

spring staging areas of 

waterfowl.

Above, Dave Trauger 

with nasal-marked 

lesser scaup.

At left, Jerry Serie 

weighs a male 

canvasback that was 

captured on the upper 

Mississippi River.

Gary Krapu holds a nasalmarked lesser scaup hen.
Waterfowl 11

Renesting after a failed nest has a major influence on 

whether ducks are successful breeders in the PPR because of 

high losses among early nests. Several NPWRC studies have 

shown renesting effort in most species is highest during wet 

years, but limited insight existed about interspecific differences and the underlying factors involved. Existing theory 

held that all species of temperate-nesting ducks are absolutely 

photorefractory (that is, terminate breeding efforts under long 

day lengths), causing ducks to stop initiating nests by early 

summer. In 1993, a dry spring followed by heavy, late-summer 

rains provided a unique opportunity to test whether prairie 

ducks were absolutely photorefractory. Krapu capitalized on 

this unusual event by organizing a study using repeated brood 

surveys during 1993–95. That study revealed that mallard, 

gadwall, and blue-winged teal continued to nest into late 

summer (that is, were not absolutely photorefractory), whereas 

northern pintail and northern shoveler did not, demonstrating that mechanisms controlling the termination of breeding are more complex and varied than previously thought. 

Reduced renesting capacity observed for northern pintails, 

combined with a low nest success rate, provided insight into 

why the pintail has been the least capable of prairie ducks 

to maintain their continental population under growing 

agricultural intensification. 

Early in the Center’s history, NPWRC researchers 

recognized brood research to be a high priority. Movements, 

habitat use, and survival of ducklings were studied in the 

prairie potholes, forested wetlands of north-central Minnesota, 

and California marshes. Doug Johnson, James D. Nichols 

(Patuxent Wildlife Research Center), and Michael (Mike) 

D. Schwartz used a mathematical model to identify brood 

survival as the second most important factor (following nest 

success) limiting recruitment of mallards and other duck 

species. Gary Krapu, Pamela (Pam) J. Pietz, David (Dave) A. 

Brandt, Deborah (Deb) A. Buhl, and Bobby Cox, with help 

from many others, conducted a series of groundbreaking 

studies using radio-marked brood hens and miniature transmitters to monitor duckling mortality events and to identify 

causes of death, with study sites distributed across a broad 

prairie pothole landscape during dry and wet periods. These 

studies established that brood loss was much higher than 

previously thought and furnished new insights into factors 

limiting brood survival. Findings reinforced conclusions from 

other NPWRC studies that seasonal wetlands are vital in 

maintaining high duck productivity in prairie pothole landscapes and also underscored the value of maintaining high nest 

success rates of early clutches. Predation by American mink 

(Mustela vison), the primary duckling predator, was reduced 

Canvasback hen with ducklings.
12 Northern Prairie Wildlife Research Center—Celebrating 50 Years of Science

Marsha Sovada holds an American mink after attaching a radio 

collar, 1979.

during post-drought periods in landscapes with few permanent 

wetlands. Exposure to cool, wet conditions was an important 

determinant of brood loss rate. A study of canvasback ducklings at Agassiz NWR by Carl E. Korschgen, Kevin P. Kenow, 

and William (Bill) L. Green highlighted the significance of 

exposure to adverse weather conditions in duckling survival; 

this finding later led Korschgen and Kenow to examine 

heat loss in ducklings and effects of transmitter attachment 

methods. These results and others provided waterfowl managers with a greatly improved understanding of factors limiting brood survival along with improved estimates of mallard 

brood survival rate for the Mallard Model, an important tool 

for predicting annual mallard recruitment rates within portions 

of the PPR.

The Mallard Model started when Doug Johnson and 

Alan (Al) B. Sargeant (Sarge) approached several NPWRC 

researchers who were studying various aspects of duck breeding biology. Johnson and Sargeant were enthused about the 

use of models after using them to examine the role of red 

fox (Vulpes vulpes) predation on nesting mallards in creating disparate sex ratios. The idea they broached was for all to 

focus on a single species (the mallard), study it in a comprehensive manner, and use a model to combine information 

and identify the most fruitful avenues for further research. 

Lew Cowardin quickly recognized the value of the modeling 

effort. He initiated a major radio-telemetry study of breeding 

mallards to evaluate assumptions made in the Mallard Model 

and to provide better estimates of parameters in the model that 

were poorly known. His research team, known as the “Mallard 

Mafia,” included a number of seasonal employees who would 

go on to have exemplary careers in the wildlife profession.

Cowardin realized that the Mallard Model, although 

initially intended to guide research, could be valuable for 

addressing questions from waterfowl managers. This recognition led to the application of the Mallard Model to a number 

of management issues, including planning a new waterfowl 

refuge, examining management options within wetland 

Lew Cowardin examines wetland maps.

Deb Buhl monitors signals from radio-marked ducks from a 

pickup truck.
Waterfowl 13

management districts, projecting the outcome of installing 

a large number of nest structures throughout the PPR, and 

many more. In a related development, Cowardin, working 

with Phillip (Phill) M. Arnold (FWS and later with NPWRC), 

recognized that certain components of the Mallard Model 

could address a critical need of waterfowl managers to provide 

annual estimates of breeding duck numbers and productivity 

from public and private lands in the U.S. portion of the PPR. 

The team developed a method using remote sensing to identify 

annual wetland conditions on 4-square-mile plots and duck 

pair-pond regression models first developed by Doug Johnson 

and later expanded by Terry Shaffer. The Mallard Model and 

what became known as the Four-square-mile Survey were so 

influential they spurred the formation of two FWS HAPET 

offices, one in Bismarck, N. Dak., and one in Fergus Falls, 

Minnesota, in 1990. The Four-square-mile Survey continues 

today as an operational FWS survey and provides a cornerstone for many conservation delivery decisions by Prairie 

Pothole Joint Venture (PPJV) partners. Perhaps the most 

powerful and widely used tool in the PPJV’s arsenal, and 

a product of the Four-square-mile Survey, is the so-called 

thunderstorm map, brainchild of long-time HAPET leader and 

NPWRC alumnus, Ronald (Ron) E. Reynolds. The thunderstorm map identifies areas with greatest potential for duck 

production throughout the PPJV area based on land cover, 

wetland data, and species ecology. The Mallard Model and 

Four-square-mile Survey have been subsequently refined and 

improved by NPWRC and HAPET staffs.

Waterfowl managers have long recognized the importance of waterfowl production on private lands. A longstanding focus of Center research has been the role of various 

cropland retirement programs, such as the USDA’s Water 

Bank, the Cropland Adjustment Program (CAP), and most 

recently the Conservation Reserve Program (CRP), in providing critical habitat for nesting ducks. Harold Duebbert, studying CAP fields in the early 1970s, and Hal Kantrud, working 

in CRP fields in the early 1990s, were first to demonstrate the 

potential of large-scale cropland retirements to enhance duck 

nest success. In one of the largest duck-nesting studies ever, 

Terry Shaffer and Wesley (Wes) E. Newton, in collaboration 

with Ron Reynolds and other PPJV partners, demonstrated a 

game-changing positive relation between the amount of perennial cover at the 4-square-mile landscape scale and duck nest 

success. They went on to show that, during peak enrollment 

years, the CRP was responsible for an additional 2 million 

ducks in the fall flight each year. This finding played a critical 

role in various congressional re-authorizations of the CRP and 

designation of the PPR as a priority area for the CRP.

The Center’s mandate to provide scientific information 

needed by decision makers at flyway and national levels laid 

the foundation for international cooperation and partnerships 

early on. Early study locations ranged from the Beaufort Sea, 

arctic and subarctic Alaska and Canada, and the Great Slave 

Lake in the Northwest Territories, throughout the prairie Provinces of Canada, to the wintering grounds in California and 

Mexico. This long-time relation between Canadian and Center 

biologists (and other State and Federal biologists in the United 

States) fostered the single most extensive international waterfowl recruitment study in North America: the Stabilized Duck 

Hunting Regulation Study (1979–85). The breeding-ground 

portion of the study, led by Raymond (Ray) J. Greenwood 

and Al Sargeant, was designed to provide an understanding 

of breeding populations, availability of breeding habitats, and 

rates of nest success and recruitment. The ultimate goal was 

to evaluate factors regulating duck populations and to determine management actions needed to ensure adequate populations. The Center’s contribution was paramount, providing an 

assessment of nest success and recruitment rates at multiple 

locations throughout the PPR of Canada. Results provided 

estimates of temporal and spatial variation in nest success; 

identification of principal causes of nest failures; identification 

of predator species composition, densities, and spatial distribution; and estimates of mallard recruitment rates. A bonus of 

the research was exposing nearly 100 seasonal technicians to 

the biology of breeding waterfowl across the prairie Provinces 

Mallard hen with ducklings. and providing a solid foundation for the many who went on 

Clay-colored sparrow nest with clay-colored sparrow eggs and 

brown-headed cowbird eggs in South Dakota.
14 Northern Prairie Wildlife Research Center—Celebrating 50 Years of Science

to leadership positions influencing waterfowl management 

and research.

In the 1970s and 1980s, Al Sargeant and Ray Greenwood 

conducted research to understand the role of predators in 

waterfowl population dynamics. Their research was the first 

to document that predation was the major factor influencing 

waterfowl recruitment and that the high levels of predation in 

modern landscapes reflect changes in land use and predator 

community composition, changes brought on by European 

settlement in the region. Sargeant and Greenwood, later joined 

by Jim Piehl and Marsha A. Sovada, conducted studies on 

many predator species, gaining insights into their biology as 

well as the dynamics of the predator community, interactions 

among the predator species, and the role of alternative prey 

species for mitigating predation pressure on nesting birds. 

Some of the greatest gains in development of management 

tools were a result of studies that examined the basic biology 

of the predator species. For example, the devastating impact of 

red fox predation on duck hens and duck nest success, coupled 

with information on interspecific relations between red fox 

and coyote (Canis latrans), helped explain why some areas 

were more productive than others and why duck nest success 

increased as coyote populations expanded across the region. 

Studies by Sargeant and colleagues evaluating the efficacy of 

predator removal as a means of increasing duck production 

were complemented with investigations by John Lokemoen, 

who examined the economics of using naturally occurring or 

constructed peninsulas and islands to exclude predators from 

duck-nesting areas.

In the 1990s and 2000s, the predator research program 

evolved to address more complex questions. These later 

studies focused on understanding the linkages among grassland landscapes, waterfowl productivity, predators, and their 

alternative prey within the context of practical management 

concerns. Sovada, Greenwood, and Rolf R. Koford collaborated with Minnesota Department of Natural Resources biologists to examine the influence of grassland fragmentation and 

patch size on nest predation and predator activity. That study 

led to another conducted by Sovada, Greenwood, and collaborators from Iowa State University and Ducks Unlimited to 

evaluate how nest success and the use of habitats by predators 

vary in relation to grassland conditions, wetland density, and 

landscape configuration. The study provided new insights for 

managing habitat composition at a landscape scale to enhance 

recruitment.

By the early 1970s, there was growing recognition of 

the importance of the wintering period and cross-seasonal 

influences to waterfowl populations. The NPWRC established 

two field stations in California: the Arcata Field Station in 

1973, led by Paul F. Springer, and the Dixon Field Station in 

1979, under the leadership of David S. Gilmer; a substation 

was also maintained at the Kern NWR for several years, led 

by Douglas A. Barnum. The field stations were well placed to 

address ongoing concerns about habitat loss, contaminants, 

and ecology of wintering waterfowl in California and Oregon. 

A radio-collared red fox in a grassland carries a duck egg in its 

mouth.

Jim Piehl and Carol Nustad collect grassland vegetation data, 

1982.

Wayne Norling tracks radio-marked ducks with a hand-held yagi 

antenna.
Waterfowl 15

Springer led pioneering work on the tule greater white-fronted 

goose (Anser albifrons elgasi) and the endangered Aleutian 

Canada (now cackling) goose (Branta hutchinsii leucopareia). Research by Dixon staff encompassed a broad range 

of ecological issues and built a more complete understanding of the impacts of irrigation drain-water contamination 

and wintering waterfowl ecology to guide water, habitat, and 

population management. Michael (Mike) R. Miller, along with 

Joseph (Joe) P. Fleskes and Dennis L. Orthmeyer, developed a 

comprehensive research program on the wintering ecology of 

northern pintails, including survival, feeding ecology, nutritional dynamics, population energetics, habitat use, harvest, 

and the role of rice and wet/dry periods to wintering birds. 

Dave Gilmer contributed to early applications of telemetry and 

remote sensing for migratory waterfowl habitat in the Pacific 

Flyway. John Y. Takekawa led investigations on survival and 

population dynamics of lesser snow geese and white-fronted 

geese in the flyway. Results from these studies have been 

instrumental in guiding wetland management and harvest 

policies in the region and provided a valuable foundation for 

continued research and management of wintering and migratory waterfowl in the Pacific Flyway. In 1993, the Dixon Field 

Station and staff were assigned to what is now the Western 

Ecological Research Center.

During the 1950s and 1960s, severe degradation and loss 

of riverine habitat in the northern portions of the Mississippi 

Flyway shifted migrating diving ducks away from traditional 

concentration areas, which led to increasing concerns among 

waterfowl biologists. In 1977, a Center field station was 

established in La Crosse, Wisconsin, under the leadership 

of Carl Korschgen, to serve as a focal point for research on 

migrating diving ducks and other waterbirds, particularly in 

the Upper Mississippi River system. Early research was linked 

to the Center’s studies of breeding canvasbacks at Minnedosa, 

Manitoba, Canada, and documented the importance of navigation pools on the Upper Mississippi River Navigation (Pools 7, 

8, and 14) as fall staging areas for canvasback, then a species 

of special concern. NPWRC studies by Jerry Serie, David 

Trauger, and Dave Sharp demonstrated that the intensive 

use of the Mississippi River by canvasback and other diving 

ducks was directly related to the diverse and abundant food 

resources available. A suite of studies on the navigation pools 

led by Carl Korschgen, with Kevin Kenow, Bill Green, and 

others, revealed the importance of American eelgrass (Vallisneria americana; also known as wild celery) to canvasback 

during fall stopovers, provided information on factors influencing aquatic food productivity, and documented the impact 

of hunting and boating disturbances to staging diving ducks. 

Research on migratory and wintering diving ducks in the 

John Takewaka and Russian colleague hold a satellite-marked 

snow goose, Wrangel Island, Russia, 1991.

Waist deep in waters of the upper Mississippi River, a technician 

pulls up a mass of Potamogeton vegetation while a second 

technician stands nearby holding a galvanized tub.

Technicians transfer canvasbacks from a swim-in trap to a 

holding box on an upper Mississippi River pool.
16 Northern Prairie Wildlife Research Center—Celebrating 50 Years of Science

region also extended to the Great Lakes. Christine M. Custer’s 

research on the Great Lakes was among the first to highlight 

the importance of invasive zebra mussels (Dreissena polymorpha) as food for staging diving ducks. These projects laid 

the foundation for the long-term management of these pools 

by the Upper Mississippi NWR and the U.S. Army Corps of 

Engineers and for the continuing research on this system by 

the USGS. In 1993, the La Crosse Field Station and staff were 

assigned to what is now the Upper Midwest Environmental 

Sciences Center.

Unprecedented declines in the continental populations 

of greater and lesser scaup (Aythya marila and Aythya affinis) 

starting in 1985 generated substantial concern among biologists and waterfowl hunters. Jane Austin led a series of workshops to explore the challenges to the scaup population with 

biologists and managers from the United States and Canada 

and initiated development of a strategic, biologically based 

decision framework for a scaup conservation action plan. The 

prototype framework that emerged from this collaborative 

effort was among the first to encompass the revised goals of 

the North American Waterfowl Management Plan, integrating 

objectives for waterfowl populations, habitat conservation, and 

societal needs and desires. 

A technician sets up a miniature camera to 

monitor predator and parental activity at a 

grassland songbird nest.

A semi-permanent wetland in Stutsman County, North Dakota.
Other Birds 17

Other Birds

Sandhill Cranes

The NPWRC has played a pivotal role in providing 

information sought by managers of the Midcontinent Population (MCP) of sandhill cranes (Grus canadensis). The MCP is 

widely hunted and has the lowest annual recruitment rate of 

North American game birds; hence, Central Flyway biologists 

sought detailed insight into population dynamics. An early 

effort involved collecting sandhill cranes migrating through 

North Dakota to determine what fraction of them were greater 

sandhill cranes (Grus canadensis tabida), considered a rare 

subspecies by FWS. From that effort, Doug Johnson and Bob 

Stewart developed a statistical tool for managers and biologists to assign individual cranes to migratory subspecies based 

on morphological measurements. 

Part of the focus of the MCP studies has been on habitat 

requirements of cranes in the Central Platte River Valley 

in south-central Nebraska, where about 80 percent of the 

population stages in spring. By the 1970s, intense competition among States and irrigators for greatly reduced flows of 

the Platte River threatened the use of the Central Platte River 

Valley by the MCP and the Aransas/Wood Buffalo population of whooping cranes (Grus americana). Gary Krapu, 

with major contributions by Kenneth J. Reinecke (Patuxent 

Wildlife Research Center), led the Platte River Ecology Study; 

they assessed sandhill crane requirements during their annual 

stopover and evaluated how loss of this migration stopover 

might impact the population. The final report became a major 

source of information used by crane managers for the next 

two decades on issues pertaining to sandhill crane use of the 

Central Platte River Valley ecosystem. The Central Platte 

River was designated as critical habitat for whooping cranes in 

1978, and Krapu served as the Government’s biological expert 

on sandhill and whooping crane use of the Central Platte 

River Valley during several legal challenges to the critical 

habitat designation.

In 1997, the USGS initiated a Platte River Ecosystem 

Initiative. NPWRC scientists contributed the biological 

studies, investigating sandhill cranes (Gary Krapu and Dave 

Brandt), invertebrate food resources for cranes in riparian 

meadows (Jane Austin and Janet R. Keough, in collaboration 

with scientists from the Whooping Crane Maintenance Trust), 

avian response to meadow restoration (Doug Johnson), and 

habitat use by staging waterfowl (Bobby Cox). Gary Krapu 

initiated a comprehensive, 10-year study to re-examine the 

role of the Central Platte River Valley for MCP cranes, along 

with an examination of the contribution of other stopover sites 

in meeting crane needs. The resulting monograph authored 

by Krapu, Brandt, Paul J. Kinzel (USGS Geomorphology and 

Sediment Transport Laboratory), and Aaron Pearse summarized key findings and identified factors influencing length and 

pattern of stay, habitat use, and the growing scarcity of waste 

corn vital to cranes’ acquisition of lipids for migration. Results 

provided crane managers throughout the Central Flyway with 

updated insight into crane habitat needs and how the MCP had 

adjusted to major changes in the Platte River ecosystem. In 

addition to the re-assessment of the Central Platte River Valley 

for cranes, Krapu and Brandt expanded the crane research 

using satellite telemetry to study the MCP across its entire 

range in North America and northeastern Asia. Results of that 

effort identified four subpopulations for management purposes 

and a means to identify size and distribution of harvest by 

subpopulation, documented spatial and temporal distributions, 

and allowed estimates of annual recruitment by subpopulation. 

Aerial view of braided 

river and sandbar habitat 

along the central Platte 

River, Nebraska.

Two technicians collect waste corn samples in a harvested field 

in early spring in Nebraska.

Dave Brandt (front left) works with colleagues to attach colored 

leg bands and a satellite transmitter to an adult whooping crane.
18 Northern Prairie Wildlife Research Center—Celebrating 50 Years of Science

Together, these findings provided Central Flyway resource 

managers with key baseline information on the MCP that will 

help guide future population management. An unexpected 

finding was that 23 percent of the MCP, or 140,000 sandhill 

cranes, breed in northeastern Russia in an area that extends 

from the eastern edge of the Chukchi Peninsula bordering the 

Bering Strait to near the Lena River Delta, 2,400 kilometers 

west into Russia. 

Center scientists also have made significant contributions to improved survey methods for sandhill cranes. Doug 

Johnson has collaborated with crane managers from across 

North America since the 1970s to develop more reliable 

survey techniques, analyze crane survey data, and interpret results. Johnson worked with Flyway pilot Douglas S. 

Benning to use high-altitude photography on the Central Platte 

River Valley in spring to provide reliable annual estimates of 

the size of the MCP. Recognition of the survey’s limitations 

led Center scientists to investigate other approaches, such as 

use of infra-red videography and comparison of survey data to 

locations of the large number of radio-marked cranes from the 

Platte River study.

For many decades, biologists assumed there were three 

subspecies of sandhill cranes, but one subspecies (Grus 

canadensis rowani) had been classified based on a very limited 

sample of morphological data. Gary Krapu, Jane Austin, Doug 

Johnson, and Dave Brandt contributed to three genetics studies 

that indicated Grus canadensis rowani should be considered a 

transitional form and included within Grus canadensis tabida.

Controversy over habitat management and crop depredation problems in southeast Idaho led to a 4-year study of 

breeding and population ecology of greater sandhill cranes at 

Grays Lake NWR. Jane Austin, collaborating with Joe Ball 

and Adonia R. Henry at the Montana Cooperative Wildlife 

Research Unit, determined that the number of breeding crane 

pairs was similar to that reported in the early 1970s but nest 

success rates had declined; water levels affected nest survival 

more than grazing or burning. Study results have contributed 

to the refuge’s comprehensive conservation and habitat 

management plans, monitoring protocol for spring and fall 

populations, and negotiations over water management.

Nongame Birds

Although the original mission of the NPWRC focused on 

research related to waterfowl production and wetland ecology, 

the Center has had a long history of research on nongame 

migratory birds that has encompassed multiple ecological levels (species, population, community, ecosystem) and 

spatial and temporal scales. Research and scientific inquiry 

on nongame birds began at the NPWRC in the early 1960s by 

Bob Stewart and Hal Kantrud. By the time the Center officially opened its doors in 1965, Stewart and Kantrud already 

had spent considerable time in the field developing sampling 

protocols and gathering information on avian and plant species 

and their distribution and habitats in the northern Great Plains. 

These early studies set the foundation for future research on 

nongame birds in grasslands, wetlands, agro-ecosystems, and 

other habitats in this region. Stewart’s extensive field work 

and knowledge of avian species were encapsulated in his 1975 

book, “Breeding Birds of North Dakota,” which remains a 

primary resource about breeding birds in the State.

Stewart and Kantrud’s pioneering study of breeding birds 

throughout North Dakota in 1967 provided important baseline 

data for Center scientists and other agencies (for example, 

USDA) to evaluate subsequent changes (for example, 

1992–93) in statewide breeding bird populations. Through 

time, Center scientists built upon these formative studies on 

nongame birds to address questions related to grassland bird 

response to disturbance (natural and human-induced), changes 

in land use and cover, biological invasions (for example, leafy 

spurge [Euphorbia esula]), USDA Farm Bill programs (for 

example, Soil Bank, CRP), water development (stock dams 

and ponds), energy development (wind, oil and gas), changes 

Adult American white pelicans at their nests at Chase Lake 

National Wildlife Refuge, North Dakota, 2009.

Adult male bobolink in grassland field in Montana, 2010.
Other Birds 19

in local and regional climate, habitat restoration, and habitat 

fragmentation (for example, Grassland Bird Conservation 

Area concept). For example, Hal Kantrud and Russell (Rusty) 

L. Kologiski surveyed breeding birds across six States in the 

northern Great Plains and identified optimal habitat for different bird species in terms of grazing, soils, and dominant plant 

species. John Lokemoen was among the first to examine the 

effects of minimum-tillage, organic, and conventional farming 

practices on ground-nesting birds (passerines, waterfowl, 

and shorebirds). Pam Pietz translated the body of knowledge 

amassed on waterfowl nest predation into new studies to 

better understand the effects of predation and land management practices on grassland-nesting passerines. Studies by 

Doug Johnson, Lawrence (Larry) D. Igl, Jill A. Dechant (later 

Shaffer), Craig Faanes, Rolf Koford, and Abby N. Powell, as 

well as numerous graduate students, have contributed to our 

broader knowledge of avian ecology.

Several Center studies highlighted the value of long-term 

over short-term approaches to studying grassland and other 

nongame birds, including Doug Johnson’s long-term evaluation (1971–2013) of breeding bird response to burning in the 

mixed-grass prairie at the Woodworth Study Area and Johnson 

and Igl’s ongoing study (1990–present) of breeding bird use 

of grasslands enrolled in the Conservation Reserve Program in 

nine counties in four States in the northern Great Plains. The 

latter study was instrumental in demonstrating the benefits of 

Farm Bill programs for grassland birds.

The Center’s expertise and leadership in avian ecology 

have proven beneficial for research on grassland birds and 

other nongame birds and have attracted new partners and 

cooperators. In 1993, the Center established the Grasslands 

Ecosystem Initiative. For more than a decade, the Initiative 

served as a focal point for studies on grassland birds and 

other topics in the Great Plains. The Initiative also served as 

a catalyst for information dissemination among partners and 

the general public, including the development of the Center’s 

award-winning website and the extensive review and synthesis 

of literature on the effects of management practices on grassland birds. Together, past and recent studies have helped to 

develop the knowledge base essential for ecologically sound 

management of habitats for grassland and other nongame birds 

in this region. The current scientific program and expertise 

placed NPWRC in a strong position to address emerging 

issues and challenges facing management and conservation of 

grassland and other nongame birds in the region.

Studies of nongame waterbirds have emphasized population biology, habitat use, and resource needs of species such 

as marbled godwits (Limosa fedoa), willets (Tringa semipalmata), American avocets (Recurvirostra americana), yellow 

rails (Coturnicops noveboracensis), and black-crowned night 

herons (Nycticorax nycticorax). Research largely focused on 

conservation of these populations and improved management 

of their habitats. For example, a study by Jane Austin and 

Janet Keough at Grays Lake NWR, a large montane wetland 

system in southeastern Idaho, examined the abundance and 

responses of waterbirds, waterfowl, and the plant community 

to grazing, burning, and idle management practices. Studies 

by Jan Eldridge and Gary Krapu demonstrated the vital role 

of dipteran larvae in prairie wetlands to Calidris sandpipers for accumulating fat reserves that fuel spring migration 

and supply part of their reproductive needs. Starting in the 

mid-2000s, there has been a special focus on American white 

pelicans (Pelecanus erythrorhynchos) because of severe 

production failures at several colonies. Studies by Marsha 

Sovada, Pam Pietz, and others revealed pelicans’ unique 

susceptibility to West Nile virus and a decline in productivity 

that is linked to climate change. Ongoing studies continue to 

assess pelican ecology.

Technician surveying grassland birds in a Conservation Reserve Program field in northeastern Montana, 2008.
20 Northern Prairie Wildlife Research Center—Celebrating 50 Years of Science

Imperiled Species

analyzed band recoveries and field data and discovered 

important wintering habitat used by this species; his recommendation of no hunting in critical areas used by the wintering 

birds resulted in an immediate recovery of the species. These 

combined efforts led to the removal of Aleutian cackling geese 

from the endangered species list in 2001.

Carnivore species of special concern, such as the gray 

wolf (Canis lupus), swift fox (Vulpes velox), island fox 

(Urocyon littoralis), and Canada lynx (Lynx canadensis), also 

have been the focus of research and conservation efforts by 

Center scientists. Studies focused not only on the ecology of 

these species but also on the issues surrounding them, which 

often are contentious. Marsha Sovada served on recovery 

teams and conducted field research on swift fox and the 

endangered island foxes. Her research objectives for swift 

fox included assessment of population status, evaluation of 

factors affecting populations, and understanding the ecology 

of the fox species and predator-prey relationships. Ultimately, 

the information gathered provided managers with the foundation to develop effective management plans and to provide 

the fundamentals for managers to respond to the concerns 

of the public. For island foxes, Sovada collaborated with 

the St. Louis Zoo to assess factors that influence reproductive success with research conducted on captive populations 

located on two Channel Islands that are occupied by island 

foxes. In 2016, the FWS removed the San Miguel (Urocyon 

littoralis littoralis), Santa Rosa (Urocyon littoralis santarosae), and Santa Cruz (Urocyon littoralis santacruzae) Island 

fox subspecies from the List of Endangered and Threatened 

Wildlife because of increased populations. This remarkably 

rapid recovery of the island fox demonstrates the power of 

partnerships, focus, and science.

L. David (Dave) Mech and Michael E. Nelson were 

assigned to the NPWRC in 1999, bringing the Wolf Project 

Forrest Lee holds a Giant Canada goose. to the NPWRC. Mech has studied wolf ecology and behavior 

Pair of Canada geese on water.

The Center has contributed its expertise to the restoration, ecology, and management of a number of imperiled birds 

and mammals. The first program focused on the restoration 

of giant Canada geese (Branta canadensis maxima) and the 

Aleutian Island subspecies of Canada geese (now classified as cackling geese). Giant Canada geese, once believed 

extirpated, were rediscovered in Minnesota in 1962. Hired 

in 1965, Forrest B. Lee pioneered waterfowl propagation 

and husbandry techniques and raised thousands of birds for 

release in North Dakota. Lee worked closely with State and 

FWS biologists in North Dakota and South Dakota to successfully restore breeding populations of giant Canada geese in 

the region. The techniques developed by Lee were widely 

disseminated to Federal and State recovery programs across 

the United States during the 1960s and 1970s and were an 

important contribution to the full recovery of the subspecies. Lee’s waterfowl propagation expertise also was a major 

contributor to an international effort with Japan and Russia to 

restore cackling geese to the Aleutian Islands. Paul Springer 
Imperiled Species 21

Marsha Sovada holds a fox pup dug out from its den, 1996.

and the species’ role within the ecosystem for half a century, 

largely in Minnesota but also throughout the world. Along 

with Shannon M. Barber-Meyer, hired to replace the retiring 

Nelson in 2011, Mech developed a broad research program 

that involved many aspects of predator-prey relationships, 

such as the role of prey nutrition in buffering wolf depredation of game animals and livestock, dynamics of prey populations such as white-tailed deer (Odocoileus virginianus) and 

moose (Alces alces) in Minnesota and elk (Cervus elaphus) in 

Yellowstone National Park, and dispersal of Canada lynx from 

Canada to Minnesota. Mech and Barber-Meyer continue to 

monitor the wolf population in the Superior National Forest to 

evaluate factors such as diseases that affect long-term population trends. These studies provide insights that are useful to 

recovery and restoration of populations and for building more 

realistic population models. Findings allow managers and 

administrators to assess the progress of restoration programs 

and recovery of wolves and to anticipate the biological and the 

political problems that might arise.

Large river ecosystems are a major feature of the midcontinent landscape and provide important habitat for migratory 

birds during breeding and migration. Federally listed piping 

plovers (Charadrius melodus) and least terns (Sternula antillarum) nest on sandbars and shorelines on several major 

midcontinent river systems, including the Platte and Missouri 

Rivers. Both river systems have been hydrologically altered by 

construction of dams and water withdrawals, with subsequent 

effects on abundance and quality of nesting habitat for these 

species. In 2005, the Center’s long-term expertise in migratory 

bird research led to an invitation from the U.S. Army Corps of 

Engineers to develop a major research effort focused on quantifying the importance of the upper Missouri River system and 

understanding relations between management of the system 

and responses by piping plovers and least terns. The Center’s 

research team (Michael [Mike] J. Anteau, Colin M. Dovichin, 

Erin A. Roche, Terry Shaffer, Mark H. Sherfy, Marsha Sovada, 

Laurence [Larry] L. Strong, Jennifer H. Stucker, and 

Mark T. Wiltermuth) has had a major presence on the upper 

Missouri and Platte River systems ever since. Studies revealed 

the importance of fluctuations in reservoir water levels to 

Missouri River plovers and identified conditions under which 

reservoirs function as a population sink. Another study uncovered major biases in the long-term population monitoring 

program for both species and proposed improvements to the 

program, many of which are being implemented. Evaluation 

of nest-site selection by least terns at multiple scales revealed 

important differences between natural and constructed sand 

bar habitat and the importance of scale in estimating available habitat. Other work included investigating effects of the 

2011 flood on tern and plover demographics and a large-scale 

mark-resight study to better understand the role of the upper 

Missouri River system in achieving recovery goals for the 

northern Great Plains population of piping plovers.

Beginning in 2009, Aaron Pearse and Dave Brandt began 

an ambitious research effort with collaborators from the FWS, 

Canadian Wildlife Service, and several nongovernmental 

organizations to study the Aransas-Wood Buffalo population of endangered whooping cranes (Grus americana). The 

Center’s experience and innovative techniques to capture 

and mark sandhill cranes provided the necessary foundation 

for this effort to be successful. This study of wild whooping 

cranes using Global Positioning System (GPS) technology 

represents a significant opportunity to enhance understanding 

of whooping cranes and to assess risks they face during their 

Swift fox holding a ground squirrel in its mouth near its den. entire life cycle.

Radio-collared gray wolf.
22 Northern Prairie Wildlife Research Center—Celebrating 50 Years of Science

Large Mammals

Although ungulates in general are not Federal 

trust species, under special circumstances the expertise 

of Center scientists has been called upon to address 

issues of concern. In partnership with the National 

Park Service, Glen A. Sargeant has been investigating 

ungulates in national parks of the northern Great Plains. 

His studies focused on population dynamics of elk that 

had been restored to Wind Cave and Theodore Roosevelt 

National Parks. Sargeant developed models to project 

growth, forecast management needs, and compare the 

likely consequences of different management strategies. Greater knowledge about the populations emerged 

as a critical information need for management agencies because chronic wasting disease was detected in 

the Wind Cave population. In another effort, a faltering moose population in Minnesota evoked a partnership among Dave Mech, Mike Nelson, and the State 

of Minnesota to study the effects of climate change on 

moose populations.

Elk cow and her calf at Theodore Roosevelt National Park, 

North Dakota. Photograph courtesy of National Park Service.

Bull elk in the rolling grasslands of Wind Cave National Park, South Dakota. Photograph courtesy of National Park Service. 
Wetlands 23

Wetlands

Given the innate ties between waterfowl and the wetland 

habitats they require, it is no coincidence that waterfowl 

research and wetland research at the NPWRC have gone 

hand-in-hand. In the late 1950s, faced with the possibility that 

irrigation and wetland drainage would change the hydrological 

characteristics of wetlands on the prairie pothole landscape, 

the USGS initiated detailed studies of prairie wetland hydrology. These studies initially focused on evapotranspiration 

from wetlands in different parts of North Dakota but were 

later expanded to examine wetland relations with groundwater. Beginning in 1961, Bob Stewart and Hal Kantrud 

surveyed vegetation of some of the same wetlands. Stewart 

and Kantrud’s work led to understanding the range of salinity 

and water permanence tolerated by different plant species and 

subsequently the development of their wetland classification 

system for prairie wetlands based on diagnostic plant communities. That classification system, published in 1971, remains 

recognized continentally and often serves as an important 

guide in wetland and waterfowl studies.

The first effort by the FWS to conduct a national inventory of wetlands was initiated in 1954 based on 20 wetland 

types identified in FWS Circular 39. That publication was 

valuable and influential at the time but had a number of 

recognized shortcomings. Numerous other wetland classification systems were developed in the 1970s, including 

that of Stewart and Kantrud, which intentionally focused on 

the glaciated pothole region. As the FWS planned the next 

national wetland inventory in the 1970s, a new classification system was needed that incorporated new knowledge 

of wetland ecosystems and provided greater uniformity in 

concepts and terminology applicable across all wetland types 

in the Nation. Lew Cowardin worked closely with colleagues 

Virginia Carter (USGS–Reston), Francis C. Golet (University 

of Rhode Island), and Edward T. LaRoe (National Oceanic 

and Atmospheric Administration) to develop what is now the 

official FWS wetland classification system and the Federal 

standard. This hierarchical classification system has been 

instrumental not only in inventorying and mapping wetlands at 

multiple scales but also as an aid to researchers investigating 

ecosystem function and services.

Cottonwood Lake Study Area

In an effort to understand factors affecting use of various 

wetland types by waterfowl, during 1966–76 George Swanson 

began a study of the chemical characteristics of wetlands and 

small lakes. In this first extensive study of prairie wetlands 

and lakes, Swanson and NPWRC chemist Vyto A. Adomaitis 

found a wide range in water salinity and chemical composition and noted that observed salinity differences were likely 

due to variations in the influence of groundwater. Armed with 

this knowledge, Swanson teamed up with Thomas (Tom) 

T. Winter, a research hydrologist with USGS in Lakewood, 

Colo., to develop a “grass roots” interagency research program 

to define hydrological characteristics and processes responsible for changes in water level and the biological communities of prairie wetlands. Winter and Swanson selected a 

complex of 16 wetlands on a waterfowl production area near 

Woodworth, N. Dak., now known as the Cottonwood Lake 

Study Area, for their investigations. James (Jim) W. LaBaugh, 

a USGS research chemist also at Lakewood, joined the team 

in 1979 to assist Swanson with explorations of the relations 

among wetland chemical characteristics, hydrological characteristics, and wetland biota at the site. In 1983, the chemical laboratory at the NPWRC closed and LaBaugh assumed 

responsibility for all water chemistry work associated with the 

Hal Kantrud stands along a barb-wired fence in native mixedgrass prairie.

Robert Stewart consults a plant taxonomy guide to verify the 

identities of voucher herbarium specimens.
24 Northern Prairie Wildlife Research Center—Celebrating 50 Years of Science

George Swanson stands next to an aluminum boat rigged with 

an aquatic invertebrate sampler.

Cottonwood Lake Study Area efforts until 1993, when Richard 

(Rick) D. Nelson, from the Bismarck Office of the Bureau of 

Reclamation, took over that component. Donald Rosenberry, 

a USGS research hydrologist at Lakewood, joined the team in 

1985, assisting with instrumentation of the site and research 

focusing on nearshore changes in flows between groundwater 

and wetlands.

Through the NPWRC’s dedication to the study of 

waterfowl and prairie wetlands, the increasingly comprehensive Cottonwood Lake Study Area datasets and ongoing 

process-oriented research have served as a magnet, attracting 

researchers from a number of universities and other Government agencies. This interest has resulted in cooperative studies 

on wetland soils, sedimentation, greenhouse gas exchange/

flux, primary production, seedbanks, climate change, pesticide 

effects on waterfowl, mineral content of glacial till, and a 

variety of other topics. Additionally, the historic and ongoing 

salient research at the Cottonwood Lake Study Area through 

the NPWRC provides a strong biological and hydrogeochemical framework that has stimulated much graduate student 

research at the site.

With George Swanson’s retirement, Ned (Chip) H. 

Euliss, Jr. transferred from the Center’s Dixon Field Station 

in California to Jamestown in 1991 to become the leader of 

the Cottonwood Lake Study Area research team, where he 

continued the tradition of cooperative research at the site. In 

1992, Euliss expanded the biological research there to include 

detailed monitoring of invertebrates, amphibians, and birds to 

complement long-term examinations of vegetation and water 

chemistry. These studies provided new insights about population changes related to hydrogeochemical dynamics of the 

wetlands. USGS scientist Martin (Marty) B. Goldhaber and his 

research staff in Lakewood, Colo., are the most recent additions to the Cottonwood Lake Study Area’s team of wetland 

experts; they provide new insights into the role of geology and 

associated geochemical processes in shaping the water chemistry and ultimately the biotic communities of prairie wetlands. 

In 2014, David M. Mushet assumed the research lead for 

the Cottonwood Lake Study Area as Euliss retired; Mushet 

continues the strong history of interdisciplinary research and 

cooperation at the site.

Other Wetland Research

Wetland losses resulting from drainage and conversion 

to crop production have been a continued area of NPWRC 

research. Historically, wetlands throughout the region were 

drained using surface drains. These drainage ditches often did 

not completely dry wetlands and left behind basins that still 

performed some of the ecological processes associated with 

undrained wetlands. However, in the more intensely farmed 

areas of the PPR such as the eastern portion of the Dakotas, 

southwestern Minnesota, and northern Iowa, subsurface tile 

drains allowed for more complete drainage and facilitated 

the loss of more than 90 percent of the wetlands in those 

areas. Prevailing high agricultural commodity demands, 

mandates for crop-based biofuels (ethanol and biodiesel), and 

genetically modified row crops that can be grown in semiarid conditions have facilitated the expansion of row-crop 

agriculture and use of subsurface tile drains into areas of the 

PPR where crops had been historically dominated by small 

grains. Wetland drainage across the region continues to be of 

great concern to the FWS and has stimulated new research on 

the effects of the expansion of tile led by NPWRC scientist 

Raymond (Ray) G. Finocchario. Another drainage practice 

of concern to the FWS, State wildlife agencies, and others is 

consolidation drainage, the process of draining wetlands in the 

upper reaches of a landscape with the drainage water collecting and contributing to the water budget of downgradient 

wetlands. Mike Anteau leads studies of the effects of consolidation drainage on waterfowl and other biotic communities 

supported by prairie pothole wetlands.

The above-mentioned research efforts provide a snapshot 

of the wide range of wetlands research that has been done at 

the Center during the past 50 years. Center scientists have also 

investigated wetland systems in the Central Valley of California, forested wetlands of Minnesota, riparian wetlands in 

the Upper Mississippi River, natural and impounded wetlands 

in the Little Missouri National Grasslands of western North 

Dakota, montane wetlands of Idaho, riparian meadows along 

the Central Platte River, and peatland systems in northern 

Michigan. Research into amphibian ecology has addressed 

questions about wetland quality, land use, and conservation 

programs. Additional significant contributions of NPWRC 

research to the wetland sciences include formulation of the 

wetland continuum concept, improvement of wetland restoration techniques and evaluation methodology, quantifications 

of the role wetlands play in carbon cycling and their potential 

to sequester atmospheric carbon, the negative impacts of 

agricultural-associated sedimentation on effective lifespans of 

wetlands, development of models facilitating quantifications 

of goods and services provided by prairie pothole wetland 

ecosystems, and more.
Invasive Species and Restoration Ecology 25

Invasive Species and Restoration Ecology

Plant ecology and habitat restoration have long been a 

part of NPWRC science, often as a facet of waterfowl habitat 

improvement. Early studies by Leo Kirsch, Ken Higgins, and 

Arnie Kruse at the Woodworth Field Station and elsewhere in 

the PPR helped define the role of fire in maintenance of prairie 

habitat. Expertise in plant identification by Bob Stewart, Hal 

Kantrud, Lew Cowardin, Russell (Rusty) L. Kologiski, Mavis 

I. Meyer, Bruce A. Hanson, and others, and the Center’s 

extensive herbarium have been important resources valued by 

the larger scientific community in the northern Great Plains. 

As the Center’s scope of work expanded in the 1990s with 

studies in national parks as well as NWRs and waterfowl 

production areas, the prevalence of invasive plant species and 

their effects on ecosystem function came to the fore. Included 

in these studies were evaluations of not only the effects of the 

invasive species, but also how control methods could influence native plant communities and the role of prescribed 

fire in invasive species management. Gary D. Willson and 

his team at the Center’s Columbia, Missouri, Field Station 

(affiliated with NPWRC during 1993–97) investigated plant 

communities and developed monitoring protocols for prairie 

national parks and assessed methods to control smooth brome. 

Research conducted by Diane L. Larson and her students and 

colleagues at the University of Minnesota described effects of 

exotic invaders such as leafy spurge, Canada thistle (Cirsium 

arvense), and smooth brome on vegetation, seed banks, pollination of native co-flowering species, and suitability of soils 

for native species. David P. Fellows investigated effects of 

prescribed burning on biological control of leafy spurge. More 

recently, Amy J. Symstad and her colleagues have developed 

models to predict vegetation changes under various climate 

scenarios for national parks in the northern Great Plains, as 

well as monitoring protocols to track long-term trends in 

vegetation, and a compilation of information to aid with the 

interpretation of monitoring data.

As the extensive conversion of native prairies to other 

uses has become more widely recognized, resource managers increasingly face issues related to prairie restoration on 

remnant habitat and even reconstruction on former cropland. 

To address these issues, NPWRC science has concentrated 

on establishing best practices to accomplish restoration and 

reconstruction and on the use of formal methods such as structured decision making to focus on key aspects of the issues 

that will move the practice of restoration and reconstruction 

forward. The Center’s involvement in large, multi-refuge 

projects—such as the Native Prairie Adaptive Management 

(NPAM) initiative (led by Terry Shaffer, Jill J. Gannon, and 

Clinton T. Moore, Georgia Cooperative Fish and Wildlife 

Research Unit) and the Prairie Reconstruction Initiative Advisory Team (led by USGS, The Nature Conservancy, and State 

agencies)—is producing tangible steps toward the transfer 

of science-based decision making into the hands of resource 

managers. Broad-scale retrospective and experimental studies 

of prairie reconstruction in Iowa and Minnesota, led by Diane 

Larson, are aimed at improving understanding of how methods 

and timing of planting can produce diverse and resilient prairie 

habitat that supports native pollinators as well as waterfowl and nongame birds. Additional pollinator research by 

Clint R.V. Otto and David Mushet includes modeling plantpollinator community networks in managed prairies, determining how pollinator communities respond to the spread of 

invasive plant species, quantifying how land use change in the 

northern Great Plains influences pollinator health and habitat 

at large spatial scales, and developing an online database of 

plant-pollinator interactions.

Invasion of leafy spurge and yellow sweetclover in a native grassland at 

Theodore Roosevelt National Park, North Dakota.

Fritillary butterfly on leafy spurge in Theodore 

Roosevelt National Park, North Dakota.
26 Northern Prairie Wildlife Research Center—Celebrating 50 Years of Science

Landscape Ecology

As evidenced by many of the studies noted above, 

NPWRC scientists have long recognized the importance of 

spatial and temporal patterns at landscape scales, particularly 

as they influenced migratory waterfowl. During the first two 

decades of the Center’s history, work at larger scales was 

pursued mainly by having multiple study sites, such as the 

Stabilized Regulations Study that extended across three Canadian prairie Provinces, and Kantrud and Kologiski’s evaluation of the effects of soils and grazing on breeding birds across 

six States. Landscape-scale research advanced starting in the 

mid-1980s, fueled by new resources and tools such as Landsat, 

geographic information systems (GISs), and satellite telemetry. The continued evolution of these resources, combined 

with increasing power of computers and software, has allowed 

Center scientists to pursue ecological and management questions at much broader and more detailed scales than ever 

before. Below are just some of the past and current studies or 

programs that address issues at landscape scales that are not 

noted elsewhere.

In the 1980s, biologists and conservation planners identified the need to move beyond single-species approaches to 

deal with widespread habitat loss and threats to biodiversity. 

The Gap Analysis Program (GAP) was originally conceived 

by J. Michael Scott, then with Patuxent Wildlife Research 

Center, and was embraced as a national program by the FWS 

in 1989. GAP provides geographically explicit information on 

the distribution of habitat types and native vertebrate species 

and their management status to determine “gaps” in biodiversity protection. The program provides geospatial information 

to decision makers about land cover, land ownership, and 

potential vertebrate habitat for conservation planning. Larry 

Strong, H. Thomas (Tom) Sklebar, and others developed the 

GAP data for North Dakota, including a detailed land-cover 

map, wildlife-habitat relation models, and potential distribution maps for 281 mammals, amphibians, reptiles, and breeding birds. Completed in 2005, the GAP data for North Dakota 

are a valuable resource for the distribution and stewardship of 

habitats and vertebrates in the State and have been used by a 

diversity of agencies and organizations.

The U.S. Environmental Protection Agency’s Environmental Monitoring and Assessment Program (EMAP) was 

initiated in 1989 to provide improved information on the 

status and long-term trends in the condition of the Nation’s 

ecological resources. The program sought to develop measures 

to monitor the status and trends of wetland conditions on a 

regional basis with known statistical confidence and to seek 

associations between response indicators of wetland condition 

and environmental stressors. Lew Cowardin and the NPWRC 

were invited to take the lead role for pilot studies on PPR 

wetlands. A team of scientists led by Cowardin and later by 

Glenn R. Guntenspergen conducted a suite of studies during 

1992–96 to develop and assess landscape- and basin-level 

measures, with study areas extending across North Dakota. 

EMAP studies identified indicators that were useful to assess 

the biological condition of wetland resources, such as invertebrate communities, amphibians, plant communities, and 

wetland basins. The studies also brought to light a number of 

challenges for implementation of the program, particularly for 

biotic measures, such as access to sites on private lands.

The NPWRC responded to the need to quantify ecosystem services influenced by Government-sponsored wetland 

restoration initiatives in the PPR. In 1997, Chip Euliss initiated an extensive survey of restored wetlands and adjacent 

uplands, and in 2004, Euliss and Robert Gleason expanded 

the effort. These surveys provided basic quantitative relation 

and estimates of ecosystem services derived from DOI and 

USDA conservation programs. Largely a result of the success 

of this preliminary work, the USGS initiated its Integrated 

Landscape Modeling (ILM) Science Thrust in 2006. Euliss 

and, more recently, David Mushet have continued to develop, 

parameterize, and validate multiple ecological models needed 

to facilitate the quantification of a wide array of goods and 

services provided by naturally functioning prairie ecosystems 

(for example, carbon sequestration, wildlife habitat, flood 

water storage, water quality improvement, crop pollination). 

These models facilitate explorations into how the provisioning 

of ecosystem goods and services valued by society might be 

influenced by future changes in climate and land use. Much 

of the ILM work conducted at the NPWRC has been accomplished through close collaborations with the USDA’s Natural 

Resources Conservation Service and Farm Services Agency. 

Providing the scientific information needed to effectively 

implement USDA programs affecting management of private 

lands is an important component of maintaining wildlife populations and functioning ecosystems.

Skunk

EXPLANATION

Successful duck 

nest

Destroyed duck 

nest

Grassland

Pastureland

Hayland

Grain crop

Temporary

Seasonal

Semipermanent

Flooded margin

Wetlands

Upland habitat

A geographic information system (GIS) was used to understand how 

the movement of skunks was related to the distribution of duck nests 

that successfully hatched versus those that were lost to a predator 

near Chase Lake National Wildlife Refuge, North Dakota.
Research Techniques and Information Transfer 27

Research Techniques and Information Transfer

Scientists at the NPWRC developed many research techniques and management strategies that are now routinely used 

by researchers and managers worldwide, many of which have 

been mentioned earlier in this report. Center staff pioneered 

methods for locating and monitoring waterfowl nests, determining incubation stage of songbird eggs, sampling invertebrate food resources used by waterfowl, and assessing wetland 

quality. Techniques developed at the Center for studying 

duck nest success and depredation and for monitoring predator populations have been widely applied across the PPR on 

many wildlife areas. Pam Pietz was among the first to demonstrate the value of miniature camera systems for documenting 

nesting behavior and depredation events at passerine nests. 

Center biologists made important advances in capture and 

marking methods for waterfowl, cranes, and shorebirds, and 

designed and evaluated innovative means to protect bird nests 

from predators. Center scientists carefully evaluated various 

marking methods, radio-transmitter designs, and attachment 

techniques to optimize data quality while ensuring minimal 

effects on the animal’s welfare and behavior. 

Research programs at the Center included cutting-edge 

use of wildlife telemetry systems, remote sensing imagery, and 

videography for gathering data. As the first remote sensing 

data became available in the 1970s from the Earth Resources 

Technology Satellite (ERTS-1) and Landsat 1, Dave Gilmer 

and Lew Cowardin were among the first to explore the potential of these data for monitoring waterfowl habitat. Beginning 

in the mid-1980s, the availability of increasingly powerful 

tools available to researchers—computers and associated 

software, GIS, better remote sensing resources, and satellite telemetry—were rapidly embraced by Center scientists 

and enhanced their capabilities to conduct ever larger and 

more complex studies. Lew Cowardin was one of the first 

in the Nation to use aerial videography (and later the first 

digital cameras) for research on natural resources, combining 

aerial videography, high-altitude photography, newly available National Wetlands Inventory data, and ground counts 

to evaluate duck habitat and estimate duck population sizes. 

David Gilmer, Larry Strong, and others developed innovative 

approaches in GIS and remote sensing analysis for natural 

resource studies and management applications, such as the use 

of QuickBird imagery to assess habitat availability for piping 

plovers and least terns on the Missouri River.

Center statisticians gained a reputation as leaders 

in development of analytical methods; in particular, they 

advanced the methods for analysis of nest success data and 

modeling populations, which ultimately provide for more 

informed management decisions. Mathematical and computer 

modeling and remote sensing have become integral parts of 

the Center’s research program. At the heart of such advances, 

and indeed the foundation of the Center’s strong research 

program, was a strong statistical support team, first developed 

by Doug Johnson and later led by Terry Shaffer and Wes 

Newton. Most importantly, NPWRC has provided the technical assistance and tools for implementing research findings to 

improve management of the continent’s migratory bird and 

wetland resources.

The Center has long recognized the importance of 

communicating research findings and ecological knowledge 

to managers, decision makers, and the broader biological 

community. Throughout the Center’s 50-year history, NPWRC 

scientists published more than 1,700 articles in peer-reviewed 

journals and other professional outlets, technical reports, and 

The Center’s geographic information systems (GIS) lab in the mid1980s: Lew Cowardin discusses GIS work with colleagues and 

technicians.

Carol Nustad enters data at an early computer system (circa 

early 1980s).
28 Northern Prairie Wildlife Research Center—Celebrating 50 Years of Science

Sheel Bansal measures gas emissions from a wetland.

other products (U.S. Geological Survey, 2017). Thousands 

of presentations have been given at professional conferences 

and other venues to partners, clients, other scientists, and the 

public. More than 15 symposia and workshops have been 

organized and hosted by the Center about waterfowl (Canada 

geese, canvasbacks, mallards, scaup), cattail management, 

prescribed fire, predator ecology and management, wetland 

ecology, wildlife marking and telemetry, and statistics. Staff 

have compiled and shared extensive bibliographies and developed synthesis publications on key subjects, such as effects 

of management practices on grassland birds; these products 

are valued resources to the larger biological and management 

community. The Center’s herbarium is the third largest in the 

State, holding nearly 6,000 specimens from the United States 

and Canada, and has been a valuable resource for many projects by Center staff and others. A professionally staffed library 

with an impressive collection of wildlife- and ecology-related 

holdings served the scholarly needs of Center researchers and 

partners for many years. The NPWRC was one of the first 

research centers within the USGS to have a web presence. The 

initial NPWRC website, launched in 1995, provided resources 

on a wide range of subjects pertinent to the northern Great 

Plains and the Nation, ranging from butterflies and moths and 

their host plants, to grassland birds and wetlands, to emerging information about malformed amphibians; it became an 

important resource for biologists, managers, students, and 

citizens and received many awards.

The Center maintains a strong tradition of providing 

technical assistance to managers and other decision makers. 

Field visits to refuges and parks to discuss research findings 

and translate them to on-the-ground applications are common. 

Center scientists are often asked to assist with developing 

monitoring programs or to develop research studies at individual refuges or parks. For example, Amy Symstad works with 

the National Park Service on inventory and monitoring needs. 

Max Post van der Burg provides science support to the Plains 

and Prairie Potholes Landscape Conservation Cooperative, 

including landscape modeling and research, technical review 

of projects, and workshops on structured decision making. 

Participation and representation at flyway, joint ventures, 

endangered species recovery teams, and other management 

partnership meetings is routine and often leads to the identification of critical research needs and initiation of new studies. 

Prairie pothole wetlands, Stutsman County, North Dakota.
References 29

Looking to the Future

The mission of the Northern Prairie Wildlife Research 

Center today remains true to the original vision: to provide 

the knowledge needed to understand, conserve, and manage 

the Nation’s natural resources for current and future generations, with an emphasis on species and ecosystems of the 

northern Great Plains. The Center’s first 50 years of applied 

biological research provides a deep scientific foundation on 

which to address emerging ecological issues. The dedicated 

scientific and support staff of the Center continue to provide 

and advance high quality science needed to carry out the 

mission of the U.S. Geological Survey and ensure that the 

Center retains its long-standing stature as a premier ecological research laboratory in the northern Great Plains. While 

much of the Center’s research remains focused on the Prairie 

Pothole Region, the Center’s research and expertise extends to 

other ecoregions. Its scientific expertise is recognized globally for informing conservation of migratory birds, wolves and 

other species of conservation concern, and their wetland and 

grassland ecosystems.

The grassland and wetland ecosystems of the northern 

Great Plains benefit society in many ways, including furnishing wildlife habitat, surface-water storage, groundwater 

recharge, erosion control, carbon storage, nutrient retention, 

crop pollination, recreational opportunities, and intrinsically 

valued aesthetics. The region is particularly important for 

populations of migratory birds during breeding. The region 

also is a critically important agricultural area and hosts extensive wind, biomass, and fossil-fuel energy resources. Thus, the 

northern Great Plains is a landscape rich in natural resources 

that are important for many reasons, including farming, 

ranching, hunting, fishing, eco-tourism, energy production, 

and wildlife conservation. Embedded in this ecologically and 

economically important region, the Northern Prairie Wildlife 

Research Center is well positioned to contribute the scientific knowledge and expertise essential to decision makers 

facing the uncertainties and challenges of changing economic, 

environmental, and political environments, and effects that 

these changes have on the region’s and the Nation’s natural 

resources.

References

U.S. Geological Survey, 2017, Northern Prairie Wildlife 

Research Center publications and reports––1960–2015: 

U.S. Geological Survey data release, accessed October 

2017, at https://doi.org/10.5066/F7QZ28ZD.

Mann, G.E., 1974, The prairie pothole region—A zone of 

environmental opportunity: Naturalist, no. 25, v. 4, p. 2–7.

Tall stand of big bluestem 

and goldenrod growing on a 

hillside in late afternoon light.
For more information about this publication, contact 

Director, USGS Northern Prairie Wildlife Research Center 

8711 37th Street Southeast 

Jamestown, North Dakota 58401 

(701) 253–5553

Or visit the Northern Prairie Wildlife Research Center website at 

https://www.npwrc.usgs.gov/

Publishing support provided by the 

Rolla Publishing Service Center

Austin and others—Northern Prairie Wildlife Research Center—Celebrating 50 Years of Science—Circular 1434

ISSN 1067-084X (print)

ISSN 2330-5703 (online)

https://doi.org/10.3133/cir1434