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Ecological Studies at the Woodworth Study Area

Waterfowl Studies at the Woodworth Study Area, Stutsman County, North Dakota: 1965-1995

Kenneth F. Higgins1* and Robert O. Woodward2
National Biological Service
1South Dakota Cooperative Fish and Wildlife Research Unit,
Brookings, SD 57007 and 2Northern Prairie Science Center,
8711 37th Street Southeast, Jamestown, ND 58401

The Woodworth Study Area (WSA) of the Northern Prairie Science Center (NPSC) is a waterfowl production area dedicated to research. Field investigations on WSA began in April 1963 and continue until present. From 1964 through 1968, land-use treatments on the WSA were maintained similar to those of prior years when the land was in private ownership. Since 1969, the WSA has been used for studying the response of wildlife to applied treatments of grazing, burning, idling, and annual cropping.

The primary waterfowl studies at the WSA were designed to address wildlife responses to land management practices (1) and to evaluate their relevance to past and future management of public and private lands, but with emphasis on those lands dedicated to wildlife production. Seventeen years (1965-1981) of waterfowl studies at the WSA were described in detail by Higgins et al. (2). During these years waterfowl use of and production from various habitats were assessed by monitoring duck breeding pairs and broods on wetlands and by conducting nesting studies in upland grassland types. Waterfowl monitoring and research studies were continued until 1988, but at a less intense scale after 1985. From 1988 until the present, studies on the WSA have been more broadly ecological, with less emphasis on waterfowl. During the past 3 decades, activities at the WSA can be partitioned into 3 distinct phases: The Initial Years, The Habitat Manipulation Years, and The Recent Years.

The Initial Years

We recognize 1963-1968 as the initial years for waterfowl work at the WSA. Land management during this period was maintained similar to that in place before federal acquisition of much of the WSA lands. During this period the study area was mapped and characterized, techniques for counting and monitoring waterfowl were developed and evaluated (2, 3), and methods of conducting large-scale waterfowl nesting studies were developed and implemented (4, 5, 6).

The staff of the WSA also were affiliated with the Land Use Section of the then Northern Prairie Wildlife Research Center (NPWRC). Besides evaluating old and developing new techniques, all members of the Section were involved in inventory studies to determine what species of upland nesting birds were using the different habitat types available in the Northern Great Plains Region (1, 7, 8, 9, 10, 11).

The Habitat Manipulation Years

We recognize 1969-1985 as the period of research to evaluate waterfowl production in relation to land use manipulations and established fields of dense nesting cover. One of the earliest studies by Leo Kirsch compared duck nesting success between native mixed grass pastures that were grazed season-long and recently idled native mixed grass fields (7). He found duck production was better on idled than on grazed native pastures. However, after a few years, duck production on idled native prairie generally declined, after which researchers began new studies evaluating duck nesting in grasslands treated periodically with fire (2, 12) and haying (8, 13), or those developed specifically for wildlife such as grasslands, commonly called "seeded" or "dense" nesting cover (2).

In addition to the studies emphasizing upland habitat manipulations to enhance production and survival of prairie ducks, several supplemental studies were conducted involving other management techniques or species. Included among these studies were those of shorebirds (4, 13, 14, 15, 16); nesting structures (17); island nesting (18, 19, 20); non-game birds (21, 22, 23, 24); and terrestrial passerine birds that will be reported on by Johnson (25) and upland vegetation that will be reported on by Meyer (26).

The Recent Years

We recognize the recent years of 1986-1995 as the post waterfowl research years even though some duck studies, duck and brood counts, and grassland burns continued through 1995 (M. Callow, pers. comm., N.H. Euliss, Jr., pers. comm.). In September 1989, however, much of the former waterfowl research ceased on the WSA. When the major thrust of the former waterfowl research studies at the WSA was terminated in 1988, it marked the end of the only long-term ecological research effort of waterfowl in the glaciated prairie pothole region of the United States. The data sets from the WSA studies are now archived at the NPSC. Many of the data sets are still being used by other researchers (e.g., Reynolds and Johnson in this symposium) to augment their research or to facilitate development of waterfowl population models. They likewise remain available for comparison should waterfowl studies begin anew.

In 1992, Higgins and others (2:pages 63 and 64) proposed the following for the future of the WSA:

"We recommend that long-term waterfowl studies be continued at the Woodworth Study Area (WSA) and additional locations within broad ecological habitat associations in the glaciated prairie pothole region. Most waterfowl ecology field studies have been relatively short-term because of graduate school tenure, funding allocations, and employee transfer. Even when graduate studies are sequential (e.g., three consecutive 2-year master's programs), their total is still relatively short-term."

"If future long-term studies are to be conducted on the WSA or some similar large tract of land, we would also recommend using aerial photography and remote-sensed data to evaluate land use changes, vegetation changes, and wet-dry conditions of wetlands. Use of these procedures would greatly enhance data accuracy and would provide better permanent records of the overall terrestrial aspects for any future study."

"Upland-nesting waterfowl were emphasized during this study; in future studies we would recommend more emphasis on over-water nesting waterfowl and shorebirds. We would also recommend a more integrated study approach with special emphasis on predator effects and behavior and on buffer-prey species abundance, particularly of small mammals, passerines, amphibians, and insects."

"Our native prairie habitat research was limited to season-long grazing and to mostly spring burning management. We support expanding of the research to include additional types of specialized grazing systems and to fall burning efforts, both of which show initial promise for increasing waterfowl production for private as well as public lands, and in wetlands as well as uplands."

Unfortunately for waterfowl and other wetlands biota and for the resource managers responsible for stewardship of lands dedicated to wildlife production and welfare, we conclude that the intensive waterfowl research at WSA was terminated prematurely in 1988. Why do we conclude that it was premature? First, a tremendous set of baseline data was available on which to initiate future research. Research plans proposed for post-1985 included land treatments combining grazing systems and prescription fires for both uplands and wetlands. Research also was planned to assess game and non-game bird use of wetlands subjected to various habitat treatments.

Second, 1987 was the beginning of a very extreme series of drought years (1988-1992) followed by a series of extremely wet years (1993-1995). One of the early charges of the WSA staff was to monitor and evaluate the effects of fluctuating climate on wildlife populations and their habitats. In retrospect, one of the greatest opportunities in the past 30 years was missed. In addition to the waterfowl studies, a similar opportunity was missed with the long-term monitoring of permanently marked vegetation transects. From the time burning was first initiated on the WSA (circa 1966), we were never able to measure the vegetation response in a series of extreme drought or wet years as were experienced during 1988-1995.

Third, future plans had already been drafted to use the on-going research and the WSA lands and wetlands as a demonstration and education center to better acquaint scientists, resource managers, farmers, ranchers, and other interested citizens with land use and other practices such as nesting structures and islands that would enhance benefits and reduce risks to the production of ducks and other prairie and wetland wildlife commonly found in the northern Great Plains Region of the U.S. and southern Canada.

Fourth and last, computer technological advances plus new statistical analytical procedures were finally available post-1985 that would better enable analysis of large, multiple data sets such as occurred for the WSA studies.

In the words of Harvey K. Nelson from the Foreword of Higgins et al. (2), "As with any research program, increasing demands for new investigations were not always matched by additional funds and personnel." Likewise, administrative research prioritization were not always matched with the everyday needs of resource managers and the resource -- the termination of the long-term monitoring and land use research relative to waterfowl and other prairie wildlife at the WSA emphasizes the overall effects of such actions. This observation provides particular insight when one considers that the WSA was one of, if not the, largest grassland tracts in North America where all treatments were totally controlled for research purposes. An obvious conclusion is that such sites should remain high on the list of priority study areas for any new waterfowl research in the Northern Great Plains.


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