Division of Bird Habitat Conservation

Birdscapes: News from International Habitat Conservation Partnerships


Evaluations Underway in North Dakota's Missouri Coteau
by Laura Houseal, Ducks Unlimited

One of the fundamental components of successful conservation is evaluating conservation efforts and subsequently modifying programs to increase their effectiveness. Ducks Unlimited (DU) is currently conducting such an evaluation of its grassland conservation programs in the wetland-rich Missouri Coteau region of North Dakota.

Ducks Unlimited and its partners focus on protecting and restoring the Coteau's grasslands to ensure high nesting success for breeding waterfowl and other birds. The current evaluation examines the relationship between waterfowl nesting success and surrounding landscape characteristics such as the abundance of grassland cover and whether the land is enrolled in the U.S. Department of Agriculture's Conservation Reserve Program or is used for grazing or agriculture.

This intensive evaluation is being led by Scott Stephens, research biologist for DU's Great Plains Regional Office, and a doctoral candidate at Montana State University. Regarding the study, Stephens says, "Research examining reproductive success across the full range of landscape types is ‘cutting edge' for ducks or any other grassland nesting birds."

Landcover maps based on satellite imagery were used to randomly select study sites that contained a certain range of grassland cover when measured at both a 4- and 36-square-mile scale. The results yielded 18 study sites that encompass a range of landscape types from grassland cover only around wetland edges and along roads to landscapes comprised entirely of native pastures.

The first year of a 2-year study took place during the spring and summer of 2000. During this time, over 2,200 duck nests were located on the 18 sites and monitored for success. Over 300 nests of other grassland birds were also studied, including marbled godwits, willets, upland sandpipers, Wilson's phalaropes, sora rails, common snipe, short-eared owls, northern harriers, American bitterns, and sharp-tailed grouse. The second year of this intensive investigation will begin in April 2001 on the same study sites. Long-term monitoring of some of these sites will continue in future years.

The data collected during this first year is still being processed and analyzed. "The resulting information," says Stephens, "will help Ducks Unlimited and its partners better understand how landscape characteristics influence nesting success of ducks and other grassland nesting birds. With this information, conservation programs will be refined to continue identifying and strategically targeting protection and restoration of landscapes where birds are and can be most successful over the long-term."

For more information, contact Laura Houseal, Ducks Unlimited, One Waterfowl Way, Memphis, Tennessee 38120, (901) 758- 3764, lhouseal@ducks.org.

Factors Affecting Duck and Shorebird Use of Prairie Wetlands
by Rex Johnson, U.S. Fish and Wildlife Service and Daniel Hubbard, South Dakota State University

Little information is available to assess agricultural effects on migrant shorebirds or waterfowl or to develop an empirical approach to integrating conservation planning for these bird groups. Our research describes landscape-scale and habitat factors that affect temporary and seasonal wetland suitability for spring-migrant dabbling ducks and shorebirds, as well as factors that affect the density of ducks using these wetlands.

Dabbling ducks and shorebirds were observed on temporary and seasonal wetlands along roadside strip transects in eastern South Dakota during spring migration in 1998 and 1999. In 1999, with eight repeated surveys, one or more ducks were observed on 95.6% of wetlands on one or more occasions, and shorebirds were observed on 56.9%. Mallards, pintails, gadwall, blue-winged teal, and northern shovelers were each more likely to occupy seasonal wetlands than temporary wetlands; however, preference for seasonal water regimes was most pronounced among wetlands less than or equal to 0.5 acres. All shorebird species used temporary and seasonal wetlands less than or equal to 0.5 acres in proportion to availability in the sample; however, shorebirds exhibited a preference for temporary wetlands that were greater than 0.5 acres.

Land use surrounding a wetland exerted no effect on probability of use by mallards or gadwall; however, blue-winged teal and northern shovelers preferred wetlands in pasture over cropland, and pintails selected wetlands in pasture over wetlands in Conservation Reserve Program (CRP) lands. Both killdeer and undifferentiated peeps preferred wetlands in crop fields over wetlands in pasture or CRP land. Conversely, greater yellowlegs were observed on a higher proportion of wetlands in CRP land than in cropland or pasture, and Wilson's phalaropes preferred wetlands in pasture or rangeland.

We developed models predicting the suitability of temporary and seasonal wetlands for migrating ducks and shorebirds. The most common landscape factors affecting suitability for dabbling ducks were temporary wetland density, seasonal wetland density, and total wetland density. Shorebirds related less to landscape wetlands than dabbling ducks, possibly indicating that they are more insular in their use of habitats during spring migration.

We used these models to classify approximately 861,000 wetlands in a geographic information system data base covering eastern South Dakota. All wetlands were classified as suitable for one or more species of dabbling ducks, and 94.8% of wetlands were classified as suitable for one or more shorebird species.

We also developed models that predicted the mean density of dabbling ducks on wetlands. Using only wetland size and landscape factors, we explained from 4% to 38% of the variation in mean number of dabbling ducks observed on temporary and seasonal wetlands. We estimate the present capacity of eastern South Dakota to be approximately 6,850,000 total dabbling ducks, including approximately 1,285,000 mallards.

The capacity of eastern South Dakota for total dabbling ducks was reduced by 44.3% following drainage of wetlands less than or equal to 1.0 acre in cropland. Northern shoveler capacity was reduced more than other species (64.5%). We estimate a mean impact (direct and indirect) of -10.6 ducks per drained wetland. Agricultural land use around a wetland does not disqualify it as suitable habitat.

This information enables managers to predict the effects of wetland restorations on migrant ducks and shorebirds as well as changes in farm program policies.

For more information, contact Rex Johnson, U.S. Fish and Wildlife Service, Division of Bird Habitat Conservation, 21932 State Highway 210, Fergus Falls, Minnesota, (218) 736-0606, rex_johnson@fws.gov, or Daniel Hubbard, Department of Wildlife and Fisheries Science, South Dakota State Univeristy, Box 2140B, Brookings, South Dakota 57007, (605) 688-6121, daniel_hubbard@sdstate.edu.

Hilliardton Marsh - Biodiversity in Action
by Kevin Loftus and Peter Davis, Ontario Ministry of Natural Resources

In an area of Northern Ontario known as the Little Clay Belt, most wetlands were drained for agricultural development in the early 1900s, leaving little remaining wildlife habitat. The Hilliardton Marsh Restoration Project was begun in 1993 to turn this situation around by providing staging habitat for migrating waterfowl and breeding and brood-rearing habitat for resident waterfowl. Another project goal was to increase biodiversity.

Construction on the 728-hectare project found within the Hilliardton Marsh Provincial Wildlife Area began with four wetland cells. The first and last cells were flooded in 1994 and 1997, respectively, with 87% of the upland area that existed prior to restoration being transformed into marsh (68%) and swamp (29%).

To assess the project's effectiveness in providing wildlife habitat and other biodiversity benefits, the project site became the focus of two graduate theses. In 1997, J.M. Gilbert, University of Waterloo, examined the dynamics of vegetation development, and in 1999 D.A. Locky, University of Waterloo, examined avifauna changes at the site.


Vegetation Study
Recognizing that the value of wetlands as waterfowl habitat is tied to the existence of suitable vegetation communities, Gilbert examined the dynamics of vegetation development in the wetland cells in relation to several factors. The factors that most strongly influenced vegetation development were water depths and pre-flood-site conditions. In particular, pre-flood-vegetation communities, which ranged from agricultural soils to wooded areas, markedly influenced vegetation development over the course of the study.

The areas exhibiting the greatest macrophyte development were open water sites, which had been agricultural fields prior to flooding. Water depths of 32 to 50 centimetres, open canopies, clear waters, and mineral soils characterized these sites. The areas exhibiting the least macrophyte development were found in flooded swamps characterized by water depths of 41 to 81 centimetres, closed canopies, murky waters, and organic soils.


Avifauna Study
Locky's study included comparisons of pre- (1993) and post-restoration (1997 and 1998) avifauna data using bird-point-count stations. Richness of avifauna increased by 55% between 1993 and 1998, mainly by obligate wetland guild species. The additional bird-point counts of these species in 1997 and 1998 indicated a much improved diversity including pied-bill grebe, horned grebe, sandhill crane, Virginia rail, semi-palmated plover, belted kingfisher, and numerous waterfowl species. Rare birds also increased from 10 species pre-restoration to 24 species post-restoration. Examples of some of the new additions were the endangered peregrine falcon and the provincially significant horned grebe.

These studies demonstrate what many involved in North American Waterfowl Management Plan efforts have known for years; namely, that well-designed wetland-restoration projects provide benefits that extend well beyond waterfowl species. These biodiversity benefits are reflected in the fact that the newly restored Hilliardton Marsh Provincial Wildlife Area is now considered a provincially significant wetland.

For more information, contact Kevin Loftus, (705) 755-1711, kevin.loftus@mnr.gov.on.ca.

Partners in the Hilliardton Marsh Project

Canadian Wildlife Service
The Nature Conservancy of Canada
Ontario Ministry of Natural Resources
Ducks Unlimited Canada
U.S. Fish and Wildlife Service
Ducks Unlimited
State of Alabama