Differential Effects of Coyotes and Red Foxes
on Duck Nest Success
Study Areas
We collected data from 36 areas in the Prairie Coteau, Missouri Coteau, and Drift Plain physiographic regions (Stewart 1975, Van Bruggen 1976, Kantrud et al. 1989) of North Dakota and South Dakota during 1990-92. We changed location each year to increase number of study areas and for geographic dispersal of sampled areas. Because of drought, annual site selection was based on water levels in the preceding fall. In 1990, 12 areas were in LaMoure, Logan, McIntosh, and Stutsman counties of south-central North Dakota. In 1991, 13 areas were in Ward and McLean counties of central North Dakota, and in 1992, 11 areas were in Brown, Day, Marshall, McPherson, Roberts, and Spink counties of northeastern South Dakota (Sovada 1993). Each area was 60-200 ha and was all or part of a federal Waterfowl Production Area or part of a national wildlife refuge; uplands on all areas were managed for nesting ducks.
The Coteau regions were moderately to steeply rolling glacial moraine. The Drift Plain was relatively flat to moderately rolling. All 3 regions contained high densities of wetlands and were farmed, intensively in most places (Higgins 1977, Cowardin et al. 1983). In the locations of our areas, most upland was cultivated annually for crops, primarily small grain; untilled uplands were pastures, hayland, and idle grassland. Much idle grassland was in the Conservation Reserve Program (Bjerke 1991).
The climate at the study locations was continental and average monthly temperature ranged -13-26 C (U.S. Dep. of Commer. 1990, 1991, 1992). Annual precipitation at study locations was 44-48 cm (U.S. Dep. of Commer. 1990, 1991, 1992). We conducted the study during a period of drought; many temporary and seasonal wetlands near areas studied were dry early in spring each year.
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