Publications

Included are the reasons for concern over the effects of agrichemicals (pesticides and fertilizers) on prairie-pothole wetlands in the United States. Summarized are the results of studies conducted to date on this topic. Identified is additional research needed to assess the impacts of agrichemicals on these wetlands. Included is a discussion of management strategies and initiatives...

Scolopacid sandpipers were studied from 1980 until 1984 during spring migration in North Dakota. Common species foraging together in mixed-species flocks differed in bill length most often by 20 to 30 percent (ratios from 1.2:1 to 1.3:1). Observed flocks were compared to computer generated flocks drawn from three source pools of Arctic-nesting sandpipers. The source pools included 51...

We estimated nest success of mallard (Anas platyrhynchos), gadwall (A. strepera), blue-winged teal (A. discors), northern shoveler (A. clypeata), and northern pintail (A. acuta) for 5 regions in North Dakota, South Dakota, and Minnesota, for 1-3 periods between 1966 and 1984, and for 8 habitat classes. We obtained composite estimates of nest success for regions and periods by weighting...

The settling of breeding habitat by migratory waterfowl is a topic of both theoretical and practical interest. We use the results of surveys conducted annually during 1955-81 in major breeding areas to examine the factors that affect the distributions of 10 common North American duck species. Three patterns of settling are described: homing, opportunistic, and flexible. Homing is...

No abstract available.

Kleptoparasitism on other raptors was one means by which Bald Eagles (Haliaeetus leucocephalus) secured food along the North Platte and Platte rivers during the winters of 1978-1980. Species kelptoparasitized were Ferruginous Hawk (Buteo regalis), Red-tailed Hawk (B. jamaicensis), Rough-legged Hawk (B. lagopus), Golden Eagle (Aquila chrysaetos), and Bald Eagle. Stealing of prey occurred...

We measured the effect of diet quality on variation in the seasonal pattern of Mallard (Anas platyrhynchos) reproduction. Twenty wild-strain hens, consisting of 10 sibling pairs, were maintained in captivity. One sib of each pair was fed an enriched diet, and the other was fed wheat. The wheat diet resulted in reduced clutch size, egg size, laying rate, number of nesting attempts, and...

Foods consumed by canvasback ducks (Aythya valisineria), food availability, and energetic relationships were studied on Navigation Pool 7 of the upper Mississippi River in 1978, 1979, and 1980. Canvasbacks fed primarily upon winter buds of American wildcelery (Vallisneria americana) and tubers of stiff arrowhead (Sagittaria rigida). In 1980, waterfowl consumed 40% of 380,160 kg of...

Age and sex ratios and body weights were obtained for northern pintails (Anas acuta), mallards (A. platyrhynchos), American wigeon (A. americana), green-winged teal (A. crecca), and northern shovelers (A. clypeata) shot at Mendota State Wildlife Area in the San Joaquin Valley (SANJV) and at Sacramento National Wildlife Refuge in the Sacramento Valley (SACV) during 1982-83 and 1983-84...

We outline a population model proposed to accommodate the full life cycle of the mallard (Anas platyrhynchos). Events during the breeding season are better understood than events at other times of the year, but recent findings suggest the importance of phenomena away from the breeding grounds. Several processes are discussed relative to mallard population dynamics. Compensatory mortality...

Abstract has not been submitted

No abstract available.