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Full-Text Articles in Social and Behavioral Sciences
Ingestion Of Lead Shot And Aluminum Bands By Bald Eagles During Winter In Nebraska, Gary Lingle, Gary Krapu
Ingestion Of Lead Shot And Aluminum Bands By Bald Eagles During Winter In Nebraska, Gary Lingle, Gary Krapu
USGS Northern Prairie Wildlife Research Center
The Bald Eagle (Haliaeetus leucocephalusis) a common winter resident along the Platte and North Platte rivers in southcentral Nebraska. Waterfowl are a major food of eagles during periods when fish are not readily available (Lingle and Krapu 1986). Eating ducks and geese can make eagles susceptible to lead poisoning, a significant cause of mortality of Bald Eagles in North America (Kaiser et al. 1980). Eagles ingest lead shot from waterfowl by eating shot imbedded in tissues or as part of the contents of digestive tracts. In this paper we describe the incidence of lead shot and Fish and …
The Influence Of Diet Quality On Clutch Size And Laying Pattern In Mallards, Jan Eldridge, Gary Krapu
The Influence Of Diet Quality On Clutch Size And Laying Pattern In Mallards, Jan Eldridge, Gary Krapu
USGS Northern Prairie Wildlife Research Center
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 total eggs laid. Diet did not affect laying initiation, duration, or the seasonal pattern of change in clutch and egg size with each renest. We believe the variation and pattern observed are adaptations to a …
Size Differences In Migrant Sandpiper Flocks: Ghosts In Ephemeral Guilds, Jan L. Eldridge, Douglas H. Johnson
Size Differences In Migrant Sandpiper Flocks: Ghosts In Ephemeral Guilds, Jan L. Eldridge, Douglas H. Johnson
USGS Northern Prairie Wildlife Research Center
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 migrant species from a global pool, 33 migrant species from a Western Hemisphere pool, and 13 species that migrated though North Dakota. The observed flocks formed randomly from the available species that used the North Dakota migration corridor but the North Dakota …
Duck Nest Success In The Prairie Pothole Region, Albert T. Klett, Terry L. Shaffer, Douglas H. Johnson
Duck Nest Success In The Prairie Pothole Region, Albert T. Klett, Terry L. Shaffer, Douglas H. Johnson
USGS Northern Prairie Wildlife Research Center
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 each habitat proportional to the number of nest initiations. The distribution of nest initiations was derived from estimates of breeding populations, preferences of species for nesting habitats, and availability of habitats. …
Determinants Of Breeding Distribution Of Ducks, Douglas H. Johnson, James W. Grier
Determinants Of Breeding Distribution Of Ducks, Douglas H. Johnson, James W. Grier
USGS Northern Prairie Wildlife Research Center
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 generally more pronounced among species that use more stable (more predictable) wetlands, such as the redhead (Aythya americana), canvasback (A. valisineria), lesser scaup (A. affinis), mallard (Anas platyrhynchos), gadwall (Anas strepera), and …