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The present report quantifies relations between weather and several aspects of the breeding biology of four duck species: mallard (Anas platyrhynchos), gadwall (A. strepera), blue-winged teal (A. discors), and redhead (Aythya americana). Data were obtained from two locations in North Dakota,--the J. Clark Salyer National Wildlife Refuge, intermittently during 1936-68, and the Northern Prairie Wildlife Research Center's Woodworth Station during 1965-77. Arrival dates varied with mean temperature before and during the usual arrival period; early-arriving species were affected by early-season temperatures, and later-arriving species by temperatures later in spring. After temperature effects were accounted for, first...
Captive American kestrels (Falco sparverius) given long-term dietary dosages of DDT and dieldrin in combination, at low and high rates, were compared with controls to determine the effects of the toxicants on reproductive success and eggshell thickness. Additional kestrels were dosed with DDE to determine its effect on shell thickness. Tissues of birds that died or were sacrificed, and eggs, were analyzed for DDE, DDD, DDT, and dieldrin. Eight paired birds, mostly males, given a high dosage of DDT + dieldrin died of dieldrin poisoning. Three periods of heavy mortality involving only dosed birds, which occurred in summer 1966, fall 1967, and spring 1968, followed temperature declines and other stress factors. Organochlorine...
This description of prairie basin wetlands of the Dakotas is part of a series of community profiles on ecologically important wetlands of national significance. The shallow wetlands of the Dakotas form the bulk of the portion of the Prairie Pothole Region lying within the United States. This region is famous as the producer of at least half of North America's waterfowl and an unknown, but large, proportion of other prairie-dwelling marsh and aquatic birds.The wetlands described here lie in relatively small, shallow basins that vary greatly in their ability to maintain surface water, and in their water chemistry, which varies from fresh to hypersaline. These wetlands occur in a wide variety of hydrological settings,...
Categories: Publication; Types: Citation; Tags: Biological Report
The investigations conducted on sea lampreys in aquariums were concerned with the duration of the parasitic phase of life, feeding, growth, and the interrelations between predator and host fish. Observations on lampreys reared from metamorphosis to maturity were made at the Fish and Wildlife Service Laboratory at Hammond Bay, Michigan. Most of the experimental lampreys were mature and ripe after 14 to 18 months of parasitic life. They exhibited signs of irreversible physical degeneration which precedes death. Three specimens were immature after 14, 18, and 26 months in aquariums, thus indicating that under certain conditions, lampreys may extend their parasitic phase. The feeding activity, growth, and shrinkage...
Categories: Publication; Types: Citation; Tags: Research Report
The impact of pesticides on the mortality rates and recruitment rates of nongame birds during the last 25 years was evaluated by studying the population dynamics of 16 species. A mathematical model showing the relations between population parameters that yielded stable populations was developed. The information needed for the model included (1) mortality rate schedule (obtained from recoveries of banded birds), (2) recruitment rates, and (3) the age of sexual maturity. The rate of recruitment necessary for a stable population and/or the annual rate of change (increase or decrease) in population levels were estimated. Population parameters were compared to determine whether changes had occurred between time periods...
Categories: Publication; Types: Citation; Tags: Wildlife Research Report