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Full-Text Articles in Social and Behavioral Sciences
Productivity, Mortality, And Population Trends Of Wolves In Northeastern Minnesota, L. David Mech
Productivity, Mortality, And Population Trends Of Wolves In Northeastern Minnesota, L. David Mech
USGS Northern Prairie Wildlife Research Center
Population parameters, mortality causes, and mechanisms of a population decline were studied in wolves (Canis lupus lycaon) from 1968 to 1976 in the Superior National Forest. The main method was aerial radio-tracking of 129 wolves and their packmates. Due to a decline in white-tailed deer (Odocoileus virginianus), the wolf population decreased during most of the study. Average annual productivity varied from 1.5 to 3.3 pups per litter, and annual mortality rates from 7 to 65 percent. Malnutrition and intraspecific strife accounted equally for 58 percent of the mortality; human causes accounted for the remainder. As wolf …
Wolf-Pack Buffer Zones As Prey Reservoirs, L. David Mech
Wolf-Pack Buffer Zones As Prey Reservoirs, L. David Mech
USGS Northern Prairie Wildlife Research Center
Abstract. In a declining herd, surviving deer inhabited overlapping edges of wolf- pack territories. There, wolves hunted little until desperate, in order to avoid fatal encounters with neighbors. Such encounters reduce wolf numbers and predation pressure and apparently allow surviving deer along territory edges to repopulate the area through dispersal of their prime, less vulnerable offspring into territory cores.
Foods Of Juvenile, Brood Hen, And Post-Breeding Pintails In North Dakota, Gary Krapu, George Swanson
Foods Of Juvenile, Brood Hen, And Post-Breeding Pintails In North Dakota, Gary Krapu, George Swanson
USGS Northern Prairie Wildlife Research Center
The Pintail (Anas acuta) is a common to abundant nesting species in North Dakota, becoming more numerous during years of favorable water conditions and less so during drought. Stewart and Kantrud (1974) estimated breeding-populations of 304,000, 111,000 and 379,000 pairs in the Prairie Pothole Region of North Dakota during 1967-69, respectively. We studied food habits of juvenile and adult Pintails during the brood-rearing and post-breeding periods in North Dakota to learn their food requirements during these phases of the life cycle. Food habits of flightless juveniles have been studied in Alberta (Sugden 1973) and limited information on downy …
Use Of Natural Basin Wetlands By Breeding Waterfowl In North Dakota, Harold A. Kantrud, Robert E. Stewart
Use Of Natural Basin Wetlands By Breeding Waterfowl In North Dakota, Harold A. Kantrud, Robert E. Stewart
USGS Northern Prairie Wildlife Research Center
Use of basin wetlands by breeding populations of 12 species of waterfowl was investigated in 1965 and during 1967-69 throughout the prairie pothole region of North Dakota. Data were obtained primarily by random sampling techniques. Of the total population occupying natural basin wetlands 55 percent occupied seasonal and 36 percent occupied semipermanent wetlands. Seasonal wetlands contained 60 percent of the population of dabbling ducks, while semipermanent wetlands supported 75 percent of the population of diving ducks. On basins with ponded water, highest concentrations of breeding pairs occurred on temporary, seasonal, and semipermanent wetlands; moderate concentrations were recorded on ephemeral, fen, …
Pintail Reproduction Hampered By Snowfall And Agriculture, Gary Krapu
Pintail Reproduction Hampered By Snowfall And Agriculture, Gary Krapu
USGS Northern Prairie Wildlife Research Center
The reproductive strategy of the Pintail (Anas acuta) shows several adaptations to the semi-arid variable climate of the prairie pothole region of north central North America where the species is a common breeder. By nesting early and using temporary and seasonal water areas replenished by snow melt waters or early spring rains, the species has successfully occupied broad areas containing limited permanent and semi-permanent water. The Pintail is prone to select new breeding grounds during periods of drought. Smith (J. Wildl. Manage. 34:9@-946, 19701 has shown that part of the population moves northward from the prairies and parklands …