Ecological Studies of Wolves on Isle Royale - Annual Report 1982-1983 (Covering the twenty-fifth year of research)
Peterson RO and Shelton PC. 1983. Ecological Studies of Wolves on Isle Royale - Annual Report 1982-1983 (Covering the twenty-fifth year of research). Department of Biological Sciences, Michigan Technological University. Houghton, MI
On Isle Royale, the rapid decline of the wolf population in 1980-82 was reversed, and wolf numbers now approximate the average level of the 1960's. In 1982, wolf pups were born to all four breeding females present in the population. Thirteen pups survived in three packs in winter 1983, bringing wolf numbers to 23. Territorial skirmishes continued, and the West Pack II claimed 2/3 of the Island. Wolf kill rates were relatively low and carcass utilization high, reflecting low vulnerability of moose in winter. The small size of some pups this winter may reflect a low food supply in summer. The author now believes that the present food supply will not be adequate to support continued survival and expansion of all three wolf packs. The current moose population is estimated at 900, including about 400 calves and yearlings. The moose calf cohort in 1982 was large, although proportionately lower than the record cohort of 1981. Recent cohorts have not been readily killed by wolves, even as calves in winter. Wolves are now preying primarily on moose born during the late 1960's (a period of high moose density). These moose exhibit a much higher incidence of arthritis than moose born during periods of lower density. The 1982 results of an aerial survey of beaver activity on Isle Royale indicate a recovery of beaver colony numbers to levels found in 1978 and 1962. One hundred twenty-five colonies were located and colonies were classified by habitat and observed for signs of recent use. Beavers were live-trapped and examined.
- Type
- Published Report
- Authors
- Peterson, Rolf; Shelton, Philip
- Date of Issue
- 1983-04-30
- Publisher
- Department of Biological Sciences, Michigan Technological University
- Units
- ISRO
- Keywords
- Aerial Survey, Beaver (Castor canadensis), Ecology, Gray Wolf (Canis lupus), Isle Royale National Park, Mammals, Michigan, Monitoring, Moose (Alces alces)