Ecological Studies of Wolves on Isle Royale - Annual Report 1991-1992
Peterson RO. 1992. Ecological Studies of Wolves on Isle Royale - Annual Report 1991-1992. Isle Royale Natural History Association. Houghton, MI
During 1991-92 the Isle Royale wolf population remained at the all-time low of 12 individuals, the same as the previous year. Two wolf pups were produced in one pack and two wolves died, resulting in no net change in population size. Three territorial packs continued to partition the Island, and an additional breeding pair formed during late February. There was no turnover or mortality among the four male-female pairs from last year. Two additional wolves were radio-collared in 1991; half of the current population has been live-captured and collared since 1988. The number of old moose in the population is now increasing rapidly, so if wolves are food-limited they should increase in number within two years. If not, genetic deterioration will remain as the likely cause for low reproduction. The moose population increased to about 1600 animals in 1992, approaching the highest level in four decades. Calf abundance in mid-winter was moderately high. However, moose calves were generally small, in poor condition, and highly vulnerable to wolves. High wolf predation on calves would limit further growth in the moose population within 2-4 years; winter ticks, though less predicatable than wolf predation, is a significant mortality factor for moose.
- Type
- Published Report
- Authors
- Peterson, Rolf
- Date of Issue
- 1992-03-31
- Publisher
- Isle Royale Natural History Association
- Units
- ISRO
- Keywords
- Aerial Survey, Ecology, Gray Wolf (Canis lupus), Isle Royale National Park, Mammals, Michigan, Monitoring, Moose (Alces alces), Radio Collar