Ecological Studies of Wolves on Isle Royale - Annual Report 2000-2001
Peterson RO and Vucetich JA. 2001. Ecological Studies of Wolves on Isle Royale - Annual Report 2000-2001. Annual Report. School of Forest Resources and Environmental Science, Michigan Technological University. Houghton, MI
After many years of slow recovery, the wolf population on Isle Royale in 2000-01 abruptly dropped by a third, from 29 to 19 animals. Although five pups were raised in 2000-01 in three packs, mortality during the past year (15 died from the 29 present in 2000) was unusually high. Last year's mild winter coupled with a simultaneous scarcity of moose calves may explain the high mortality. Exposure to diseases will be determined when wolf live-capture efforts are resumed in spring 2001. Reorganization of wolf pack territorial bondaries continued during the past year. Wolf density on the east quarter of Isle Royale was over four times higher than in the western three-quarters, explained by a three-fold difference in moose density. The moose population changed little in size from 2000 to 2001. Recruitment of calves from the 1999 cohort was low, but adult survival in the past year was relatively high. Calf abundance in winter 2001 (14%) approximated the long-term average, and the population was estimated at 900 moose. The winter of 2000-01 brought above average snow depths, leading to above average kill rate for wolves. Calf moose were particularly vulnerable, constituting two-thirds of the wolf-kills that were ground checked. Assuming there are no new diseases, we expect wolf numbers to recover, based on abundant food (winter-weakened moose plus an ample cohort of calves born in 2000). The moose population should slowly climb for many years.
- Type
- Published Report
- Authors
- Peterson, Rolf; Vucetich, John
- Date of Issue
- 2001-03-31
- Publisher
- School of Forest Resources and Environmental Science, Michigan Technological University
- Units
- ISRO
- Keywords
- Aerial Survey, Beaver (Castor canadensis), Ecology, gray wolf (Canis lupis), Isle Royale National Park, Mammals, Michigan, Monitoring, Moose (Alces alces), Radio Collar