[6] Cook, Koochiching, Lake and St. Louis Counties
[7] All 15 Upper Peninsula counties
[8] Last described wolf range in Wisconsin (Thompson 1952)
The white-tailed deer (Odocoileus virginianus) would be the major prey for wolves in Michigan, and there appear to be sufficient numbers to support wolves. The Michigan Department of Natural Resources pellet count estimates for the spring deer population in the Upper Peninsula in 1973 was 10 ± 21.9% deer per square mile (3.9 ± 21.9% per km²). Deer densities of 10 to 15 per square mile (3.9 to 5.8 per km²) supported wolf densities of one wolf per 10 square miles (26 km²) in Algonquin Provincial Park, Ontario (Pimlott 1967).
The population of deer wintering on the 14 square-mile (36 km²) Huron Mountain deer yard in winter 1973–74 was estimated at 73.3 ± 49.5% deer per square mile (28.3 ± 49.5% deer per km²) by the pellet count method (Laundre 1975). Thus total wintering population on the Huron Mountain Club, the wolf release area, would be about 1,000 deer.
The utilization of available browse by deer in the Huron Mountain deer yard reached 95% by March 8, 1969 and 92% by March 5, 1970 (Westover 1971). The minimum winter deer loss (actual number found) in 1969 was 40 animals, of which at least 12 had starved, and it was estimated that perhaps up to 33% of the deer starved in the Huron Mountain Yard in 1968–69 (Westover 1971). The Huron Mountain yard continues to be overbrowsed, with high deer mortality expected in severe winters. Many other northern deer yards of the Upper Peninsula are also overbrowsed and are dwindling in area. Thus we expected that numbers of vulnerable deer (Pimlott et al. 1969; Mech and Frenzel 1971) would be available to wolves.
Beavers (Castor canadensis) are an important food source for wolves in many areas during summer (Mech 1970), and they are common throughout the Upper Peninsula. The beaver population on the 26 square-mile (67 km²) Huron Mountain Club was estimated at 46.9, or about 1.9 beavers per square mile (0.7 per km²) (Laundre 1975). Moose (Alces alces) are rare on mainland Michigan.
METHODS
The general procedure for this study was to attempt to capture an intact pack of wolves in Minnesota, fit each animal with a radio-collar (Cochran & Lord 1963), release them in northern Michigan, and follow their fate through aerial and ground radio-tracking (Kolenosky and Johnston 1967).