Yellowstone Wolf Project: Annual Report 2004

Smith, Douglas; Stahler, Daniel; Guernsey, Debra

At the end of 2004, at least 171 wolves in 16 packs occupied Yellowstone National Park (YNP). This represents no gain of wolves from 2003, marking the second year since reintroduction that the wolf population did not increase (1999 was the other year). Four new packs formed: Hayden Valley, Gibbon Meadows, Biscuit Basin, and Specimen Ridge. Each of the 16 packs counts toward the breeding pair objective for the Yellowstone Recovery Area. At least 86 pups were born and 59 (69%) survived in 16 packs, which was slightly less than the long-term average of >75% pup survival. The number of pups per litter ranged from one to nine, with an average of 5.1 pups counted at den sites in May and June. Average pup survival per pack was 3.7 pups. Pup survival was highly variable by pack. Mange was reported for the fi rst time inside Yellowstone National Park. A Chief Joseph wolf was sighted on Daly Creek with hair loss. This is the only location in Yellowstone National Park where mange has been observed, and so far, no mortalities have resulted from mange. Mange is common on all sides of the park except the south, where it is unrecorded. All of the 31 originally reintroduced wolves are dead, and all wolves currently alive in the population are descendants of reintroduced wolves. Twenty-one wolves were captured and collared in 2004: 20 via darting from a helicopter and one (Slough Creek wolf #453M) after being accidentally caught in a coyote trap. At the end of 2004, 40 (24%) of the 171 wolves that use Yellowstone National Park were radio collared. The Wolf Project deployed fi ve GPS collars in the 2004 capture season to enhance understanding of 1) seasonal predation patterns; 2) spatial and temporal interactions with other wolf packs and carnivores; 3) movements with respect to dens during pup-rearing season; and 4) territory size, use, and overlap. Project staff detected 295 kills (defi nite, probable, and possible combined) made by wolves in 2004, including 240 elk (81%), 19 bison (6%), 1 moose (<1%), 4 deer (1%), 4 pronghorn (1%), 1 badger (<1%), 2 cougars (1%), 6 coyotes (2%), 1 golden eagle (<1%), 2 grizzly bear cubs (1%), 1 raven (<1%), 3 wolves (1%), and 11 unknown prey (4%). The composition of elk kills was 18% calves (0–12 months), 16% cows (1–9 years old), 16% old cows (≥10 years old), 38% bulls, and 12% elk of unknown sex and/or age. Bison kills included 4 calves (unknown sex), 8 cows, 5 bulls, and 2 of unknown sex and age. Winter kill rates for 1995–2000 showed that wolves residing on the northern range killed an average of 1.8 elk per wolf per 30-day study period during the winter. Using the same method for calculating kill rates, wolves on the northern range killed an average of 1.1 elk/wolf/30-day study for the period 2001–2004. This 40% decrease suggests changing ecological conditions for wolves in this part of the park.

Yellowstone Wolf Project: Annual Report 2004

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