PARENT SESSION

Population Ecology 2 -- Session Chair: Brock McMillan-- Van Duzer Theater

MONITORING A REESTABLISHED POPULATION OF MUSKOXEN IN THE ARCTIC NATIONAL WILDLIFE REFUGE, ALASKA. Patricia E. Reynolds. U.S. Fish and Wildlife Service, Arctic National Wildlife Refuge, 101 12th Ave. Box 20 Room 236, Fairbanks, Alaska, USA.

ABSTRACT- Muskoxen (Ovibos moschatus) disappeared from Alaska before 1900. The species was reestablished in Alaska in 1936 with animals brought from Greenland. Translocations of muskoxen near the Arctic National Wildlife Refuge (Arctic Refuge) returned muskoxen to regions of former range in 1969 and 1970. In 1982-2003, annual precalving censuses and post-calving composition counts recorded changes in abundance and age-sex structure of the population. Relocations of radiocollared muskoxen in 1982-2002 documented patterns of habitat use and shifts in distribution. Numbers of muskoxen increased for over a decade in the Arctic Refuge after which the population began to expand its range into new regions. In the Arctic Refuge, numbers of muskoxen ranged from 282 to 355 in 1987-1998, but decreased to <70 in 2002 and 2003. In 1999-2003, calves were 1% to 10% of the total animals classified in late June compared with 10-23% calves in 1983-1998. Adult mortalities also increased in 1999-2003 in the Arctic Refuge. Ice and snow conditions that reduced the availability of forage and increased energetic costs as well as predation by grizzly bears (Ursus arctos) contributed to these changes. Dispersal also contributed to the decline in abundance in the Arctic Refuge. By 2003, the range of the entire population extended from the Colville River, Alaska, to beyond the Babbage River in Canada. The total population was relatively stable from 1998-2001 (range = 620-654 muskoxen) and numbers continued to increase in regions outside the Arctic Refuge until 2002.

KEY WORDS: Ovibos moschatus, alaska, muskox, population change