PARENT SESSION

Conservation 3 -- Session Chair: Patrick Kelly-- University Center, Kate Buchanan Room

THE DECLINE OF THE OLYMPIC MARMOT: EVALUATING THE SPATIAL EXTENT AND CAUSES. Suzanne C. Griffin¹, L. Scott Mills¹ and Mark L. Taper². ¹ Wildlife Biology Program, University of Montana, Missoula, MT, USA; ² Department of Ecology, Montana State University, Bozeman, MT.

ABSTRACT- Anecdotal reports of local declines and extinctions of Olympic marmots (Marmota olympus) during the last decade, coupled with the precipitous decline of the closely related Vancouver Island marmot, have led to management concerns about this endemic mammal. Our objectives were to determine if there was evidence of a decline, and if so, to evaluate its spatial extent and causes. In 2002 and 2003, we surveyed historically occupied sites. At sites where marmots remain, and at several additional sites, we use capture-mark-resight of tagged animals, supplemented with radio-telemetry, to estimate vital rates and determine timing and causes of mortality. In addition, we have begun surveys of potential habitat throughout Olympic National Park. We will use the results to test spatial patterns of extinctions consistent with different causes of declines. In 2002, marmots were absent from 48% of historically occupied sites and had declined by 70% at sites where they were still present; marmots disappeared from three more by 2003. Annual survival estimates differed greatly between groups of colonies (0.40 vs. 0.95); all mortalities seemed due to predation. Proportions of females weaning litters and litter size were lower in both years than in 1967-1969, as were marmot weights. Of 400 surveyed plots, 20% were currently occupied, 9% appeared to have been previously occupied, and 68% showed no occupancy. Plot area and geographic region were correlated with occupancy. Our results to date indicate that Olympic marmots have declined, and are consistent with predation, or predation and habitat deterioration together as the cause of the declines.

KEY WORDS: Marmota olympus, predation, climate change, Olympic marmot