I used population count data collected from 1979 to 1998 to evaluate the relative importance of “chronic” versus “episodic” mortality patterns in Vancouver Island marmots (Marmota vancouverensis). I hypothesized that some factors (e.g., gradual vegetation change, forestry effects, or predation) should produce chronic patterns of mortality, and others (disease and weather) should produce episodic patterns. A few colonies had consistently low survival. These results are consistent with a hypothesis of poor quality “sink” habitats that are maintained by immigration from nearby “sources.” However, most colonies had distinct episodes of high mortality, and these appear to be the primary cause of recent population declines. Spatial and temporal patterns of survival are consistent with a hypothesis of disease outbreak or increased hunting effort by predators within a small geographic area. The impact of both factors was probably exacerbated by forestry activities...
Bryant, Andrew A.. 1999. Relative Importance of Episodic Versus Chronic Mortality in the Decline of Vancouver Island Marmots (in Proc. Conference Biology & Management of Species and Habitats at Risk). Ministry of Environment, Lands and Parks; University College of the Cariboo. Conference Biology & ManagementProceedings
Topic: Species and Ecosystems at Risk
Keywords: Marmota vancouverensis, mortality, population surveys, Vancouver Island marmot
Scientific Name: Marmota vancouverensis
English Name: Vancouver Island Marmot
Other Identifier: University College of the Cariboo
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