Factors Affecting Moose Survival in BC

Moose pair http://www.flickr.com/photos/usfwshq/6862339335/

Photo: Ryan Hagerty/USFWS

A provincial framework for moose management in British Columbia (BC) is being developed, partially in response to declining moose numbers in certain areas of central BC. Landscape change from mountain pine beetle (MPB) and associated salvage logging is hypothesized to have reduced moose population growth rates by increasing hunting efficiency of predators and hunters.  Other potential factors influencing moose survival in relation to MPB are disease, parasites, nutrition and climate. One recommendation of the framework is to initiate a long-term health monitoring program for moose throughout BC.

Moose population declines have occurred in eastern and central North American.  In some cases declines were attributed to parasites (such as Parelaphostrongylus tenuis) and positively correlated with increased white tailed deer densities that serve as the normal host for this parasite. Surveillance for P. tenuis in the past has not found infected moose west of the Saskatchewan/Manitoba border in Canada, but it is unknown whether this situation has changed and whether BC has ever been sampled. Overall changes in climate resulting in conditions more likely to support parasite density and transmission are likely to change parasite distribution and potentially host prevalence. An external parasite, winter tick (Dermacentor albipictus) is well documented to affect moose populations in northern climates.  Heavy winter burdens of this one-host tick can lead to late winter mortality and are directly related to previous spring weather conditions and female tick survival.  Documentation of tick related mortality of BC moose is largely anecdotal but significant losses have been reported.  There has been no recent assessment of internal or external parasite infections of moose in BC.

A provincially-coordinated research project is being implemented to test the landscape change hypothesis and associated mechanisms.  Comparisons of moose population dynamics in eight study areas will be made with adult cow survival as a key response variable.

The BC Wildlife Health Program is initiating an assessment of moose health utilizing archived and newly collected serum and fecal samples.  The analysis of samples will provide data to inform a general assessment of the status of moose health in the province and provide a baseline for comparison to evaluate the potential future impacts of cumulative effects on moose populations in BC. The assessment will assist managers in ruling out pathogens as factors in the population declines observed in the central interior.

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