The effect of climate on hoary marmot demography: a retropestive analysis [L'effet du climat sur la démographie de la marmotte givrée : une analyse retropestive].

Résumé

The Hoary marmot (Marmota caligata) is an alpine specialist that has been proposed as a model species for predicting the effects of climate change on alpine fauna in northern Canada. Previous research has shown that hoary marmot survival is closely correlated with large-scale climate indices, but it is impossible to make long-term predictions about population dynamics without accounting for the influence of other demographic rates. We are using Life Table Response Experiments based on matrix models parameterized with 8 years of mark-recapture data (1999-2004, 2007-2008) from a population in the Yukon Territory to identify the relative influence of age-specific survival, fecundity, and dispersal on observed variation in population growth. We then examine these models in the context of local climate patterns in order to predict how interactions between climate change and life history are likely to shape the population dynamics of this species. Ultimately, this project will be combined with work using genetic markers to determine the effects of landscape (treeline position) on dispersal patterns to build a climatically and spatially explicit model of hoary marmot demography in the southern Yukon. Preliminary results suggest that, while realized population growth (l) does not correlate as closely with climate indices as survival, variation in l is more strongly linked to adult survival than to any other demographic parameter. However, immigration appears to contribute significantly to recruitment in most family groups, yet immigration rates appear to be most responsive to social, rather than environmental pressures.