Forestry and historical population dynamics of Vancouver Island Marmots (Marmota vancouvrensis) [Forestrie et histoire de la dynamique de la population de armottes de l'île de Vancouver].

Résumé

We used data from systematic population surveys, ear-tagged or radiotagged animals, GIS-based landscape measurements, and missing values analysis to clarify changes in the abundance and distribution of Vancouver Island marmots (Marmota vancouverensis). Data are insufficient to assess population dynamics or the timing of marmot disappearance from parts of northern Vancouver Island. On southern Vancouver Island, clearcut logging of old-growth forests was associated with profound changes in marmot abundance and patterns of habitat occupancy. Marmots began to colonize recently logged (0-15 year old) clearcuts during the early 1980s. By the 1990s half of the world’s population of this species was living in clearcuts. However this expansion was temporary and limited in geographic scope. Overall marmot numbers declined from a peak of 300-350 animals during the mid-1980s to fewer than 70 animals in 1999. The principal effect of forestry was to concentrate the population, apparently making marmots more susceptible to mortality from unsuccessful hibernation, predators and disease. The prognosis for continued survival of this critically endangered species remains hopeful provided that current plans for captive-breeding and reintroduction are pursued aggressively.