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The endangered Vancouver Island marmot : allee effects and reintroduction success Werner, Jeffery R.

Abstract

The Vancouver Island marmot (Marmota Vancouver ens is) is a large social rodent endemic to Vancouver Island, whose population has declined by 80-90% since the 1980s. It is one of the most highly endangered mammals in North America. Compared to its congeners this marmot has received little research, and many questions concerning basic ecology remain unanswered. The first objective of this study was to compare information on contemporary animals (2002-2004) with those of an earlier time period (1973-1975). Data on time allocation, social activity and ranging behaviour of several colonies in the late stages of decline were compared with historical data collected under more stable conditions. Contemporary marmots interacted with conspecifics less, had larger home ranges, devoted more time to vigilant behaviour, and did not exhibit bi-modal activity patterns previously described for this and other marmot species. Contemporary marmots also fed less, gained daily mass at a lower rate, and may have entered hibernation later than members of historical populations. These findings suggest an Allee Effect; a positive connection between aspects of fitness and population size imply the need to identify threshold group sizes necessary for recovery. The second objective of this study was to compare wild marmots with captive-raised marmots released into the wild (2002-2005). Time budgets, wariness to potential sources of danger, and home range activities were compared. Despite similarities in behaviour, released marmots continued to have lower survival than wild marmots. Sources of mortality included predation and unsuccessful hibernation: High mortality is likely linked to dispersal from the release site. Release methods are discussed which may foster cooperative behaviours and philopatry among reintroduced marmots intended to form new colonies. Applying our new understanding of marmot ecology to captive breeding programs may improve the success of conservation efforts for this highly endangered species.

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