COSTS AND BENEFITS OF SOCIALITY IN YELLOW-BELLIED MARMOTS (MARMOTA-FLAVIVENTRIS) - DO NONCOLONIAL FEMALES HAVE LOWER FITNESS

Whether an animal lives alone or in a group may have fitness consequen ces. Among yellow-bellied marmots (Marmota flaviventris), fitness is t hought to be lower for noncolonial than for colonial females because j uvenile survival, as indicated by trapping, is lower. Trapping, howeve r, may not be an accurate estimate of survival. Low recapture rates of noncolonial juveniles may result from early dispersal due to maternal behavior, or higher mortality due to predation or inadequate resource s for overwinter survival. Our objective was to determine if survival was lower for noncolonial than for colonial juveniles, and to determin e the cause of the low recapture rate of noncolonial juveniles. Our re sults show that survival of noncolonial juveniles was not lower than t hat of colonial juveniles. Noncolonial juveniles were not more vulnera ble to predation during the active season, nor was overwinter mortalit y higher. Some noncolonial juveniles did disperse early, and most move d away from the natal burrow to hibernate, thereby explaining the low recapture rate reported previously. Early dispersal was not related to maternal behavior. Noncolonial females do not enjoy the benefits of g roup-living, especially the opportunity to form matrilines; but they a lso do not suffer the costs, such as competition for resources.