ARE IMMIGRANT VERVET MONKEYS, CERCOPITHECUS-AETHIOPS, AT GREATER RISK OF MORTALITY THAN RESIDENTS

In general, dispersing animals are often thought to have a higher risk of mortality than their philopatric conspecifics. One possible cause for their increased risk of mortality is that dispersers move into unfamiliar areas where they are more vulnerable to predation. To examine this, mortality rates of vervet monkeys who were unfamiliar with their home ranges were compared with those of vervets who were familiar with their home ranges. Vervets who moved abruptly into unfamiliar areas as a result of group fusions had significantly greater mortality within the first 6 months than the residents they joined, and this difference decreased thereafter as the immigrants became more familiar with their new habitat. In contrast, vervets who moved into unfamiliar areas from groups that continued to exist after their dispersal suffered no greater mortality than the residents they joined. We suggest that these vervets were able to minimize their risks by timing dispersal to their advantage. © 1993 The Association for the Study of Animal Behaviour. All rights reserved.