Edge effects on survival and behaviour of juvenile red squirrels (Tamiasciurus hudsonicus)

Abstract

Much research has examined parasitism and predation rates on avian nests within the context of edge effects. Few studies, however, have considered the influence that behavioural compensation for high predation risk may have on subsequent survival rates and edge effects. We attempted to determine whether juvenile red squirrels (Tamiasciurus hudsonicus) experience edge effects by comparing the survival and behaviour of individuals born along a forest edge with those of individuals born in the forest interior. A combination of telemetry, direct observation, and livetrapping was used to determine the fate of juveniles born during the summers of 1987 through 1998 and the behaviour of juveniles born during the summers of 1997 and 1998 in Kluane, Yukon. There were no differences in survival between edge and interior juveniles from birth to emergence but there was a trend towards higher survival rates for edge juveniles from emergence to weaning. Behavioural differences between edge and interior juveniles were consistent with these survival differences: edge juveniles spent less time travelling and foraging and more time resting near the time of weaning than did interior juveniles. Edge and interior mothers differed little behaviourally during the early emergence period. The significant differences in juvenile behaviour which we found suggest that behaviour may indeed moderate differences in predation risk between edge and interior habitats and thus should be considered in other studies that examine the influence of edges on survival or nest predation.