Summer Activity Patterns of Insectivorous Bats and Their Prey in Tasmania

Abstract

Nightly activity patterns of seven species of bats (Eptesicus vulturnus, E. regulus, E. sagittula, Nyctophilus geoffroyi, N. timoriensis, Chalinolobus morio and FalsistreNus tasmaniensis) and their volant insect prey were studied during late spring and summer at four sites in Tasmania. Activity of bats was assessed from trapping results. Bats exhibited a biomodal pattern of foraging activity being most active in the first hours after dark, declining to low levels in the middle part of the night and rising again to a secondary peak in the three hours before dawn. These patterns of activity in bats closely reflected the patterns of insect activity. The insectivorous bats thus appear to have adjusted their nightly activities to match those of their prey, thereby maximising foraging success and energy gains.