Browsing by Subject "lepakot"

Even though bats have no specialized predators in the temperate zone, they are still predated on. In fact, 11% of their annual mortality is caused by avian predators, especially owls. Bats are particularly vulnerable at emergence from their roost because this behaviour is very predictable. Because a successful predation event is mortal, it would be expected that bats need antipredatory responses to avoid it. The time and focus for these responses need to be shared with foraging in a way that maximizes survival. I studied antipredatory responses of bats in two settings: 1. during roost emergence and 2. during foraging at tawny owl territories and at places where there have been no tawny owl sightings. I collected acoustic data from 24 roosts and 11 foraging grounds for 10-13 nights. The roost emergence data was collected with the help of citizen science. Two controlled predation threats, recorded tawny owl calls and nestling sounds, were used. Nestling sounds were only played during roost emergence. In both tests music and silence were used as controls. Owl calls, music or tawny owl territory have no effect on bat presence when they are foraging. However, bats alter their emergence time and leave over 20 minutes later when tawny owl calls are played outside the roost. There is no difference in exit time when music or nestling sounds are played. These results show that bats have antipredatory responses. They also suggest that bats may be able to recognize high-risk situations and allocate their behaviour accordingly or that they place higher importance on foraging than avoiding predation.