Development of prey capture in the Indian false vampire bat Megaderma lyra

Abstract

We studied development of prey capture, under captive conditions, on five newly weaned Indian false vampire bats Megaderma lyra. We tested the hypothesis that the young bats are able to improve the ability of hunting by trial and error. An additional hypothesis was that their rate of prey consumption and method of handling prey improve with age. We separated the juveniles from their mothers and observed them individually at different ages. At 58 d of age, M. lyra roosted 2 m above floor level, flew down only towards moving frogs, landed >1 m away from them and returned to roosts without showing attempt to capture. At day 60, bats roosted at 50-cm heights, landed approx. 1 m away from frogs and moved towards them. Although bats intercepted frogs, their attempts to capture were still unsuccessful. At day 62, bats landed <1 m from frogs, made similar attempts and most of them were successful. Bats carried frogs, roosted at heights of 100 cm and started consuming. Numbers of jumps made by frogs and attempts made by bats during successful captures decreased with increase in age of bats. Furthermore, the distance between landing sites of bats and places where frogs stayed during landings decreased with advancement of age. Until 75 d of age, M. lyra devoured frogs with legs-first on significantly more occasions. After 75 d, most of the consumptions started with heads of frogs, similar to adults. Duration of feeding on single frogs was significantly longer compared with that of mothers until young were 75-d old. The study revealed that juveniles were inefficient on localization, rate of consumption, and handling prey at earlier ages (e.g. 60 d). They became efficient on these behavioural components at later age, i.e. after 75 d. Thus, the results were in accordance with both the hypotheses. Bats did not respond to stationary frogs.