Influence of Wing Loading on the Selection of Prey Size in the Indian False Vampire Bat Megaderma lyra

Abstract

We studied wing loading of adult male (n=6) and female (n=5) of the Indian false vampire bat Megaderma lyra under seminatural conditions in an outdoor enclosure. Before releasing the bats into the enclosure, we measured their body mass, forearm length, wing area and wingspan. They were fed with frogs of four different categories of body lengths such as A = 3.0-3.5, B = 4.0-4.5, C = 5.0-5.5 and D = 6.0-6.5 cm. Bats were able to capture frogs A - C and carry them to roosts, that were at a height of 260 cm from the ground. However, when they captured frogs of the size D, most of the times they dropped the latter either after reaching the roost or even while carrying them. Alternatively, the bats carried the frogs (size D) but landed at a place (n = 30) closer to the ground and began consuming the prey. In general, greater the size of frogs, higher the wing loading of bats.