EVENING BAT ISOLATION CALLS PROVIDE EVIDENCE FOR HERITABLE SIGNATURES

Vocalizations of infant evening bats, Nycticeius humeralis, have unique characteristics that contain sufficient information for a mother to distinguish her offspring from other offspring in a colony. Using seven acoustic variables, all 306 isolation calls recorded from 39 pups in one attic nursery colony at 2-5 days of age were classified to the correct pup without error. Studies of captive bats reveal that the amount of among-bat variation in call variables remains constant from birth through to at least the next 14 days. Though several variables change as pups grow, an individually distinctive pattern of frequency modulation can be recognized at all ages. Isolation calls also contain information about family identity, as expected when call characteristics arc heritable: calls of wild pup twins were assigned to the correct family 68% of the time and three variables had significant heritabilities between 0.61 and 0.85. Factor analysis indicates that infant isolation calls exhibit independent variation in at least four dimensions. Consequently, over 1800 pups could produce calls without overlap in any dimension of acoustic space. Copyright © 1993 The Association for the Study of Animal Behaviour.