Solitary adult males in a polygynous-mating bat (Cynopterus sphinx): A forced option or a strategy?

Abstract

The Indian short-nosed fruit bat (Cynopterus sphinx) is thought to use a resource-based polygynous mating system. Breeding colonies typically consist of a few harems with 1 or more solitary males nearby. Essential to understanding the mating system of C. sphinx is identification of the reasons for solitary roosting behavior in adult males. In this study, we attempt to elucidate the impetus behind solitary roosting by investigating the following 2 questions: Are solitary males less competitive and so remain isolated from breeding activities? Are trees and foliage suitable for tent-making a scarce resource? We carried out weekly censuses and mark-recapture studies from January to December 2000. We assessed impact of available resources on roosting patterns of adult males. Examination of our results suggests the following about the mating system of these bats. Female aggregation in C. sphinx cannot be attributed to scarce resources. Morphological variables did not differ between harem and nonharem males. Approximately 50% of nonharem males had scrotal testes. These results suggest that nonharem males are reproductively active, gain access to females, and presumably obtain some reproductive success. © 2005 American Society of Mammalogists.