Morphometric Patterns of Secondary Sexual Dimorphism and Seasonal Differences in Rousettus madagascariensis from Northern Madagascar

Abstract

On the basis of four visits to the Grotte des Chauves-souris (12°57′S, 49°07′E), Parc National d'Ankarana, northern Madagascar, we examine patterns of sexual dimorphism and seasonal differences in body mass of Rousettus madagascariensis, an endemic Malagasy Pteropodidae. Two visits per season were made over the course of two years, dry season (September 2014 and 2015) and rainy season (January 2015 and 2016). Individuals of this species were trapped when exiting the cave after dusk or entering before dawn. Animals were aged, sexed, and then individually marked before being released. In total, 271 adult males and 289 adult females were captured. Although some overlap was found in measurement ranges, males showed significantly larger mean forearm length and body mass than females, including separate analyses of the four different capture periods and in the combined season dataset. For the September 2015 visit, for which a considerable number of adults of both sexes were captured at dusk and dawn, animals en...