The Calling Behavior and Mating System of a Non-Lekking Population of Hypsignathus monstrosus

A question central to understanding the evolution and maintenance of lek mating systems is why do males cluster in the first place. Two prominent models explaining this behavior are the Hotspot (Bradbury and Gibson 1983) and Hotshot models (Beehler and Foster 1988). The Hotspot model proposes males cluster at locations determined by high female encounter rates resulting from large, overlapping female ranges. The Hotshot model proposes that male clustering is the result of non-reproductively successful males gathering around reproductively successful males in order to increase their encounter rate with females. Evidence supporting either model has been equivocal.I chose to address this question by studying a non-lekking population of a species whose lekking behavior had been well studied. For each of the two models, I made novel predictions as to what types of mating behaviors I should encounter in a non-lekking population. A single key point separating the two models involves the spatial and temporal patterns of the male display sites. The Hotshot model suggests male display sites will be dispersed at the beginning of the mating season and there will be a gradual clustering around several static sites as the mating season. The Hotspot model predicts male display sites will be ephemeral and follow resources important to the females.The hammer-headed bat, Hypsignathus monstrosus, is a well studied lekking species found across much of Equatorial Africa. At Ta{\"ı forest, in Côte d’Ivoire, this species does not lek. Instead, the male H. monstrosus show a highly dispersed pattern of calling that still utilizes the "court display" behavior seen in other parts of Africa. I tracked the male display patterns of this population, both in time and space, for 24 months over a four year period and found males displayed in close proximity to resources that were important to the females. Two distinct patterns and resources were identified. One pattern involved fruit trees where females were feeding. Such sites where ephemeral in nature and calling activity was constrained to a six hour portion of the night. The second resource was roost sites used by large numbers of individuals. Calling was most consistent at these sites throughout the year, however, calling was limited to the half hour around sunset and the hour preceding dawn. Both of these patterns support the Hotspot prediction of males using resources important to the females as calling hotspots.