Differences in the male mating calls of co-occurring epauletted fruit bat species (Chiroptera, Pteropodidae, Epomophorus wahlbergi and Epomophorus crypturus) in Kruger National Park, South Africa

Abstract

Background: Almost nothing is known about the mating ecology and behavior of epauletted fruit bats (Epomophorus spp) of which eight species occur worldwide. Two species of epauletted fruits bats (Epomophorus wahlbergi and Epomophorus crypturus) overlap in their distributional ranges in Kruger National Park (KNP), South Africa. Morphologically, these two species are nearly identical to the human eye and field recognition is based upon the number and position of palatal rugae of captured individuals. In addition, the males of both species perform mating rituals during overlapping breeding seasons that appear quite similar and involve wing flapping and monotone vocalizations from calling stations in proximity to fruiting sycamore fig trees where females congregate to feed. The overlap in breeding seasons as well as physical and behavioral characteristics between these two species brings into question how species recognition occurs, and no research is available to understand how males are identified by the females of each species for mating purposes. We recorded vocalizations from calling males in local areas of KNP known to support both species and compared the sonograms to determine if the call structure of mating vocalizations between males of each species differs. Results: We recorded 25 mating vocalizations from seven male epauletted fruit bats near the Shingwedzi Research Camp and 31 mating vocalizations from nine individuals along the Sabie River near Skukuza. Analysis of calls showed significant distinctiveness of male mating vocalizations between the two species in terms of mean fundamental frequency, mean high frequency, mean low frequency, mean bandwidth, and mean call slope at the two sites. Conclusions: We hypothesize that differences in male mating vocalizations recorded at each of our study sites represent call structure differences that potentially may be used to avoid cross-mating between species.

Social Communication in Big Brown Bats

“…Insectivorous bats, such as the big brown bat, use sight to find their way out of a roost and to orient themselves ( Bradbury and Nottebohm, 1969 ) and studies indicate that they can integrate vision with echolocation to aid navigation ( Horowitz et al, 2004 ; Jones and Moss, 2021 ). While there is no current evidence that big brown bats use vision to communicate socially, this has been documented in other bat species: Carollia perspicillata will extend its tongue and shake its wings when displaying aggression, and Epomophorus wahlbergi performs a wing-flapping courtship display in which the male erects white tufts of hair ( Fleming, 1988 ; Adams and Snode, 2015 ). Centurio senex bats perform wing-flapping displays and cover their faces with a skin flap during courtship behavior ( Rodríguez-Herrera et al, 2020 ).…”