Reproductive strategy of the Egyptian free-tailed bat, Tadarida aegyptiaca, from a subtropical latitude (25°S) in South Africa

Abstract

Free-tailed bats (Molossidae) are widely distributed in Africa and exhibit considerable reproductive flexibility. The Egyptian free-tailed bat, Tadarida aegyptiaca, is one of the most widespread of the molossids and is therefore an excellent model to study the variation in reproduction through latitudinal changes. Bats were collected during 2008 and 2009 from Pretoria (25°S), South Africa. In males, spermatogenesis was already underway in January (summer) and spermatozoa were first noted in the epididymis during May (late autumn), where they are stored until the end of September. From September, the testes showed little spermatogenic activity and possibly remained quiescent until early summer. In females, follicular development started prior to January with large Graafian follicles present in June. Ovulation, copulation and subsequent fertilization occurred in late August (spring). When compared to the same species from a low temperate latitude (33°S) it is apparent that spermatogenesis and follicular development were initiated earlier in the year at 25°S. We propose that the seasonal monoestry displayed by T. aegyptiaca at 25°S may be the norm throughout their distributional range and that a latitudinal difference of just eight degrees could influence the timing of events in the reproductive cycle of a free-tailed bat.