Reproduction, growth and maturity in the black flying-fox, Pteropus alecto (Megachiroptera : Pteropodidae)

Abstract

This paper reviews the timing of reproduction, growth rates and age at maturity of the black flying-fox, Pteropus alecto. This species is found from Sulawesi, Indonesia, south to the central east coast of Australia. In northern Australia at 12ºS most young are born in January–March, in contrast to October–November at 27ºS in eastern Australia, but a small percentage of young are born outside the major birth peaks in both areas. The birth peaks of P. alecto appear to be aligned with periods of maximum plant productivity, rather than day length. The plasticity of breeding season is likely to be an important factor enabling P. alecto to colonise areas from near the equator to 29ºS.

Individual growth rates were calculated for 27 P. alecto. The weight growth rate of these animals was 2.40 3.14 g day^-1 (mean s.d.), while growth rate of the forearm was 0.19 0.18 mm day^-1 (mean s.d.). The growth rate of the forearm of females was significantly greater than for males (P = 0.08). From the mean forearm lengths of animals trapped, separate growth curves were developed for juvenile males (n = 566) and females (n = 610); these indicate that growth rate of females is about 8% higher than that of males. Primiparous females had a forearm length of 171.1 3.4 mm (mean s.d.) (n = 5), which is achieved 15–17 months after birth, but about a third of females with forearm lengths of 160–170 mm have suckled young. Males mature at an age greater than females due to their slower growth rate, a phenomenon known from other megachiropteran species.