The Biology of the Common Sheath-Tail Bat, Taphozous-Georgianus (Chiroptera, Emballonuridae), in Central Queensland

Abstract

A field study was carried out over a 4-year period on the common sheath-tail bat, Taphozous georgianus, in central Queensland. Mating occurred in late August and early September, and females gave birth to a single young in late November or early December. Females mated at about 9 months of age. Spermatogenesis commenced in males at about 9 months but they were not able to take part in mating until they were approximately 21 months old. Bats were born well furred with their eyes open, and weighed an average of 24% of their mother's post-partum weight. Young bats attained independence at 3-4 weeks old when they reached 50% of their mothers' body weight. At 3 months old young bats were within a few millimetres of adult dimensions. Marked seasonal variations in body weight resulted from the deposition of fat. Peak weights were recorded in April and minimum weights in September. The mean annual survivial rate was estimated to be 0.61. Mature males have a mortality rate substantially greater than females and this is reflected in a sex ratio strongly biased towards females in older bats. The sex ratio was nearly even in young bats. Most roost caves were occupied by less than 20 individuals. There was little difference between the temperature and humidity at which bats roosted, and the temperature and humidity of available roosts. Most bats were known from only one cave, and few movements of more than 2 km were recorded. Bats appeared to regularly relocate their roosting site, however, and they may have been utilising roosts outside the study area.