Colony sizes, roost use and foraging ecology of Hipposideros diadema reginae, a rare bat from tropical Australia

Abstract

Hipposideros diadema reginae is a rare subspecies of Diadem Leafnosed Bat confined to tropical Queensland. Few data are available on its population size or ecology. From July, 1990 to December, 1993, I conducted colony counts at Chillagoe and Iron Range to assess its abundance, and radio-tagged six males at Chillagoe to provide data on roosting and foraging ecology for management purposes. I recorded the subspecies in nine of 18 caves surveyed at Chillagoe. Two or more bats were regularly observed in only four caves, each of which had =250 m of passage, large chambers with high domed ceilings, and multiple entrances. The largest colony was found in Trezkinn Cave (range of 6?65 bats). Both Trezkinn and a nearby cave, Donna, were fully developed tourist caves, but were frequently used as day roosts by radio-tagged bats. Each cave had a gate at its entrance. At Iron Range, between 70 and 250 bats roosted in Gordon's Mine. Bats used multiple day roosts, but did not change roost every day. The main foraging behaviour was perch hunting, with continuous flight as a secondary behaviour. The mean foraging range of tagged bats was 1.08 km from the day roost (range of 0.3?2.5 km). Foraging occurred within all available types of vegetation; use of vegetation showed intraspecific variation. Hipposideros d. reginae exhibits flexibility in its foraging ecology, but has specific roost requirements. Recommended management actions are: prevent or regulate human access to roosts, search for additional colonies at Chillagoe by targeting potentially suitable caves, and ban scientific collecting at both sites.