Rediscovery of short-tailed bats (Mystacina sp.) in Fiordland, New Zealand: Preliminary observations of taxonomy, echolocation calls, population size, home range, and habitat use

Short-tailed bats (Mystacina sp.) were rediscovered in Nothofagus dominant rainforest in the Eglinton Valley in February 1997, representing the first records of these bats in Fiordland since 1871. Breeding females, adult males and juveniles were captured. This paper presents preliminary observations of taxonomy, echolocation calls, population size, habitat use, activity patterns, home range size, movements, roosting, and singing behaviour. Compared to lesser short- tailed bats (M. tuberculata) on Codfish and Little Barrier Islands, the Fiordland bats were heavier, had larger wings and smaller ears, and were sexually dimorphic. The Mystacina echolocation calls were of low intensity (quiet), making them difficult to detect. Call durations in free-flying bats were only 1.0-2.9 ms long. In a comparative trial the majority of calls that were detected at 25 kHz using the Batbox III bat detector were not recorded at 40 kHz, indicating that there was little overlap with the calls of long-tailed bats (Chalinolobus tuberculatus). In February, roosting groups numbered from 107 to 279 individuals and the bats ranged over 130 km(2) of the valley. Bats began emerging c. 20 minutes after sunset and were active at the roost sites throughout the night. Radio-tagged bats were active for an average of 372 minutes at a time. All roosts were in large diameter (67-146 cm dbh) red beech (N. fusca) trees.