Aspects of the ecology of a long-tailed bat, Chalinolobus tuberculatus (Gray, 1843), population in a highly fragmented habitat

Abstract

The two species of bats that still survive in New Zealand are both believed to be threatened. Both have suffered extensive habitat loss since humans arrived in New Zealand and have subsequently declined significantly. Their current conservation status is unknown and what is known of their ecology is largely anecdotal. Threats to populations have yet to be determined but introduced mammalian predators are suspected as potentially having an impact. South Canterbury, which retains very little indigenous forest surprisingly retains a population of long-tailed bats (Chalinolobus tuberculatus).

Between January 1994 and June 1995, the distribution and abundance, habitat use, activity patterns and roost selection of this population was assessed by radio tracking, automatic monitoring of echolocation calls and direct observation. Most of the field work was carried out in two very dissimilar areas; Peel Forest (the largest indigenous forest remnant in South Canterbury) and Hanging Rock (retains no indigenous forest but is characterised by extensive outcrops of limestone).

Contrary to expectation, bats were found to be more abundant in the Hanging Rock area than at Peel Forest. Feeding rates were similar in both areas and bats followed parallel nocturnal and seasonal activity patterns to other temperate insectivorous bats indicating that food was not a limiting resource. Although bats preferentially foraged in certain habitats they were flexible about the type of habitat they foraged in suggesting that suitability of foraging habitat was not a limiting factor. Subsequently, roost site security was identified as the primary influence on the distribution of bats in South Canterbury. At Hanging Rock, bats roosted in crevices in limestone outcrops that were inaccessible to ground predators. This argument was extended to explain how long-tailed bats have persisted in South Canterbury.