Ecology, genetics and taxonomy of Peka peka (Chiroptera: Mystacina tuberculata and Chalinolobus tuberculatus)

Abstract

New Zealand has two species of microbat; the Short-tailed Bat (Mystacina tuberculata) and the Long-tailed Bat (Chalinolobus tuberculatus). Despite having special significance as being New Zealand's only native terrestrial mammals, the short- and long-tailed bat are both currently under threat. The objective of this investigation was to collect zoological information on New Zealand's native bats to test current hypotheses regarding their biology and to provide management recommendations to assist in the preservation of wild populations of bat.

DNA analysis was performed on tissue samples collected from seven populations of short-tailed bats and from five populations of long-tailed bats from throughout New Zealand. In order to preserve the genetic diversity present through out the country, wild populations of native bat should be given their separate conservation status. Molecular markers were located within the mitochondrial DNA of long- and shorttailed bats to allow an individual of unknown origin to be reliably ascribed to a particular geographic region.

Three hundred and eighty eight short-tailed bats were caught during an eighteen month period from October 1994 to February 1996 on Hauturu (Little Barrier Island). External examination was used to assess the timing of the major events in the annual reproductive cycle. Short-tailed bats on Hauturu exhibit an annual reproductive cycle typical of a temperate zone microchiropteran. No sexual dimorphism was found with respect to the standard measure of bat size, radius bone length (mean male forearm length = 40.76 mm; mean female forearm length = 40.89 mm). No significance difference was detected between the mean weight of nonreproductive females (11.53 g) or males (11.32 g). No bats were caught in mid-winter, suggesting that they may enter prolonged periods of torpor at that time.

Spatial and temporal activity patterns of short- and long-tailed bats were monitored in the coastal forest on Hauturu using an automated bat detector system during austral Summer 1995/96. Short-tailed bats were previously thought to be restricted to the interior of indigenous forests; this study provides evidence that they intensively utilise coastal forests and grassland to forage on nectar and pollen. Activity patterns of short tailed bats were highly correlated with the flowering cycle of pohutukawa trees (Metrosideros excelsa) on Hauturu, while those of long-tailed bats were not.

Data relating to the nationwide variation in bat morphology was combined with the results of DNA sequence analysis to assess the validity of the current taxonomic classifications of New Zealand bats. The data supports the elevation of the existing taxonomic classification of the northern short-tailed bat to specific status (i.e. Mystacina auporica ). Changes in the nomenclature of the other two subspecies are required due to alterations in the geographic delineation of their ranges. The large mainland beech forest morph is named M. t. tuberculata with the southern shorttailed bats requiring a new trinomial designation. The specific status of M. robusta was based on size differences that I show to be overestimated. The robust bat once present in the Southern Titi Islands was more probably a southern extension of the range of the larger beech forest morph than a separate species. Data also supports the designation of a northern and southern subspecies of long-tailed bat.