Tasmanian bat ecology : conservation of native fauna

Abstract

Conservation of biodiversity is one of the most important issues globally. Chiropteran fauna contributes one quarter of mammalian species but little information is known about most species. Tasmania has eight known species of bats including one endemic species, Nyctophilus.sherrini. There have been a number of studies conducted in Tasmania, yet much of the biology and ecology of most species remains unclear. Effective conservation of local biodiversity requires scientific information such as distribution, habitat relationships, and feeding behaviours. The present study contributes new information about the distribution for most species in Tasmania by using Anabat detector systems. Identification of species by their echolocation calls sampled from free flying individuals was achieved, by developing a regional key derived from trapped bats and an automated identification program, Anascheme. Six species/species groups were successfully distinguished by the key. Distribution records were gathered by echolocation recordings and the key newly developed for the study. I found that most sites have high bat species richness, as more than four species were recorded at the majority of sites. Three Vespadelus species were the most commonly observed and the Southern Forest Bat, V. regulus, was recorded at 100% of sites. In contrast, the high-flying Eastern Falsistrelle, Falsistrellus tasmaniensis, was only present at only 17% of sites. Species-habitat relationships were analysed where possible. Tasmanian bats appeared to have less species-specific requirements in their preferred activity areas. In addition to spatial partitioning of niches, the possibility of discrete temporal activity patterns of species was examined. Calls recorded for each species were assigned into 10 equal-time intervals between sunset and sunrise. There were no significant differences in a total activity index between time intervals by species, suggesting a high level of activity throughout the night. Evidence of a weak bimodal pattern in nightly activity was recognised in several species. Emergence timing was also compared between species, and F. tasmaniensis was shown to have a significantly later emergence time, and thus later peak activity timing than the others. Although analysis detected no significant effects of weather conditions on different observation nights, nightly fluctuations in the activity of several bats were apparent.