Year

1993

Degree Name

Master of Science

Department

Department of Biology

Abstract

This thesis examines the response of insectivorous bat activity to different logging regimes and habitat types in the Kioloa State Forest. Bats were sampled by electronic echolocation detection and trapped with harp traps. Trapping was employed to develop an overall species list and to establish an echolocation call reference library to aid in the identification of free flying bats electronically detected. The main findings of this study are based upon the results of the echolocation detection sampling. This sampling regime allowed bats to be non-intrusively monitored within forest stands without the biases associated with trapping. Bats were studied by monitoring nocturnal activity patterns along transects using sonar detection and by trapping along tracks and creeks adjacent to these sample sites. Twelve transects were monitored, with three transects in each of four logging regimes. The bat activity on ridges and in gullies of high and low quality forest stands was also examined. A total of 16 species were trapped andlor detected in the study area. The most common species detected by sonar were Vespadelus darlingtoni, V. vulturnus and Scotorepens orion, these three species made up 56% of all bats. This was in contrast to results from trapping, where V. regulus, V. vulturnus and Chalinolobus morio comprised of 72% all bats captured. There was no significant difference found between the bat activity level of the ridges and gullies. Regrowth forest (20 years since clear felling) had significantly lower foraging and activity levels compared to mature forest (50 years since selective logging) for five species. In addition, several sites were sampled immediately before and after selective logging. There was a significant decrease in bat foraging and activity levels for five species just after (within 2 months) selective logging. However, sites that were sampled 9-12 months after selective logging did not show a significant difference in activity level for the most common species, compared to mature forest stands. The reasons for decreases in bat activity are not clear, but may be due to a reduction of understorey vegetation, which can influence the diversity of insects available as potential food items.

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.