Satellite tracking Ghost Bats (Macroderma gigas) in the Pilbara, Western Australia

Abstract

Little is known about the extent of the foraging habitat and characteristics of the threatened Ghost Bat (Macroderma gigas) in the arid regions of Western Australia. We used GPS satellite tracking technology to accurately measure the Pilbara Ghost Bat's foraging characteristics. We provide detailed foraging and commuting data for ten bats, eight males and two females tracked over multiple nights. From the time and location data collected, results for five foraging characteristics were calculated. These were the minimum time spent outside the diurnal roost, the time spent for short periods in a specific foraging area, the typical area used for during a foraging period, the maximum radial distance flown from the diurnal roost, and the minimum 'cave-to-cave' distance covered. The time spent outside the roost varied widely with bouts lasting from under half the night to the full period of darkness. The average time spent at a particular foraging area was 116 minutes during which the bats used multiple perches for typically 20 minutes each. Little pattern was evident in the areas used for foraging. The bats made use of the majority of an area available once they had begun to forage there. During foraging bouts, the average radial distance from the roost from all available data was 8.5 km and the maximum distances recorded was 17.7 km. The average return flight distance from all data was 19.4 km with a maximum length of 41 km. One bat totaled over 90 km in four nights. A one-way commute of 27.4 km was also recorded. The Pilbara Ghost Bat is confirmed to be foraging across a varied habitat and over distances not previously recognised. Generally, thinly wooded areas of Mulga, other Acacia or Eucalypt spp. or linear woodland features are preferred in areas with a moderate percentage of open ground (typically 30-70%) to facilitate the perch and sally 'surface' foraging strategy used for terrestrial prey. No pattern was evident in substrate type.