Lindy Lumsden some years ago came to the conclusion that almost nothing was known about the Australian Bats, and she decided that she would try to do her bit to improve on that. We had the good fortune to be able spend an evening with her while she explained to us about bats, while doing a survey of what bats were present.
We held this evening in the vicinity of a fire dam, some 5 km from Halls Gap. We had about 20 people there, mainly FOGS members, with some visitors who had seen our notices. Lindy uses a number of devices. In the pictures we are watching her assembling a Harp Net, which consists of fine fishing lines stretched vertically over an aluminium frame. This is put up about half a metre above the ground, and when a bat hits the lines it slides down the lines and come to rest in a padded canvas bag, where it sits perfectly quietly until collected to be inspected and have its vital statistics recorded. We also put up a mistnet, but that needs constant supervision, because any bat entangled in the mistnet needs to be released reasonably promptly.
A lot of bats can be identified by their sounds, so we had an idea what we might catch before we looked in the nets. In fact we identified the white striped bat by its noise only as it is a fast high flying bat, it did not come down low enough to be caught.
Time then came to sort our catch. We caught:
* 18 Little Forest Bats (Vespadelus vulturnus) (15 females, 3 males)
* 5 Large Forest Bats (Vespadelus darlingtoni) (all females)
* 3 Lesser Long Eared Bats (Nyctophilus geoffroyi) (1 female, 2 males)
* 2 Gould’s Wattled Bats (Chalinolobus gouldii) (1 male, 1 female)
* White-striped Freetail Bat (Taladira Australis) was heard overhead but not caught.
We then gathered around for a lecture while the bats collected themselves. Lindy has a frequency translator attached to a notebook computer, which collects the bats’ hunting noises, and divides them by 16 (the frequency that is). These are then displayed on the screen, and can be played back through a loudspeaker. As the bats squeak between 20 and 60 kilohertz, we can hear them at the lower frequency. This was an absolutely riveting experience. We could hear the hunting noise of a bat, and as we looked up at the darkling sky, we suddenly saw the silhouette overhead.
We then had a chance to look at our bats. They were beautiful, quite relaxed, and allowed us to have a good look. Lindy had been inoculated against the virus the bats may be carrying; we used gloves when looking at them. The females were all lactating, so would have had young back in the tree hollows. These species only breed once a year, with the young born in late November – early December. I think the bat Lindy is holding here is a Large Forest Bat, but I will have to check with her. Finally we were all equipped in turn with gloves and given a bat to admire and release.