Guest contributor Maree, shares with us her love of all things batty…
Scrambling along rocky shorelines between sea cliffs and the incoming tide. Commando crawling through boulder piles. It’s all in a day’s work when seaching for roosting sites of Australia’s elusive Coastal Sheathtail Bat (Taphozous australis).
This cave-dweller is restricted to a narrow strip along Australia’s northeastern coast, nearby islands and the southern coast of Papua New Guniea. Although they are listed as ‘near-threatened’ by the IUCN, Coastal Sheathtails are ‘vulnerable’ in Queensland – where populations are declining. It is estimated that less than 10,000 mature individuals remain.
This species is realtively large for a cave-dwelling microbat with a wing span of approximately 39.5 cm and a length of 7 cm. When roosting, they are readily identified by the unusual, spiderlike way they cling to and move around cave walls using their feet and thumbs.
Coastal Sheathtail Bats appear to have specific roost requirements and I’ve only found them within a few kilometres of the coastline, in seacaves that are commonly airy and have several entrances. It is especially pleasant on humid summer days to sit in a coastal roost and enjoy the fresh sea breeze.
Like all microbats they use echolocation to locate the flying insects they prey upon. We have observed individuals foraging on insects drawn to sporting field floodlights, next to some mangroves: they drop rapidly from a height of up to 30m, then climb again, dropping and swooping in a lovely figure-eight pattern. They continued this behavior for some time above and between two floodlights until they were turned off.
Radiotracking studies have shown this species has highly specific roosting and foraging requirments, which makes them very vulnerable to reduction or modification of their coastal habitat. And a roost with a view is in high demand – coastal development is one of the major threats to these bats.
Next time you are looking for buried treasure in a seacave keep an eye (and ear) out for a fluffy little bat crawling around on the walls, jibbering in protest at your intrusive torch light. Take down a GPS point and let me know where you saw it!