Searching for roosting sites of Australia's elusive coastal sheath-tailed bat is a very hard way to do science. Scrambling along rocky shorelines between sea cliffs and the incoming tide, crawling through boulder piles and dodging waves to skip from boats onto slippery rocks is all in a day's work.
And that's part of how Maree Cali earned the Bat Conservation International Prize as the best conservation report of the 2010 Australasian Bat Society Conference in Darwin, Australia.
This cave-dwelling bat is found only in a narrow strip of Australia's northeastern coast and islands, along with scattered reports from coastal Papua New Guinea. It is listed as near-threatened by the IUCN and its population is believed to be declining.
Previous observations suggest the coastal sheath-tailed bat is a rather solitary animal, with colonies mostly ranging from 2 to 25 individuals, although as many as 100 have been reported historically. Known roosts, all within a few miles of the coastline, are primarily in sea caves or abandoned mines. These bats typically forage high above the canopy for flying insects.
No systematic research had ever targeted coastal sheath-tailed bats until Cali and her team began their study to produce habitat maps for this unique species. They surveyed potential cave roosts along the tropical eastern coast of Queensland and radiotracked individual bats to document the roosting and foraging needs. Cali, Conservation Officer Tina Ball and Resource Ranger Eddie Adams, all with the Queensland Department of Environment and Resource Management, coordinated the project.
They used their data to begin mapping the bats' habitat, including how far inland they travel to forage. The results are being used to plan and execute conservation action for the species, and the new information will provide a vital tool for protecting the habitat.
They surveyed sea caves, boulder piles and rock fissures along the coastline and islands for use by coastal sheath-tailed bats and also visited inland caves to confirm that the bats roosted only on the coast. Of the 15 roosts they found, all were within yards of the high-tide line and were often partly underwater at high tide.
Determining the bats' foraging range required the use of miniature radiotransmitters attached to coastal sheath-tailed bats that were tracked from their roosts.
The radiotagged bats foraged within just two miles (3 kilometers) of the coast. The longest distance traveled within that range was less than 10 miles (15 kilometers) from the roost. Foraging above mangroves appeared to be a nightly activity. The radiotracked bats usually did not forage together and flew off in different directions.
The researchers used the results of the two-year study to create a computer model of known and probable habitat for coastal sheath-tailed bats within the Central Queensland Coast Bioregion, essentially calculating the complete habitat needs the region's entire population of these bats.
"We hope this wealth of new information can be used to legislate protection for these bats through appropriate regulation of development along this stretch of coastline," Cali says.
Members of BCI can read the whole story of Australia’s Bats by the Sea in the Spring 2011 issue of BATSmagazine.