Traditional prejudices and bad press have made the general public blind to the wonders and ecological importance of bats, even though they comprise about one quarter of all the living mammal species of Australia. It is poorly understood how landscape features influence bat activity.
Existing conservation measures in logged public forests in NSW concentrate on retaining narrow creekside vegetation corridors with ad hoc retention of individual habitat trees, habitat strips, and reserves scattered throughout the forest. After agriculture took the better sites, much of the public forests today consist of drier, less productive forest types.
The adjacent farmland, which would have been rich bat habitat prior to clearing in the 19th century, still carries habitats used by bats, such as paddock trees and creek edges.
Around Bega, in the Eden woodchip region of south-east NSW, wildlife has endured ongoing loss and degradation of habitat since settlement in 1830. The coastal forests around Mumbulla Mountain to the north-east of Bega contain 17 species of bats; one flying-fox species and 16 insectivorous species.
This is 40% of the mammal fauna of these forests. Two species live in caves or old mine shafts, and the others depend on hollows in old trees. Of the 16 insectivorous species, six are threatened species under the NSW Threatened Species Conservation Act 1995.
OEH carried out a study in the coastal forests of Bega to find the main areas of bat activity, and how this varied among the species of bats. The project analysed the calls of wild bats in flight that were collected while driving transects along 405 km of bush tracks in and around Mumbulla State Forest and farmland during the nights in the late summer of 2003 and 2005.
OEH searched for differences in bat call activity in relation to plant communities, vegetation productivity (based on soil fertility and moisture gradients), elevation, land tenure, time of night, temperature and rainfall.
OEH employed Anabat – a hand-held device for detecting and identifying bat calls, which are ultrasonic and thus not audible to the human ear. OEH simultaneously used visual identification by switching on a spotlight whenever the Anabat recorded a bat call. Visual cues used in spotlight identification included relative size of the bat, wing proportions and wing tip shape, ear shape, and fur colour. This is one of the few studies to use visual cues to assist in identifying the bats making the calls.
A recent Foundation-funded analysis used Geographic Information System (GIS) software to overlay the location of the bat calls onto a vegetation map, to link bats with plant communities. OEH were able to determine that bat species have preferential habitat use – by correlating bat call activity and habitat productivity.
OEH's overall results mean that management prescriptions for bats need to pay greater attention to retaining the most productive vegetation and to focus more on individual bat species rather than generalising about bats, and that private land, including agricultural land, needs to be included in bat management strategies. Their findings will also lead to significant improvements in planning bat conservation strategies.
The NSW government has approached the conservation of bat species within a framework of threatened species recovery. Replacement to the previous requirement to prepare recovery plans, was the introduction of Priorities Action Statements (PAS) in 2005.
One of the merits of the PAS initiative is that it has produced a single statement of the parlous position of bats in NSW and the actions needed to reverse the threats. There are 361 actions for the 20 bat species listed as threatened. Research (163 actions, or 45%) and habitat management (95 actions, or 26%) are the dominant themes in the recovery actions for bats.
The cryptic nature of the small, nocturnal insectivorous bats means that there needs to be major initiatives in education and research for bats. This will assure their continuing place as part of Australia’s complement of native fauna.
