Acoustic Lures Increase the Effectiveness of Catching Rare and Endangered Forest-Edge and Forest-Interior Bats

Abstract

Acoustic lures, using a range of bat social, feeding and distress calls, are being used increasingly to improve capture rates in surveys and ecological studies of bats globally. However, much information on their effectiveness is anecdotal. We tested the effectiveness of the Sussex Autobat acoustic lure system using a standard Bechstein's bat (Myotis bechsteinii) social call for catching two rare and endangered New Zealand bat species, the long-tailed bat (Chalinolobus tuberculatus) and lesser short-tailed bat (Mystacina tuberculata) during lactation and post-lactation periods. The long-tailed bat forages primarily along forest edges, whereas the lesser short-tailed bat forages largely within cluttered forest interiors. Harp traps were set in paired locations over 18 nights in each of the late-lactation and post-lactation periods with an equal treatment/control (lure/no lure) sampling design. Sixty-four long-tailed bats and 97 lesser short-tailed bats were captured, with 100% of long-tailed bats and 93% of short-tailed bats being caught while using acoustic lures. Lesser short-tailed bats were caught more frequently than long-tailed bats, perhaps reflecting the greater abundance of lesser short-tailed bats. Captures were biased towards juveniles and males in both species, regardless of sampling period. Capture rates using lures were about 100 times higher than catch-rates from ‘expert-placed’ traps. Further research is needed to determine (a) if calls of New Zealand bat species (or other calls) can be used to increase capture rates further, and (b) if capture rates of female bats can be improved.