Influence of Trap Environment on the Effectiveness of an Acoustic Lure for Capturing Vespertilionid Bats in two Temperate Forest Zones in Japan

Abstract

Bats that typically forage in the forest understorey can be difficult to capture using mist nets or harp traps alone. We assessed the effectiveness of an ultrasonic lure for increasing capture rates of vespertilionid bats in two forest zones in Japan. One sequence of stimuli was modelled on social calls of four species that typically forage in narrow-space; the other on those of four species that forage along edges and in forest gaps. The lure increased capture rates by 24.5 times in cool temperate deciduous forest in Hokkaido, and 9.75 times in warm temperate evergreen rain forest in Yakushima, compared with the control condition. Narrow-space foraging bats of the genus Murina dominated the catch at both sites and were caught most frequently when the trap was located in the cluttered environment of the forest understorey. There was no significant effect of call type on capture rate. The lure is an effective method for increasing capture rates of bats and particularly for narrow-space foraging species within the forest, which are otherwise difficult to catch. Acoustic lures have great potential for enhancing study and survey capabilities for forest bats.