Testing the efficacy of an acoustic lure on bat mist-netting success in North American central hardwood forests

Abstract

Severe population declines in numerous North American bat species makes population monitoring increasingly difficult. We tested the effectiveness of an acoustic lure at increasing capture success of bats in mist nets. Increasing detection rate is especially relevant for species that have been heavily affected by white-nose syndrome, such as the Indiana bat ( Myotis sodalis ), little brown bat ( M. lucifugus ), and northern long-eared bat ( M. septentrionalis ). We conducted our study at 3 properties in southern Indiana during summer 2014. We set up 7 mist-netting sites at each property, netting 2 times at each site, with and without the use of an UltraSoundGate Player BL acoustic lure. The lure played recordings of various social calls from Myotis , Eptesicus , and Lasiurus spp. recorded in Europe and North America on a loop throughout the mist-net night. A total of 21 bats were caught using the lure, while 46 bats were caught without the use of the lure. We ran a series of zero-inflated Poisson generalized linear models on number of bats captured per trapping night to test whether the lure produced a difference in bat captures overall and for each genus while accounting for additional sources of variability. Using an information theoretical approach, we determined the most parsimonious models for each species grouping. For bats overall and those in the genera Myotis and Eptesicus , the top performing models contained an effect for use of the lure. This effect was positive and significant ( P = 0.007) for our Myotis model, while the Eptesicus model showed a marginally significant and negative effect of the lure. We conclude that level of sociality in bat species influences the effectiveness of an acoustic lure on bat capture success. Understanding this distinction can inform when and where the use of an acoustic lure may enhance conservation goals.