QUANTIFYING WING DAMAGE OF SUMMER BATS IN THE NORTHEASTERN UNITED STATES

Abstract

While conducting mist net surveys for the federally endangered Indiana bat (Myotis sodalis) in West Virginia, New York, and Pennsylvania, we quantified wing damage on 422 bats of four species: big brown (Eptesicus fuscus, N = 190), eastern red (Lasiurus borealis, N = 82), little brown (M. lucifugus, N = 55), and northern myotis (M. septentrionalis, N = 95) bats. From 15 May – 15 August 2010, we photographed back-lit wings to reveal damage such as scars, holes, and blotching (non-uniform pigmentation). After quantifying the percent cover of these damage types using image-analysis software, we used generalized non-linear mixed models to determine if percent area of damage differed among scores associated with the categorical wing damage index (WDI) developed by Reichard and Kunz (2009). Although quantified damage did generally increase with WDI score across all species, statistical separation by WDI was only documented for the big brown bat (blotching, scars, blotching + scars combined) and northern myotis (blotching, blotching + scars). We suggest that studies like ours can provide quantitative species-specific datasets that can be examined in a more precise manner than a categorical index.