Carcass age and searcher identity affect morphological assessment of sex of bats: Identifying the Sex of Bat Carcasses

Carcasses provide an important resource for assessing the vulnerability of bat species and sexes to threats, but the reliability of sex data derived from the external morphology (sex(morph)) of bat carcasses remains uncertain. We used genetic-based assessment of sex (sex(gen)) to evaluate the effect of carcass age and searcher identity on sex(morph)-based assessments of eastern red (Lasiurus borealis) and hoary (Lasiurus cinereus) bat carcasses identified by 15 different searchers at a wind-energy facility. The proportion of carcasses for which sex(morph) was unknown increased from 0.11 for those recovered within a day of death, to 0.56 within 2-3 days of death, and to >= 0.82 at >= 4 days after death. The proportion of carcasses for which sex(morph) was correct decreased from 0.9 for those recovered within a day of death, to 0.65 within 2-3 days of death, and to 0.25 at >= 4 days after death. The proportion of sex(morph) misidentifications of the 108 fresh carcasses (collected within 24hours of death) varied (0.0-0.43) among searchers. These results suggest that sex(morph)-based assessments should be limited to fresh carcasses. Furthermore, additional training of people who collect and identify bat carcasses from renewable-energy facilities may improve the accuracy of sex(morph) data obtained from carcasses. (C) 2018 The Wildlife Society.