Presentation Abstract

Title: Carcass ecology: forensic techniques shed light on the possible causes of bat susceptibility to turbines.
Session Title: "Bats and wind energy: Ecology, behavior, and methodology"
Session Number: 81
Session Time: Wednesday, Oct 17, 2012, 1:30 PM - 5:20 PM
Presentation Time: Wednesday, Oct 17, 2012, 4:00 PM - 4:20 PM
Presentation Number: 8
Author(s): Paul Cryan1, Ernest Valdez2, Craig Stricker3, Michael Wunder4, Erin Baerwald5, Robert Barclay5, Joel Jameson6, Craig Willis6, Apple Snider7, Elizabeth Crichton8, 1USGS Fort Collins Science Center, Fort Collins, CO, 2USGS Arid Lands Field Station-Fort Collins Science Center, Albuquerque, NM, 3USGS Stable Isotope and Gas Chemistry Laboratory, Denver, CO, 4University of Colorado Denver, Denver, CO, 5University of Calgary, Calgary, AB, Canada; 6University of Winnipeg, Winnipeg, MB, Canada; 7US Forest Service, Steamboat Springs, CO, 8University of Queensland, Gatton, Australia. Contact: cryanp@usgs.gov
Abstract Body: Bats are often found dead beneath industrial wind turbines during late summer and autumn. Although bat fatalities at turbines occur on several continents, the exact reasons for such susceptibility remain a mystery. In this talk, we describe three projects in which forensic techniques were used to better understand the possible causes and population impacts of turbine fatality. The majority of bat fatalities at turbines in the temperate zones of North America involve Lasiurus cinereus, L. borealis, and Lasionycteris noctivagans. It has been hypothesized that mating, feeding, and/or migration behaviors of these species play a role in their susceptibility. We analyzed reproductive tracts of specimens found at turbines to assess the plausibility of the mating hypothesis. Histological analysis revealed evidence of mating readiness in all three species. We found that high proportions of juvenile males of each species can be sexually mature in their first autumn, a unique trend for North American bats. We analyzed gastrointestinal tracts from L. cinereus to assess the feeding hypothesis. Similar to a prior study, most of the carcasses we examined had full stomachs and intestines, indicating they fed mostly on moths in the hour prior to death. We did not find insect parts in the mouths or throats of carcasses that would be expected if bats regularly fed close to turbine blades. We analyzed stable hydrogen isotope signatures in fur of L. cinereus found at turbines to infer the geographic origins of individuals and better understand population impacts. Isotopes indicated that bats often died during migration and that individuals originated from many different areas and arrived at the wind facilities in no structured phenology. Combined with earlier isotope results, new patterns in the continental migration of L. cinereus are emerging. Forensic approaches are currently underutilized despite the potential wealth of information they can provide.



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