Abstracts Biological Sciences

An investigation of tree bat migration ecology using fatty acid signatures

by Jeffrey Crawford Clerc

Bat migration ecology is an important, yet understudied facet of natural history and conservation. We know little about the movement patterns of migrating bats and the physiological demands that bats experience in preparation for and during migration. This has particular relevance to tree bats (Lasiurus spp. and Lasionycteris noctivagans) that make the longest annual migrations across North America and have recently become subject to alarming fatality rates by wind turbines. As the absence of effective methods to study tree bat migration has made conservation efforts challenging, I investigated the potential for a non-lethal lipid extraction method (fine needle adipocyte aspiration). This method uses fatty acid signatures as an intrinsic geo marker potentially capable of answering questions about migration ecology. If fatty acid signatures remain stable throughout migration, they have the potential to indicate an individual???s diet at their origin. Samples taken during the resident period can tell us about the dietary shifts that may take place prior to migration. These samples can indicate the summer residence region of migrants sampled during migratory movement. Of 136 attempts, our lipid extraction method had a 72.79% success rate. I used fatty acid signatures produced from fine needle adipocyte aspiration to compare a group of resident and a group of migrant silver-haired bats. I used a multivariate statistical approach for our analysis and found significantly different fatty acid signatures between residents and migrants. It remains unclear whether geographic segregation or temporal shifts in diet are driving the separation of migrants and residents. However, I observed greater fatty acid signature dispersion in migrating individuals, which led to the conclusion that if geographic segregation caused the observed separation, then more than one unique resident group used the migration route where we captured and sampled bats. But if temporal shifts in diet caused the separation, then it may indicate that the bats began to exhibit varied individual dietary preferences during migration. However, the latter seems less likely; we expect the bats to form the majority of their fat deposits during summer residency, and we also expect that they would have a net depletion of fat reserves during migration. The results of this study provide a new non-lethal approach to studying bat migration ecology. Advisors/Committee Members: Szewczak, Joseph M..