STABLE HYDROGEN ISOTOPE ANALYSIS OF BAT HAIR AS EVIDENCE FOR SEASONAL MOLT AND LONG-DISTANCE MIGRATION

Although hoary bats (Lusiurus cinereus) are presumed to be migratory and capable of long-distance dispersal, traditional marking techniques have failed to provide direct evidence of migratory movements by individuals. We measured the stable hydrogen isotope ratios ol" bat hair (60,,) and detemiined how these values relate to stable hydrogen isotope ratios of precipitation (6Dp). Our results indicate that the major assumptions of stable isotope migration studies hold true for hoary bats and that the methodology provides a viable means of detemiining their migratory movements. We present evidence that a single annual molt occurs in L. cinereus prior to migration and that there is a strong relationship between 6Dh and 6Dp during the molt period. This presumably reflects the incorporation of local 6Dp into newly grown hair. Furthermore, we present evidence that individual hoary bats are capable of traveling distances in excess of 2.,000 km and that hair is grown at a wide range of latitudes and elevations. Stable hydrogen isotope analysis offers a promising new tool for the study of bat migration. Key word.s: deuterium, hoary bai, hydrogen. Lusiiims cinereus. (iiigralion. inoli, stable isotopes