M.A. Bogan R. O. Rye G. P. Landis C.L. Kester P.M. Cryan 2004 <p>Although hoary bats (<i>Lasiurus cinereus</i>) 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 of bat hair (δD_h) and determined how these values relate to stable hydrogen isotope ratios of precipitation (δD_p). 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 determining their migratory movements. We present evidence that a single annual molt occurs in <i>L. cinereus</i> prior to migration and that there is a strong relationship between δD_h and δD_p during the molt period. This presumably reflects the incorporation of local δD_p 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.</p> application/pdf 10.1644/BRG-202 en American Society of Mammalogists Stable hydrogen isotope analysis of bat hair as evidence for seasonal molt and long-distance migration article