Zoological Studies

Vol. 43 No. 3, 2004

Flight Activity and Food Habits of Three Species of Myotis Bats (Chiroptera: Vespertilionidae) in Sympatry

Ya-Fu Lee1,* and Gary F. McCracken

1Department of Ecology and Evolutionary Biology, the University of Tennessee, Knoxville, TN 37996, USA

Ya-Fu Lee and Gary F. McCracken (2004) Spatiotemporal distributions in nocturnal flight activities and variations in food resource use among the little brown (Myotis lucifugus), northern long-eared (M. septentrionalis), and Indiana myotis (M. sodalis) were studied in central and northern Indiana where the 3 species occur in sympatry. We netted pairs of these 3 species on the same nights at 4.3% to 8.5% of the total netting sites, while all 3 species were netted on the same night at only 1 site (~1.1%). When each species was captured alone, the mean capture time of the little brown myotis was earlier than those of the Indiana and northern long-eared myotis; but the 3 species did not differ in heights of capture. At sites where paired species were caught, the mean capture time of the Indiana myotis shifted from being no different from, to being earlier than, that of the northern long-eared myotis; and the mean capture height of the Indiana myotis shifted from being no different from, to being higher than, that of the little brown myotis. Based on analyses of feces, the little brown myotis has a more-diverse diet, feeds on more beetles of a smaller size range, and consumes more aquatic insects than do the Indiana and northern long-eared myotis. While the northern longeared myotis fed primarily on beetles, moths, and dipterans, and took greater quantities of large-sized (4~6 mm and > 6 mm) beetles, moths were the major prey of the Indiana myotis. Variations in diets among these 3 species are consistent with their foraging behavior, are correlated to their temporal activities, and support predictions based on previously reported differences in their mean lengths of the maxillary tooth-row.

Key words: Activity, Diets, Bats, Myotis, Sympatry.

*Correspondence: Department of Life Sciences and Institute of Biodiversity, National Cheng Kung University, Tainan 701, Taiwan. Tel: 886-6-2757575 ext. 65524. Fax: 886-6-2742583. E-mail: yafulee@mail.ncku.edu.tw