We report characteristics of seven tree cavities used as day-roosts by female northern long-eared bats (Myotis septentrionalis) during the maternity season in a deciduous forest in north-central Kentucky. Understanding the characteristics of cavities selected by bats will help us better understand the ecology of cavity roosting bats and the tree species and condition necessary for providing day-roost habitat. Cavity openings were created by either fungal decay or primary excavators. Length and volume of cavities were positively related to number of entrances. Mean area of entrances was positively related to the proportion of entrances created by primary excavators. The use of trade, fi rm, or corporation names in this publication is for the information and convenience of the reader. Such use does not constitute an official endorsement or approval by the U.S. Department of Agriculture or the Forest Service of any product or service to the exclusion of others that may be suitable. Quality Assurance This publication conforms to the Northern Research Station's Quality Assurance Implementation Plan which requires technical and policy review for all scientifi c publications produced or funded by the Station. The process included a blind technical review by at least two reviewers, who were selected by the Assistant Director for Research and unknown to the author. This review policy promotes the Forest Service guiding principles of using the best scientifi c knowledge, striving for quality and excellence, maintaining high ethical and professional standards, and being responsible and accountable for what we do. Cover Photo A white oak (Quercus alba) snag provides roosting opportunities for female northern longeared bats on the Fort Knox Military Reservation, Kentucky, USA. Photo by Alexander Silvis, Virginia Tech, used with permission.