Historic and recent changes in the structure, composition, and distribution of riparian forests have likely influenced populations of bats through their effects on habitat quality for reproductive females. This project seeks to identify natural structures used by maternity colonies, determine criteria used in the selection of these roosts, and interpret how historic and current human activities may positively or negatively impact bat populations in the bosque. This paper reports first season results from this ongoing project. Thirteen reproductive female bats (5 little brown myotis, 5 Yuma myotis, 1 red bat, and 2 pallid bats) captured on the Bosque del Apache National Wildlife Refuge in the summer of 1997 were radiotracked daily to their maternity roosts. Four little brown and Yuma myotis colony roosts were found. Colony size ranged from 90 to over 1800 bats. Two colonies were in manmade structures. Two other colonies and numerous solitary roosts were found in natural structures (dead cottonwoods). A pallid bat roosted in a rocky butte, and the red bat roosted in the foliage of a large, live cottonwood. Six of the nine tree roosts were in burned areas of forests directly along the river. Individuals and colonies of little brown and Yuma myotis used under-bark crevices and snags rather than more permanent types of roosts. Additional data from subsequent years will help determine whether the use of ephemeral bark roosts, snags, and riverside forests are characteristic of bat roost selection in the bosque.