Foraging Behavior and Nocturnal Activity Patterns of Missouri Bats, with Emphasis on the Endangered Species Myotis grisescens and Myotis sodalis

Foraging behavior of nine species of bats, especially Myotis grisescens and M. sodalis, was studied in eastern Missouri by observing 400 bats to which were affixed Cyalume chemical lights. Observers viewed the bats either from a helicopter or from widely-spaced stations on the ground. Individuals of M. grisescens foraged mostly over the water of streams with well-developed riparian vegetation. Helicopter observations indicated that M. grisescens distributed themselves along as much as 17 kilometers (km) of the river upstream and downstream from the roost cave. Myotis sodalis, however, foraged mostly under the forest canopy on ridges and hillsides. Foraging M. sodalis were not observed more than 2 km from the cave of release, because individuals were very easily lost from view in the dense forest in which they foraged. The other species foraged in a variety of situations, but sample sizes were small.