Population ecology of the gray bat (Myotis grisescens): philopatry, timing and patterns of movement, weight loss during migration, and seasonal adaptive strategies.
Abstract
(Uploaded by Plazi for the Bat Literature Project) An intensive banding and recovery study of M. grisescens resulted in 19,691 recoveries at 120 locations. Included were many multiple recaptures and roundtrip recoveries between maternity and hibernating caves. Gray bats demonstrated strong loyalty to a summer home range, often including six or more caves, as well as to their wintering site. Adult females emerged from hiberation first, in early April, followed by yearlings of both sexes and lastly by adult males. Once at the summer home range, adult females congregated in one preferred maternity site to rear young, while adult males and yearlings clustered in smaller groups, usually in caves other than the maternity cave. After tl1e fledging of young, sex and age segregation weakened, and indi viduals were more evenly dispersed thrnugh the home range. Fall migration took place in approximately tl1e same order as spring emergence, with adult females leaving in early September and juveniles remaining behind with tile last males to leave, usually by mid-October. Distances regularly traveled in · migration ranged from 17 to 437 km ( one way, direct distance), wiili nearly the entire southeastern population congregating in three major hibernacula. Migratory movements appeared to be direct and rapid for adult females in particular, and weight loss during migration was directly proportional to distance traveled. No significant winter movements were observed after hibernation began.