ONSET OF VOLANCY AND FORAGING PATTERNS OF JUVENILE LITTLE BROWN BATS,MYOTIS-LUCIFUGUS

In this paper I quantify and compare patterns of use of habitat and di et of adult and juvenile little brown bats (Myotis lucifugus). Individ uals were captured in mist nets as they foraged. Clutter indices (CIs) ranging from 0 (least cluttered) to 5 (most cluttered) were used to c ategorize feeding microhabitats based on density of vegetation. A tota l of 378 M. lucifugus was banded over a 2-year period and dietary anal ysis was performed on fecal samples from 90 individuals. Foraging patt erns of juveniles and adults differed significantly, and patterns of a dult were density dependent. When population density was high, adults moved from foraging primarily in open areas close to the ground (CI1) to semiclutter and heavy clutter microhabitats (CI3, CI4, and CI5). Ad ults shifted foraging areas in mid-July when juveniles developed volan cy. When density of the population was low (the result of a population crash at the site), adults foraged in CI1 throughout summer and did n ot shift habitats. Juveniles foraged predominantly in the least-clutte red microhabitat (CI0) in both years independent of density of populat ion.