THE NONHIBERNATING ECOLOGY OF BATS IN INDIANA WITH EMPHASIS ON THE ENDANGERED INDIANA BAT, MYOTIS SODALIS

VIRGIL WILLMER BRACK, Purdue University

Abstract

The objectives of this study were to determine the distribution and habitat of the endangered Indiana bat, Myotis sodalis, in Indiana during the season of reproduction. Because interspecific relationships may exist between M. sodalis and several other species of chiroptera, the distributions and habitats of these bats were also determined. Distributions were determined from past records, supplemented with captures at caves and in woodlands. Distribution was subdivided by sex and age to provide precise seasonal information. Winter recapture of summer banded bats provided additional information. Habitat use was determined by a variety of methods including observation of a nursery colony previously located by James B. Cope, observation of light-tagged bats, analysis of food habits, and comparison of habitat characteristics at netting sites with bat capture. In Indiana the summer distribution of M. sodalis is sexually allopatric. Males are most common in southern karst areas; reproductive females and their offspring are virtually absent from this area. This provides evidence a polygynous mating system may exist. Lasiurus cinereus and Nycticeius humeralis are also seasonally sexually allopatric. Myotis sodalis foraged predominantly around woodland tree crowns of both riparian and nonriparian habitat. Prey were predominantly Lepidoptera and Coleoptera, although more Diptera and Trichoptera were eaten when the foraging habitat was largely riparian. In late summer, post-reproductive females and juveniles ate foods similar to, and foraged in areas similar to, those used by males. This indicates that mid-summer dietary and habitat use differences between the sexes when they are allopatric are due to differences in habitat availability. In nonriparian areas M. sodalis was captured most frequently in open woods. This corresponds to the crown foraging habit of the species. A greater netting efficiency and use of streams as travel ways by the bats produced multiple captures in riparian habitat which was uncharacteristic of captures in nonriparian habitat. Characteristic habitat usages were also noted for species other than M. sodalis. Similarly, diet varied among the different species of bats. Jaw lengths and diet diversity indices of each species added to the evaluation of food resource usage and partitioning.

Degree

Ph.D.

Subject Area

Forestry

COinS