Ecological Observations on Lasiurine Bats in Iowa

During field studies in Iowa in 1960, 1961 and 1963, 253 red bats and hoary bats were discovered in roosts in foliage, and 197 individuals were captured. In late July and early August, many red bat families were breaking up; evidently waves of migrants passed through western Iowa at this time. Females and young red bats found in clusters occurred in a 1:2.2 ratio. Young hoary bats develop to flight stage later than young red bats and initiation of migration is delayed accordingly. Female and young hoary bats occurred together in a 1:2 ratio. Although adult male and female red bats were present in an equal ratio, no adult male hoary bats were taken. Lasiurine bats occupied “edge” areas of tree growth bordering crops. Rat shelters were on the undersides of vine-infiltrated canopies, lush leafy overhangs or tufts of leaves. Families and solitary young bats roosted at higher elevations than solitary adults. Certain roosts were occupied successively by different bats of the same or dissimilar species. Habitat, shelter and intraspecific and interspecific use of the same roosts are comparable among lasiurine bats occurring in Georgia, California and Iowa.