Colonies of the Big Brown Bat (Eptesicus fuscus) were located and studied in Blackford, Delaware, Grant, Henry, Jay, Madison, and Randolph Counties, Indiana, from June 12, 1988 through August 25, 1989. During the study, 24 colonies were located. Attempts were made to capture as many bats as possible during visits to the colonies. Colony sites were revisited several times during the two year study. A total of 1,846 bats were captured, banded and examined. During examinations bats were sexed, aged, weighed, and checked for wing damage and ectoparasites. The weights from the captured bats provided data on differences in bat weights for the summer of 1988 and 1989. The summer of 1988 was characterized by drier than normal precipitation, and the summer of 1989 had wetter than normal precipitation. Several comparisons were carried out on the data. The comparisons showed a correlation between increased rainfall and increased bat weights. In the wet year of 1989, adult bats were significantly heavier than they were in 1988. Juveniles were slightly heavier but not significantly. Further detailed data regarding age and sex ratios; wing damage and ectoparasite occurence are discussed briefly. / Department of Biology

Maternal colonies of the big brown bat, Eptesicus fuscus were studied in Delaware and Grant Counties from 21 May to 22 September, 1992. Nineteen colonies of bats were located and revisited several times during the summer. Bats were captured, sexed, aged, weighed and banded at each site. The weight gain pattern of the bats was related to rainfall and temperature during the summer. Other factors that might affect weight gain such as ectoparasites, tooth wear, and wing damage were also measured.The summer of 1992 had below normal rainfall in May and above normal rainfall in June and July. Temperatures were below normal during the study period. The weights of captured bats were compared to weights of bats captured at similar colonies during the same period in 1988, a dry year, and 1989 a wet year. Both of these years had near normal temperatures. Lower weight gain for juveniles and for adult females in late spring and early summer of 1992 was associated with higher than average precipitation and lower than average temperatures during the period. / Department of Biology