In the fall and winter of 1958 and 1959 four species of bats, Myotis lucifugus, Myotis sodalis, Eptesicus fuscus, and Pipistrellus subftavus, were found in five Dubuque County caves. M. sodalis was a new species record for Iowa. Migration of bats into the caves began when the minimum temperature dropped to 24° F. The greatest increase in cave population occurred when the daytime high temperature was below freezing and nighttime lows ranged from 13° F. to 1° F. Midwinter copulation of E. fuscus was observed, and drinking of condensed water on cave ceilings by M. lucifugus was noted. No intercave movements occurred but intracave movements did occur when cave temperature reached 43° F.
Proceedings of the Iowa Academy of Science
©1960 Iowa Academy of Science, Inc.
Muir, Ted J. and Polder, Emmett
"Notes on Hibernating Bats in Dubuque County Caves,"
Proceedings of the Iowa Academy of Science, 67(1), 602-606.
Available at: https://scholarworks.uni.edu/pias/vol67/iss1/75