The Indiana bat (Myotis sodalis) is a federally endangered species that was first discovered roosting in Wyandotte Cave in southern Indiana in the early 1900s. Due to declining populations in caves, the species was one of the first to be listed as endangered when the Endangered Species Act was written in the late 1960s. Since the late 1990s, the Center for Bat Research, Outreach, and Conservation at Indiana State University (ISU) has monitored the status of a population of the Indiana bat near the Indianapolis International Airport in central Indiana. In compliance with the Endangered Species Act, the Indianapolis Airport Authority and US Fish and Wildlife Service implemented a series of proactive conservation measures during two major periods of airport expansion. Early conservation efforts included habitat protection and regular capture surveys in the vicinity of the Airport; when Indiana bats were captured, biologists glued tiny radio transmitters to their backs to track the bats to roost trees and while they are out foraging at night. Both activities gave us critical information on the whereabouts of the bats, population size and sex/age ratios, and a better understanding of the bat’s biology and ecology. The Airport Authority also set aside almost 400 acres of land to provide a permanent home for the Indiana bat colony that was discovered in the mid-1990s, planted thousands of trees, funded outreach efforts by the Bat Center at ISU, and funded annual monitoring surveys. Some of the protected land is now a county park—Sodalis Nature Park—named after the Indiana bat.
The Indiana bat maternity colony, which includes adult females and their pups plus the occasional adult male, has hovered around 150 bats since 1997. At least seven other bat species reside in the same protected areas, including the federally threatened northern long-eared bat (Myotis septentrionalis). By placing unique forearm bands on bats captured during summer and then coordinating with biologists who survey wintering sites, we’ve learned that Indiana bats make annual migrations to the Airport site from caves 50-100 miles away in southern Indiana. Adult females begin the summer season roosting in sheltered sites within the forest, but move as a large group to tall roosts with lots of solar exposure once pups are born in early June; these warm roosts help females and their pups to conserve energy. By July, juvenile bats have begun to fly and the colony starts to break up into smaller groups, with some individuals choosing to roost in sheltered trees in small woodlots again. Throughout the summer, Indiana bats often forage along a 1.5 mile section of stream corridor that runs through their main roosting area, but some individuals make long forays across neighborhoods and busy highways to forage over ponds and other creeks. A few stragglers roost in small groups across the study site until late September/early October; then the bats move to their hibernation sites in southern Indiana.
It’s really nice to know that endangered Indiana bats can co-exist with development when natural areas are also conserved. This long-term conservation success story demonstrates the effectiveness of the Endangered Species Act and proactive conservation efforts!