Indiana Bat Recovery

A Hopeful Outlook

 

Indiana bat being held by a researcher. Notice the antenna of the radio transmitter.   Photo by Adam Mann, Environmental Solutions and Innovations

One of the first animals to be identified as an imperiled species in the United States, the Indiana bat was declared endangered in 1966 under a precursor to the Endangered Species Act we know today.  Indiana bats (so named because the species was first identified in southern Indiana) once numbered in the millions, but by the 1960s, their numbers had plummeted to several hundred thousand.   This decline was most likely linked to habitat loss, especially the caves and mines where the bats hibernate by the thousands each winter. 

 

Even after passage of the 1973 Endangered Species Act, Indiana bats continued to decline.  Bats are extremely sensitive to disturbance and to changes in airflow and temperatures during hibernation.  The Indiana Bat Recovery Plan, developed in 1983, called for protection of the most important hibernacula (caves and mines where the bats hibernate).  Bat-friendly gates on cave and mine entrances restrict entry by humans but allow bats in and out and keep conditions stable.  Conservation of summer habitat –  forested areas that provide a sustained supply of large, dead trees for maternity roosts and foraging areas – has also been a key to recovery.

 

Indiana has become a stronghold for Indiana bats, with approximately half of the total hibernating population of the species, and far-sighted, long-term plans to conserve summer habitat in the state.

 

Wyandotte Cave in southern Indiana currently supports 50,000 hibernating Indiana bats each winter.  Wyandotte – the site where the species was first identified – is also a commercial cave managed by the Indiana Department of Natural Resources, offering tours to thousands of visitors each year.  Until 2002, Wyandotte was open during the winter, with tours entering and exploring the cave while Indiana bats and other species were present.  The Indiana DNR, recognizing the impact that human disturbance could have on the imperiled species, halted winter tours, closing the cave to visitors in September and opening it again on May 1.  The results were remarkable – the number of hibernating Indiana bats increased 76 percent in the first year after the cave discontinued winter tours, and bats were found hibernating in areas of the cave where they hadn’t been seen in decades.

 

Efforts to conserve summer habitat are also benefiting Indiana bats.  At Indianapolis International Airport, a novel approach is underway to conserve important summer roosting and foraging habitat for an Indiana bat maternity colony.  Amid construction of new runways, air terminal and connecting highways, the Indianapolis Airport Authority and their partners developed a Habitat Conservation Plan that permanently protected 373 acres of habitat, and conserved another 346 acres used by female Indiana bats and their young each year.  Additional acreage has been conserved since the plan was implemented in 2002 and the area remains home for the Indiana bat maternity colony that the plan was designed to protect. 

 

Such efforts in Indiana and other states across the species’ range are beginning to show success, with Indiana bat numbers showing a rangewide increase of about 43 percent from 2001 to 2007. The Indiana Bat Recovery Plan is being updated to include new information on recovery strategies for hibernacula and summer habitat.

 

Challenges remain, however.  Efforts continue to protect and enhance hibernation sites, and managers continue to seek new information on the species’ summer habitat needs.  Last winter, a new threat to the Indiana bat was identified:  a fungus found on hibernating bats in the Northeast appears to be linked to high mortality of several species, including Indiana bats.  Scientists are studying “white-nose syndrome” to determine whether the fungus on the bats is the cause of death or a symptom, how it might spread, and its overall potential impact on bat populations in the eastern United States.

 

Back