The Indianapolis Airport Authority (IAA) is the proud steward of around 2,000 acres of land, maintained as a conservation area to provide critical habitat for the endangered Indiana bat. Researchers from Indiana State University monitor bats within the conservation area since its creation, and have installed bat boxes to help bats find a suitable roost. These creatures provide many benefits for humans, and you can help protect this endangered species by putting up you own bat box and being mindful of the challenges bats face.
When construction of the Indianapolis airport terminal was planned in 1992, efforts were quickly turned toward the establishment of a conservation area in accordance with federal law. In conjunction with the U.S. Fish and Wildlife Service, the IAA mapped a habitat conservation plan for its many animal inhabitants, in particular the endangered Indiana bat. From 1992 to 1996, 3,204 artificial roosts, or bat boxes, of nine different varieties were installed in forested areas of the reserve in an attempt to provide Indiana bats, Myotis sodalis, with suitable habitat, and to determine potential future applications of such structures in suburban areas (Whitaker Jr., Sparks, & Brack Jr., 2006). This study was undertaken by experts at Indiana State University, which remains in coordination with the IAA today, working within the IAA's authority to study and monitor bat population and roosting sites. By using net and release methods and counting bats as they leave their maternity roosts, these bat researchers have observed the continued return and summer roosting of bats over the last decade, as despite airport expansions, the 2,000 acres of wildlife habitat has been maintained as a sanctuary for these valuable creatures.
A Place to Call Home
After five years of study beginning in 1992, ISU researchers determined that five of the nine types of bat boxes were not in use by any bats, nor were a number of other boxes in particular areas of the mitigation land being used. These boxes were removed in 1997, leaving 801 in-use roosts on the premises (Whitaker, Jr., 2006). The Indiana bat prefers to roost under the loose bark of trees, often those that are dead, so human-provided structures were likely alien to the species. For about the first decade after the implementation of the bat boxes, the Indiana bat made little use of the artificial roosts, and in fact, for that span of time, northern long-eared bats were the only species that frequented them. However, in 2003, a tree that had been in use by a maternity colony of Indiana bats blew down and the colony relocated to two available bat boxes in the conservation area. Sustained observation of the colony noted that they continued to use the boxes for the next two years, and Indiana bats were observed exiting other bat boxes in the ensuing summers. It appears that after over a decade, the Indiana bat has adapted and is now using the artificial roosts.
The graphic below describes the numbers of the different bats found per year by researchers at Indiana State University. As the IAA expands, it works to maintain balance between any new construction and the preserve, making sure that bats can continue to roost on the protected grounds.
Survey of Bats on IAA Conservation Land
Netted from 2002-2015
There are many misperceptions about our night-flying friends, most of which make them sound scary or harmful. Bats are actually far from scary, and are beneficial to humans rather than harmful. Although many people think of bats as "flying mice" (the German word for bat, Fledermaus, actually means "flying mouse"), bats are actually not rodents. Bats are of the order chiroptera, which means "hand wing," and indeed bats display five tiny fingers stretched along their wings. Most North American bats are insectivores, bats that feed off of insects. All of the bats at Sodalis Nature Park are insectivores, and consume many insects that would otherwise damage human crops. The big brown bat in particular makes a massive contribution to pest control, scarfing down various species of beetles and other insects in large quantities. A pregnant female can consume her body weight in insects in one night (Bat Conservation International, 2015)! Other bats from tropical climes pollinate fruits and flowers, providing humans with food (and scenery) that would be much less abundant without them. Humans also use bat guano as a fertilizer, often in our gardens, creating further fruits and vegetables through the help of our winged friends.
Bats face many threats in the wild, many of which are brought about by human activity. Bats lose habitat every year to logging and construction, and can be harmed by the pesticides that are applied to agricultural fields. Wind turbines are also a danger, especially to migrating bats who fly too closely to the blades. White Nose syndrome, a fungus accidentally brought over from Europe, has also devastated bat populations in recent years (White-Nose Syndrome.org), prompting the prohibition of visiting many caves where humans might disturb bats. Despite these threats, there are many actions that we can take to promote bat populations. Here are several things you can do to give bats a helping hand:
- Put up a bat house. Bat houses are best placed out in the open where they can get sunlight, such as on a pole or barn rather than a tree. Don't be discouraged if it takes some time for a bat to arrive.
- Educate others. Point out the good qualities of bats and help others to realize that they are not scary or dangerous. A little knowledge can go a long way towards a positive outlook on bats.
- Leave standing dead trees rather than cutting them down. Dead trees are a favorite roosting place for bats, and leaving such trees alone preserves bat habitat.
- Don't enter caves inhabited by bats, as a human presence disturbs them easily.
Bat Conseration International. (2015). Species profiles. Retrieved from http://www.batcon.org/resources/media-education/species-profiles
Center for Bat Research, Outreach, and Conservation, Indiana State University. Retrieved from http://www.isubatcenter.org/
Whitaker Jr., J.O., Sparks, D.W., & Brack Jr., V. (2006). Use of artificial roost structures by bats at the Indianapolis International Airport. Environmental Management, 38, 28 – 36. DOI: 10.1007/s00267-005-0117-2
White-Nose Syndrome.org (n.d.). A coordinated response to the devastating bat disease. Retrieved from https://www.whitenosesyndrome.org/