At MNA, our Mission is to protect special natural areas and the rare species that live there. The goals of our blog are to cover the latest environmental issues affecting these areas and provide information about the efforts of our volunteers. Our weekly “ENDANGERED!” column serves to inform you about the endangered plant and animal species found in and around these special natural areas, and how you can contribute to conservation efforts before it is too late.
By Brandon Grenier
While we do not often see bats, they play an active role in the environment. With an appetite for bugs such as mosquitoes, moths and other pests, bats help manage insect populations. They also aid in the pollination of plants and seed dispersal of fruits and nuts.
First listed as endangered in 1967, the Indiana bat (Myotis sodalis) is only found in the eastern United States and there are only about 400,000 individuals left in the world. It is believed that the population of bats is now less than half of what it was in 1967, according to 2009 estimates.
The Indiana bat is incredibly light, weighing only seven-to-eight ounces, roughly the weight of two sugar packets. It has a wingspan of 9-to 11-inches and usually is about five inches long. It has dark, grayish brown fur, with pink undersides and a dark petagium (wing membrane). Its ears are short and rounded. While it can sometimes be difficult to tell it apart from its relative the little brown bat, the Indiana bat has tri-color hairs that make it easy to distinguish upon close inspection.
The Indiana bat has a very specific habitat, with 85 percent of the current population found in only seven caves. The largest caves support 20,000-50,000 bats. In Michigan at the northern end of their range, Indiana bats prefer savanna habitats with sun-exposed trees for maximum warmth. In the winter, bats hibernate in large caves in Kentucky, Indiana and Missouri. However, a relatively new hibernacula (a cave where bats hibernate for the winter) has been found in northern Michigan at the Tippy Dam spillway. Because of their hibernation habits, Indiana bats are incredibly vulnerable to human disturbances.
Throughout the past decade, there have been reported occurrences of the bat in Calhoun, Cass, Washtenaw, Van Buren and St. Joseph counties.
In the spring, Indiana bats leave their hibernacula, sometimes travelling hundreds of miles. In early fall, Indiana bats flock the entrance of caves or mines and mating takes place. Sperm is stored in the female’s body until the eggs are fertilized in the spring. One bat is born to each female in late June, and it can fly within one month. Indiana bats generally live to be 14 years old.
As human activity increases in the areas where Indiana bats hibernate, their delicate habitat shrinks. The bats are protected federally and are listed as endangered in Michigan. Commercialization of caves, the logging of dead trees and the use of pesticides and contaminants contribute to the decline of this species.
The Indiana bat is also threatened by a disease called white nose syndrome. More than one million bats have died from it since its discovery in 2006 in New York. The name refers to a white ring of fungus found on the faces of infected bats.
The presence of white nose syndrome has been found in more than 25 different caves and mines so far, and a moratorium has been placed on caving activities in those areas. Fortunately, the disease has not yet been found in Michigan.
The Michigan Department of Natural Resources is collaborating with state, federal and local government officials as well as university researchers and bat conservation groups to develop a response plan to white nose syndrome that prevents the disease and minimizes its impact on the species.
Indiana bat’s habitat can be protected by protecting mature forests, leaving dead trees standing to promote habitat and refraining from using insecticides.
How You Can Help:
To help protect this rare species, abstain from demolition and land clearing such as canopy removal and clearing snags. Cutting down trees significantly reduces bats’ habitat. However, if you must remove trees, you can build a bat house. Bat houses mimic the space between a tree trunk and bark and provide warmth. To learn how to build your own bat house, click here.
MNA volunteers are currently working to protect this and other endangered species, and you can help too. Join our efforts as a volunteer removing invasive plants in the special natural areas where this species lives. Or, become a steward and take responsibility for planning efforts to maintain a specific MNA sanctuary. To find out how to get involved, visit our website.