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Inspecting a bat wing. Photo by USFWS; Ann Froschauer

Inspecting a bat wing.

Photo by USFWS; Ann Froschauer


Bat Facts Calendar



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Summer is drawing to a close, but it’s not too late to participate in the “Bats and Pools” survey.  Indiana State University is studying how bats use pools as a source of drinking water.  If you have seen bats around your pool, consider helping out by participating in their online survey.
By now, young Indiana bats are nearly adult size and members of maternity colonies are busy foraging to put on weight, stored as fat, for fall migration and the winter ahead. The amount of fat stored often depends on how far a bat must migrate. The longer the journey, the more energy required.
Indiana bat maternity colonies begin breaking up as fall migration starts. The number of bats roosting together in the same tree typically peaks in mid-July and slowly diminishes through August. Numbers drop off quickly in September, and almost all Indiana bats have left maternity habitat by the beginning of October.
We don’t know if Indiana bats migrate alone or in groups. We do know that not all members of a maternity colony travel together because numbers within the colony diminish gradually in the fall.
Not all members of an Indiana bat maternity colony migrate to the same hibernaculum. They part ways for the winter and then meet at the colony site again next spring.
Most people know that birds migrate, but not that bats migrate. Whereas birds migrate to exploit seasonal food resources, most bats migrate to find better hibernating conditions so they can wait out the winter while insect prey is not available.
Wind energy is an expanding source of renewable energy in the United States. An unforeseen consequence is high numbers of bat fatalities at wind facilities.
Initially, wind energy and wildlife research focused on birds. However, results of their studies showed that, generally, many more bats than birds were killed, particularly in the Midwest and Eastern U.S. Research to understand bat interactions with turbines provides new insights into this problem.
Studies show that turbines consistently kill certain species of bats in many different areas of the continent. “Migratory tree bats” including hoary bats, red bats, and silver-haired bats make up a large proportion of the bats killed.
Indiana bats appear to be much less susceptible to wind turbine strikes compared to migratory tree bats. owever, some Indiana bats have been killed at wind farms.
Research suggests that bats are more likely to be killed by wind turbines during fall migration than at other times in their annual cycle. Cumulative totals of bats killed by wind turbines in North America may range into the hundreds of thousands of bats per year.
Some wind facilities are applying for incidental take permits and developing Indiana bat Habitat Conservation Plans. These permits allow for limited take of Indiana bats if the facility follows the Habitat Conservation Plan. An example is a permit for a wind farm in Ohio issued by the U.S. Fish and Wildlife Service.
Most bats are killed at wind turbines when wind speeds are relatively low. At one facility, more than 80% of bat fatalities occurred on nights when median wind speeds were under 6 meters/second, which is 13.4 miles/hour.
The most effective way to reduce bat fatalities at wind turbines is to reduce turbine operation during low wind conditions. Working with the wind industry, researchers have found significant reductions in bat fatalities by reducing turbine operation when wind speeds are low.
There is an economic cost to wind companies when they reduce turbine operation to reduce bat fatalities. However studies show that losses in power production may be less than 1% of total annual output if the reduction in turbine operation is only during fall migration, when most bat fatalities occur.
Researchers are also studying acoustic deterrents to prevent bat fatalities at wind turbines. Ultrasound broadcasts may discourage bats from approaching sound sources. An effective and technically feasible system has not yet been developed, but further work is being done.
Researchers are devising a way to observe bat presence and behavior at wind turbines using a video system of high-powered illuminators and near-infrared camera. A better understanding of bat behavior around wind turbines, and why they approach turbines, will help reduce bat strikes.
Are bats killed at wind turbines because they are attracted to the turbines? We aren’t sure, but one theory is that some species of bats are attracted to the tallest trees on the landscape to mate during migration. Bats may be aggregating at turbines because turbines replace trees as the tallest structures on the landscape. Go here to read more theories.
Solutions to the problem of reducing bat fatalities at wind turbines are not easy, but too much is at stake not to seek those solutions. Our challenge is to work with the wind industry and others to provide both sustainable wind energy development and sustainable bat populations.
Public lands provide habitat for bats and other wildlife, as well as providing us places to view wildlife. Show your appreciation by making plans to celebrate National Public Lands Day on the last Saturday in September. This is the nation's largest, single-day volunteer effort for public lands.
Bats have many unique and fascinating adaptations; hibernation and echolocation are two that people most commonly associate with bats. Over the next few days, we’ll highlight some less well known adaptations.
Bats belong to the order Chiroptera, which means “hand wing.” If you examine the skeleton of a bat you’ll understand the name, the wing of a bat has the same bones as a human hand. The bones that you can see in an outstretched bat wing are modified fingers.
Why do bats hang upside down? Bat wings don't produce enough lift to take off from the ground. Sleeping upside down in a high location is an adaptation that allows bats to take flight quickly; they simply drop and open their wings. If a bat is on the ground, it uses the front claws to climb to a high spot, and then falls into flight.
The legs of bats are attached so their knees bend the opposite way to those of humans: backwards and outwards instead of forwards. This adaptation allows bats to move rapidly on all fours across a surface such as a cave roof, rather like a spider. Backward-flexing knees also enable them to move the tail membrane downwards in flight to help catch food and maneuver in flight.
If you want to hold onto an object, you contract several muscles in your arm to clench your fist. You relax those muscles to let go. A bat's claws work the opposite way, muscles are used to open the claws, but to grab hold of a surface the bat simply lets its body relax. So, while hanging, the claws are locked into position and hold the bat tight without expending energy.
Fireflies light up to find potential mates, but predators can see them too. So, fireflies have a secret weapon in the form of a nasty chemical that makes them taste bad. Bats to steer clear of these light-up snacks rather than swoop in for an easy meal. Not only are the fireflies chemically defended, this study also found that their light show actually warns bats to stay away. 
The scientific name of the Indiana bat is Myotis sodalis. What does that mean? The genus name, Myotis, means “mouse ear” and the species name, sodalis, means comrade or companion. So, the Indiana bat is a mouse eared bat (all Myotis bats have small ears compared to other bats) and it is very social, always hanging out with companions. Decipher more bat names!
Bats are typically divided into two big suborders: the fruit-eating megabats and insect-eating microbats. Scientists thought that the mega- and microbats are so different that they may have evolved flight separately.
Results from a recent genomic analysis study indicate that bats’ ability to fly dates back some 90 million years to a common lineage.  Megabats didn’t split from microbats for another 10 million years, after which the microbats developed echolocation to help hunt insect prey.
Although little brown bats have been hit hard by white-nose syndrome in the Northeast, some little browns are surviving over multiple years. Researchers tracking bats from a maternity colony in Vermont recaptured two females that were banded in 2006. Now researchers are trying to find out why and how these bats have managed to survive.
Last updated: August 30, 2016