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Northern long-eared bats in a bat box in Indiana.  Photo by Nick Gikas, Indiana State University.

Northern long-eared bats in a bat box in Indiana. Photo by Nick Gikas, Indiana State University.



Indiana Bat Calendar


<April - June>

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Indiana bats migrate from their winter hibernacula to areas where they spend summer, but little is known about their migration.  We don’t know if they migrate singly or in groups, how high or how fast they fly, or how they navigate.  Why is so little known?  We’ll highlight one reason tomorrow.
Bat migration is difficult to study. Attaching radio transmitters to animals is a common way to study migration.  However, bats are so small that the transmitters must be very light weight and have a limited range. Following migrating bats requires aerial tracking at night, which is difficult and expensive. Challenges of  studying bat migration
We know that individual Indiana bats usually migrate from the same hibernaculum to the same summer area, and back, every year.  But how do these bats navigate during migration.  How do they find their way “home”?
Bats appear to depend on vision during migration, but they may also use celestial, solar or magnetic clues.  The details are a mystery, but it is likely that they use a combination of sensory inputs.
It’s Cinco de Mayo and a day to celebrate Mexican culture and heritage.  Murciélagos, Spanish for bats, are part of the shared natural heritage of the United States and Mexico.  Many species of bats summer in the U.S. and migrate to Mexico for the winter, including the Mexican free-tailed bat.
Colonial bat species, including Indiana bats, form the largest aggregations of any mammals.  Bracken Cave in Texas is the summer home of the world's largest bat colony.  Millions of Mexican free-tailed bats live in the cave from March thru October.
Carlsbad Caverns National Park in New Mexico is home to 17 bat species, including a large colony of free-tailed bats.  The limestone rock that forms the caverns is full of ocean fossil plants and animals from a time before the dinosaurs when this area was a coastline similar to the Florida Keys. 
Radar provides a window into airspace and has been used to study weather.  Now scientists are evaluating radar for studying migrating animals, including bats.  One problem with radar is that it is difficult to distinguish bats from birds or even insects. Storm Chasing Radar Used to Track Bat Populations
We know much more about bird migration than bat migration.  Birds tend to migrate considerably further than bats, sometimes thousands of miles.  Bat migrations of this distance are rare. 
Although bats and birds both fly, they have very different adaptations for flight.  Birds have hollow bones, but bats have lightweight versions of marrow-filled bones, typical of mammals.  For more comparisons see http://reut.rs/h3nAey
Today is International Migratory Bird Day.  This year’s theme is Life Cycle of Migratory Birds: Conservation Across the Americas.  Take time today to enjoy migratory birds. 
Happy Mother’s Day!  Here’s a special bat fact in recognition of amazing mothers everywhere.  The weight of bats at birth is high in proportion to the mother. Newborn bats weigh about 1/4 the weight of their mother.  That would be like a 120 lb. woman giving birth to a 30 lb. baby.
Like birds, bats come in an amazing range of sizes. The world’s smallest bat is also the world’s smallest mammal, the bumblebee bat that weighs less than a penny.  The largest bat, the flying fox, has wingspans up to 6 feet.   
Sodalis Nature Park was dedicated two years ago today.  The 209-acre park near Indianapolis is named for the Indiana bat, Myotis sodalis, and offers visitors a place to hike, fish and learn more about the endangered bat that inhabits its woods. 
Conserving endangered species has many benefits.  Sodalis Nature Park in Indiana is an excellent example.  The land is protected because Indiana bats live there but the park is also a haven for many songbirds and wildlife that need forests. It’s also a great place for outdoor recreation in a rapidly developing area.
During May, female Indiana bats arrive at maternity colony sites.  They return to the same site every summer, so it is important that habitat at traditional maternity areas remain suitable.  Searching for new habitat would be an additional stress at a time when female bats’ fat reserves are already low, they have just finished migration and they are pregnant.
Today is Endangered Species Day, a day to recognize the importance of protecting endangered species and what you can do for our nation’s disappearing species.  Indiana bats and all other endangered species need your help.
In addition to Indiana bats, there are six other bat species that are federally endangered in the U.S.: Virginia big-eared bat, Ozark big-eared bat, Mexican long-nosed bat, lesser long-nosed bat, Hawaiian hoary bat, and gray bat.
The endangered Ozark big-eared bat and Virginia big-eared bat are closely related but are not found in the same places as their ranges do not overlap.  As the names imply, these bats have huge ears. .
The endangered Hawaiian hoary bat is the only land mammal native to Hawaii.   “Hoary” means frosted and individual hairs on this bat are tipped or frosted with white. 
The lesser long-nosed bat and the Mexican long-nosed bat are both nectar feeders.  They emerge at night to feed on the flowers of cacti and agave plants.  A mutual relationship exists as the bats depend on the plants for food and the plants are pollinated by the bats.
After migrating from her hibernaculum in the spring to her traditional summer area, a female Indiana bat will visit previously used roost trees.  There she finds other female bats, and the maternity colony is re-established.
A maternity colony of Indiana bats typically includes no more than 100 female bats and they usually come from many different hibernacula.   
Most roosts used by maternity colonies of Indiana bats are found in dead or dying trees.Pregnant females cluster together under the loose bark of these trees.
An Indiana bat maternity colony uses 10 to 20 trees each year.  Sometimes the colony is clustered all together in one tree and other times smaller groups of females will be found in multiple trees.
Indiana bats are occasionally found roosting during summer in artificial structures such as bat boxes or utility poles.  A few colonies have also been found in buildings, including an abandoned church in Pennsylvania and a barn in Iowa.   
Memorial Day, originally called Decoration Day, is a day of remembrance for those who have died in our nation's service.  Over the next few days, we’ll discuss how military lands contribute to endangered species conservation, including the Indiana bat.
The Department of Defense is the third largest federal land managing agency in the U.S. with 25 million acres on 425 major military installations.  These lands are home to 220 federally listed species.  In the eastern U.S. many Defense installations provide habitat for the Indiana bat.
Why do so many Defense installations have Indiana bats?  Defense facilities have some of the largest remaining blocks of mature forest in parts of Indiana bat range, where much of the land has been converted to agriculture or developed.  The Department of Defense works with the U.S. Fish and Wildlife Service to conserve the Indiana bat on military areas.
Fort Drum, a 107,000-acre Army installation in northern New York has extensive habitat suitable for all 9 bat species found in New York.   Indiana bats were confirmed there in 2006 and in 2008 Fort Drum established a 2,200-acre Bat Conservation Area for Indiana bats.
Fort Knox in Kentucky also provides habitat for the Indiana bat.  About 1,500 acres has been set aside for bat conservation.  The habitat on this acreage is ideal for Indiana bat maternity colonies. 
Last updated: April 14, 2015