Download 02.03.11_Evening Bat - Texas Master Naturalist

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The Evening Bat
The state of Texas is home to thirty-two species of bats. Seven of those species make their home here in Milam
County. I wrote about one of those seven last year, the Mexican Free-Tailed bat.
The United Nations has named 2012 the “International Year of the Bat”. I know this is a year away, however, I
thought this year I would write an article on each of the remaining six bats that live in our county.
Approximately 1,200 species of bats live throughout the world. They are the only flying mammals. Many are
insectivores, and devour many pests that plague our crops. Others serve as pollinators and seed dispersers. They
are an integral part of our ecosystem maintenance.
Worldwide bat populations are declining, and many bat species are endangered. Here in the U.S. the disease,
White Nose Syndrome, is attacking our bats that hibernate in cold weather areas. This disease has not made it to
Texas, yet. I’ll get more specific about this disease in a separate article.
Back to Milam County, besides the Mexican Free-Tailed bat, we have the Silver-Haired bat, Eastern Red bat, Hoary
bat, Northern Yellow Bat, Cave Myotis, and the Evening bat.
Bats are nocturnal creatures, which makes it difficult to study them. The Evening bat is no exception. Not much is
known about their migratory habits, or their winter requirements. Evening bats that live farther north will migrate
to Texas for the winter. And while they don’t hibernate, they become torpid, meaning they decrease their body
temperature and metabolism to conserve energy.
Evening bats are small, with a wingspan no longer than eleven inches. They weigh less than half an ounce and can
fit in the palm of your hand. Their fur is dark brown with black wings and ears.
Evening bats have a stretch of skin between their legs called a “uropatagium” that acts like a catcher’s mitt, which
they will use to capture insects.
The bats live in trees, not caves. They may also roost in barns or other man-made structures. At times the Evening
bat and Mexican-Freetailed bat will actually share space.
Whether roosting with the Freetailed bat, or just with their own species, only the females will live together in
colonies as small as twenty-five up to 1,000 individuals. Males roost separately.
The bats mate in the fall. Come May and June the females will give birth to two to three pups. By three weeks they
can fly on their own.
While the pups are still nursing, the females may share feeding duties. However, once they can forage on their
own, males leave the roost. Not much is known about what males do once they leave, except that they are
solitary. Females stay with their mothers.
The Evening bat averages a two to five year lifespan, with tops being ten years. This is a short lifespan compared to
other bats that can live for thirty years.
You will see these bats flying alongside woods and over water searching for insects. They mainly eat beetles,
particularly the cucumber beetle. They are slow and steady flyers, and will forage in the evening and before dawn
during the warm months. They come out only once in the winter.
It’s estimated that a small colony of 300 Evening bats can consume 6.3 million insects over the summer.
The Evening bat is not threatened in Texas. However, it is considered endangered in Indiana, mainly because it has
been studied in more depth in that state.
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Don’t forget the Milam County Nature Festival, coming up Saturday, April 9 th. For more information, you can go to
this website: txmn.org/elcamino/naturefest/.
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[email protected]; El Camino Real Master Naturalists: txmn.org/elcamino/; Little River Basin Master
Gardeners: txmg.org/milam/