Little Brown Bats 02/09

The nocturnal little brown bat is one of Ohio’s 13 native bat species.  It is found in North America from the Alaskan and Canadian boreal forest south through most of the U.S. and into central Mexico.  Once the most common bat species in Ohio, it is now listed as endangered in the state and is being considered for listing as endangered Federally.

This small bat is about 3.5 inches long with a wingspan of 9 to 11 inches and weighs less than half an ounce.  It has long dark brown fur, a dark brown or black face and dark brown wing membranes.  It has sharp teeth and prominent canines to grasp hard-bodied insects while flying.  The bones in the lower part of this bat are smaller in size and thickness, reducing its weight during flight.  This adaptation is part of the reason they hang upside down when roosting; their skeletal structure is incapable of supporting an upright roosting position.  Little brown bats consume a variety of night flying insect pests. Using echolocation, they feed while flying.  One little brown bat can eat up to half its weight in insects every night and nursing females will eat up to 110% of their body weight.  It’s estimated that they capture and eat one insect every seven seconds.  Their predators include owls, snakes, racoons, fishers, weasels, and domestic cats. 

Little brown bats have been in decline throughout eastern North America due to a fungal disease called white-nose syndrome.  In Ohio the population has fallen by about 95%.  They are also threatened by habitat loss, collisions with wind turbine blades and light pollution.  Bats adapted to a life of darkness partly to avoid predators.  Artificial light falling on or near a bat roost can prevent or delay bats from leaving the roost, resulting in reduced foraging time, and missing the peak time for feeding on insects. Long-used commuting and foraging routes will be avoided if artificial light spills into these areas.  Researchers are working hard to find a cure for white-nose syndrome before this bat becomes extinct.  Reducing or eliminating light pollution is something we can all do to help this bat.  We can start in our own backyards by installing dark-sky friendly light fixtures and lamps. Let’s do our part to save this bat.

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