Missouri's Winter Bats

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Published on: Dec. 2, 2007

Last revision: Dec. 6, 2010

Missouri is known for its thousands of natural caves. Many of these caves are famous for their vast numbers of hibernating bats, including the endangered Indiana and gray bats.

Until recently, we believed that three species of bats usually not associated with caves spend their summers in Missouri but travel south to more favorable climates when the days get short and the nights cold.

Research, however, has shown that Eastern red bats (Lasiurus borealis), evening bats (Nycticeius humeralis) and silver-haired bats (Lasionycteris noctivagans) remain throughout the winter, having adapted to withstand the rigors of snow, ice and occasional prescribed fires or wildfires.

Red bats are by far the most common of the three species. They can be seen flying on warm winter evenings and nights as they forage over forest openings and urban parks, often taking advantage of insects attracted to lights when the temperature gets above 50 degrees.

Red bats are common throughout North America. They range from the Rocky Mountains eastward and from Canada to Mexico during summer months. During those months they roost in the foliage at the tops of deciduous trees, seldom, if ever, roosting in tree cavities or caves.

Research conducted by the Missouri State University biology department at Taney County’s Drury/Mincy Conservation Area and Carter County’s Peck Ranch Conservation Area indicate that these bats exhibit unique behaviors to cope with Missouri’s winters.

In 2003, when research first began, a red bat was captured on a warm late-winter evening. We fitted the bat with a radio transmitter, but soon after release the temperature dropped to below freezing. The next day remained very cold, and when we tracked the red bat we found it deep in torpor (a light hibernation) on the ground, nestled under the leaf litter. Since that time more than 50 red bats have been tracked to leaf litter roosts on cold winter nights.

Evening bats, found in the eastern United States and northern Mexico, also forage for insects over forest openings. They are known to roost in tree cavities and occasionally in buildings, but only rarely in caves.

The silver-haired bat can be found in every state including Alaska. It has been found most commonly roosting on or under the bark of trees, but also in tree cavities, open sheds or outbuildings and the occasional rock crevice.

Evening and silver-haired bats can also be seen in the winter, though there are fewer of them, and they can be hard to distinguish from

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