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Desert Diary
Mammals/Snowbirds with Fur


Snowbirds with fur? Well, yes, in the tradition of tourists flocking south during the winter. Although most bats in the northern part of the Chihuahuan Desert hibernate, Mexican Free-tailed Bats head south for warm Mexico. At times, the immense numbers leaving a temporary roost in Chihuahua have formed a cloud so thick it was picked up by El Paso radar, far to the north.

Although the chance of contracting rabies from bats tends to be over-played, special care should be taken during migration time. Bats found in the open usually are sick and should be treated as suspect; call Animal Control and let the professionals handle it. If the bat is on the ground, a container placed over it will keep domestic animals away. Curious children should learn to respect—but not fear—these animals.

"Oh, those horrible bats," you might think. But the good they do far outweighs any harm, and you're in far greater danger from your fellow humans driving down the road. As with many species, we have wrought far more damage to bats than vice versa.
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Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.


Contributor: Arthur H. Harris, Laboratory for Environmental Biology, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP Public Radio at the University of Texas at El Paso.

evening flight of bats

Evening flight of Mexican Free-tailed Bats leaving U-Bar Cave, Hidalgo Co., NM. Photograph by A. H. Harris.



Benson, S. B. 1947. Comments on migration and hibernation in Tadarida mexicana. Journal of Mammalogy 28:407-408.

Cockrum, E. L. 1969. Migration in the guano bat, Tadarida brasiliensis. University of Kansas Museum of Natatural History, Miscellaneous Publication 51:303-336.

Constantine, D. G. 1967. Activity patterns of the Mexican free-tailed bat. University of New Mexico Publicatons in Biology No. 7. 79 pp.

Davis, R. B., C. F. Herreid II, and H. L. Short. 1962. Mexican free-tailed bats in Texas. Ecological Monographs 32:311-346.

Villa, B., and E. L. Cockrum. 1962. Migration in the guano bat, Tadarida brasiliensis mexicana (Saussure). Journal of Mammalogy 43:43-64.

Wilkins, K. T. 1989. Tadarida brasiliensis. Mammalian Species No. 331. 10 pp.