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Desert Diary
Mammals/Harvest Mice


To the ordinary layman, a mouse is a mouse. But certainly that's not the case with mammalogists who study mice, and certainly that's not the case with mice themselves. Among the many species of mice so often lumped together is one little fellow common in the Chihuahuan Desert. This is the Western Harvest Mouse, with a name—Reithrodontomys megalotis—nearly as big as itself. Despite its small size, this mouse is versatile, ranging from southern Canada to the southern Mexican plateau, and from desert lowlands to over 10,000 feet in Southwestern mountains. Open areas with rather dense, herbaceous growth seems to be favored.

Locally, in the El Paso region, weedy areas in the Rio Grande Valley are a common habitat, but it's by no means limited to such areas. The mouse most likely to be confused with this fellow is our introduced House Mouse. But if you can get one to smile at you, the difference is immediately apparent—unlike House Mice, harvest mice have a groove running down the front of each upper incisor.
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Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.

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

Western Harvest Mouse

Reithrodontomys megalotis. Photographer: Dr. Lloyd Glenn Ingles. Copyright © 1999 California Academy of Sciences.