Smithsonian National Museum of Natural History, North American Mammals
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Myotis yumanensis

Yuma Myotis

Order: Chiroptera
Family: Vespertilionidae

sound   Click to play (0:09, 797 kb)
Credit: New Mexico Bat Call Library, W. L. Gannon
Image of Myotis yumanensis
Myotis yumanensis - light-colored desert variant is shown, with darker forest variant in inset
Click to enlarge. (94 kb)

Conservation Status: Least Concern.

The skull and jaws of the Yuma myotis suggest a dependence on relatively soft insects, and the little dietary information available supports this. It fits well with the bat's habit of foraging over water, where moths and other soft-bodied insects tend to be common. The bats are often seen cruising back and forth just a few inches above the water, and have never been found living far from a pond or river. In captivity, if they do not have water, they quickly become dehydrated and die. Groups of bats roost together in the summer, under bridges, in buildings, mines, or caves, and even in mud nests made by cliff swallows. This species varies in size and coat coloration over its extensive north-south geographic distribution, sometimes making it difficult to distinguish them from the closely related little brown bat. So far, genetic studies have shown them to be two distinct species, however.

Sexual Dimorphism:

Average: 80.6 mm
Range: 75-89 mm

Average: 5.9 g
Range: 4.7-7.1 g


Allen, H., 1864.  Smithsonian Miscellaneous Collection, 7:58.


Mammal Species of the World

Distribution of Myotis yumanensis

Image of Myotis yumanensis
Click to enlarge. (81kb)

Bones and Teeth

Myotis yumanensis
Side view of the breastbone, with head-end to the right. Click to enlarge. (6kb)

Myotis yumanensis
Underside of the rib cage and part of the shoulder complex. Click to enlarge. (23kb)