San Diego Natural History Museum--Your Nature ConnectionSDNHM Field Guide
Myotis sp.

Family: Vespertilionidae (Plain-nosed Bats)


Twenty-three species of bats are currently known from San Diego County.

The California myotis (Myotis californicus) has a body length of 2 7/8 to 3 3/8 inches and a wingspan of about nine inches. It has long, dull fur, which is light to dark brown with a golden cast on the head, and paler fur below. The ears are of a medium length and dark brown or black. The mask, wings, and tail membrane are also dark brown or black.

Fringed Myotis, Photographer: Drew Stokes, courtesy of USGS
Fringed Myotis
Photographer: Drew Stokes
Courtesy of USGS
The long-eared myotis (Myotis evotis) has a body length of 3 to 3 ¾ inches with long, shiny brown fur. It has long, narrow ears that are dark brown or black.

The fringed myotis (Myotis thysanodes) has a body length of 3 1/8 to 3 ¾ inches and a wingspan of about twelve inches. The fur is a reddishbrown to brown. The ears are of medium length and dark brown or black. The membrane between the legs and tail is covered with a fringe of hair.

Range and Habitat

The California myotis can be found across most of western North America. It lives in desert scrub, semi-arid regions, and rocky canyons. It roosts under tree bark or bridges and in buildings.

The fringed myotis is found in western North Americafrom British Columbia south to Mexico, including most of California. It lives in oak and juniper forests and desert scrub. It roosts in caves, abandoned mines, and buildings.

Natural History

Myotis bats feed mostly on small insects and spiders. The California myotis sometimes hibernates in mineshafts. It forms small nursery colonies and bears a single young each year. Unlike the California Myotis, the fringed myotis roosts in colonies; its nursery colonies number up to several hundred individuals. It too bears a single young each year.

Conservation Status

Bat Conservation International is concerned that bats essential to the balance of nature and human economies are in alarming decline.

The Bat Conservation International website states, "We understand that the needs of wildlife must be balanced with the needs of humans and that increasing populations, poverty, and agricultural practices must be considered in meeting our goals. We also know that by safeguarding the future of bats and their habitats, we will help ensure the preservation of our planet's biodiversity, creating a healthier environment for both wildlife and people."

See Also

Bats—an essay by Scott Tremor, Field Associate, Birds and Mammals Department, and Drew Stokes.

Text by Connie Gatlin
Photo credit: Dr. Lloyd Glenn Ingles
© California Academy of Sciences

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