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Salt Marsh Harvest Mouse Reithrodontomys raviventris


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Salt Marsh Harvest Mouse
© U. S. Fish and Wildlife Service

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Family: Muridae, Mice and Rats view all from this family

Description A small reddish mouse from the San Francisco Bay area. The subspecies from the south end of the bay (R. r. raviventris) has dark, cinnamon-colored back with a tawny lateral line and a pale to cinnamon belly. Mice from the north end of the bay (R. r. halicoetes) have paler upperparts with no lateral line and a white belly.

Dimensions 118-175mm, 56-95mm, 7-15g

Endangered Status The Salt Marsh Harvest Mouse is on the U.S. Endangered Species List. It is classified as endangered in California, where it lives only in the San Francisco Bay area. This species lives in salt marsh habitat and was once found throughout the bay shoreline. Encroaching urbanization has left it with only about 20 percent of its historical range, and even parts of the remainder are under threat of development. The mouse and some of its habitat are protected in the San Francisco Bay National Wildlife Refuge, but even there it is in jeopardy. A nearby sewage treatment plant pumps millions of gallons of fresh water into the bay each day, and the resulting changes in salinity levels could change the shoreline vegetation and make the habitat unsuitable for the mouse.

Similar Species Similar to Western Harvest Mouse, but with a more unicolored tail.

Breeding They may have 2 or 3 litters per year, but populations are small due to habitat destruction.

Habitat Swamps, marshes & bogs, Beaches, shorelines & estuaries

Range California

Discussion Known for its docile behavior, this species is endangered and restricted to salt marshes bordering San Francisco Bay. Although they are good swimmers, they prefer the dense cover offered by pickleweed, a key component of these salt marshes.