Don Edwards San Francisco Bay National Wildlife Refuge, Fish and Wildlife Service

Shellhammer, Howard. 1998. A Marsh is a Marsh is a Marsh . . . But not Always to a Salt Marsh Harvest Mouse. Tideline Vol 18 No. 4 1-3.

A Marsh is a Marsh is a Marsh . . .
But not Always to a Salt Marsh Harvest Mouse

by Howard Shellhammer, Phd.

Scientific names are often quite illuminating Reithrodontomys raviventris, for example, means the "grooved-toothed mouse with a red belly" but most of us call the animal the salt marsh harvest mouse. These mice, who live only in the salt marshes of the San Francisco Bay, are listed as an endangered species at both the federal and state levels because so much of their habitat has disappeared in the last 150 years. The salt marsh harvest mouse does have grooved upper front teeth, and many of them living in the southern end of their range have reddish bellies. Unusual for land mammals, the salt marsh harvest mouse can tolerate quite salty water and food. Mice of the northern subspecies can survive on sea water but prefer fresh, while those of the southern subspecies prefer water midway between fresh and salt.

Salt marsh harvest mice are what scientists call "cover dependent species" in that they only live under thick vegetation, and possibly as a result are much calmer-acting than their grassland cousins, the western harvest mice, and most other mice for that matter. Salt marsh harvest mice are among the smallest rodents in the United States; the body of an adult mouse is about the size of your thumb and weighs a bit less than a nickel. Try holding one nickel

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Last updated: May 27, 2008

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