The salt marsh harvest mouse (Reithrodontomys raviventris), also known as the red-bellied harvest mouse and sometimes called the saltmarsh harvest mouse, is an endangered rodent endemic to the San Francisco Bay Area salt marshes in California. There are two distinct subspecies, both endangered and listed together on federal and state endangered species lists. The northern subspecies (Reithrodontomys raviventris halicoetes) is lighter in color and inhabits the northern marshes of the bay, and the southern subspecies (Reithrodontomys raviventris raviventris) lives in the East and South Bay marshes. They are both quite similar in appearance to their congener species, the [Western harvest mouse, R. megalotis], to which they are not closely related. Genetic studies of the northern subspecies ha