Salt Marsh Harvest Mouse, Howard Shellhammer
Species Information
For kids from fourth grade up.
Salt Marsh Harvest Mouse
STATUS
Endangered. This means that the species is in danger of dying out. We are working hard to prevent this.
DESCRIPTION
The salt marsh harvest mouse is a small rodent.
It is about 69-75 mm long (2.75-3.0 inches). It weighs 9-14 g (0.3-0.5 ounces). The tail can be as long or longer than the body.
There are two subspecies: northern and southern. The northern ones in the marshes of the San Pablo and Suisun bays. The southern ones in the marshes of Corte Madera, Richmond and South San Francisco Bay.
FOOD
Leaves, seeds and stems of plants. In winter, the mice seem to prefer fresh green grasses. The rest of the year, they prefer pickleweed and saltgrass.
The northern subspecies can drink sea water but prefers fresh water. The southern subspecies can't live completely on sea water but it prefers moderately salty water over fresh.
HABITAT
Dense pickleweed. Mice also move into adjoining grasslands during the highest winter tides.
MATING
Breeding goes on from spring through autumn. But each female usually has only one or two litters per year. Average litter size is about four. Nests are quite minimal, often built over old birds' nests. Members of the southern group often don't make a nest at all.
PREDATORS
Hawks, snakes and owls. Shorebirds and larger mammals. House cats.
THREATS
Most of the marshes that used to be around the San Francisco Bay are gone. Lots of the remaining marsh is not good for the mice.
MORE READING
Researchers seek secrets of Suisun salt marsh harvest mouse, Suisun-Fairfield Daily Republic, June 24, 2011. Photo gallery
Salt Marsh Harvest Mouse (91 KB PDF) from the California Dept. of Pesticide Regulation. This publication is designed to help farmers avoid salt marsh harvest mice. But it has lots of pictures and information.
Salt Marsh Harvest Mouse (533 KB PDF) from the Invasive Spartina Project. We provide some of the funding for this project.
Thelander, C. ed. 1994. Life on the edge: a guide to California's endangered natural resources. BioSystem Books. Santa Cruz, CA. p 80-81.
Words to Learn
Biologists call salt marsh harvest mice Reithrodontomys raviventris. Scientific names are in Latin or Greek. The name means "groove toothed mouse with a red belly."
They are in the Cricetidae family, which includes field mice, lemmings, muskrats, hamsters and gerbils.
The northern subspecies (ssp.) is called Reithrodontomys raviventris halicoetes.
The southern ssp. is called Reithrodontomys raviventris raviventris.
