Georgia Wildlife Web

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Species Description

Marsh Rice Rat

Oryzomys palustris


Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Order: Rodentia
Family: Muridae


Back and sides, grayish brown. Belly, grayish white. Feet, white. Tail sparsely haired, brownish above and white below. A medium - sized rodent, 18 - 29 cm (7.1 - 11.4 in) in total length. The ears are medium in size and low on the head. The scaly-looking tail is as long as the head and body combined.

Life Cycle

Breeding takes place from late winter through late fall. After a gestation period of about 25 days, the female gives birth to 4 - 5 young in a globular nest of grasses or shredded leaves. The nest may be in a shallow burrow or depression among tangled vegetation or suspended as high as 0.9 m (3 ft) above water in wetland habitats. Sometimes this species simply remodels an abandoned nest of the Marsh Wren Cistothorus palustris. The young are weaned at about 11 days after their birth. They become sexually mature at 50 - 60 days and breed during their first summer.

Natural History

As its common name suggests, this rodent inhabits brackish and salt marshes along coastal areas. Inland, it prefers wetland sites such as freshwater marshes, swamps, bayous, edges of streams and lakes, grassy ditches, and old fields with wetland soils. The Marsh Rice Rat is active at night. It searches for food such as seeds, succulent parts of marsh grasses and sedges, insects, snails, crustaceans, and bird eggs. Major predators include hawks, owls, snakes, and mink. This semi - aquatic rodent is a good swimmer and diver. To escape predators it can swim for some distance underwater as well as on the surface.


The Marsh Rice Rat occurs throughout Georgia where favorable habitat is present. The species ranges throughout the southeastern United States.

Conservation Status

The Marsh Rice Rat is common in the appropriate habitat.

Similar Species

The Marsh Rice Rat can be confused with the Hispid Cotton Rat. However, the Hispid Cotton Rat has long coarse fur, blackish feet, and its tail is shorter than its combined head and body length.