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Marsh Rice Rat

Oryzomys palustris

Marsh rice rats have a scaly tail that is usually longer than their head and body. (Roger Barbour)
Marsh rice rats have a scaly tail that is usually longer than their head and body. (Roger Barbour)

The marsh rice rat is a grayish-brown rodent with a long tail. It lives in tidal marshes near the Chesapeake Bay in Delaware, Maryland and Virginia.


The marsh rice rat has a long, slender body covered in coarse, grayish-brown fur with some blackish hairs. Its scaly tail is usually longer than its head and body (about 7 inches long). Its belly, feet and the underside of its tail are light grayish or whitish. These rats grow to about 5 inches long and weigh less than 3 ounces.


Tidal marshes and swamps, preferring areas with plenty of grasses and sedges. Semi-aquatic, spending time both on the land and in the water. Mostly nocturnal.


Found throughout the Delmarva Peninsula and within the coastal plain in Maryland and Virginia.


An opportunistic feeder, the march rice rat eats whatever is available, including insects, snails, fishes, bird eggs and fiddler crabs as well as grasses, sedges and aquatic plants.


Owls are a major predator. Other predators may include hawks, minks, weasels, raccoons, foxes and snakes. These rats will often dive underwater when threatened.

Reproduction and Life Cycle:

Breeding occurs several times between March and October. Females can produce several litters of 3 to 5 young each year. The marsh rice rat builds a softball-sized nest of woven grasses and sedges in hidden areas above the high-tide mark. Gestation lasts about 25 days. Young are born blind and helpless; by early in their second week of life, young open their eyes and are able to eat solid food. Females reach sexual maturity within six weeks of age. Marsh rice rats usually do not live longer than one year.

Other Facts:

  • The marsh rice rat is a skilled swimmer that is able to dive more than 30 feet deep and swim across nearly 1,000-foot stretches of water.
  • Their undercoats are water-repellant.
  • Marsh rice rats will occasionally take over the nests of blackbirds for their own use.

Sources and Additional Information:


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