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marsh rice rat

(Oryzomys palustris palustris)


This is a medium-sized generalized rat with a total length of 226-305 mm and a weight of 45-80 grams. The dorsal coloration varies from gray to grayish brown and the underparts including the tail and feet are much lighter. The underfur is dense, soft, and water repellent. The breeding season occurs year round and several litters of 1-6 young are born per year. This species is nocturnal and will enter the water and swim for distances greater than 10 meters. The nests are grapefruit-size of woven grasses and sedges. They are usually placed on high ground under debris, at the base of shrubs, or at the end of shallow burrows. They are opportunistic feeders and will take whatever is available. Owls are a major predator. They frequently coexist with hispid cotton rats and meadow voles.


This species is primarily found in the coastal plain region of Virginia. It is semi-aquatic and found in the greatest numbers in Atlantic coastal marshes. It is found in other habitat types which include hydric hammocks, swamps, and freshwater marshes and meadows.


This is an opportunistic feeder and it will eat whatever is available. Plant foods and Animal foods are consumed including insects, fiddler crabs (Uca), and snails. They are considered a major predator on the eggs and young of long-billed marsh wrens (Telmatodytes palustris).

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