Marsh Rice Rat

The marsh rice rat (Oryzomys palustris) is a semiaquatic North American rodent in the family Cricetidae. It usually occurs in wetland habitats such as swamps and salt marshes. It is found mostly in the eastern and southern United States, from New Jersey and Kansas south to Florida and northeasternmost Tamaulipas, Mexico; its range previously extended further west and north, where it may have been a commensal in corn-cultivating communities. Weighing about 40 to 80 g (1.4 to 2.8 oz), the marsh rice rat is a medium-sized rodent that resembles the common black and brown rat. The upperparts are generally gray-brown, but are reddish in many Florida populations. The feet show several specializations for life in the water. The skull is large and flattened, and is short at the front.

John Bachman discovered the marsh rice rat in 1816, and it was formally described in 1837. Several subspecies have been described since the 1890s, mainly from Florida, but there is disagreement over their validity. The Florida Keys population is sometimes classified as a different species, the silver rice rat (Oryzomys argentatus). Data from the mitochondrial cytochrome b gene indicate a deep divergence between populations east of Mississippi and those further west, which suggests that the western populations may be recognized as a separate species, Oryzomys texensis. The species is part of the genus Oryzomys, which also includes several others occurring further south in Mexico, Central America, and northwestern South America, some of which have previously been regarded as subspecies of the marsh rice rat. One, Oryzomys couesi, occurs with the marsh rice rat in Tamaulipas and southern Texas.

The marsh rice rat is active during the night, makes nests of sedge and grass, and occasionally builds runways. It has a diverse diet that includes plants, fungi, and a variety of animals. Population densities are usually below 10 per ha (4 per acre) and home ranges vary from 0.23 to 0.37 ha (0.57 to 0.91 acres), depending on sex and geography. Litters of generally three to five young are born after a pregnancy of about 25 days, mainly during the summer. Newborns are helpless at birth, but are weaned after a few weeks. Several animals prey on the marsh rice rat, including the barn owl, and it usually lives for less than a year in the wild. It is infected by many different parasites and harbors a hantavirus that also infects humans. The species is not of conservation concern, but some populations are threatened.

Read more about Marsh Rice Rat:  Taxonomy, Description, Distribution and Habitat, Behavior and Ecology, Human Interactions

Other articles related to "marsh rice rat, rat, rats, rice rat":

Marsh Rice Rat - Human Interactions
... The marsh rice rat is generally of little importance to humans, which is perhaps why it is not as well-studied as some other North American rodents ... on the habits and life history of the marsh rice rat since the 1854 publication of Audubon and Bachman's description ... Lodge notes that although the name "rat" may associate it unpleasantly with the introduced black and brown rats, its appearance is more endearing, even cute ...
Oryzomys Gorgasi - Taxonomy
... and Central American populations now divided into several species, including the marsh rice rat (O ... curasoae has also been known as the "Curaçao Rice Rat" and the "Curaçao Oryzomys" ... then placed in Oryzomys from the genus in 2006, retaining only the marsh rice rat and related species, including O ...
Oryzomys - Taxonomy - Species
... Merriam recognized 21 species within his group, but Goldman consolidated them into eight—the marsh rice rat in the United States, O ... couesi and the marsh rice rat into a single species, Oryzomys palustris, and thereafter, other localized forms were also included in O ... After 1979, the marsh rice rat and O ...
Oryzomys - Distribution, Ecology, and Behavior
... marshes, streams, and mangroves, but both the marsh rice rat and O ... Behavior is known mainly from the marsh rice rat and O ... spending much time in the water, and otherwise mainly live on the ground both the marsh rice rat and O ...
Oryzomys
... It includes eight species, two of which—the marsh rice rat (O ... have had eventful taxonomic histories, and most species were at one time included in the marsh rice rat additional species may be recognized in the ... was established in 1857 by Spencer Fullerton Baird for the marsh rice rat and was soon applied to over a hundred species of American rodents ...

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