Oryzomys palustris 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Rodentia Cricetidae

Scientific Name: Oryzomys palustris (Harlan, 1837)
Common Name(s):
English Marsh Rice Rat
Spanish Un Ratón Arrozalero
Taxonomic Notes: Analysis of cranial variation in Oryzomys by Humphrey and Setzer (1989) indicated that O. argentatus should be included in this species. Goodyear (1991) reinstated O. argentatus as a species, but this was not followed by Baker et al. (2003), and Musser and Carleton (in Wilson and Reeder 1993, 2005) cited the more thorough study by Humphrey and Setzer (1979) in not accepting argentatus as a species (though they did state that the status of argentatus merits further study using genetic techniques).

Oryzomys palustris and O. couesi formerly were considered to be conspecific (Hall 1981); they were regarded as separate species by Honacki et al. (1982), Jones et al. (1986, 1992), and Musser and Carleton (in Wilson and Reeder 1993, 2005), following Benson and Gehlbach (1979). An electrophoretic study by Schmidt and Engstrom (1994) also concluded that O. palustris and O. couesi are distinct species. The taxonomic scope of the genus Oryzomys is unsettled, as are the taxonomic limits of some of the species included in the genus Oryzomys (Musser and Carleton, in Wilson and Reeder 1993, 2005).

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2016
Date Assessed: 2016-08-09
Assessor(s): Cassola, F.
Reviewer(s): Amori, G.
Contributor(s): Hammerson, G.A. & Linzey, A.
Listed as Least Concern because it is very widespread, and common in suitable habitat throughout most of its range, its populations are stable and there are no major threats.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This species occurs from eastern Texas to southeastern Kansas, east to southern New Jersey/Delaware and Florida (Honacki et al. 1982). The previously recognized species O. argentatus, is now included in O. palustris, and is known to occur on nine islands in the lower Florida Keys and probably occurs on several others (Goodyear 1992).
Countries occurrence:
United States (Alabama, Arkansas, Delaware, Florida, Georgia, Illinois, Kansas, Kentucky, Louisiana, Maryland, Mississippi, Missouri, New Jersey, North Carolina, Oklahoma, Pennsylvania - Regionally Extinct, South Carolina, Tennessee, Texas, Virginia)
Additional data:
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:This species is considered secure in its range (NatureServe). Reported densities range from about 4/ha in a Texas coastal prairie to >50/ha in the Florida Everglades.
Current Population Trend:Stable
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:It prefers saltwater and freshwater marshes (semi-aquatic). It may also be found in swamps and moist meadows. Uplands bordering wetlands may be important as refuges during high tides (Kruchek 2004). Able to move between adjacent islands by swimming across salt water; in Virginia, ten movements between two islands separated by 50 m and one movement between two islands separated by 300 m were documented (Forys and Dueser 1993). Nests are placed in grassy vegetation under debris, or woven in aquatic emergents a foot or more above the high water line.

Breeding may occur throughout the year, particularly early spring. Gestation lasts 21-28 days. Litter size is 4-6 (range 1-7). Several litters per year, up to six are known. Young are weaned within two weeks.

The average home range is one acre (Negus et al. 1961). This species is an effective disperser over water and a good colonizer of barrier islands (Loxterman et al. 1998). Diet includes rice and seeds of herbaceous plants. When available (in season), arthropods make up 75% of the diet (Negus et al. 1961). It is primarily nocturnal.
Systems:Terrestrial; Freshwater
Generation Length (years):0-1

Threats [top]

Major Threat(s): There are no major threats to this species.

Conservation Actions [top]

Conservation Actions: This species occurs in several protected areas throughout its range. The subspecies in the Florida keys may be of conservation concern.

Errata [top]

Errata reason: This errata assessment has been created because the map was accidentally left out of the version published previously.

Citation: Cassola, F. 2016. Oryzomys palustris (errata version published in 2017). The IUCN Red List of Threatened Species 2016: e.T42675A115200837. . Downloaded on 25 September 2018.
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