Rice rats
| Rice rats | ||||||||||||
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Rice rat ( Oryzomys palustris ) |
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| Oryzomys | ||||||||||||
| Baird , 1857 |
The rice rats ( Oryzomys ) are a species of rodent living on the American continent from the group of the New World mice . They include 43 species.
features
Rice rats reach a head body length of 9 to 20 centimeters, the tail is 8 to 25 centimeters long and the weight is 40 to 80 grams. Their coarse, but not spiky, fur is gray-brown on the upper side, while the underside is white or light brown. The tail is relatively long and sparsely hairy.
distribution and habitat
Rice rats are found on the American continent from the central USA to northern Argentina , but the greatest biodiversity is found in Central and northern South America . They occur in forests as well as in swamps, meadows and even mountain regions.
Way of life
The way of life is only known from a few species, especially O. palustris . This species builds nests of grass and is active both day and night. In dry regions it also digs burrows, it can also swim well and it also looks for food in water.
Their diet consists of grasses, seeds and fruits, but also insects, crustaceans and small fish.
Several times a year the female gives birth to two to five young animals after a gestation period of 25 to 28 days.
Rice rats and humans
Some rice rat species are widespread, they sometimes invade plantations and are considered pests. Some other species are threatened. Two island endemics , O. curasoe (endemic to Curaçao ) and O. nelsoni (endemic to the Marias Islands ), have died out.
Systematics
The system and number of species of rice rats is controversial. Wilson and Reeder (2005) list the following 43 species:
Species list
- Oryzomys albigularis occurs in mountain forests from Panama to northern Peru.
- Oryzomys alfaroi is distributed from Mexico to Ecuador.
- Oryzomys angouya inhabits southeastern Brazil, Paraguay, and northern Argentina.
- Oryzomys auriventer lives in Ecuador and Peru.
- Oryzomys balneator is known from Ecuador and northern Peru. Its exact range is unclear.
- Oryzomys bolivaris is distributed from Honduras to Ecuador.
- Oryzomys caracolus is restricted to northern Venezuela.
- Oryzomys chapmani lives in mountainous regions in eastern and southern Mexico.
- Oryzomys couesi is distributed from the southern USA (South Texas) across Central America to Colombia.
- Oryzomys curasoae was endemic to the island of Curaçao and - possibly due to competition from introduced rats - became extinct.
- Oryzomys devius lives in Costa Rica and western Panama.
- Oryzomys dimidiatus is only found in southeastern Nicaragua.
- Oryzomys emmonsae was only described in 1998 and is restricted to central Brazil.
- Oryzomys galapagoensis is endemic to the Galápagos Islands and is considered endangered.
- Oryzomys gorgasi lives exclusively in northwestern Colombia and is critically endangered according to the IUCN.
- Oryzomys hammondi is only found in northwestern Ecuador.
- Oryzomys keaysi is restricted to eastern Peru.
- Oryzomys lamia lives in a small area in central Brazil and is potentially endangered.
- Oryzomys laticeps occurs in southeastern Brazil.
- Oryzomys legatus lives in the east of Bolivia to northern Argentina.
- Oryzomys levipes inhabits forests in Peru and Bolivia.
- Oryzomys macconnelli is found in rainforests in northern South America.
- Oryzomys maracajuensis is only known from southern Brazil and was only described in 2002.
- Oryzomys marinhus is only found in the Brazilian state of Goiás and was only discovered in 2003.
- Oryzomys megacephalus is distributed in South America from Venezuela to Paraguay.
- Oryzomys melanotis lives in western Mexico. Their degree of risk is not known.
- Oryzomys meridensis is restricted to western Venezuela.
- Oryzomys nelsoni was endemic to the Marias Islands off the west coast of Mexico. The species is - probably because of the introduced rats and cats - extinct.
- Oryzomys nitidus lives in eastern Peru, eastern Bolivia and western Brazil.
- Oryzomys palustris is distributed in the southern and eastern United States. It is the best researched and most northerly living species. The Florida Keys populations were formerly considered to be O. argentatus as a distinct species.
- Oryzomys perenensis inhabits the east from Colombia to Bolivia.
- Oryzomys polius is restricted to northern Peru.
- Oryzomys rhabdops lives in highlands in southern Mexico and Guatemala.
- Oryzomys rostratus lives in forest areas from Mexico to Nicaragua.
- Oryzomys russatus lives in southeastern Brazil, Paraguay and northeastern Argentina.
- Oryzomys saturatior is common in mountain forests from Mexico to Nicaragua.
- Oryzomys scotti lives in central Brazil and was only described in 2002.
- Oryzomys seuanezi is restricted to southeastern Brazil.
- Oryzomys subflavus is known from eastern Peru, eastern Bolivia and eastern Brazil. The exact distribution area is unclear.
- Oryzomys talamancae is distributed from Costa Rica to Ecuador.
- Oryzomys tatei is only found in Ecuador.
- Oryzomys xanthaeolus is native to Ecuador and Peru.
- Oryzomys yunganus lives in rainforests in the Amazon basin.
The Galápagos rice rats ( Nesoryzomys ) and the dark rice rats ( Melanomys ) are sometimes divided into this genus.
Division of the genus?
According to Weksler et al. (2006) the rice rats are not a natural group; some of the species are more closely related to other New World mice than to each other. You are therefore introducing ten new genres:
- Aegialomys (for O. xanthaeolus and related species)
- Cerradomys (for O. subflavus and related species)
- Eremoryzomys (for O. polius )
- Euryoryzomys (for O. nitidus and related species)
- Hylaeamys (for O. megacephalus and related species)
- Mindomys (for O. hammondi )
- Nephelomys (for O. albugularis and related species)
- Oreoryzomys (for O. balneator )
- Sooretamys (for O. angouya ) and
- Transandinomys (for O. bolivaris and O. talamancae ).
In this sense, Oryzomys only includes a few species such as O. palustris and O. cuesi . Six species are transferred to the already existing genus Handleyomys .
However, this division is not yet generally recognized.
literature
- Ronald M. Nowak: Walker's Mammals of the World. 2 volumes. 6th edition. Johns Hopkins University Press, Baltimore MD et al. 1999, ISBN 0-8018-5789-9 .
- Don E. Wilson , DeeAnn M. Reeder (Eds.): Mammal Species of the World. A taxonomic and geographic Reference. 2 volumes. 3. Edition. Johns Hopkins University Press, Baltimore MD 2005, ISBN 0-8018-8221-4 .
- Marcelo Weksler, Alexandre Reis Percequillo, Robert S. Voss: Ten new genera of oryzomyine rodents (Cricetidae: Sigmodontinae). In: American Museum Novitates. No. 3537, 2006, ISSN 0003-0082 , pp. 1-29, online .
Web links
- Endangerment level of the individual species in the IUCN Red List of Threatened Species .