Cotton rats
| Cotton rats | ||||||||||||
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Sigmodon hispidus |
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| Scientific name | ||||||||||||
| Sigmodon | ||||||||||||
| Say & Ord , 1825 |
The cotton rats ( Sigmodon ) are a rodent genus from the New World mouse group that lives on the American continent . It includes 14 species.
features
Cotton rats are relatively large representatives of the New World mice. They reach a head-trunk length of 13 to 20 centimeters, the tail is 8 to 14 centimeters long. The weight is 70 to 210 grams. Their mostly rough fur is gray-brown to black-brown on the upper side and light brown or light gray on the underside. The ears are small. The generic name Sigmodon ("S tooth") is derived from the S-shaped arrangement of the chewing cusps on their molars .
distribution and habitat
The distribution area of the cotton rats extends from the southern USA over Central America to northern South America (to Brazil and Peru ). They prefer grasslands and areas covered with bushes as habitat.
Way of life
These rodents are among the most common mammals in their range. You can be active both day and night. As hiding places, they create nests of grass in depressions in the ground or in the abandoned buildings of other animals. They are omnivores and eat plants, insects and other small animals (such as crustaceans, bird eggs and chicks).
Reproduction
In the north of their range, the mating season falls from April to November; in the south, mating can take place all year round. The females can have several litters a year. After a gestation period of around 27 days, five to seven (in individual cases up to 12) young animals are born. They leave their mother after just seven days, and become sexually mature between 40 and 60 days.
Most animals do not grow older than six months in the wild; in human care an age of 5 years is proven.
Cotton rats and humans
Cotton rats sometimes invade fields and plantations and eat sugar cane , sweet potatoes or cotton plants and are considered a nuisance. Sigmodon hispidus is used in animal experiments and played an important role in research into poliovirus , among other things .
None of the species is endangered according to the IUCN .
Systematics
The cotton rats are divided into 14 species, which are divided into 2 subgenus:
- Subgenus Sigmodon
- Sigmodon alleni lives in western Mexico from Sinaloa to Oaxaca.
- Sigmodon arizonae is native to the southwestern United States (California, Arizona, New Mexico) and northwestern Mexico.
- Sigmodon fulviventer occurs in the southwest of the USA (Arizona to Texas) and in large parts of Mexico.
- Sigmodon hirsutus is distributed from southern Mexico to Venezuela.
- Sigmodon hispidus lives in the southeastern United States (from Nebraska and Virginia to Florida) as well as northeastern Mexico.
- Sigmodon inopinatus is only known from a small area in Ecuador.
- Sigmodon leucotis lives in the interior of Mexico.
- Sigmodon mascotensis lives in western Mexico.
- Sigmodon ochrognathus occurs in the southwest of the USA (Arizona to Texas) and in northern Mexico.
- Sigmodon peruanus lives in western Ecuador and northwestern Peru.
- Sigmodon planifrons is only known from the Mexican state of Oaxaca.
- Sigmodon toltecus lives in eastern Mexico, its exact range is unclear.
- Sigmodon zanjonensis lives in southern Mexico and Guatemala.
- Subgenus Sigmomys
- Sigmodon alstoni is widespread from Colombia to northern Brazil.
The cotton rats are isolated in the New World mouse system and have no close relatives. They are classified in a separate tribe , Sigmodontini, within the Sigmodontinae . Possibly they represent a basic, primeval genus of the New World mice.
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 .
Web links
- Endangerment level of the individual species in the IUCN Red List of Threatened Species .