The tawny-bellied cotton rat (Sigmodon fulviventer ) is a species of rodent in the family Cricetidae. It is found in Mexico and in the US states of Arizona and New Mexico.
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OmnivoreAn omnivore is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and ani...
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
Among animals, viviparity is the development of the embryo inside the body of the parent. The term 'viviparity' and its adjective form 'viviparous'...
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starts withSexual dimorphism is not present, but the adult male weighs slightly more than the female at 222 grams (7.8 oz) compared to 206 grams (7.3 oz). The tail has small scales and is covered in hair which distinguishes it from the larger scales of the closely related hispid cotton rat (Sigmodon hispidus ). Another characteristic distinguishing it from S. hispidus is a short and broad rather than elongated skull. The dentition is marked by well-developed maxillary incisors and high-crowned molars.
The fur is tawny on the belly (the origin of the species' common name), and black and tan speckled on the back. The fur body contains three types of hair: guard-awl hair, guard hair, and under hair. The guard hair is the longest with the guard-awl and under hair following in decreasing length. Whiskers are located on the face and have been observed to play a role in maintaining body position while swimming.
The species inhabits the grasslands of central Mexico, expanding north to the central and southwestern parts of New Mexico and southeastern parts of Arizona. It prefers areas with dense grass, in which it makes navigational trails called runways that resemble a tunnel with a grass covering. It feeds on grasses, specifically bunchgrass, which they also use in nest-building. Its range in central New Mexico is expanding westward due to an increase in precipitation and in temperature from climate change.
The tawny-bellied cotton rat occurs in the same area as the closely related hispid cotton rat, with the former occupying the moister areas and the latter the more arid areas. When living in adjacent habitats, one species tends to become more numerous while the other maintains a smaller population. Even though both species seem to avoid one another, there is a passive, indirect competition between the species. In Durango, Mexico, S. fulviventer was found to be dominant, probably due to being a specialist compared to the generalist S. hispidus.
