Yellow-nosed cotton rat | |
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Scientific classification ![]() | |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Rodentia |
Family: | Cricetidae |
Subfamily: | Sigmodontinae |
Genus: | Sigmodon |
Species: | S. ochrognathus |
Binomial name | |
Sigmodon ochrognathus Bailey, 1902 | |
The yellow-nosed cotton rat (Sigmodon ochrognathus) is a species of rodent in the family Cricetidae. [2] It is native to Mexico and to the states of Arizona, New Mexico, and Texas in the United States, where it inhabits mountain grassland, scrub, and pinyon-juniper woodland. It is common over much of its wide range and the IUCN considers it to be of "least concern".
In captivity, male yellow-nosed cotton rats grow to a maximum head and body length of about 155 mm (6 in) with females being slightly shorter and heavier. No significant sexual dimorphism has been noted in the wild. [3] The head is short and broad and the tail is hairy, with many small scales no more than 0.5 mm (0.02 in) wide. The fur on the head, back, and sides is a dull gray color, apart from the snout and a ring round the eye which are ochre, features that distinguish this species from other members of the genus Sigmodon . The underparts are grayish-white, the feet grayish-buff, the upper side of the tail blackish and the underside gray. [3]
The yellow-nosed cotton rat is native to Mexico and to the states of Arizona, New Mexico, and Texas in the United States. Its range extends from the eastern side of the Sierra Madre Occidental to central Durango and western Coahuila in Mexico, and from Arizona to New Mexico and scattered desert ranges of the Mesa del Norte in trans-Pecos Texas in the United States. Its habitat is mountainous areas with grassy meadows, rocky slopes, shrubland, ponderosa pine, Douglas fir, and pinyon-juniper woodland. [1] It is generally found on the lower, drier slopes at altitudes below 1,950 m (6,400 ft) . [3] This species is the most xerophilous in its genus. [3]
Nests of the yellow-nosed cotton rat are often hidden inside tussocks of grass or other dense vegetation. They are made of grass and are 18 to 40 cm (7 to 16 in) in diameter. Females become sexually mature at around 45 days of age. The gestation period is about 34 days and usually two to six young are born in a litter. They are precocial and able to leave the nest soon after birth, their eyes open during the first day, they grow rapidly, and are weaned at around 15 days. [4]
The yellow-nosed cotton rat does not compete well with other species of cotton rats, such as the white-eared cotton rat (Sigmodon leucotis), and where their ranges overlap, it occupies thinly vegetated, rocky slopes with tussocks of grass. In Arizona, it is often found on open slopes among scattered Emory oak, Arizona oak, alligator juniper, yucca, agave, mimosa, sugar sumac, prickly pear, and desert spoon. These plants often have long foliage growing at their bases, and the cotton rat uses these for cover. It shares its habitat with the fulvous harvest mouse (Reithrodontomys fulvescens) and southern pocket gopher (Thomomys umbrinus) and uses the burrows of the latter, as well as cavities under boulders. [4]
Where it is the only cotton rat in a locality, the yellow-nosed cotton rat inhabits grassy meadows and alluvial fans where the soil is deeper. In these habitats, it makes runs between the clumps of grass, but in sparsely vegetated areas, these runways are difficult to discern. It is primarily active during the day, moving fast along its runways so as to be exposed to predation for as little time as possible. It feeds primarily on blue grama grass (Bouteloua gracilis), but also the green parts of other plants such as muhly, three-leaf groundsel, gumweed, and three-awn tangle-head, and less frequently on seeds and fruits. [4] It cuts sections of grasses and forms small piles of grass blades on the surface and caches further piles of dried foliage underground, often in the abandoned burrows of southern pocket gophers. [3]
The yellow-nosed cotton rat has a wide range and is common in parts of that range. The total population is presumed to be large, and although it is thought to be decreasing in numbers in some places, it is expanding its range in others. For these reasons, the IUCN lists it as being of "least concern". [1]
The rodent subfamily Sigmodontinae includes New World rats and mice, with at least 376 species. Many authorities include the Neotominae and Tylomyinae as part of a larger definition of Sigmodontinae. When those genera are included, the species count numbers at least 508. Their distribution includes much of the New World, but the genera are predominantly South American, such as brucies. They invaded South America from Central America as part of the Great American Interchange near the end of the Miocene, about 5 million years ago. Sigmodontines proceeded to diversify explosively in the formerly isolated continent. They inhabit many of the same ecological niches that the Murinae occupy in the Old World.
A cotton rat is any member of the rodent genus Sigmodon. Their name derives from their damaging effects on cotton as well as other plantation crops, such as sugarcane, corn, peanut and rice. Cotton rats have small ears and dark coats, and are found in North and South America. Members of this genus are distributed in the Southwestern United States, Mexico, Central America, and South American countries of: Venezuela, Ecuador, Colombia, Peru, Brazil, Guyana, and Suriname. Many of the species are found in Mexico.
The hispid cotton rat is a rodent species long thought to occur in parts of South America, Central America, and southern North America. However, recent taxonomic revisions, based on mitochondrial DNA sequence data, have split this widely distributed species into three separate species. The distribution of S. hispidus ranges from Arizona in the west to Virginia to the east and from the Platte River in Nebraska in the north to, likely, the Rio Grande in the south, where it meets the northern edge of the distribution of S. toltecus. Adult size is total length 202–340 mm (8.0–13.4 in); tail 87–122 mm (3.4–4.8 in), frequently broken or stubbed; hind foot 29–35 mm (1.1–1.4 in); ear 16–20 mm (0.63–0.79 in); mass 50–250 g (1.8–8.8 oz). They have been used as laboratory animals.
The American gray flycatcher, or American grey flycatcher, or just gray flycatcher as it is known in North America, is a small, insectivorous passerine in the tyrant flycatcher family. It is common in the arid regions of western North America, especially the Great Basin. From sagebrush steppes to pinyon-juniper woodlands and ponderosa pine forests, this flycatcher forages for insects from shrubs or low tree branches.
Ord's kangaroo rat is a kangaroo rat native to western North America, specifically the Great Plains and the Great Basin, with its range extending from extreme southern Canada to central Mexico.
The white-throated woodrat is a species of rodent in the family Cricetidae. It is found from central Mexico north to Utah and Colorado in the United States. It is primarily a western species in the United States, extending from central Texas west to southeastern California. Populations east of the Rio Grande in New Mexico and Trans-Pecos Texas, previously considered to be variants of the white-throated woodrat, have since 1988 been assigned to the white-toothed woodrat.
Stephen's woodrat is a species of rodent in the family Cricetidae found in Arizona, New Mexico and Utah in the United States.
The brush mouse is a species of rodent in the family Cricetidae. It is found in mountainous areas of Mexico and the western United States at altitudes over 2,000 m (6,600 ft).
Allen's cotton rat is a species of rodent in the family Cricetidae. It is endemic to western Mexico, where its distribution extends from Sinaloa to Oaxaca. The formerly recognized S. planifrons and S. vulcani are now considered conspecific with S. alleni by the IUCN.
The Arizona cotton rat or Colorado River cotton rat is a species of rodent in the family Cricetidae. It is found in Mexico and the United States.
The tawny-bellied cotton rat is a species of rodent in the family Cricetidae. It is found in Mexico and in the US states of Arizona and New Mexico.
The Jaliscan cotton rat or Mexican cotton rat is a species of rodent in the family Cricetidae. It is found only in Mexico. They commonly have brown fur with white fur on the belly. They are ground-dwelling and prefer open habitats.
The southern pocket gopher is a species of rodent in the family Geomyidae. It is found in Mexico and the United States, usually in high altitude grassland and shrubland. It feeds on plant material and has an extensive burrow above which is a large heap of earth on the surface of the ground.
A pack rat or packrat, also called a woodrat or trade rat, are any species in the North and Central American rodent genus Neotoma. Pack rats have a rat-like appearance, with long tails, large ears, and large, black eyes. Pack rats are noticeably larger than deer mice, harvest mice, and grasshopper mice, and are usually somewhat larger than cotton rats.
Pinyon–juniper woodland, also spelled piñon–juniper woodland, is a biome found at higher elevations near deserts in the Western United States, characterized by being an open forest dominated by low, bushy, evergreen junipers, pinyon pines, and their associates which vary from region to region. The woodland's density and crown height varies dramatically depending on a variety of factors, with mature trees ranging in height from as low as 2 meters up to 15 meters. At lower elevations, junipers often predominate and trees are spaced widely, bordering on and mingling with grassland or shrubland. As elevation increases, pinyon pines become common and trees grow closer, forming denser canopies. Historically, pinyon-juniper woodland has provided a vital source of fuel and food for peoples of the American Southwest.