Arizona Cotton Rat
Encyclopedia
The Arizona cotton rat or Colorado River cotton rat (Sigmodon arizonae) is a species of rodent
in the family Cricetidae
. It is found in Mexico
and the United States
.
-like appearance, and is sufficiently similar to the hispid cotton rat
that it was considered to be part of the same species until 1970, when genetic analysis confirmed its distinct nature. It has bristly brownish fur over most of its body, with whitish underparts and grey feet. The scaly tail is dark in color, with very sparse fur. Adults range from 25 to 36 cm (9.8 to 14.2 ) in total length, including the 10 to 15 cm (3.9 to 5.9 ) long tail, and weigh anything from 83 to 300 g (2.9 to 10.6 ). Males are slightly larger than females, but the two sexes are otherwise similar in appearance.
Females have ten or twelve teats, suggesting a maximum litter size of around this number. Reproduction is thought to occur year-round.
, the extreme southwestern corner of New Mexico
, and in western Mexico
from Sonora
to Nayarit
. They live close to rivers, streams, and other sources of fresh water in semidesert, open grassland, or swampy habitats throughout the region. They rely particularly on areas of dense grassy vegetation. Two of the five recognized subspecies
are believed to have gone extinct during the twentieth century, including the nominate subspecies, Sigmodon arizonae arizonae. Three subspecies therefore remain:
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
in the family Cricetidae
Cricetidae
The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, and New World rats and mice...
. It is found in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
and the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
.
Description
The Arizona cotton rat has a typical ratRat
Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...
-like appearance, and is sufficiently similar to the hispid cotton rat
Hispid Cotton Rat
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. Carroll et...
that it was considered to be part of the same species until 1970, when genetic analysis confirmed its distinct nature. It has bristly brownish fur over most of its body, with whitish underparts and grey feet. The scaly tail is dark in color, with very sparse fur. Adults range from 25 to 36 cm (9.8 to 14.2 ) in total length, including the 10 to 15 cm (3.9 to 5.9 ) long tail, and weigh anything from 83 to 300 g (2.9 to 10.6 ). Males are slightly larger than females, but the two sexes are otherwise similar in appearance.
Females have ten or twelve teats, suggesting a maximum litter size of around this number. Reproduction is thought to occur year-round.
Distribution and habitat
The Arizona cotton rat is found in southern and central ArizonaArizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
, the extreme southwestern corner of New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
, and in western Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
from Sonora
Sonora
Sonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....
to Nayarit
Nayarit
Nayarit officially Estado Libre y Soberano de Nayarit is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 20 municipalities and its capital city is Tepic.It is located in Western Mexico...
. They live close to rivers, streams, and other sources of fresh water in semidesert, open grassland, or swampy habitats throughout the region. They rely particularly on areas of dense grassy vegetation. Two of the five recognized subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
are believed to have gone extinct during the twentieth century, including the nominate subspecies, Sigmodon arizonae arizonae. Three subspecies therefore remain:
- Sigmodon arizonae cienegae - Arizona, northern Sonora
- Sigmodon arizonae major - southern Sonora, SinaloaSinaloaSinaloa officially Estado Libre y Soberano de Sinaloa is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 18 municipalities and its capital city is Culiacán Rosales....
, Nayarit - Sigmodon arizonae plenus - western La Paz County, ArizonaLa Paz County, ArizonaLa Paz County is a county in the western part of the U.S. state of Arizona. As of the 2010 census its population was 20,489. The county seat is Parker...