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hispid cotton rat

Sigmodon hispidus

What do they look like?

Hispid cotton rats are small to medium sized rodents, with adults weighing 100 to 225 g (average 159 g). Total length ranges from 80 to 320 mm, with males slightly longer than females. Regional size variation exists; hispid cotton rats in Virginia are smaller than those found in North and South Carolina. The color of both sexes consists of a mixture of tan, brown, and black fur on their dorsal parts, giving them a coarse, or "hispid," appearance. The underparts are white to greyish, the tail is sparsely haired and considerably shorter than the combined length of the head and body. Regional variation in color is common, hispid cotton rats from the Coastal Plain of North and South Carolina are darker than those from Maryland and Virginia. (Choate, et al., 1994; Linzey, 1998; Mengak and Laerm, 2007; Schwartz and Schwartz, 1981; Webster, et al., 1985)

  • Sexual Dimorphism
  • male larger
  • Range mass
    100 to 225 g
    3.52 to 7.93 oz
  • Average mass
    159 g
    5.60 oz
  • Range length
    224 to 365 mm
    8.82 to 14.37 in
  • Average length
    295 mm
    11.61 in
  • Range basal metabolic rate
    0.96/g to 2.89/g cm3.O2/g/hr
  • Average basal metabolic rate
    1.33/g cm3.O2/g/hr

Where do they live?

Hispid cotton rats have an extensive range. The southern range reaches northern South America in Peru, Ecuador, Columbia, Venezuela, Guyana, French Guiana, and Brazil. The range extends northward through central America and Mexico. In the United States, they are found as far north as Nebraska in the west and coastal and central Virginia to the east. In the past 50 to 100 years hispid cotton rats have been extending their range northward and to higher elevations. (Cameron and Spencer, 1981; Cameron, 1999; Choate, et al., 1994; Dunnum, et al., 2002; Francl and Meikle, 2009)

What kind of habitat do they need?

Hispid cotton rats prefer dense, grassy areas. They are most commonly captured in grassy fields, brushy pastures, canal banks, roadsides, and edges of cultivated fields overgrown with weeds and other brushy vegetation such as broomsedge and honeysuckle. They occasionally have been observed in areas of dense cacti, salt marshes, and in grasslands bordering brackish waters. In Mexico, hispid cotton rats range from sea level to 1130 m in elevation. (Cameron and Spencer, 2008; Espinoza and Rowe, 1979; Linzey, 1998; Rehmeier, et al., 2005; Schwartz and Schwartz, 1981; Webster, et al., 1985)

  • Range elevation
    0 to 1130 m
    0.00 to 3707.35 ft

How do they reproduce?

Little has been published about the mating systems of hispid cotton rats, though they are assumed to be polygamous, meaning one male mates with multiple females. (Sulok, et al., 2004)

In tropical and semi-tropical portions of their range, hispid cotton rats breed year-round. In temperate regions, however, breeding seems to be determined by temperature. In non-pregnant females heat occurs about every 7 to 9 days. The gestation period is about 27 days. A single adult female typically produces 3 to 4 litters per year, averaging 5 to 7 young per litter. Newborns average 76 mm in total length and 6.5 g. They are usually weaned at about 3 weeks and can be reproductively active in 35 to 40 days. However, most do not reproduce until 2 months. Hispid cotton rats are fully grown at 5 months of age. (Espinoza and Rowe, 1979; Linzey, 1998; Schwartz and Schwartz, 1981; Webster, et al., 1985)

  • How often does reproduction occur?
    Breeding occurs year-round or 3 to 4 times per year, varying by region.
  • Breeding season
    Breeding occurs in summer months in temperate portions of their range and year-round in tropical portions.
  • Range number of offspring
    1 to 15
  • Average number of offspring
    5-7
  • Average number of offspring
    5
    AnAge
  • Average gestation period
    27 days
  • Average gestation period
    27 days
    AnAge
  • Range weaning age
    5 to 25 days
  • Average time to independence
    21 days
  • Range age at sexual or reproductive maturity (female)
    2 (low) months
  • Average age at sexual or reproductive maturity (female)
    5 months
  • Range age at sexual or reproductive maturity (male)
    2 (low) months
  • Average age at sexual or reproductive maturity (male)
    5 months

Female hispid cotton rats produce more than one litter per year. The young stay in the nest until they are about 3 weeks old when they are weaned and begin to care for themselves. (Linzey, 1998)

  • Parental Investment
  • altricial
  • female parental care
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female

How long do they live?

Hispid cotton rats, like many rodents, are not long lived in the wild. Few cotton rats (13.2%) live beyond six months. The oldest recorded Sigmodon species individual lived 12 months in the wild. In captivity, the oldest hispid cotton rat recorded is five years, two months old. (Linzey, 1998)

How do they behave?

Hispid cotton rats are active year-round and during all hours of the day. Maximum activity is concentrated from late afternoon to about midnight. They are less active during heavy rains and extreme cold.Hispid cotton rats are generally solitary, but also show cooperative behavior in cooler months, huddling together for warmth. During the breeding season, older males display dominance over younger males. Members of this species also tend to be aggressive towards other rodent species occupying the same habitat.

Hispid cotton rats construct nests using dry grass, fibers stripped from larger plants, and other materials. Nests are built under logs and rocks for protection. Sometimes they use abandoned dens of larger mammals such as skunks or squirrels. They also construct a maze of runways, about 7.5 to 10 cm wide, and tunnels from 2.5 to 5 cm wide and from 2.5 to 10 cm below the surface. New growth of grasses and sedges is trimmed from main runways and trimmings are piled up in an irregular manner. (Cameron and Spencer, 1981; Linzey, 1998; Schwartz and Schwartz, 1981)

Home Range

Hispid cotton rats have a home ranges from 0.10 to 0.50 ha. Males usually have larger home ranges (0.40 to 0.50 ha) than females (0.10 to 0.30 ha). Adult home ranges are larger than those of young adults or juveniles. Movements are typically less than 100 m per day, but can be upwards of 300 m in rare cases. They typically do not defend territories, but there have been reports that females may occasionally do so. (Cameron and Spencer, 1981; Espinoza and Rowe, 1979; Linzey, 1998; Schwartz and Schwartz, 1981)

How do they communicate with each other?

Little information regarding communication of hispid cotton rats has been reported. However, like most mammals, hispid cotton rats have a keen sense of smell and hearing. (Cameron and Spencer, 1981)

What do they eat?

Hispid cotton rats are folivorous, granivorous, and lignivorous. In addition they feed on the eggs and young of ground-nesting birds, insects, crayfish, fiddler crabs, and carrion where possible. They do not cache food. When feeding on tall plants they cut down the plant near its base then cut the whole plant into smaller sections. They drink water but do not require a permanent water source in their habitat. (Linzey, 1998; Schwartz and Schwartz, 1981)

  • Animal Foods
  • eggs
  • carrion
  • insects
  • aquatic crustaceans
  • Plant Foods
  • leaves
  • roots and tubers
  • wood, bark, or stems
  • seeds, grains, and nuts
  • fruit

What eats them and how do they avoid being eaten?

Hispid cotton rats avoid predation by staying in their runways, being alert, and taking advantage of their cryptic coloration. Hispid cotton rats are preyed on by a wide variety of predators including fire ants, owls, hawks, red foxes, bobcats, raccoons, coyotes, domestic cats, weasels, mink, and snakes. (Cameron and Spencer, 1981; Ferris, 1994; Pedersen, et al., 2003)

  • These animal colors help protect them
  • cryptic

What roles do they have in the ecosystem?

Hispid cotton rats are prey for many larger animals such as foxes, dogs, coyotes, weasels, raccoons, minks, domestic cats, bobcats, hawks, and snakes. This makes them an important food source.

Hispid cotton rats have an important relationship with bobwhite quail (Colinus virginianus) because they compete with quail for food resources and feed on the quail eggs. In addition, hispid cotton rats are host to many internal and external parasites. External parasites are hosts to mites, ticks, lice, and fleas. They are also hosts to cestode species (Choanotaenia nebraskensis, Hymenolepis diminuta, Raillietina bakeri, Taenia taeniaeformis), bacteria (Rickettsia rickettsii), nematodes (Longistriata adunca, Physaloptera hispida, Mastophorus muris), and ascarid worms. (Linzey, 1998; Mengak and Laerm, 2007; Schwartz and Schwartz, 1981)

Commensal or parasitic species (or larger taxonomic groups) that use this species as a host
  • cestodes (Choanotaenia nebraskensis)
  • cestodes (Hymenolepis diminuta)
  • cestodes (Raillietina bakeri)
  • cestodes (Taenia taeniaeformis)
  • bacteria (Rickettsia rickettsii)
  • nematodes (Longistriata adunca)
  • nematodes (Physaloptera hispida)
  • nematodes (Mastophorus muris)
  • ascarid worms (Ascarididae)

Do they cause problems?

Hispid cotton rats can greatly reduce crop production. They cause damage to a variety of crops, including cotton, rice, alfalfa, grains, vegetables, fruits, squash, sugarcane, corn, sweet potatoes, and melons. Dense populations of hispid cotton rats also cause damage to canal banks. (Espinoza and Rowe, 1979)

  • Ways that these animals might be a problem for humans
  • crop pest

How do they interact with us?

There is no evidence hispid cotton rats are economically beneficial.

Are they endangered?

Over much of their range hispid cottons rats are common and populations are stable. In Kentucky hispid cotton rats are listed as vulnerable because they occur in only a portion of the state, in portions of just 8 counties in the southwestern and southeastern corners. (Mengak and Laerm, 2007)

Contributors

Dwight Meikle (author), Radford University, Karen Powers (author, editor), Radford University, Gail McCormick (editor), Animal Diversity Web Staff, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends.

carrion

flesh of dead animals.

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

endothermic

animals that generate their own body heat through metabolic processes.

female parental care

parental care is carried out by females

folivore

an animal that mainly eats leaves.

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

polygynous

having more than one female as a mate at one time

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland
savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland
visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

References

Anderson, A., J. Mithchell, J. Pagels, H. Mansfield. 2001. Mammals of Fort A. P. Hill, Caroline County, Virginia and Vicinity. Virginia Journal of Science, 52: 163-226.

Cameron, G. 1999. The Smithsonian Book of North American Mammals. Washington: Smithsonian Institution Press.

Cameron, G., S. Spencer. 2008. Mechanisms of Habitat Selection by the Hispid Cotton Rat (Sigmodon hispidus). Journal of Mammalogy, 89/1: 126-131.

Cameron, G., S. Spencer. 1981. Sigmodon hispidus. Mammalian Species, 158: 1-9.

Choate, J., J. Jones, Jr., C. Jones. 1994. Handbook of Mammals of the South-Central States. Baton Rouge: Louisiana State University Press.

Dunnum, J., J. Frey, D. Tinnin, J. Salazar-Bravo, T. Yates. 2002. Elevational Range Extension for the Hispid Cotton Rat, Sigmodon hispidus, (Rodentia: Muridae). Southwester Naturalist, 47: 637-639.

Espinoza, H., F. Rowe. 1979. Biology and Control of the Cotton Rat, Sigmodon hispidus. International Journal of Pest Management, 25/3: 251-256.

Ferris, K. 1994. Parental responses of hispid cotton rats (Sigmodon hispidus) to intrusion by red imported fire ants (Solenopsis invicta) into simulated nests - M.S. Thesis. College Station, TX: Texas A & M University.

Francl, K., D. Meikle. 2009. A Range Extension of the Hispid Cotton Rat, Sigmodon hispidus, in Virginia. Banisteria, 33: 54-55.

Genoways, H., D. Schlitter. 1966. Northward dispersal of the Hispid Cotton Rat in Nebraska and Missouri. Transactions of the Kansas Academy of Science, 69: 356-357.

Linzey, D. 1998. The Mammals of Virgina. Blacksburg, Va: The McDonald and Woodward Publishing Company.

Mengak, M., J. Laerm. 2007. Hispid Cotton Rat. Pp. 374-380 in M Trani, W Ford, B Chapman, eds. The Land Managers Guide to Mammals of the South. Atlanta: USDA Forest Service and The Nature Conservancy.

Pagels, J. 1977. Distribution and habitat of cotton rat (Sigmodon hispidus) in Central Virginia. Virginia Journal of Science, 28: 133-153.

Pedersen, E., T. Bedford, W. Grant, S. Vinson, J. Martin, M. Longnecker, C. Barr, B. Drees. 2003. Effect of Red Imported Fire Ants on Habitat Use by Hispid Cotton Rats (Sigmodon hispidus) and Northern Pygmy Mice (Baiomys taylori) Effect of Red Imported Fire Ants on Habitat Use by Hispid Cotton Rats (Sigmodon hispidus) and Northern Pygmy Mice (Baiomys taylori). Southwestern Naturalist, 48/3: 419-426.

Rehmeier, R., G. Kaufman, D. Kaufman, B. McMillan. 2005. Long-Term Study of Abundance of the Hispid Cotton Rat in Native Tallgrass Prairie. Journal of Mammalogy, 86/4: 670-676.

Schwartz, C., E. Schwartz. 1981. The Wild Mammals of Missouri. Columbia: University of Missouri Press.

Sulok, M., N. Slade, T. Doonan. 2004. Effects of Supplemental Food on Movements of Cotton Rats (Sigmodon hispidus) in Northeastern Kansas. Journal of Mammalogy, 85/6: 1102-1105.

Webster, W., J. Parnell, W. Biggs, Jr.. 1985. Mammals of the Carolinas, Virginia, and Maryland. Chapel Hill: The University of North Carolina Press.

 
University of Michigan Museum of ZoologyNational Science Foundation

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Meikle, D. and K. Powers 2011. "Sigmodon hispidus" (On-line), Animal Diversity Web. Accessed April 17, 2014 at http://www.biokids.umich.edu/accounts/Sigmodon_hispidus/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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