Peromyscus gossypinuscotton mouse

Geographic Range

Peromyscus gossypinus is native to North America and can be found in the southeastern United States as far west as eastern Texas and southeastern Oklahoma, and as far north as southeastern Virginia and southern Illinois Within this range, however, the Appalachian Mountains disrupt this species' distribution. (Wilson and Ruff, 1999; Wolfe and Linzey, June 1977)


Peromyscus gossypinus can be found in a variety of habitats, ranging from swamplands to much drier sand dunes. Generally, these mice reside on the forest floor, using hollowed logs, vines, and brushes as shelter. One study concluded that the primary habitiat of cotton mice is underground tortoise burrows, presumably for the stable microclimate they provide.

This species is common in wooded areas along the edges of streams and in areas of potential flooding. However, this species can also be found in areas of less dense vegetation, such as fields cleared by humans, old buildings, and the previously mentioned sand dunes. (Frank and Layne, 1992; Wilson and Ruff, 1999)

Physical Description

Peromyscus gossypinus is one of the largest members of the genus Peromyscus in the US, and can be recognized by its dark color. The dorsal pelage of this species consists of two different types of hair: short, dark brown hair that covers the majority of the body, and longer, darker hair that covers the middle of the dorsum. The hair on the feet and ventral side is white. The tail is sparsely haired and relatively short, compared to other rodents.

The top of the skull is flattened and there is little or no postorbital process. The dental formula is 1/1, 0/0, 0/0, 3/3.

These mice measure 142 to 206 mm in length, of which 55 to 97 mm is the tail. They can weigh between 17 and 46 g. (Frank and Layne, 1992; Wilson and Ruff, 1999)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    17 to 46 g
    0.60 to 1.62 oz
  • Range length
    142 to 206 mm
    5.59 to 8.11 in


The mating system of this species has not been described. However, information on home ranges indicates that the species is probably polygynous. Males have larger home ranges than females, and their home ranges overlap extensively with those of other males and of females. Females, on the other hand, have restricted home ranges, which may overlap those of males, but not those of other females. It is likely then that males have access to many females during breeding, but females are not likely to have access to many males. (Wolfe and Linzey, June 1977)

Although this is a reasonable assumption, it should be noted that reproductive patterns within the genus Peromyscus as a whole are highly variable. In some species, like Peromyscus polionotus or Peromyscus californicus, mating appears to be strictly monogamous. In other species, like Peromyscus leucopus and Peromyscus maniculatus, breeding can be polygynous or monogamous, depending upon ecological conditons. (Nowak, 1999)

Because P. gossypinus occurs in a great variety of habitats and ecological conditions, it is likely that there is some variability in mating systems. Like their sister taxon, P. leucopus, these mice probably form monogamous pairs under some cirumstances.

During estrous, females of this species show little or no consistancy in their patterns of external signals. Swelling and protrusions of the vaginal area are observed inconsistently. It is likely, therefore, that these signals, used by people to determine the reproductive status of the female, are not that important to males of the species. (Pornelle, February, 1952)

Males and females probably use a combination of scent cues and behaviors to determine when another animal is ready to mate.

Peromyscus gossypinus produces at least 4 litters per breeding season. This species averages a 23 day gestation period in non-lactating females and a 30 day gestation period in lactating females. There is a post-partum estrus in this species, which allows a female to rapidly produce addtional litters. (Davis and Schmidly, 1994)

Peromyscus gossypinus females give birth to their young in a nest constructed of primarily cotton. Births usually occur in the early hours of morning. One specimen, observed in captivity by Pournelle, was extremely active on the night prior to parturition, moving around anxiously and frequently stretching her entire body. Once morning arrived, she had quieted down and slept until the first birth. (Pornelle, February, 1952)

Litters of 1 to 7 young have been reported, with the average size being 3.7 young. In the sister species of cotton mice, Peromyscus leucopus, variation in litter size with latitude has been reported. Average litter size increases with lattitude, so that litters are larger in northern populations. Because P. gossypinus is also a very widespread species, it is likely that such litter size variation with lattitude also occurs in this species. (Millar, 1989; Wolfe and Linzey, June 1977)

All Peromyscus neonates are altricial. They are born hairless, with their eyes closed, incisors underneath the gumline, and pinnae folded. However, cotton mice develop quickly. The ear pinnae are erect by about 4 days of age. By the age of 5 days, these mice are beginning to have a noticable hair cover on their backs. Around day 7 of life the incisors have broken through the gums. The young are fully furred by the time they are 10 days old, and appear to be alert and able to respond to stimuli in their environment. Most baby cotton mice open their eyes for the first time between the ages of 12 and 14 days. (Wolfe and Linzey, June 1977)

In terms of their body size, neonates average only 2.19 g at birth. They are about 47 mm in length, and their tails are relativle short, measuring only 11 mm. They double in size within the first two weeks of life, and reach 93% of their adult length by the age of 60 days. (Wolfe and Linzey, June 1977)

The pelage of baby mice is grayish. They undergo their first molt between the ages of 34 and 40 days, with the adult pelage appearing first on their sides, then on the head and face, and finally spreading back over the back and the rump. (Wolfe and Linzey, June 1977)

Females in captivity reach reproductive maturity between the age of 43 and 73 days. The average age at which the vagina opens up is 43 days, and the average age of first conception is 73 days. It is difficult to say how this is mirrored in wild populations, because nutrition is different in captivity, as are other social and environmental cues which could affect reproductive development. (Millar, 1989; Pornelle, February, 1952; Millar, 1989; Pornelle, February, 1952)

Male reproductive maturity is harder to determine. A captive male had sperm in his epididymides at about 45 days of age.

Breeding season in this species may vary geographically. In Florida, these mice breed throughout the year, with a peak in breeding activity in the late autumn and early winter. There is a lull in breeding in the middle of the summer. Although the precise reason for this lull is not known, it may be related to temperature, since male reproductive condition appears to be affected by temperature. (Millar, 1989; Pornelle, February, 1952; Wolfe and Linzey, June 1977; Millar, 1989; Pornelle, February, 1952; Wolfe and Linzey, June 1977)

In other parts of the range, P. gossypinus has been seen in breeding condition in spring, summer, and autumn. Records from the Great Smokey Mountains do not show animals in breeding condition during the winter months, but it is not clear whether or not animals were examined at this time. (Wolfe and Linzey, June 1977)

  • Breeding interval
    Females can produce as many as four litters in a breeding season, with litters born approximately every 30 days.
  • Breeding season
    Year-round in Florida
  • Range number of offspring
    1 to 7
  • Average number of offspring
  • Range gestation period
    22.86 to 23.34 days
  • Average weaning age
    3 to 4 weeks
  • Average time to independence
    3-4 weeks
  • Range age at sexual or reproductive maturity (female)
    43 to 73 days
  • Range age at sexual or reproductive maturity (male)
    45 (low) days

Females care for their young in a nest, providing shelter, warmth, and milk to nourish the altricial neonates. It has been shown that in several species of the genus Peromyscus, the male remains with the female to help care for the young, although no data exist for P. gossypinus. (Nowak, 1999; Wolfe and Linzey, June 1977)

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


As with most species of the genus Peromyscus, the cotton mouse has a relatively short lifespan, averaging four to five months. (Nowak, 1999; Wilson and Ruff, 1999; Wolfe and Linzey, June 1977)

  • Range lifespan
    Status: wild
    15 (high) months
  • Average lifespan
    Status: wild
    4 to 5 months


Peromyscus gossypinus is nocturnal, foraging for food during dark hours. It is a strong climber and swimmer, which is thought to be a result of its tree-filled, swampy habitat. Cotton mice can dig well, as demonstrated by the burrows they create as shelter. This species tends to establish a home range, then wander from that range in search of resources. Animals will eventually return to their nesting area. While they do not hibernate, cotton mice enter torpor during the increased temperature of the summer months. (Griffo, 1961; Wilson and Ruff, 1999; Wolfe and Linzey, June 1977)

Home Range

The average home range size varies by location, and is between 0.18 and 0.49 hectares, with the ranges of males being larger than those of females. (Wolfe and Linzey, June 1977)

Communication and Perception

The genus Peromyscus uses a combination of vocal, visual, tactile and scent communication. Species in this genus are known to vocalize with high pitched squeaks and buzzes. When excited, mice of this genus have been observed to hit their front feet on the ground, producing a drumming sound. (Nowak, 1999)

Food Habits

The food habits of P. gossypinus are numerous and varied. As an omnivore, the cotton mouse feeds on all types of food, from fruits and berries to insects and animal matter. Studies have shown that P. gossypinus is an opportunistic feeder, consuming whatever food is available. Its diet may consist of up to fifty percent animal matter. The cotton mouse primarily feeds at night.

Foods eaten include: seeds, fruits, nuts, insects, arachnids and slugs. (Davis and Schmidly, 1994; Nowak, 1999)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • mollusks
  • Plant Foods
  • seeds, grains, and nuts
  • fruit
  • flowers
  • Other Foods
  • fungus


Cotton mouse behavior is influenced by the many predators in its environment. Peromyscus gossypinus is active primarily at night. With darkness protecting it from predators, it is able to move about more freely. This behavior has led to well developed senses of sight, smell, and hearing. This species is also cryptically colored and secretive.

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Because P. gossypinus consumes fruit as part of its diet, it plays a role in the seed dispersal of a variety of plants. As a prey item, populations of cotton mice maybe important to sustaining predator populations. This species may also play a role in the decomposition of other animals because of its scavenging food habits.

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

Because a large amount of the cotton mouse's diet consists of animal matter, mainly insects, this species might aid in the control of pests in areas inhabited by humans.

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

The cotton mouse has been known to extend its habitat to older, dilapidated buildings and, therefore, act as a household pest if these buildings are inhabited by humans. Additionally, as with most wild mammals, P. gossypinus acts as a reservoir of various infectious pathogens that can also infect humans.

Conservation Status

Peromyscus gossypinus is not considered endangered by any organizations. However, there are several subspecies of P. gossypinus, two of which are considered to have attained a conservation status with various organizations.

Peromyscus gossypinus allapaticola, the Key Largo cotton mouse, has received the Vulnerable D2 status with the IUCN, which means that the population is restricted to an acutely small area of occupancy, in which any disturbance could result in the endangerment or extinction of the subspecies. It is also considered endangered by the U.S. Fish and Wildlife Service.

Peromyscus gossypinus restrictus, the Chadwick Beach cotton mouse, is extinct, according to the IUCN. This subspecies was native to Florida. (Hilton-Taylor, 2000)

Other Comments

Peromyscus gossypinus possesses a diploid chromosome number of 48. This species has hybridized with several other species of the genus Peromyscus in laboratory conditions, but hybridization has not been observed in the wild. In areas where this mouse is found with P. leucopus, the suspected sister species of P. gossypinus, cotton mice show a great deal of aggression to these other mice, and tend to avoid them if possible. This is considered reproductive issolation by behavior, because these two species will readily hybridize in laboratory conditions. (Nowak, 1999)


Tanya Dewey (editor), Animal Diversity Web.

Nancy Shefferly (editor), Animal Diversity Web.

Adam Eatroff (author), University of Michigan-Ann Arbor, Kate Teeter (editor), University of Michigan-Ann Arbor.



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


uses sound to communicate


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. Synapomorphy of the Bilateria.

causes or carries domestic animal disease

either directly causes, or indirectly transmits, a disease to a domestic animal


uses smells or other chemicals to communicate


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.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.


animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.


union of egg and spermatozoan


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.


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).


Having one mate at a time.


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.


active during the night


an animal that mainly eats all kinds of things, including plants and animals


having more than one female as a mate at one time


Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season


remains in the same area


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


lives alone


living in residential areas on the outskirts of large cities or towns.


a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.


uses touch to communicate


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).


Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.


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

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.


uses sight to communicate


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


Davis, W., D. Schmidly. 1994. "Cotton mouse (Peromyscus gossypinus)" (On-line). The Mammals of Texas Online. Accessed October 29, 2001 at

Frank, P., J. Layne. 1992. Nests and Daytime Refugia of Cotton Mice (Peromyscus gossypinus) and Golden Mice (Ochrotomys nutalli) in South-Central Florida. The American Midland Naturalist, 127: 21-30.

Griffo, J. 1961. A Study of Homing in the Cotton Mouse, Peromyscus gossypinus. The American Midland Naturalist, 65: 257-289.

Hilton-Taylor, C. 2000. "The 2000 IUCN Red List of Endangered Species" (On-line). Accessed November 7, 2001 at

Millar, J. 1989. Reproduction and Development. Pp. 169-232 in G Kirkland, J Layne, eds. Advances in the Study of Peromyscus . Lubbock, Texas: Texas Tech University Press.

Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition. Baltimore and London: The Johns Hopkins University Press.

Pornelle, G. February, 1952. Reproduction and Early Post-Natal Development of the Cotton Mouse, Peromyscus gossypinus gossypinus. Journal of Mammalogy, 33: 1-20.

Wilson, D., S. Ruff. 1999. The Smithsonian Book of North American Mammals. Washington and London: Smithsonian Institution Press.

Wolfe, J., A. Linzey. June 1977. Peromyscus gossypinus. Mammalian Species, 70: 1-5.