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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.
Known Predators:
Anti-predator Adaptations: cryptic
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.
Range mass: 17 to 46 g.
Range length: 142 to 206 mm.
Other Physical Features: endothermic ; heterothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike
As with most species of the genus Peromyscus, the cotton mouse has a relatively short lifespan, averaging four to five months.
Range lifespan
Status: wild: 15 (high) months.
Average lifespan
Status: wild: 4 to 5 months.
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.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: desert or dune ; savanna or grassland ; forest ; scrub forest
Wetlands: swamp
Other Habitat Features: suburban ; riparian
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.
Biogeographic Regions: nearctic (Native )
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.
Animal Foods: insects; terrestrial non-insect arthropods; mollusks
Plant Foods: seeds, grains, and nuts; fruit; flowers
Other Foods: fungus
Primary Diet: omnivore
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
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
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.
Negative Impacts: causes or carries domestic animal disease ; household pest
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.
US Federal List: endangered; no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
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.
Communication Channels: visual ; tactile ; acoustic ; chemical
Perception Channels: visual ; tactile ; acoustic ; chemical
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.
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.
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.
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.
Males and females probably use a combination of scent cues and behaviors to determine when another animal is ready to mate.
Mating System: monogamous ; polygynous
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.
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.
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.
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.
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.
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.
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.
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.
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.
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: 3.7.
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.
Key Reproductive Features: iteroparous ; seasonal breeding ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous ; post-partum estrous
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.
Parental Investment: altricial ; pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)
Key Largo cotton mice are omnivorous and feed on a wide variety of plant and animal materials. Over 70 percent of the tropical hardwood hammock trees and shrubs produce fruits and berries that may provide important food items for the Key Largo cotton mouse (USFWS 2008 and references therein).
The Key Largo cotton mouse is closely associated with the Key Largo woodrat (Neotoma floridana smalli). It is often found in woodrat holes, nests, or runways (Humphrey 1992, cited in USFWS 1999). Both of these species are dependent upon the
structure, composition, and quality of tropical hardwood hammocks. Several species listed by the USFWS as threatened or endangered occur in the same habitat or adjacent habitat, including the American crocodile (Crocodylus acutus), eastern indigo snake (Drymarchon corais couperi), and Schaus swallowtail butterfly (Papilio aristodemus ponceanus). In addition, there are at least seven state-protected animals and 20 state-listed plants that also share the same habitat, such as the threatened white-crowned pigeon (Columba leucocephala) and Miami black-headed snake (Tantilla oolitica) and the endangered lignumvitae tree (Guaiacum sanctum), prickly apple (Harrisia simpsonii), tamarindillo (Acacia choriophylla), powdery catopsis (Catopsis berteroniana), and long strap fern (Campyloneurum phyllitidus) (USFWS 1999).
Some of the behavioral and ecological information available for the Key Largo cotton mouse is inferred from other cotton mouse populations in Florida. The Key Largo cotton mouse builds leaf-lined nests in logs, tree hollows, and rock crevices. The holes occupied by these mice measure 3 to 9 cm in diameter, are often partially covered by leaves or bark, and may be located at the bases of trees and near or in woodrat nests. The Key Largo cotton mouse can move at least 2 km in 1 to 2 days. Male cotton mice have larger home ranges than females and home ranges overlap because cotton mice do not defend territories. Other Florida populations of cotton mice are primarily nocturnal and often run and climb on tree limbs and Key Largo cotton mice probably share these behaviors. Cotton mice use a variety of short musical barking sounds to communicate, which is probably also true for the Key Largo cotton mouse (USFWS 1999 and references therein).
Cotton mice are among the most common small mammals in South Florida and throughout the southeastern United States, but the Key Largo cotton mouse is endemic to (i.e., found only in) Key Largo. Although at one time it occurred throughout the tropical hardwood hammocks in the Upper Keys south to near Tavernier, today the Key Largo cotton mouse is restricted to the northernmost portion of Key Largo. Urbanization of Key Largo has decimated the tropical hardwood hammock forests and has reduced the availability of food, shelter, and habitat for the Key Largo cotton mouse, threatening its continued existence (USFWS 1999).
Data from 2007 suggest a stable population, but a rigorous monitoring program is only now being established. Conservation history, status, and plans for the future were reviewed by the U.S. Fish & Wildlife Service in 2008 (USFWS 2008).
The Key Largo cotton mouse formerly occurred throughout the tropical hardwood hammock forests of Key Largo, Monroe County, Florida, but is now restricted to the northern portion of Key Largo. Remaining hammocks on south Key Largo are small, isolated, and disturbed. Hammock fragments up to four hectares in size remain on south Key Largo, but may be too small and isolated to support viable cotton mouse populations (USFWS 1999).
A translocation project was initiated on Lignumvitae Key (outside the historic range of the Key Largo cotton mouse) in 1970, during which 14 individuals were released. A single individual was documented on the Key in 1977, but the population was considered extirpated by 1990 and a trapping survey in 2007 yielded no additional captures (USFWS 2008 and references therein).
The Key Largo cotton mouse uses a variety of tropical hardwood habitats, including recently burned, early successional, and mature hammock forests, and Salicornia coastal strand (the beach community just above the high tide line) adjacent to these forests (Humphrey 1992, cited in USFWS 1999). Much of the original tropical hardwood hammock on Key Largo was cleared in the past for development or agriculture. The southern portion of Key Largo is nearly completely developed, and the only remaining large contiguous tract of tropical hardwood hammock occurs on the northern half of the Key (USFWS 2008). Although a 1979 field study by Barbour and Humphrey (1982) found that a mature forest site had nearly twenty times the density of Key Largo cotton mice as did an intermediate-stage forest, more recent studies have suggested at least a somewhat greater degree of habitat flexibility (USFWS 2008 and references therein).
About a thousand hectares of tropical hardwood hammock remain in north Key Largo, mainly within the boundaries of Crocodile Lake National Wildlife Refuge and Dagny Johnson Key Largo Hammock Botanical State Park, which were acquired in 1980 and 1982, respectively (USFWS 2008). Both of these sites have been managed to maintain and restore the native tropical hardwood hammock vegetation on which the Key Largo cotton mouse depends and acquisition of the little additional remaining hammock habitat on north Key Largo has continued. Many tracts on these sites were cleared for development or agriculture during the 20th century, but hammock vegetation has returned to many of these previously cleared sites. The remaining forest is now composed of a variety of successional stages of tropical hardwood hammock vegetation, reflecting the time since and extent of disturbance (USFWS 2008).
The Key Largo Cotton Mouse is listed as endangered by both the U.S. Fish & Wildlife Service (USFWS) and the Florida Fish and Wildlife Conservation Commission (FWC) (USFWS 2008). The USFWS first listed this species in 1983 (Federal Register, 48 FR 43040-43043).
Cotton mice are short-lived, with an average life expectancy of perhaps just 5 months, although potential longevity is 2 to 3 years (USFWS 1999).
Key Largo cotton mice are larger and more reddish in appearance than other subspecies of cotton mice from peninsular Florida.The coat is reddish dorsally (above), with dusky brown sides, sharply contrasting white underparts, and a cinnamon buff wash on the throat and chest. The feet are white with dusky ankles. The bicolored tail is darker brown on top and whiter underneath. Body length is 170 to 189 mm, tail length is 72 to 87 mm, and hind foot length is 21 to 23 mm (Schwartz 1952).
In a 1979 trapping survey on Key Largo, population density was estimated at 21.8 individuals per hectare in a mature forest site and just 1.2 individuals per hectare in an intermediate-stage forest site (Barbour and Humphrey 1982).
In a later study, Humphrey (1988) found that density estimates varied considerably among sites, but averaged 15.5 individuals per hectare in three sites near housing subdivisions and 26.9 in three sites distant from such developments, yielding an overall average density for the study of 21.2 cotton mice per hectare. Using an estimate of 851 hectares of remaining forest habitat on north Key Largo at the time, Humphrey estimated the total Key Largo cotton mouse population at about 18,000 individuals.
The Key Largo cotton mouse breeds throughout the year. producing two to three litters annually, with an
average of four young per litter (Brown 1978, cited in USFWS 2008).
Peromyscus gossypinus allapaticola has been recognized as a valid subspecies since it was first described in 1952 (USFWS 2008) and is distinguished mainly by its overall larger size and brighter, reddish-colored fur. Its name is derived from the Seminole word "allapattah", which refers to the tropical dry hammocks of South Florida where this mouse is most abundant (Schwartz 1952).
The main threats currently facing the Key Largo cotton mouse are population fragmentation (as a result of habitat fragmentation), small total population size (2007 estimate: 17,000 individuals), and predation. Habitat degradation and loss have continued and threats from non-native animals and invasive exotic plants have increased, although efforts are underway to manage these threats (USFWS 2008).
The Key Largo cotton mouse has a number of natural predators, including raptors (birds of prey), corn snakes (Elaphe guttata), diamondback rattlesnakes (Crotalus adamanteus), Florida black racers (Coluber constrictor priapus), Keys rat snakes (Elaphe
obsolete deckerti), owls, and possibly raccoons (Procyon lotor). Non-native predators include free-roaming domestic cats (Felis catus), fire ants, and possibly young Burmese pythons (Python molurus bivitattus). Predation would probably not be a major concern if Key Largo cotton mouse population levels were robust and plenty of suitable habitat were available. However, in the face of habitat and population fragmentation, predation pressure can have a substantial negative impact (USFWS 2008).
In studying the spatial distribution of Key Largo cotton mice, Keith and Gaines (2002, cited in USFWS 2008) detected a relationship between the presence of the mice and the absence of invasive exotic plants.
The cotton mouse (Peromyscus gossypinus) is a species of rodent in the family Cricetidae[2] found in the woodlands of the US South.
Adults are about 180 mm (7.1 in) long, with a tail around 78 mm (3.1 in), and weigh 34-51 g. Its general appearance is very similar to the white-footed mouse, but the cotton mouse is larger in size and has a longer skull and hind feet. They have dark brown bodies and white feet and bellies.[3]
The common name derives from the observed habit of using raw cotton in building nests.[3]
One subspecies, the Chadwick Beach cotton mouse (P. g. restrictus) was last seen in 1938 and is now presumed extinct.[4] Another subspecies, the Key Largo cotton mouse (P. g. allapaticola) is currently on the United States Fish and Wildlife Service list of endangered species.
The cotton mouse occurs in the Southeastern United States in an area roughly bordered by southeastern Virginia, Florida, Texas, and Kentucky. It makes use of a variety of habitats, including hardwood forests, swamps, the margins of cleared fields, edges of salt savanna and dunes, scrub, and rocky bluffs and ledges. They probably prefer terrain that is regularly inundated. Once native to Illinois, it is now considered extirpated from that state.[1]
Cotton mice use underground refuges such as stump holes, tree cavities, root boles, and burrows where they can avoid predators and wild fires. Such underground refuges also provide lower temperature and humidity during the summer season.[5]
Most Peromyscus species show great decrease in population after fire events through emigration, increase in predation, or from direct damage by fire from loss of habitat/protection. However, due to the behavior of using underground refuges, cotton mice are to survive with no significant loss of population from the fire.[5]
Cotton mice are omnivorous, and eat seeds and insects. Breeding may occur throughout the year, and usually occurs in early spring and fall. They may have four litters a year of up to seven young, which are helpless and naked at birth. Cotton mice are weaned at 20–25 days, and become sexually mature around two months. Lifespans are four to five months, with a rare few living to one year. They are preyed upon by owls, snakes, weasels, and bobcats.[3] Cotton mice are also parasitized by Cuterebra fontinella, the mouse botfly.[6]
The golden mouse (Ochrotomys nuttalli) has similar characteristics and shares similar habitat and geographic regions with the cotton mouse. The coexistence of the two being possible when sharing similar habitat was due to their use of the common refuges had different daily and seasonal patterns. The cotton mouse shows broader selection in choosing refuges as they switch from one to the other, which is suggested to be the most significant component for such relationship to be possible.[7]
Due to their small population size and reduced chances of reproduction, evidence for cotton mouse hybridizing with white-footed mouse has been found. Although they are known to be conspecific, hybridization will occur when limited options for reproduction are available. Identification through toe-clip sampling made possible finding hybridization between the cotton mouse and the white-footed mouse on a heterozygous GPI-1 marker.[8]
The cotton mouse (Peromyscus gossypinus) is a species of rodent in the family Cricetidae found in the woodlands of the US South.
