Key Largo Cotton Mouse

Peromyscus gossypinus allapaticola

Description

The Key Largo cotton mouse, Peromyscus gossypinus allapaticola, is a small, inconspicuous field mouse with a relatively large head. Upper parts are dark brown, sometimes cinnamon, and the under-parts are white. The furry tail is brown above and white below; ears are brown, edged in white. The genus Peromyscus comprises 49 species.

Behavior

Research shows that the average life span of a Key Largo cotton mouse lasts a year or less. Nocturnal in nature, the mice build small, leaf-lined nests in burrows, tree hollows, crevices, or under logs. Females have two or three litters a year, with litter sizes ranging from two to six young and averaging four. Weaning takes place at about four weeks of age. Females are ready to mate when slightly more than 70 days old. The mouse feeds mostly on the buds and seeds of fruits, herbs, and other plant species.

Habitat

The Key Largo cotton mouse is restricted to undisturbed tropical hardwood forests (hammocks), which represent a climax vegetation type. The closed forest canopy provides a more moderate, humid environment than adjacent grasslands and marshes and supports a rich biota, including many rare plant and animal species. Hardwood hammocks were originally found from Key West north into southern peninsular Florida. Habitat elevation is about 13 ft (4 m).

Distribution

This species is endemic to the Florida Keys and contiguous peninsular Florida. In the last two decades, development of the northern keys and the southern two-thirds of Key Largo eliminated much of the cotton mouse's original habitat. In 1970, the mouse was introduced into the Lignumvitae Key State Botanical Site. Its status there is uncertain; a 1984 trapping effort failed to detect the species. In the early 1990s, an estimated 18,000 cotton mice were thought to survive in the remaining 2,100 acres (850 hectares) of forested habitat on north Key Largo. About half of this land is publicly owned, as parts of the Crocodile Lake National Wildlife Refuge and a state resource conservation zone.

Threats

Because of encroaching residential and commercial development, tropical hardwood hammocks are one of the most limited and threatened ecosystems in Florida. The hammocks on north Key Largo represent one of the largest remaining tracts of its vegetation type.

Conservation and Recovery

In June 1983 the Florida Keys Electric Cooperative sought a federal loan to construct a power substation that would provide electricity for up to 6,000 new residential units proposed for northern Key Largo. The housing units were slated for construction in the heart of the last pristine hardwood hammocks on Key Largo. State biologists pushed to add the Key Largo cotton mouse and the Key Largo woodrat (Neotoma floridana smalli ) to the federal list under emergency provisions of the Endangered Species Act. The effort was successful. In September 1993 both species were provided temporary protection while biologists studied the impact of the proposed substation and housing development. Protection was formally extended the following year, when it was determined that construction would seriously endanger the species' remaining habitat. Subsequently, federal loans for the power project were denied. In 1986, a proposal to designate critical habitat for the cotton mouse was withdrawn after an agreement was worked out with private landowners that allowed a minimal amount of residential development in exchange for wider conservation of hardwood hammock habitat. The U. S. Fish and Wildlife Service has expressed confidence that the agreement will preserve the integrity of populations of both the Key Largo cotton mouse and woodrat.

Contact

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
1875 Century Blvd., Suite 200
Atlanta, Georgia 30345
http://southeast.fws.gov/

References

Barbour, D. B., and S. R. Humphrey. 1982. "Status and Habitat of the Key Largo Woodrat and Cotton Mouse." Journal of Mammalogy 63: 144-148.

Schwartz, A. 1952. "Three New Mammals from Southern Florida." Journal of Mammalogy 33: 381-385.