Key Largo Cotton Mouse: Peromyscus gossypinus allapaticola

Taxonomic Classification

Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Cricetidae
Genus/Species: Peromyscus gossypinus
Subspecies: Peromyscus gossypinus allapaticola
Common Name: Key Largo cotton mouse

Listing Status

Federal Status: Endangered
FL Status: Federally-designatedEndangered
FNAI Ranks: G5T1Q/S1 (Globally: Demonstrably Secure, Sub sp. Critically Imperiled [Classification as a subspecies question]/State: Critically Imperiled)
IUCN Status: Not ranked

Physical Description

The Key Largo cotton mouse is the largest of all subspecies of cotton mouse found in peninsular Florida (U.S. Fish & Wildlife Service, 1999).  This cotton mouse subspecies can reach a body length of seven inches (17.9 centimeters) with a tail length of three inches (7.7 centimeters).  Key Largo cotton mice have a dark hazel back with reddish brown sides, a white belly, white feet, and a tail that is brown on top and white on the bottom (Florida Natural Areas Inventory 2001). 

Life History

The diet of the Key Largo cotton mouse consists of berries, seeds, nuts, and insects (M. Tucker pers. comm. 2012).  Berries from tropical hardwood hammock trees and shrubs may be an important food supply for the Key Largo cotton mouse (U.S. Fish & Wildlife Service 1999). 

The Key Largo population of the cotton mouse constructs nests in hollow tree stumps, fallen logs, and crevices in limestone outcrops (Barbour and Humphrey 1982).  Breeding occurs throughout the year with a peak breeding season in the fall and early spring (U.S. Fish & Wildlife Service 1999, Bigler and Jenkins 1975).  The average litter size is 3 young per litter, with three to four litters per year (Bigler and Jenkins 1975).    

Habitat and Distribution

Key Largo Cotton Mouse Distribution MapThe Key Largo cotton mouse inhabits tropical hardwood hammocks in Key Largo Florida.


Habitat loss and fragmentation have isolated populations of the Key Largo cotton mouse, which increases the severity of all other threats.  Isolated populations have reduced gene flow which leads to lower genetic diversity, and potentially lower survival (U.S. Fish & Wildlife Service, 2009).  Fragmentation along its small range also makes the Key Largo cotton mouse vulnerable to tropical storms and hurricanes.  Trash dumping (a result of increased urbanization) also threatens the Key Largo cotton mouse, leading to an increased population of black rats (Rattus rattus).  Black rats may out-compete the Key Largo cotton mouse for food and other resources (U.S. Fish & Wildlife Service, 1999).  Sea level rise is an impending threat to the Key Largo cotton mouse population.

Conservation and Management

The Key Largo cotton mouse is protected as an Endangered species by the Federal Endangered Species Act and as a Federally-designated Endangered species by Florida’s Endangered and Threatened Species Rule External Website.

Federal Recovery Plan External Website

Other Informative Links

Florida Natural Areas Inventory External Website
U.S. Fish & Wildlife Service 5-Year Cotton Mouse Review External Website
U.S. Fish & Wildlife Service Species Conservation Guidelines External Website
U.S. Fish & Wildlife Service Species Profile External Website
U.S. Fish & Wildlife Service Multi-Species Recovery Plan External Website



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Barbour, D.B. and S.R. Humphrey. 1982. Status and habitat of the Key Largo woodrat and cotton mouse (Neotoma floridana smalli and Peromyscus gossypinus
allapaticola). Journal of Mammalogy 63(1): 144-148.

Bigler, W. J. and J.H. Jenkins. 1975. Population characteristics of Peromyscus gossypinus and Sigmodon hispidus in tropical hammocks of south Florida. Journalof Mammalogy 56(3): 633-644.

Florida Natural Areas Inventory.  2001.  Field guide to the rare animals of Florida. External Website

U.S. Fish & Wildlife Service. (1999, May 18). Key Largo Cotton Mouse Peromyscus gossypinus allapaticola. Retrieved from Multi-Species Recovery Plan for South Florida: External Website

U.S. Fish & Wildlife Service. (2006, June 8). Key Largo cotton mouse. Retrieved August 2, 2011, from Multi-Species Recovery Plan for South Florida : External Website.

U.S. Fish and Wildlife Service.  2009.  Key Largo cotton mouse (Peromyscus gossypinus  allapaticola) 5-Year review: summary and evaluation. U.S. Fish & Wildlife Service, Vero Beach, FL. External Website.

Image Credit USFWS

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