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Key Largo Cotton Mouse

Peromyscus gossypinus allapaticola

Listing Status

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


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). 


Key Largo Cotton Mouse

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).    


The Key Largo cotton mouse inhabits tropical hardwood hammocks in Key Largo Florida.


Key Largo Cotton Mouse map

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.

Federal Recovery Plan


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.

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

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

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.