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Perdido Key Beach Mouse

Peromyscus polionotus trissyllepsis

Listing Status

  • Federal Status: Endangered
  • FL Status: Federally-designated Endangered
  • FNAI Ranks: G5T1/S1 (Globally: Demonstrably Secure, Sub sp. Critically Imperiled/State: Critically Imperiled)
  • IUCN Status: Not ranked


The Perdido Key beach mouse is a subspecies of the small old-field mouse that can reach lengths of up to 5.5 inches (14 centimeters) and a tail length of two inches (five centimeters) (Florida Natural Areas Inventory 2001).  This beach mouse species has a gray-colored fur on the back that extends to between the eyes, with white cheeks, tail, and belly.


The diet of the Perdido Key beach mouse primarily consists of dune plant seeds and insects. 

Breeding peaks during the winter months for beach mice; however, breeding can occur year around if the mice have available food.  Beach mice are monogamous and will mate with only one partner at a time.  The total gestation period for a beach mouse is 23 days, with the female giving birth to up to four pups per litter.  Females are also capable of breeding 24-hours after birth (Bird et al. 2009).  The offspring are weaned 18 days after birth (NatureServe 2011).  Beach mice reach sexual maturity around the age of 30 days old (Foust 2002).


perdido key beach mouse map

Perdido Key beach mice inhabit the coastal dunes along Perdido Key in Escambia County, Florida.  This species also occurs in Baldwin County, Alabama.


The main threat facing the Perdido Key beach mouse is continued development along beaches.  Development along beaches can cause destruction or degradation to sand dunes limiting areas of habitat for the beach mouse, and increase fragmentation which will lead to the isolation of populations.  Increased traffic on sand dunes is also a threat as increased traffic damages vegetation on dunes that the beach mice rely on for food and shelter.  Hurricanes also pose a risk to the beach mouse as they can cause damage and destruction to sand dunes with the accompanying intense winds and storm surge.  Other threats include increased predation from feral and free-ranging cats, foxes, raccoons, and coyotes.

Conservation and Management

perdido key beach mouse

The Perdido Key beach 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
Federal 5-year Review

Learn more about how you can live with and conserve beach mice.


Bird, B. L., Branch, L. C., & Hostetler, M. E. (n.d.). Beach Mice. Retrieved June 2, 2011, from IFAS Extension:

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

Foust, D. 2002. "Peromyscus polionotus" (On-line), Animal Diversity Web. Accessed August 10, 2011

NatureServe. 2011. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available  (Accessed: August 12, 2011 ).