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Anastasia Island Beach Mouse

Peromyscus polionotus phasma

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 Anastasia Island beach mouse is a subspecies of the small old-field mouse that can reach a length of 5.5 inches (14 centimeters).  This species of beach mouse has a yellowish-brown to gray-pink dorsal (back) color, with a white belly.  The tail of the Anastasia Island beach mouse is usually white, but it can have a light stripe on the back side of the tail (Florida Natural Areas Inventory 2001).  This species also has a white nose and white spots/blemishes over both eyes.


The diet of the Anastasia Island beach mouse consists of insects and the seeds and fruit of dune vegetation.

Very little information is available about the life history of the Anastasia Island beach mouse, so information about the old-field mouse species (Peromyscus polionotus) is generally accepted as the same.  Breeding peaks during the winter months, but can occur year around if there is adequate food available.  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 four pups per litter.  Females are also capable of breeding 24-hours after giving birth (Bird et al. 2009).  Pups are weaned 18 days after being born (NatureServe 2011).  Beach mice reach sexual maturity at around 30 days of age (Foust 2002).


anastasia island beach mouse map

The Anastasia Island beach mouse currently inhabits sand dunes only on Anastasia Island, Florida, although it originally ranged north to Mickler’s Landing in St. Johns County.   Since 2006, no mice have been captured on public lands north of the St. Augustine Inlet, although the mice may persist in very low numbers (USFWS 2011).


The main threat facing the Anastasia Island beach mouse is the continued development along beaches.  Development along the beaches can cause destruction or degradation to sand dunes limiting areas of habitat for the beach mouse, and increasing fragmentation, leading to isolation of populations.  Increased traffic on sand dunes is also a threat for the beach mouse, as the increased traffic damages vegetation on dunes that the beach mice depend on for food and shelter.  Hurricanes also pose a risk to the beach mouse as they can cause damage and destruction to their sand dune habitat 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

The Anastasia Island 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.

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 10, 2011 ).

USFWS. 2011.  Statewide Programmatic Biological Opinion for Shore Protection Activities along the Coast of Florida.