Key Largo cotton mouse

The Key Largo cotton mouse (Peromyscus gossypinus allapaticola) is a subspecies of cotton mouse, a rodent in the family Cricetidae. It is a subspecies of the genus Peromyscus, a closely related group of New World mice often called "deermice". The subspecies is endemic to Key Largo in the upper Florida Keys. It is a slightly larger mouse with a more reddish color than other mouse species from mainland Florida. The Key Largo cotton mouse can breed throughout the year and has an average life expectancy of five months.

The Key Largo cotton mouse is on the United States Fish and Wildlife Service list of endangered species, due to urbanization of Key Largo. The subspecies previously lived in a variety of tropical hardwood habitats, but urbanization has decimated these areas, reducing the availability of food, shelter, and habitat for the Key Largo cotton mouse. Surveys show that the Key Largo cotton mouse has lost up to 50% of its habitat due to this urbanization.

Due to its longer overall length, tail length, skull measurements, and reddish fur color, the Key Largo cotton mouse was described as a distinct subspecies by Schwartz in 1952. Its subspecific epithet allapaticola originates from the local Seminole Native American term allapattah, which indicates the tropical, dry, deciduous hammocks of South Florida.

The Key Large cotton mouse has large ears, protuberant eyes, and a furry tail. Its coloration follows a pattern of red dorsal fur, dusky brown sides, and white ventral fur. Its tail follows a similar pattern being darker brown on top and whiter underneath. Body length range is 170–189 mm (6.7–7.4 in), as compared with the average length of 100 mm (3.9 in) for other cotton mouse subspecies. Tail length is 72–87 mm (2.8–3.4 in), and hindfoot length is 21–23 mm (0.83–0.91 in).

Both the Key Largo cotton mouse and the Key Largo woodrat (Neotoma floridana smalli) are endemic to Key Largo, Florida. Due to habitat destruction from development and fires, the Key Largo cotton mouse has been pushed to the northernmost portion of Key Largo, North Key Largo. Although historically the Key Largo cotton mouse was once found as far south as Plantation Key, near Tavernier, they are now only found in a confined area north of the U.S. 1-C.R. 905 intersection. This range shift can be attributed to the increased urbanization of Key Largo which has decimated the forests of tropical hardwood hammocks, thus reducing the availability of food, shelter and habitat for the cotton mouse. Surveys indicate that the Key Largo cotton mouse has lost more than 50 percent of its habitat due to this urbanization, and much of the remaining habitat has been degraded or fragmented. This has led to isolation of populations, making proper reproduction and dispersal more difficult.^{[citation needed]}

This fragmentation and range limitation makes the Key Largo cotton mouse more vulnerable to fires and hurricanes. These natural catastrophes pose a threat to both existing populations as well as their limited hammock habitat.

Additionally, habitat degradation poses a large threat to this species as trash dumping (a common side effect of urbanization) leads to increased populations of black rats (Rattus rattus) and predation by domesticated animals. Rodent control techniques used to combat these black rats also kill cotton mice. Black rats compete with cotton mice and have previously led to the extinction of other cotton mouse subspecies.

While the cotton mouse is one of the most common small mammals in South Florida and throughout the southeastern United States, the Key Largo cotton mouse subspecies is endemic to Key Largo. In addition to being only found in North Key Largo, the Key Largo cotton mouse's preferred habitat is coastal strands adjacent to these forests. The hardwood hammocks they prefer are highly productive forests with a tall canopy and open understory, consisting of a diverse range of species.