The Key deer (Odocoileus virginianus clavium) is the smallest subspecies of the white-tailed deer. Prior to declines associated with hunting, habitat loss and car collisions, some 600-700 ranged across the extreme southern tip of Florida from about Key Vaca to Key West . Key deer swim easily between islands. Their seasonal distribution is primarily influenced by availability of fresh surface water. During the wet season they may occupy all islands, but during the dry season they appear only on the 14 with fresh surface water, especially Big Pine and No Name Keys which offer the greatest extent of freshwater . Prior to human colonization, the species encountered few predators or competitors, and had evolved to thrive in a landscape shaped by hurricanes, fire and drought.
Hunting was the first major impact, reducing the population to low levels in the 1920s and prompting a famous 1934 political cartoon by “Ding” Darling depicting savage hunters driving the "toy deer" from the forest to shoot them on the beach. The State of Florida banned hunting in 1939, but illegal hunting continued until the creation of substantial penalties under the Endangered Species Act of 1973.. By the early 1950s the population had fallen to just 25 deer . The National Key Deer Refuge was established on Big Pine Key in 1957 and the Great White Heron National Wildlife Refuge was later established. The species was placed on the endangered list in 1967.
Human-caused death is the greatest known source of deer mortality. In 1998, road mortality accounted for 67 percent of all known deaths . Since 1985, more than 90% of all deer road kills occurred on Big Pine Key, mainly on U.S. Highway 1 and Key Deer Boulevard. Other sources of mortality include poaching, drowning in ditches and canals, running by dogs, entanglement in fences, sparring between bucks, and foreign debris in the digestive tract from feeding in trash containers . Development is believed to have both benefited and harmed the Key deer . Creation of grasslands, artificial uplands, and water sources has improved deer habitat, while fences, roads and high density housing have reduced it.
Local trend data suggest the population increased in the late 1970s, declined through the mid-1980s, and increased relatively steadily again through 2001. The total population declined from about 400 deer in the 1960s to 200 in 1971, then increased to 629 in 1998 and about 750 in 2001. 700-800 Key deer currently occupy approximately 26 islands from Big Pine Key to Sugarloaf Key, with the majority (600) occurring on Big Pine and No Name Keys [1, 2]. The National Key Deer Refuge and Great White Heron National Wildlife Refuge encompass much of this territory and are managed for the Key deer and other imperiled species. Big Pine Key, the largest of the Lower Keys, is the center of the key deer's range and supports about two-thirds of the entire population .
 U.S. Fish and Wildlife Service. 1999. South Florida Multi-Species Recovery Plan. United States Fish and Wildlife Service, Atlanta, GA.
 Lopez, R.R. 2001. Population ecology of the Florida Key deer. Ph.D. Dissertation. Texas A&M University, College Station. 202 pp.
 U.S. Fish and Wildlife Service. 1990. Key deer (Odocoileus virginianus clavium) in Endangered and Threatened Species of the Southeastern United States. U.S. Fish and Wildlife Service website (http://www.fws.gov/endangered/i/a/saa09.html).
 NatureServe. 2005. NatureServe Explorer: An online encyclopedia of life [web application]. Version 4.5. NatureServe, Arlington, Virginia. Available http://www.natureserve.org/explorer. (Accessed: September 16, 2005 ).
 Lopez, R.R. 2004. Population density of the endangered Florida Key deer. Journal of Wildlife Management 68(3):570-575.