The Key Deer (Odocoileus virginianus clavium), is an endangered species of deer that lives only in the Florida Keys. It is considered a subspecies of the White-tailed Deer (Odocoileus virginianus).
The deer can be recognized by its characteristic small size. Adult males (also known as bucks) usually weigh from 55 to 75 pounds (25 to 34 kg) and stand about 30 inches (76 cm) tall at the shoulder. Females (also known as does) usually weigh between 45 and 65 pounds (20 to 29 kg) and stand an average of 26 inches (66 cm) at the shoulders. The deer’s coat is a reddish-brown to grey-brown in color. Antlers, which are only grown by males, are shed between February and March but are re-grown by June. The species otherwise generally resembles the White-tailed Deer in many physical features.
Mating can occur at any time of the year but usually peaks in September and October. Key deer have a relatively low reproductive rate, averaging 1 fawn per adult doe per year.
The range of the Key Deer originally encompassed most of the Florida Keys, but is now limited to an approximately 6 mile (9.7 km) stretch of the lower Florida Keys. The islands of Big Pine, Big Torch, Cudjoe, Howe, Little Pine, Little Torch, Middle Torch, No Name, Sugarloaf, and Summerland Keys are the only places where the deer permanently reside. The deer also can be found on the islands of Annette, Big Munson, Little Munson, Johnson, Knockemdown, Mayo, Porpoise, Ramrod, Toptree Hammock, Wahoo, Water Key (east) and Water Keys (west) but only in transient use because of their lack of a ready supply of fresh water during the dry season. Key deer swim easily between keys and use all islands during the wet season when drinking water is more generally available retreating to islands with a perennial supply of fresh water in dry months.
Key deer utilize all habitat types within their range, including pine rocklands, hardwood hammocks, mangroves, and freshwater wetlands. The species feed on over 160 types of plants but Red, White, and Black mangrove make up the most important part of their diet. Pine rockland habitat is important as well because it often offers the only reliable source of fresh drinking water though Key Deer can tolerate drinking mildly brackish water. The increasing human encroachment into Key Deer habitat means that many deer now feed on non native ornamental plants.
It is believed that Key Deer are a subspecies of White-tailed Deer which migrated to the Florida Keys from the mainland over a land bridge during the Wisconsin Glacial period. The earliest known written reference to Key Deer comes from the writings of Hernando d’Escalante Fontaneda, a Spanish sailor shipwrecked in the Florida Keys in the 1550s. Deer were hunted as a food supply by native tribes, passing sailors, and early settlers. The hunting of Key Deer was banned in 1939, but widespread poaching continued. Key Deer were hunted to near extinction by the 1950’s. The National Key Deer Refuge was established in 1957.
Recent population estimates put the Key Deer population variously between 300 and 800 putting it on the list of endangered species. Loss of habitat and past over hunting are the primary reasons for the species’ endangered status. Road kills from drivers on U.S. Highway 1 which traverses the deer’s small range are also a major threat averaging between 30 and 40 kills per year or about 70 percent of the annual mortality.
The population has made an encouraging rise since 1955 when population estimates ranged as low as 25, and appears to have stabilized in recent years but recent human encroachment into Key deer’s fragile habitat and the deer’s relatively low rate of reproduction point to an uncertain future for the species.
Conservation steps include the establishment of the National Key Deer Refuge consisting of approximately 8,500 acres (34 km) on Big Pine and No Name Keys and several smaller uninhabited islands and the strict control of free roaming domesticated dogs which often attack the deer. Portions of U.S. Highway 1 have also been reconfigured and elevated to allow the deer to pass safely beneath the roadway lessening the chance of a road kill. Scientists have recently begun relocating some Key Deer from Big Pine Key to other islands since that island’s population has reached its sustainable limit.