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The Gopher Tortoise (Gopherus polyphemus) is a tortoise species native to the southeast United States. The gopher tortoise is seen as a keystone species because it digs burrows which provide shelter for hundreds of other species. They are threatened by predation and habitat destruction. The gopher tortoise is the state reptile of Georgia.

Anatomy and physiology

Gopher tortoises can have a shell up to 37 centimeters or 14.6 inches in length. On average, they are a bit less than one foot long. The gopher tortoise's carapace is a solid dark-brown to grayish color. They have hind legs reminiscent of those of an elephant, shovel-like forelimbs, and a gular projection on a yellowish, hingeless plastron. Hatchlings are lighter in color. Males are distinguished from females by their concave plastron and longer tail, but the sexes may be difficult to tell apart.
Gopher tortoise males have two subdentary scent glands under the chin.The genus Gopherus contains four species, all of which are commonly called gopher tortoises. This genus is the only type of tortoise native to North America.

Ecology

Gopherus polyphemus is most common in the state of Florida, but their range also extends to Georgia, Alabama, Mississippi, southeast Louisiana, and the southernmost corner of South Carolina.

Behavior/Diet

external image 200px-Gopher_Tortoise.jpg Gopher Tortoise photographed in Cocoa, Florida.
Gopher tortoises are herbivores. They consume a very wide range of plants, but mainly eat broad-leaved grasses, wiregrass, and legumes. They also eat mushrooms, as well as fruits such as gopher apple, pawpaw, blackberries, and saw palmetto berries. In addition, gopher tortoises eat flowers from the genera Cnidoscolus (nettles), Tillandsia (Spanish and ball moss), Richardia, and Dyschoriste. Juvenile tortoises tend to eat more legumes, which are higher in protein, and fewer grasses and tough, fibrous plants than mature tortoises. Gopher tortoises have been known to scavenge carrion and eat excrement. As gopher tortoises usually get water from the food they eat, they usually only drink standing water in times of extreme drought.

Burrowing

external image 200px-Gopher_tortoise_entering_burrow.JPG Gopher tortoise entering burrow
Gopherus polyphemus, like other tortoises of the genus Gopherus, is known for its digging ability. Gopher tortoises spend most of their time in long burrows, up to 14.5 metres (48 ft) in length and 3 metres (9.8 ft) deep. In these burrows, the tortoises are protected from summer heat, winter cold, fire, and predators. The burrows are especially common in longleaf pine savannas, where the tortoises are the primary grazers, playing an essential role in their ecosystem. Except during breeding season, gopher tortoises are solitary animals, inhabiting a small home range. Within their range they dig several burrows. On average, each gopher tortoise needs about four acres to live.

Breeding and reproduction

Gopher tortoises reach maturity at about 10-15 years of age, when their shells are around 9 inches (23 cm) long. Gopher tortoises may mate from February through September, with a peak throughout May and June. Females may lay clutches of 3-14 eggs, depending on body size, in a sandy mound very close to the entrance of their burrow. The eggs hatch about 100 days later. Tortoises in Florida hatch in less time, about 80–90 days. Sex is determined by the temperature of the sand in which the eggs are laid.
90% of clutches may be destroyed by predators such as armadillos, raccoons, foxes, skunks and alligators before the eggs hatch, and less than 6% of eggs are expected to grow into tortoises that live one year or more after hatching.

Conservation concerns

external image 180px-Gopher_tortoise_shell_up.jpg Bleached shell of dead gopher tortoise
Since July 7, 1987, the U.S. Fish and Wildlife Service has listed Gopherus polyphemus as "Threatened" wherever the tortoises are found west of the Mobile and Tombigbee Rivers in Alabama, Mississippi, and Louisiana. Its status is listed as "Under Review" in Florida and in other locations. On November 9, 2009, the U.S. Fish and Wildlife Service proposed rulemaking to include the eastern population of Gopherus polyphemus, in the List of Threatened Wildlife. Gopherus polyphemus appears on the IUCN Red List as a "Vulnerable" species; however, it has not been assessed for the purposes of this list since 1996.
Gopher tortoises are known as a keystone species. The Florida Fish and Wildlife Conservation Commission states that the gopher tortoise provides refuge for as many as 350 to 400 species. The burrows are used for feeding, resting, reproduction, and protection from temperature extremes, moisture loss, and predators. These species include gopher frogs (
Rana capito), several species of snake, such as the eastern indigo snake (Drymarchon corais couperi), small invertebrates, and burrowing owls (Athene cunicularia//). Therefore, conservation efforts focused on the gopher tortoise aid these species as well.
Conversion of gopher tortoise habitat to urban areas, croplands, and pasture along with adverse forest management practices has drastically reduced the historic range of the gopher tortoise. The taking of gopher tortoises for sale or use as food or pets has also had a serious effect on some populations. The seriousness of the loss of adult tortoises is magnified by the length of time required for tortoises to reach maturity and their low reproductive rate. According to the website of the Brevard Zoo in Melbourne, Florida, current estimates of human predation and road mortality alone are at levels that could offset any annual addition to the population, and sightings of gopher tortoises have become rare in many areas and the ones sighted are much smaller than in the past. A number of other species also prey upon gopher tortoises including the raccoon, who is the primary egg and hatchling predator; gray foxes, striped skunks, nine-banded armadillos, dogs, snakes, and raptors. Red imported fire ants also have been known to prey on hatchlings. A 1980 report indicated that clutch and hatchling losses often approach 90 percent
In the past, many gopher tortoises in Florida have been destroyed as developers could acquire Incidental Take Permits to build in the gopher tortoises' natural habitat without regard to the safety of the tortoises. This has changed. On July 31, 2007, a new policy was implemented requiring developers to relocate tortoises.[16] Starting on April 22, 2009, three types of permits were available in Florida for developers wishing to build on gopher tortoise habitat. Two of these permits allow for the relocation of gopher tortoises, either to some other place on the site being used for construction, or to a recipient site which has been certified by the Florida Fish and Wildlife Conservation Commission. The third type of permit allows for temporary relocation of tortoises while major utility lines are installed. In the third case, the tortoises are returned to their habitat after construction is complete.[16]