Facts about the Gopher Tortoise from the printable Fact Sheet ↑
Tortoises can be observed on all major landmasses in the world except for Australia and Antarctica. The Gopher Tortoise (Gopherus polyphemus) is one of four species that lives only in North America. It has a large dark-brown to grayish shell, elephantine limbs, and a large grayish-black rounded head. Its shovel-like forefeet are used to excavate burrows that provide shelter.
The Gopher Tortoise can reach lengths of more than 35cm (13.78 inches) and weigh over 10kg (22.05 pounds). There are physical differences between males and females. Female tortoises have a flattened bottom shell, or plastron and small tail, whereas males exhibit a highly concave plastron and large tail. Male Gopher Tortoises also have two visible scent glands beneath the chin.
The generic name of the Gopher Tortoise, Gopherus, is derived from the word gopher that was used to describe the burrowing habits of this species. The species name polyphemus refers to a cave-dwelling mythical creature.
Daudin was the first to describe the Gopher Tortoise as polyphemus in 1802. Rafinesque used this species as the type, or standard to define the features of Gopherus and assign this generic name to the North American tortoises. All four species in this genus exhibit adaptations for burrowing such as claws and flattened forelimbs; however, they can be distinguished based on anatomical features including limb-bone and skull structure.
The Gopher Tortoise is most closely related to the larger Mexican, or Bolson Tortoise (G. flavomarginatus) that is endemic to the Chihuahuan Desert that straddles the U.S.-Mexico border.
The Gopher Tortoise inhabits the southeastern United States throughout Florida, southern Georgia, southern South Carolina, Mississippi, southern Alabama and southeastern Louisiana. High numbers of Gopher Tortoises still remain in Florida, Georgia, and parts of Alabama; however, few individuals exist in South Carolina and Mississippi. This species has been driven nearly to extinction in Louisiana.
Gopher Tortoise density varies considerably among locations primarily due to differences in habitat type, quality, and availability. The range of this species has been drastically reduced due to agriculture, forest management, and mining processes. Predators such as raccoons, foxes and humans have also reduced tortoise numbers.
Gopher Tortoises usually occupy pine-oak, beach scrub, oak hammocks and pine flatwoods, though they can also be found in disturbed habitats. They are dependent on well-drained deep sandy soils for burrowing and nesting. The amount of herbaceous vegetation present at a site affects population density and tortoise movements. Tortoise activity such as grazing and burrow excavation has significant impacts the environment through increasing plant succession and moderation of soil temperature.
The Gopher Tortoise is considered to be a keystone species because it creates burrows that are used by many other species including small mammals, frogs, and other endangered species like the Eastern Indigo Snake. A Gopher Tortoise will dig several burrows throughout its lifetime and even use burrows that have been abandoned by other individuals. A burrow is usually a straight tunnel excavated in sandy soil that can be more than 6m (19 feet 8 inches) long and nearly 3m (9 feet 10 inches) deep. Tortoises are protected against unfavorable environmental conditions when they are in burrows because temperature and humidity remain relatively constant within them.
Natural, periodic wild fires play an important role in maintaining the longleaf pine sandhill habitat that is preferred by tortoises. Fire suppression promotes the growth of dense vegetation that is unsuitable to eat and shades areas that tortoises require for thermoregulation and nesting. Prescribed burns are used to maintain canopy openings and herbaceous food plants for tortoises.
Movement and Home Range
The Gopher Tortoise can be active throughout the year depending on location. It seeks shelter in its burrow during periods of inclement weather. Tortoises are most active during the warmest part of the day and can often be seen basking at the burrow entrance. Individuals have well-defined home ranges that can vary from less than 0.5ha (1.24 acres) to more than 3.0ha (7.413 acres). Several burrows may be located within an individual's home range.
The Gopher Tortoise is primarily herbivorous and consumes grass and grass-like plants, broad-leaved plants, and fruit. Dissected tortoise scats have contained bone, charcoal, and insects and individuals have been observed eating carrion. This species may play an important role in seed dispersal for some plants.
Male and female Gopher Tortoises reach sexual maturity between 10-20 years old and 220-265mm (8.661 to 10.43 inches). Mating occurs mainly in the spring though it has been observed at other times of the year. Multiple males may peruse a single female at the same time. Males periodically bob their heads and bite their potential mates on the forelegs during courtship. If the female is receptive, she will stretch her legs and allow the male to mount her shell in preparation for copulation.
Nesting occurs mainly in May and June. Eggs are often deposited at the burrow entrance or nearby. A female lays one clutch containing up to 25 eggs each year. Hatchling tortoises emerge from the nest about 90 days following egg deposition sometime between August and October.
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Gopher Tortoise Conservation
The mission of the Gopher Tortoise Conservation Program within the Indigo Snake Initiative is to monitor and maintain the health of Gopher Tortoise populations on the Orianne Indigo Snake Preserve (OSIP).
The Gopher Tortoise may be one of the most important species in the longleaf pine ecosystem of the southeastern U.S. Coastal Plain, and the species is critically important to the survival of the Eastern Indigo Snake in Georgia. Gopher Tortoises dig extensive burrows in sandy soil which offer refuge to Eastern Indigo Snakes, as well as over 300 other species, including many species of insects, quail, mice (including the rare Florida Mouse), rabbits, Burrowing Owls, Eastern Pine Snakes, and the elusive Gopher Frog. These burrows typically reach 15 feet in the length and six feet in depth — although some burrows may be up to 40 feet long! Because of the vast array of cohabitants that use the burrows, the Gopher Tortoise has earned the title as a keystone species in the Coastal Plain.
Gopher Tortoise populations are declining, however, throughout much of its range. The Gopher Tortoise is federally listed as threatened in Alabama, Mississippi, and Louisiana, and is currently under review for federal listing in Georgia, Florida, and South Carolina.
Gopher Tortoises reach maturity late in life and often produce small clutches with high nest and hatchling mortality, resulting in low recruitment into the population. Low reproductive output combined with extensive habitat loss, human collection for food, and a wide-spread respiratory disease (that infects most individuals) have had a considerable negative effect on the population as a whole — and in turn, has also affected the many species that rely on Gopher Tortoise burrows for habitat and refuge, including the Eastern Indigo Snake.
Because of the importance of the Gopher Tortoises to the health of the longleaf pine ecosystem — and the Eastern Indigo Snake in particular — The Orianne Society has placed a high priority on ensuring the health and well being of Gopher Tortoise populations on the OSIP in Telfair County, Georgia. The Preserve is very important to the conservation of Gopher Tortoises because the preserve protects a series of dry sandhills which provide prime Gopher Tortoise habitat.
Gopher Tortoise Monitoring
In 2011, we conducted our first preserve-wide surveys for Gopher Tortoises to estimate tortoise density and population size. Our results showed that the Preserve supports a sizable tortoise population of almost 500 individuals. To monitor the status of our tortoise populations, we will initiate a long-term monitoring project by repeating these surveys at five year intervals. This will allow us to detect any changes in our population status but will also allow us to determine how our populations respond to management actions on the preserve. Data from these surveys will also provide information on the age class distribution within our population and a rough estimate of the amount of recruitment occurring in the population.
Because Gopher Tortoise recruitment into the population is typically low, we need to ensure that our Gopher Tortoise population is growing. To better accomplish this, we will begin developing field protocol that will allow us to better estimate the amount of recruitment within our populations. The results from this study will help us determine if active measures need to be taken to improve Gopher Tortoise survival within the Preserve, particularly nest and hatchling survival.
Gopher Tortoise Translocation
Even though the Orianne Indigo Snake Preserve supports a sizable Gopher Tortoise population, portions of the Preserve contain very few tortoises. To enhance tortoise populations in one of these areas, we translocated 16 adult Gopher Tortoises in September 2011 from a nearby private property to a two-and-a-half acre enclosure on our Preserve. In conservation biology, this approach to translocation is called a "soft release," which allows the animals a period of adjustment to their new surroundings. Soft releases generally are more successful than hard releases (where the animal is immediately released into a new area), so we will keep the tortoises in their enclosure until June 2012. In order to determine the success of our translocation, we will use radio telemetry to monitor the movements and habitat use of several translocated and resident tortoises for one year and compare their home range size, movement patterns, habitat use, and survival.