Gopher Tortoise - Gopherus polyphemus
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Florida Fish and Wildlife Conservation Commission:
Permit Guidelines, April, 2008
The gopher tortoise (Gopherus polyphemus) is a cold-blooded reptile that averages 25 cm (10 in.) long and 4 kg (9 lb.) in weight. They are extremely long-lived animals; estimates for wild tortoises range from 40 - 60 years, while tortoises in captivity can live more than 100 years. Their range extends from southeastern Louisiana to southeastern South Carolina and throughout all 67 counties in Florida. The gopher tortoise is federally protected as a threatened species except in Florida, where it is listed as a Species of Special Concern by the Florida Fish and Wildlife Conservation Commission.
||The gopher tortoise is an obligate burrower with many adaptations for digging. The limbs are very stout and strong, with wide flat claws. The front legs are protected with small scales. The shell of the tortoise (and all turtles) is an outgrowth of the skeleton and is their major means of protection. When the tortoise pulls his head completely into the shell and covers the openings with his limbs, there are very few predators, other than humans, that can harm him.|
Male & Female
||Male tortoises can be distinguished from female tortoises by their concave plastron (bottom shell). Many males also have a projection on the front of the plastron underneath the chin, but that characteristic is not always reliable. Females' plastrons are perfectly flat. It takes a tortoise ten to 20 years to reach reproductive maturity.
Click here to see a closer shot of the Mother
Gopher Tortoise covering her eggs
and photos of baby Gopher Tortoises.
|Females lay an average of six eggs, but can lay from three to 14 eggs, depending on their body size. They lay one clutch of eggs per year and it takes about 100 days for the eggs to incubate.|
Like many other reptiles, gopher tortoises have temperature-dependent sex determination. That means that when the eggs are laid, they are neither male nor female. The sex of the offspring is determined by the temperature of the sand or dirt where the nest is incubating. For gopher tortoises, if the temperature is above 30° C (85° F), the hatchling tortoises will be females. Temperatures below 30° C produce males.
Tortoises are 3 - 5 cm (1.5 - 2 in.) long at hatching and grow very slowly, less than 2.5 cm (1 in.) per year. They have soft shells that leave them extremely vulnerable to predation.
Gopher tortoises are primarily herbivorous, although they will eat bones from dead animals, presumably to get calcium. Their primary food sources are low-growing grasses and herbs. Examples of their favorite foods are gopher apple and saw palmetto berries. They will eat the pads, fruits, and flowers of prickly pear cactus. One of the gopher tortoise's important roles in the ecosystem is to spread the seeds of many plants in its droppings.|
Along the beach.
Gopher tortoises use a variety of upland habitats that are common in central Florida, including scrub, pine flatwoods, and the dune along the beach. They will also spend time feeding in shallow freshwater wetlands called swales. Each tortoise occupies a specific area which is called its home range. In east-central Florida, male tortoises have an average home range size of 1.9 ha (4.7 ac) and females have an average home range size of 0.65 ha (1.6 ac). The most important features of good tortoise habitat are sandy soil for digging burrows and nests, an open tree canopy so that plenty of sunlight reaches the ground, and small plants for food.|
The author placing a probe down a burrow to see,
on the little screen, what is down there.
Without a doubt, the burrow is the most important feature of gopher tortoise biology. In east-central Florida, burrows average 4.5 m (15 ft.) long and 2 m (6 ft.) deep. The tortoise digs the burrow at about a 30° angle from the surface. Having a burrow provides many advantages for the tortoise, such as protection from predators, fire, and the weather. The burrow has a fairly constant environment that is not too hot, too cold, too humid, or too dry. This is very important for a cold-blooded animal that is at the mercy of the elements. The open sandy area in front of the burrow, called the apron, is often used by the female tortoises for a nest site.
Each tortoise will dig and use several burrows within its home range. In east-central Florida studies, males used an average of 17 burrows, but some males only used eight burrows and some males used as many as 35 burrows. Generally, females don't use as many burrows as males. They averaged nine burrows, but used as few as three burrows or as many as 17. In the winter, both males and females maintain a smaller home range and use fewer burrows. Some burrows are visited at different times by several different tortoises. Sometimes, more than one tortoise will be in a burrow at the same time.
There are many factors in our world that threaten the gopher tortoise's existence. Several years ago, one of the biggest problems was that people enjoyed having tortoises as pets. They would take them from the wild and keep them at home. Even though these animals were usually treated well, they could not reproduce and add new tortoises to the population. Tortoise racing was also popular years ago, but the animals were rarely returned to their original home ranges after the races were over. Since becoming protected by the U.S. Fish and Wildlife Service and the Florida Fish and Wildlife Conservation Commission, keeping tortoises as pets, racing them, or removing them from their home ranges is illegal.
Today, the greatest threat to the survival of the gopher tortoise is habitat destruction. Tortoises can not live if they do not have undeveloped land with plenty of food and room to dig their burrows. Another less obvious threat that is related to development is land fragmentation. Buildings, roads, borrow pits, landfills, parking lots, and all other kinds of facilities break the natural habitat into pieces, resulting in fewer large parcels of land. It is difficult for a tortoise to go about its business without coming into contact with humans, or worse yet, their automobiles. Road mortality is believed to be one of the greatest causes of adult tortoise deaths.
NOTE: The vegetation is very thick and there is little open space ... no food for tortoises,
scrub jays or most other scrub inhabitants.
|In east-central Florida, land fragmentation has another effect that indirectly harms tortoises. When the land is broken up by concrete, it can no longer burn in a natural manner. Central Florida is the lightning capital of the United States, and in the summer months, severe thunderstorms can oftern start wild fires. Before so much of the area was developed and heavily populated, these fires could burn thousands of acres before they would go out. Now, when a fire starts sweeping across the landscape, it soon runs into something that acts as a firebreak, or it is put out by humans who need to protect their property. The phenomenon of a natural fire that is important to the health of the ecosystems can no longer happen. Without fire, vegetation grows very tall and thick. Little sunlight can reach the ground, and herbs that are the primary food source for tortoises can not live in the shade.|
Additional controlled burn information can be found in our articles on Scrub Ecosystems
and the Enchanted Forest Burn.
After a few years without fire, much of the habitat becomes unsuitable for tortoises. Even though the land appears to be "natural", it can not provide the things that tortoises need to live. The lack of fire is also detrimental to many other species of wildlife that depend on habitats that evolved with fire, such as the Florida scrub-jay, eastern indigo snake, and Florida scrub lizard.|
|It is too late to "let nature take its course" when it comes to fire. We can not go back to previous natural conditions that allowed the landscape to burn, so we must actively manage the land with fire. Many federal and state agencies have controlled burning programs on public lands that serve to keep the habitats healthy and in as natural a condition that can now be achieved. By burning individual parcels of the landscape at a time, there is plenty of habitat left for wildlife. Controlled burning also reduces fuel loads that can be very dangerous in the event of a wildfire.|
NOTE (in the picture): Open ground that is good for herbs to grow (i.e. tortoise food) as well as open sand for burrowing.
6 months after a burn.
Problem from Exotics
Another factor that has negatively influenced tortoise populations, as well as many other species of native wildlife, is the introduction of exotic plants and animals. Vegetation, such as Brazilian pepper, Australian pine, and melaleuca have been brought to Florida by humans, either purposely or by accident. They often are successful in our warm weather and good growing conditions, and soon take over much of the habitat that would normally belong to our native plants. Non-native animals such as feral pigs, cats, dogs, and exotic lizards also take a toll on wildlife by killing individuals, eating eggs and young, and competing with native species for resources.
The newest threat to gopher tortoise populations is Upper Respiratory Tract Disease (URTD). This extremely contagious and nearly always fatal illness is caused by the bacterium Mycoplasma agassizii. URTD was first discovered in gopher tortoises from Sanibel Island, Florida, in 1991, and has since been found throughout the tortoise's range in the southeast U.S. Symptoms include an inflamed respiratory tract, wheezing, runny nose, and swollen eyelids. An infected tortoise eventually starves to death because it can not find food or eat. A test that detects antibodies for URTD in tortoise blood has been developed, but so far, there is no vaccination against the disease, nor is there a cure. Tortoises that test positive for the disease (i.e. have been exposed to it) do not always show symptoms. URTD is spread between populations by the introduction of a diseased tortoise into a healthy population. We do not know if URTD was accidentally brought to the U.S. from somewhere else, or if it is a natural illness that is currently cycling.
What Can You Do For The Gopher Tortoise???
- Learn more about gopher tortoises and tortoise habitat so you can teach others. Good information sources include the library, zoo, and the Gopher Tortoise Council (below).
- Discourage your friends and neighbors from taking tortoises or moving them to new homes. Although a person might feel he is doing the right thing by rescuing a tortoise from a bad situation, there are many reasons why it is not a good practice. Any tortoise problems can be referred to the Florida Game and Fresh Water Fish Commission for resolution.
- Learn about the beneficial effects of fire and other management tools that can keep the landscape in a healthy state for our native plants and wildlife.
- Remember that conservation of land is not enough, because in order for land to truly be conserved, it must be properly managed.
- Last of all, be an informed, educated voter. Support city and county officials who value our natural resources as much as they value economic growth. With forward thinking and good planning, it is possible to have both.
The State of Florida (MyFlorida.com) has excellent information. In the Search Box, enter "Gopher Tortoise."
Try doing a search for Gopher Tortoise on any Search Engine. You'll find lots of interesting sites.
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