African Spurred Tortoise
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 Juvenile sulcata tortoise, Geochelone sulcata
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| Geochelone sulcata (Miller, 1779) |
The African Spurred Tortoise, also called the African Spur Thigh Tortoise, most commonly called Sulcata tortoise, is a species of tortoise which inhabits the southern edge of the Sahara desert, in northern Africa. Their diet provides them with most of their water requirements, but they do drink. They coat their skin with mud when available to cool off. When mud wallows are not available, they retreat to cooler burrows. Spurred tortoises are important to deserts because their burrows provide shelter for other animals. They do not hibernate, unlike many other types of tortoises, due to their natural environment being so close to the equator, and therefore temperate throughout the year. Though they are known to hibernate in climates colder than their natural habitat. They love to dig, and make very long burrows, often much damper than the ground surface, which other species frequently sublet, making dens in alcoves off the main burrow.
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[edit] Captivity
Due to the availability of these animals in the pet trade, and due to their reputation for having a pleasant temperament, more and more sulcata tortoises are brought home as pets, in fact they are officially the second most common pet tortoise after the Mediterranean Spur-Thighed. However, these animals provide significant challenges to their keepers, due to their dietary and temperature requirements, and their size. For one thing they make quite effective battering rams at 100 lb or more. They are very powerful and very persistent if they think you have something tasty in your house or on the other side of the fence.
They require high fiber diets (grass) as many "wet" vegetables can cause health problems in large quantities. Red leaf lettuce, prickly pear cactus pads, hibiscus leaves, hay from various grasses and dandelions are some of the better foods to make up the bulk of their diet. They will attempt to eat most types of plants eventually and some common garden plants can be very toxic to them, such as azaleas. They will eat such things as caterpillars and snails if given the opportunity, but this also should be a very small portion of their diet. Sulcatas need a large enclosure as they get bigger and should be given a generous grazing area. Sulcatas should be kept above 60F, which means most areas will require special winter accommodations.
Unfortunately many people do not research them properly and purchase them without an understanding of the responsibility they are taking on. This is compounded by the relatively low price for a large exotic tortoise.
Per CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora), a zero annual export quota has been established for Geochelone sulcata for specimens removed from the wild and traded for primarily commercial purposes.
[edit] Diet
A captive diet for G. sulcata should be organized around five important factors: high dietary fiber, low protein, low fruit or sugary foods, adequate calcium, and not overfeeding.
The sulcatas' native habitats are semi-arid, and the plants available to this terrestrial herbivore are primarily dry grasses and weeds. Grasses should make up at least 75% of a captive sulcata's diet, to provide the high dietary fiber found in the wild.
Protein is lacking in their natural diet. A captive diet with a high protein content will quickly overpower the tortoise's renal system, as unused amino acids in the bloodstream are strained out and deposited in the kidneys. A misconception exists that high protein causes pyramiding, it instead causes increased growth rates. Environmental humidity instead has the greatest effect on pyramidal growth. Sulcatas kept in high temperatures combined with high humidity have virtually no pyramiding. Lack of calcium and high protein do contribute to some of the shell malformations and defects. Fruit, and other sugary foods not present in their natural diet can be harmful to the tortoises if they change the pH balance of the sulcata's gut. If the pH changes kill off their intestinal flora, they can be subject to toxic shock, which can be fatal.
Young sulcatas grow very fast - they can easily double in size each year during the first three years. For proper bone and shell development, their diet must include adequate calcium. In the wild, this is provided by a high calcium content in the soil, and therefore in their diet, but in captivity calcium supplementation is required.
Last, the diet that is available to captive sulcatas can be much more nutritious than in the wild, which offers its own challenges. Sulcatas are naturally voracious, to offset the dearth of nutrients in their habitat; care must be taken to insure the tortoise does not overfeed. Bedding, or other plant material in their enclosures, should be restricted to grasses or grass-based hay, to ensure that the animal does not take in too much nutrition.
[edit] Temperature and Humidity
Coming as they do from the southern Sahara, G. sulcata is well adapted to hot, dry climates. They derive most of their moisture from their diet, and they regulate their temperature and humidity needs by retreating into burrows. Most sulcatas, especially hatchlings, spend much of their time in these burrows, and the humidity requirements for hide boxes in captivity are higher than might be expected - around 40-60%. In other words, no special care needs to be taken to ensure their areas are dry enough - in reality, care must be taken to humidify their enclosures, as hatchlings especially are prone to dehydration.
In much of the United States, their temperature requirements are of greater concern to their keepers. Given their large size, sulcatas are most easily kept out of doors, but should not overnight outside when the temperatures drop below 60 degrees Fahrenheit. As this describes most of the US, especially during winter, prospective sulcata keepers may find housing them to be impossible after their first few years of age.
[edit] Size and Lifespan
The Sulcata is the third largest species of tortoise in the world, and is the largest of the mainland tortoises. Adults are usually 18 inches in shell length, and weigh 70 to 100 pounds. Specimens with 24 to 36 inch long shells weighing 150 pounds are not unknown. They grow from hatchling size (2-3 inches) very quickly, reaching 6-10 inches within the first few years of their lives. An adult sulcata will need a great deal of space. The oldest known of this species was 56 years old although it is believed they can live up to about 80 years.
[edit] References
- Tortoise & Freshwater Turtle Specialist Group (1996). Geochelone sulcata. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 11 May 2006. Listed as Vulnerable (VU A1cd v2.3)
[edit] External links
- ARKive - images and movies of the African spurred tortoise (Geochelone sulcata)
- Sulcata Tortoise - also known as African Spurred Tortoise. Care Sheet and Pictures
- CITES - the Convention on International Trade in Endangered Species of Wild Fauna and Flora
- Spurred Tortoise care sheet - Housing, feeding and temperature information
