Geochelone sulcataAfrican Spurred Tortoise
Geographic Range
The African spurred tortoise (Geochelone sulcata) occurs along the southern edge of the Sahara, from Senegal and Mauritania east through Mali, Niger, Chad, the Sudan, Ethiopia, along the Red Sea in Eritrea.
Habitat
The Sulcata tortoise lives in hot, arid environments of the Sahelian type. These areas range from desert fringes to dry savannahs. Standing water is only around for limited amounts of time. Much of it's range has been disturbed by urbanisation, domestic animal grazing, and desertification.
- Terrestrial Biomes
- desert or dune
- savanna or grassland
Physical Description
G. sulcata is the largest of the African mainland tortoises. Only the Galapagos tortoises are larger. These tortoises have broad, oval, flattened carapaces that are brown to yellow in color. The carapace is flattened dorsally, with abruptly descending sides and a deep cervical notch. The anterior and posterior marginals are serrated, and the posterior marginals upturned. They do not have a cervical scute. The plastron is ivory colored with divided anal scutes and paired forked gulars. They have growth rings on the scutes that are strongly marked with age. Skin color is golden to yellow-brown and very, very thick. Mature males usually develop reverted marginal scales in the front. The large scales on the front legs overlap. On the rear legs, there are spurs which are not known to serve any particular purpose.
Their head is moderate in size, with a slightly hooked upper jaw and nonprotruding snout. It is brown, with the jaws being a slightly darker brown. Externally, it is hard to tell males from females. Males have slightly longer, thicker tails and a more concave plastron, but otherwise appear similar to females.
- Other Physical Features
- ectothermic
- bilateral symmetry
-
- Range mass
- 36 to 50 kg
- 79.30 to 110.13 lb
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- Average mass
- 0.043 kg
- 0.09 lb
Reproduction
Sulcatas breed very well in captivity. Males reach sexual maturity when their carapace is about 35 cm in diameter. Sulcatas are very aggressive toward each other, especially during breeding time. Males ram each other repeatedly and sometimes end up with bloody limbs and heads. Copulation can take place anytime from June through March. However, it occurs most frequently after a rainy season in September through November. When mating, the male first circles the female and will occasionally ram her with his shell.
After mating, the female's body will swell with eggs and she will decrease her food intake. She becomes increasingly restless as she looks for good places to make a nest. Nesting season is in the autumn. She begins by kicking loose dirt out of the way and eventually creates a depression, which she urinates in. She digs until the depression reaches approximately 0.6 m in diameter and 7-14 cm deep. This may take her up to five hours. Four or five nests may be dug before she finally selects one to lay her eggs in. Once she selects one, an egg is laid every three minutes. Her clutch size may reach 15-30 eggs, sometimes more. The eggs are white and spherical with brittle shells. After the eggs are laid, the female will fill in her nest. It may take her more than an hour to cover all the eggs up.
The eggs incubate underground for about eight months. When they hatch, the tortoises are only 4-6 cm in carapace length. They are oval-shaped and weigh less than 25 gm. They are yellow to tan with rounded, serrated carapaces.
- Key Reproductive Features
- gonochoric/gonochoristic/dioecious (sexes separate)
Lifespan/Longevity
-
- Average lifespan
Status: captivity - 54.3 years
- AnAge
- Average lifespan
Behavior
Sulcatas are very aggressive towards each other. This aggression starts from the time they hatch. Ramming into each other and attempts to flip each other over are common behaviors by males.
Sulcatas like to burrow and are well adapted at doing it. They are very strong and active tortoises and when the weather gets too hot or too cold for them, they retreat to a burrow. This also helps them to avoid dehydration, since they depend mainly on metabolic water and the moisture in food for water. They will stay in their burrow for hours and if mud is available, they will flip it onto their backs. When temperatures reach more than 40 C, they salivate and smear the saliva on their forearms to help with cooling.
They are most active at dusk or dawn and generally bask in the morning to raise their body temperature after the chill of the night.
- Key Behaviors
- motile
Food Habits
Geochelone sulcata is a vegetarian. It relies on succulent plants for food and much of its water. In captivity, it will eat a variety of grasses, lettuce, berseem, and morning-glory leaves.
Economic Importance for Humans: Positive
Sulcatas are popular in the pet trade due to the fact that they can breed very well in captivity.
Conservation Status
Many populations of G. sulcata are rapidly disappearing, especially in Mali, Chad, Niger, and Ethiopia. In Senegal there are still limited populations in the north and north-east, but there is a lot of overgrazing and desertification here too that is wiping this tortoise out.
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- IUCN Red List
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Vulnerable
More information
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- IUCN Red List
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Vulnerable
More information
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- US Federal List
- No special status
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- CITES
- Appendix II
Other Comments
Some African cultures regard the Sulcata as a mediator between men and the gods. As a result, the tortoise is often kept in villages to intercede between the Head of the village and the Ancestors. In Dogon countries today, the tortoise is kept with the village leader at all times to allow him to communicate with the village ancestors.
In Senegal, these tortoises, are signs of virtue, happiness, fertility, and longevity. Therefore, it is easier to promote programs that support the conservation of the tortoise. The Senegalese respect the symbolic nature of the tortoise and are very important in helping conservationists ensure reproduction and repopulation of it.
Contributors
Andria Harrold (author), Bethel College, Andria Harrold (editor), Bethel College.
Glossary
- Ethiopian
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living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- desert or dunes
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in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.
- ectothermic
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animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- motile
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having the capacity to move from one place to another.
- native range
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the area in which the animal is naturally found, the region in which it is endemic.
- tropical savanna and grassland
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A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
- savanna
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A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
- temperate grassland
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A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
References
Ernst, C., R. Barbour. 1989. Turtles of the World. Washington D.C., and London: Smithsonian Institution Press.
Fedorchuck, W. 1999-2000. "African Spurred Tortoise Profile and Maintenance Guide" (On-line). Accessed April 5, 2001 at http://www.tortoiseaid.org/sulcata.html.
Harless, M., H. Morlock. 1979. Turtles: Perspectives and Research. New York and Canada: John Wiley & Sons, Inc..
Kaplan, M. 1996. "Sulcata Tortoises" (On-line). Accessed April 5, 2001 at http://www.anapsid.org/sulcata.html.
The Turtles' Village of Senegal, December 9, 1997. "Biology et Ecology of Geochelone sulcata" (On-line). Accessed April 25, 2001 at http://gallery.uunet.be/FRD/ebiosulc.htm.