South American yellow-footed tortoise

Physical characteristics and appearance

Several yellow head scales and a horizontal bar behind its eye. The carapace (shell top) is black with a small, distinct yellow area around the areola on each scute (shell scale). Adult males reach a length of up to up to 13.5 inches (30.4 cm) in length, while the maximum size of females is 11.25 inches (28.9 cm) in length. Mature specimens have distinctive incurving of sides, giving them a well-defined "waist." The plastron (shell bottom) is a relatively bland yellow-brown; there may be some reddish tint and vague dark marks along areas of more recent growth. The plastron is extremely concave in adult males. Consequently, the male is much lighter than the female. The female has a very flat plastron and short, stubby tail. There is quite a bit of variation in coloring, with the legs and head often having patches of orange, yellow or red. The skin is black with bright yellow marks on the head and lower jaw. Many of the scales on the limbs and tail are bright scarlet. Specimens from west of the Andes have a grayish or brownish carapace. Light limb scales are yellowish or slightly orange, but not scarlet. The plastron ranges from predominantly yellow to black. Note: There is considerable variation in color over the range of the red-foot tortoise, so no one description will accurately describe every specimen.

Natural habitat

There is some disagreement as to which habitat is the preferred type for red-footed tortoises. Some feel that red-foots prefer grasslands and dry forest areas, and that rain-forest habitat is most likely marginal. Others suggest that humid forest is the preferred habitat. Regardless, they are found in drier forest areas, grasslands, and the savanna, or rainforest belts adjoining more open habitats. The red-footed tortoise shares some of its range with the yellow-footed tortoise. In ranges that are shared in Surinam, the red-footed tortoise has moved out of the forests into grasslands (that are a result of slash and burn agriculture) while the yellow-footed tortoise has remained in the forest.

Distribution

The Red-footed tortoise is found in extreme southern Central America, and central and northern South America including the countries of Panama, Colombia, Venezuela, Guyana, Surinam, French Guyana, Brazil, Bolivia, Paraguay, Argentina, and on several Caribbean islands.

Behavior

These turtles make a sound like a baby cooing with a raspy voice. Tortoises also identify each other using body language. The male tortoise makes head movements toward other males, but the females do not make these head movements. Male tortoises also swing their heads back and forth in a continuous rhythm as a mating ritual. Mating occurs all year round for the Yellow Footed Tortoise. There is no parental care of the young and the baby tortoises will fend for themselves, starting by eating calcium rich vegetables.

Diet

This South American tortoise eats many kinds of foliage. They are too slow to capture any fast animals. In the wild, their diet consist of grasses, fallen fruit, camion, plants, bones, mushrooms, excrement, and slow moving animals such as snails, worms, and others they are able to capture. In captivity, they are fed oranges, apples, bananas, hard-boiled eggs, kale, endive, collard greens, spinach, carrots, and alfalfa pellets. Each Yellow Footed Tortoise in the wild reaches the age of maturity at about 8-10 years. The fecundity of a female generally depends on the size, the bigger they are, the more eggs they can produce. On average, a female will create approximately 6-16 eggs per year, although some female individuals may not reproduce each year. The eggs have brittle shells and are elongated to spherical, approximately 3-6 cm in diameter. The egg size will increase with the body size of the turtle. The young are self-sufficient from birth. The Yellow Footed Tortoise can live for approximately 50-60 years. Geochelone denticulata is an endangered species. The major populations are located in South America, and they are protected under the Convention on International Trade in Endangered Species, also known as CITES (Appendix II).

Housing and husbandry

Even though red-footed tortoise are medium-sized, they still need a large area or enclosure to roam in. Three square yards (2.7 square meters) per tortoise is recommended. Red-foots seem to do best when housed outside in areas where the relative humidity is moderate to high, and nighttime temperatures do not drop below 50 degrees F (10 degrees C). If housed outside, the tortoises must be provided with shaded shelter areas. Red-foots prefer to spend the majority of their time underneath bushes or tall grass (make sure the vegetation is non-toxic). The tortoises must be provided with a shallow pool of clean water they can soak in and drink from, as red footed tortoises are not aquatic, they do not require a deep pool of water for captive purposes. If a breeding group of five animals is housed indoors, their enclosure must be at least 15 square yards (13.5 square meters). Indoor enclosures can be constructed from a variety of materials, but the bottom material should always be water resistant. Concrete floors are not recommended because they tend to be very cold and have been reported to cause prolapse of ######### in male red-foots. The sides of the enclosure should be at least three feet (.9 meters) tall or taller to prevent the tortoises from crawling out. For substrate, a mixture of peat moss and playground sand works well. For juveniles while kept in smaller enclosures, newspaper may be a safer substrate (less likely to consume, and easier to clean). The tortoises should be provided with hiding and humidity areas. An easy way to accomplish this is to bury a tall plastic trash container horizontally in the substrate so that a tortoise could fit inside. Moisten the substrate inside the hiding area to increase the humidity. The cool end of the enclosure should be 70-75 degrees F (21 to 24 degrees C) and the heated end should be 85-88 degrees F (29 to 31 degrees C). Make sure to provide several heated areas so the tortoises do not have to compete for basking sites. The nighttime temperature can drop to 55-60 degrees F (13 to 16 degrees C), but have some supplemental heating available at 80 degrees F ( 27 degrees C). Full Spectrum lighting that emits UVB should be suspended over the enclosure to promote the synthesis of vitamin D3 ,which is necessary for calcium absorption. It is best however, to allow the tortoises access to unfiltered, natural sunlight, weather permitting. Many breeders house their tortoises outside during the spring and summer, and bring the animals indoors during inclement weather and the fall and winter months. Red-footed tortoises do not hibernate and cannot tolerate extended periods of cold temperatures. A large, shallow water pan should be available at all times.

Reproduction and growth

Breeding is synchronized with the onset of the rainy season, (from July to September) where a general increase in activity is noted. Males identify each other eliciting a characteristic head movement, a series of jerks away from and back to mid-position. Another male will make the same head movements. If he gets no head movement in response, it is the first indication that the other tortoise is a female. Scientific experimentation and observation has also indicated that the head coloration has to be correct. He will then sniff the cloacal region of the other tortoise. Copulation usually follows, though sometimes there is a period of biting at the legs. During courtship and copulation the male makes clucking sounds that sound very much like a chicken. There is a set pattern in pitches of the clucking sounds. Rival males will battle, attempting to overturn each other, however neither the males or females will defend a territory. They are considered nomadic in their movements. It is interesting to note than in almost every tortoise species where male combat occurs, the males are always larger than the females. This is in comparison to aquatic species, where the males are usually smaller than the females and do not engage in male to male combat. It is thought that species with male combat evolved larger males because larger males have a better chance of winning a bout and mating with a female, thus passing on their larger size to their offspring. Species with smaller males evolved because smaller males are more mobile and can mate with a large number of females, thus passing on their genes.

Nesting

The female will lay a clutch of 5 to 15 eggs from July to September in excavations or deposited in leaf litter. She might lay several clutches during the nesting season. The eggs have brittle shells and incubation is generally from 105 to 202 days (mean 150), depending on the temperature. Hatchlings are round, flat, 1.5 inches in diameter. Unlike the yellow-footed tortoises, they do not have tooth like projections on their shells. Red-footed tortoises, and many other tortoise species, are slow to mature and do not reach sexual maturity for several years. This, coupled with a relatively low clutch size, makes the red-footed tortoise susceptible to over hunting. With over hunting, more sexually mature animals are removed from the population than can be replaced by maturing juveniles, consequently, the overall population begins to decline. Conservation efforts include the establishment and protection of wildlife reserves and national parks, where red-footed tortoises and other animals are protected from hunting.

Wild population

The population is very little outside of conservation.

uggested reading

*Alderton, David. Turtles and Tortoises of the World. New York: Facts on File Publications,1988.
*Halliday, Dr. Tim, and Dr. Kraig Adler, eds. The Encyclopedia of Reptiles and Amphibians. New York: Facts on File Publications, 1986.
*Hagan, J.W. "What's the Difference: Differentiating Geochelone denticulata and Geochelone carbonaria Tortuga Gazette 1989. [http://www.tortoise.org/archives/carbdent.html]
*Ward, B. Sedgwick County Zoo. 2 May 2001. [http://www.scz.org/animals/t/satort.html]