The red-footed tortoise (Chelonoidis carbonarius) is a species of tortoise from northern South America. These medium-sized tortoises generally average as adults, but can reach over . They have dark-colored (nearly black), “loaf”-shaped carapaces (top shell) with a lighter patch in the middle of each scute (shell segment), and a somewhat lighter-colored plastron (underbelly). They also have dark limbs dotted with brightly-colored scales, from which they get their name, that range from pale yellow to vivid or dark red. Visible differences are noted between red-footed tortoises from varying eco-regions. They are closely related to the more easterly-distributed yellow-footed tortoise (C. denticulatus) of the Amazon Basin.
Their natural habitat ranges from savannah to forest edges around the Amazon Basin. They are omnivorous tortoises, consuming a wide assortment of plants, grasses, flowers, fruit and (notably) fungi, as well as the occasional earthworm or other invertebrate. When presented with the opportunity, many tortoises will also scavenge on carrion. They do not brumate, due to their equatorial home range, but may aestivate in the hotter, drier months.
Red-footed (and yellow-footed) tortoises are popularly kept as pets. Over-collection of eggs, and the capturing of mature animals, from their native habitat has caused them to be listed as “vulnerable” to extinction, despite the relative ease of captive breeding and the availability of captive-bred tortoises. Additionally, many remote tribal groups living in South America still consider the tortoises a basic source of meat, and many are unaware of the species’ overall plight; many travelers and activists report seeing live red-footed tortoises for sale in markets where bushmeat and live animals are sold. Eggs, hatchlings, and even mature tortoises are food for many animal predators, including caimans, crocodiles and giant otters (if near water), as well as birds of prey, bushdogs, jaguars, jaguarundis, margays, certain monkeys, ocelots, pumas and tayras. Population density ranges from locally common to very scarce due, in-part, to habitat destruction and the aforementioned over-collection for food and the pet trade.
The species name has often been misspelled as carbonaria, an error introduced in the 1980s when Chelonoidis was elevated to genus and mistakenly treated as feminine, an error recognized and fixed in 2017.
Names Red-footed tortoises have many common names: red-leg, red-legged, or red-foot tortoise (often without the hyphen) and the savanna tortoise, as well as local names, such as carumbe or karumbe, which means 'slow moving' (Brazil, Paraguay), wayapopi or morrocoy (Venezuela, Colombia), and variations of jabuti such as japuta and jabuti-piranga (Brazil, Argentina). p. 27-29. In Portuguese, jabuti (jaboti) refers to both the red-footed tortoise and the yellow-footed tortoise.
It is also called kati in NatúPompeu Sobrinho, Thomaz. 1958. Línguas Tapuias desconhecidas do Nordeste: Alguns vocabulários inéditos. Boletim de Antropologia (Fortaleza-Ceará) 2. 3-19. and sambó in Kiriri.
Taxonomy
Red footed tortoises were originally assigned to the genus Testudo (named by Carl Linnaeus in 1758) for a short time, but it soon became the term for turtles with high-domed shells, elephantine legs, and completely terrestrial habits—the tortoises. In 1835, Leopold Fitzinger used Geochelone to differentiate some non-Mediterranean tortoises, apparently based on size and lack of specific identifying characteristics such as the hinged shell in the African hingeback tortoises. He used the term Chelonoidis as a subgenus for the species from South America. Few people used these terms until they were resurrected by Hewitt in 1933 and Loveridge and Williams in 1957.
In 1982, Roger Bour and Charles Crumly each separated Geochelone into different genera based on anatomic differences, especially in the skulls. That resulted in the formation or restoration of several genera: Aldabrachelys, Astrochelys, Cylindraspis, Indotestudo, Manouria, and Chelonoidis. Chelonoidis was distinguished from other Geochelone by their South American location, as well as the absence of the nuchal scute (the marginal centered over the neck) and the presence of a large, undivided supracaudal (the scute or scutes directly over the tail), as well as differences in the skull. Many of these generic names are still debated; for example, no specific definition of Geochelone is given, and Chelonoidis is primarily used for geography rather than unique anatomic characteristics., p. 204.
The species name carbonarius means 'coal-like' referring to a dark coal with glowing patches. It was originally identified by Johann Baptist von Spix in 1824. The holotype was kept in the Zoologischen Sammlung des Bayerischen Staates in Munich, Germany, but was lost. Paulo Vanzolini believes it may have come from near the city of Manaus, Brazil, on the Rio Negro. No subspecies of red-footed tortoise are recognized, although many believe the species has five or more variants that may be subspecies or even separate species.
Description Red-footed tortoises show sex, regional, and individual variations in color, shell shape, and minor anatomical characteristics. Adult carapaces are generally an elongated oval with sides that are nearly parallel, although the sides of males may curve inwards. They are fairly highly domed and smooth with a rather flat back (although the scutes may be raised or 'pyramided' in some individuals, especially captive specimens). Often, a high point over the hips is seen, with a small sloped section over the neck. The vertebral and costal scutes (the scutes along the center and sides of the carapace) are black or dark brown with a pale yellow areole in the center. The marginals (scutes along the edge of the carapace) 'tuck under' along the sides and flare slightly over the limbs. They are dark with the pale aureole along the middle of the lower edge. The nuchal scute (the marginal over the neck) is absent, and the marginals over the tail are joined as one large supracaudal. Growth rings are clearly evident in most individuals, but become worn smooth with age.
The plastron (bottom shell) is large and thick along the edges. The gulars (frontmost pair of plastron scutes) do not protrude much past the front of the carapace. The plastron of a male is deeply indented, and the anal scutes (rearmost pair of plastron scutes) may be used to sex the animal while the color pattern varies by region.
The head is relatively small with a squared-off profile and flat on top, longer than it is wide. The eye is large with a brown, almost black iris, and rarely any sclera visible around it. The upper jaw is slightly hooked, and the upper jaw is notched in the front middle. About 15 to 20 'teeth' or fine grooves occur on each side of each jaw. A nearly circular tympanum is located behind and below the eye and is covered with a dark scale. The scales of the head are generally smallish and irregular, becoming small and pebbly on the neck. Many of the scales are colored pale yellow to brick red, especially those on the top of the head, above the tympanum, around the nostrils, on the lower jaw, and on the sides of the neck. Males are usually slightly more colorful than females, and colors vary by region.
The limbs are generally cylindrical with five claws on the fore limbs and four on the hind, but no visible toes. The fore limbs are slightly flattened and the front surface is covered with large scales, mostly with the same color as the head. They are not as large or protrusive as they are in more primitive species such as the African spurred tortoise (Geochelone sulcata). The tail is muscular, varies in length and overall shape by sex, and lacks any sort of claw on the tip.
Average adult sizes vary by region and sex, and 'giants' are often encountered. Red-footed tortoises average with males slightly larger overall. Tortoises up to are fairly common and over are occasionally discovered. The largest known specimen, from Paraguay, was long, and weighed over . It is unknown if the 'giants' represent diet availability, genetic issues, longevity, or other possibilities.
Hatchling and young red-footed tortoises have much rounder and flatter carapaces that start off as mostly pale yellow to brown. New growth adds dark rings around the pale center of each scute. The marginals of very young tortoises are serrated, especially over the hind limbs. This probably aids in both camouflage against the leaf litter and in making the small animals harder to eat. Young tortoises are generally more colorful overall.
Males are slightly larger and more colorful overall. The carapace of a male from north of the Amazon basin shows a 'wasp waist', or constrictions along the sides. The male's plastron is deeply indented to help with positioning during mating. The male's tail is long and muscular, generally carried along a side while the female's tail is short and conical.
The anal scutes vary to allow the male's tail more mobility and allows more protection for the female's hind end. The gap between the points of the anal scales and the marginals is wider and the anal scutes form a broader angle—almost a straight line across—in males to allow the tail to move laterally. The angle is more closed (to about a 90° angle) and the points are closer to the marginals in females.
Distribution and habitat
Red-footed tortoises range from southeastern Panama to Venezuela, Guyana, Suriname, and Guiana in the north; south along the Andes to the west in Colombia, Ecuador, Peru, and Bolivia; east to Brazil, and along the southern range in Bolivia, Paraguay, and possibly northern Argentina. In Panama they live from the Darien Gap to the canal. They are not evenly distributed within their range. For example, they are not often found in central Brazil or in heavily forested areas in general, and have only documented in Peru since 1985. Accurate range information is complicated by the sheer size of the range, political and geographic barriers, and confusion about where many specimens were collected.
They are also found on several Caribbean Islands, although it is not always clear if they are native or brought by humans. Many of the colonies seem to have been established in the 17th century as food supplies or as pets. They are found on the former Netherlands Antilles, Trinidad, Tobago, Grenada, Barbados, St. Vincent, the Grenadines, Santa Lucia, Martinique, Dominica, Guadalupe, the Leeward Islands, the Virgin Islands, Barbuda living in sink-holes forests and Puerto Rico.
The preferred habitat of the red-footed tortoise varies somewhat by region, but generally includes fairly consistent seasonal temperatures near that rarely get lower than or over , generally with high humidity and plenty of rainfall, although some of the areas can get quite dry. Most of the range experiences cooler wet seasons (April to August) and warmer dry seasons (September to March), but some parts of the southern range have occasional cold snaps. Red-footed tortoises are often found in or near transitional areas between forest and savannah, such as forest clearings, wood edges, or along waterways.
Regional variations Various authors have divided the red-footed tortoise into different groups by anatomy and geography. Peter Pritchard recognized seven types, but DNA research has identified five genotypes.
The most obvious differences are between the groups found north or south of the Amazon basin. The 'northern' variants all look very much like the holotype and are distinguished primarily by shell, head, and limb coloration. The variants south of the Amazon are generally both larger and smaller than the holotype, have a very different plastral pattern, and have an enlarged scale or 'spur' on the inside of the fore limb elbow.
Northeastern variant