Natural History

The Red-footed Tortoise (Chelonoidis carbonaria, Spix, 1824) is a medium to medium-large species that is found in much of the northern half of South America, into Panama and on several islands, including some where they have been introduced. They are commonly kept as pets, but there is still much we do not know about them.

Yellow-footeds are a true rain forest species, well adapted to the darker, more humid forest floor where little of the available food holds much nutrition and there is much competition for it. They share some locales with the more savanna-dwelling Red-footed, but the Red-footed generally prefer openings, edges, grasslands, etc.

Taxonomy and Fossil History

Red- and Yellow-footed Tortoises are known by several common names such as Red-leg, Red-legged or Red-foot Tortoise and the Savanna Tortoise, as well as by many local names, such as “morrocoy” (Venezuela, Colombia) and  variations of “jabuti” such as “japuta” and “jabuti-piranga” (Brazil).  [Vinke 2008, pp. 27-29] For the purposes of this website, we will use Red-footed or Yellow-footed tortoise as the default term.

The currently recognized genus name Chelonoidis means “turtle-like”. The genus name of Geochelone (“earth turtle”) was initially used by Leopold Fitzinger in 1835 to differentiate some tortoises from the rest of the turtles. The name was not widely used until people like Hewitt (1933) or Loveridge and Williams (1957) resurrected it to apply to various Indian, African, and South American Tortoise species. [Pritchard 1984, pp. 201-204; Vinke 2008, p. 16]. Before this, J. B. von Spix used ‘Testudo‘ to refer to all Chelonians.

The Red-foot species name carbonaria means “coal-like”. [Vinke 2008, p.16 and 24]. Yellow-footeds are denticulata, which refers to the tooth-like serrations on the hind end marginals.

In 1980, Roger Bour argued that based on anatomical characteristics, several tortoise groups should be separated from Geochelone to their own genera, including Aldabrachelys, Astrochelys, CylindraspisIndotestudoManouria, and the South American Chelonoidis. Two typical characteristics of Chelonoidis are a lack of a nuchal scute (the marginal over the neck) and a large undivided supercaudal scute (the marginals over the tail). Not everyone agrees with this ranking, preferring to use Geochelone for most or all of these tortoises. [Pritchard 1984, p. 204; Vinke 2008, pp. 16-17].

Chelonoidis includes two sub-groups: the carbonaria-group with the Red- and Yellow-foot tortoises, and the very different looking chilensis-group with the Galapagos tortoise (Chelonoidis niger) and the Chaco tortoise (C. chilensis), which do not seem to be closely related genetically.  The relationship between these two groups is unclear, as they do not seem to share a common fossil history in South America and may represent two or three separate colonizations. [Vinke 2008, pp. 101-105; Vargas-Ramirez 2010] DNA evidence also suggests that the carbonaria-group may be more closely related to the African Hinge-back Tortoises (Kinyxs species) than they are to other Geochelone or Chelonoidis species. [Le 2006].

The earliest known carbonaria-group fossil is Chelonoidis hesterna (Auffenberg 1971)The current theory is that as the rain forest and savannas of the region changed over time, C. hesterna split about 13.3 million years ago in the Miocene, with the Red-footed Tortoise generally colonizing the outer, more savanna-like habitats and the Yellow-foot mostly colonizing the central rain forest basin.  [Vinke 2008, pp. 101-104; Vanzolini 1994; Vargas-Ramirez 2010]. DNA studies suggest that the Red-footed Tortoise formed five distinct populations during this time that may be recognized as sub-species or true species with further investigation.  [Vargas-Ramirez 2010].

Description

Red-footed Tortoises

Although there are no currently recognized sub-species of red-footed tortoise, mitochondrial DNA research suggests that there are five distinct phylogeographicclades that may qualify [Vargas-Ramirez 2010]. Other authors have also theorized that there are up to seven types or races over their large territory [Pritchard 1984, pp. 214-216]. There are some significant and consistent differences between the types, but the holotype from Venezuela, Guyana, Surinam, French Guiana, and the northern edge of Brazil is representative of the most commonly seen clade, race or type [Vinke 2008, p. 30].

The adult carapace is elongated, often called “loaf-shaped” compared to the more “bowl-shaped” shells of young Red-footed Tortoises or that of many other species. It is smooth with distinctive growth rings on each scute, although each scute can form conical projections, called”‘pyramiding”, in some conditions. The front of the carapace is slightly sloped, and the back end is rounded down to protect the tail. Depending on the type or gender, the back is either generally level or slightly peaked at each end. As with all members of Chelonoidis, there is no nuchal or cervical scute and the supercaudal scute is wide and undivided. The marginals are smooth-edged and ‘tucked in’ in adults [Pritchard 1984, pp. 207-208].

There is a pale yellow to reddish orange areola in the center of each scute, with the surrounding color ranging from dusty brown to deep black. There are also variations ranging from very pale to all black. Some coloration patterns can suggest specific regions, but there is also much variation within a single nest [Pritchard 1984, p. 210; Vinke 2008, p. 63].

The plastron is also elongated and curves up at the anterior and posterior to more fully protect the tortoise. The gular scutes are smallish, thickened and do not project forward of the carapace. The pectoral scutes share a very short seam, and the abdominals are very wide. The anal scutes tend to come close to the marginal making  a very narrow opening for the hind legs and tail. The bridge is wide and blends smoothly into the marginal. The plastron base color is a pale yellow that may show darker markings that are often symmetrical. The plastron markings can also help identify some clades [Pritchard 1984, p. 210].

From above, the head is triangular and longer than it is wide. The upper jaw is slightly hooked, and there is a strong central tooth-like point in the lower jaw that is hidden when the mouth is closed. The chewing surfaces of each jaw have about twenty grooves or ridges. The nares are close together and fairly high on the snout.  The eyes are black, sometimes with a whitish ring around them. The tympanum is oval, sitting behind and below the eye, separated by the postsubocular scale and covered with dark skin  [Pritchard1984, p. 210].

The scales of the head and neck are generally small and variable, usually with a largish frontal scale between the top of the eyes. The skin between scales is a dark grey to flat black, getting paler closer to the base of the neck. The scales of the head can vary from pale yellow to orange, red, dark red, or even near-black  [Pritchard 1984, p. 210].

The front of a Red-footed Tortoises’s slightly flattened forelimbs are covered with heavier overlapping scales, usually in the same color patterns as the head and neck. The scales are much smaller than the same scales on many other species. There are five claws on the end of each forelimb that often wear down to nubs as the tortoise grows.  Red-footed Tortoises from south of the Amazon rain forest have an enlarged spur on the inside of each “elbow” that they can use to help bend plants over [Pritchard 1984, p. 210; Vinke 2008 p. 158].

The hind limbs are rather small and elephant-like with fewer scales and four claws. Because of the way the shell curves over the back end, the hind limbs have a more limited range of motion than many other tortoise species. The Red-foot Tortoise’s tail is a rather large, flat triangular with no terminal claw or spine. It is covered with flat scales the color of those on the hind limbs, arranged linearly on the upper surface [Pritchard 1984, p. 210].

A “typical” adult Red-footed Tortoise averages 30cm/12in straight-line carapace length and 8kg/17.5lb, although this varies by type and gender (males are generally larger than females) [Pitchard 1984, p. 211]. The largest known Red-footed Tortoise was a captive originally from Paraguay or Bolivia that reached 60cm/23.5in and 28kg/61.7lbs and specimens over 40cm/15.75in are often found [Vinke 2008, p. 71].

Sexual dimorphism is seen in overall size with males being larger than females, contrary to the pattern seen in many tortoise species. It is also evident in the carapace shape with males, especially from the northern regions, showing stronger indentation along the sides of the shell as well as a slight concave curve along the central scutes. Male plastrons are deeply indented, and their tails are much longer than the female’s.  The posterior opening of the male is also wider, presumably to allow freer movement of the tail in mating [Pritchard 1984, p. 210].

Yellow-footed Tortoises

Yellow-footeds are bigger than Red-footeds, reaching 20in/50cm routinely and have hit 28in/71cm, making them one of the largest mainland species. The colors include more browns and yellows than blacks and oranges, but they look enough alike that people are often fooled and they were even considered the same species for some time (Testudo tabulata, etc.). One key anatomical difference is the “toothed” marginals at the back of the carapace. Young Red-footeds often show some “denticulation”, but they quickly grow out of it. On the other hand, it often “smooths over” in larger Yellow-footeds as well.

Differentiating Red- and Yellow-footed Tortoises

The following table can help identify the two species. Not all characteristics are present in all individuals:

Yellow-footed

Feature

Red-footed

Chelonoidis denticulata

Latin Name

Chelonoidis carbonaria

Amazon drainage basin,

North-central South America

Range

Panama to French Guiana, south to
Brazil, Bolivia, Paraguay

Humid rainforest

Habitat

Rainforest, forest edge, scrub grasslands
     

Pointed nose with black tip

Head Shape

Rounded nose with colored tip

Pre-frontal1 divided “nose to neck”

Head Scales

Pre-frontal1 divided “eye to eye”

Olive brown, less contrast to pale areas

Shell Color

Dark with sharp contrast to pale areas

Faint (except in very young)

Growth Rings

Prominent (except in very old)

Jagged or “toothed’ over hind legs

Shell Margin

Smooth (except in some young ones)

Gular scutes3 protrude in males

Plastron

Gular scutes3 do not protrude

Narrow

Anal Notch4

Wide

Large scales, mostly yellows

Limbs

Small scales, usually some red shades

Male

Female

  Male Female

Oval

Round

Body Shape

Wasp-waist1 Oval

Flat-topped shell

1 Hump on shell

Body Profile

2 Humps on shell Flat topped shell

16”/40cm

22”/56cm5

Average Length

14”/35cm 12”/30cm

20”/50cm

29”/73cm

Largest Known

20”/50cm  


Notes:

  1. “Pre-frontal” refers to the scales between the eyes on top of the head
  2. “Wasp-waist” refers to a “pinched-in” look in the middle of the shell.
  3. “Gular scutes” are the scales under the chin on the plastron
  4. “Anal Notch” refers to the opening between the shell back and plastron. Also called the “tail opening”
  5. This species is sometimes called the South American or Brazilian Giant Tortoise because of the size.

The difference in care is all based on the difference in habitat. Yellow-footeds like subdued light, steady temps in the 85ºF/29ºC zone with high overall humidity, 95%+.  They like warm rains and it may help trigger eating and mating.  Yellow-footeds are also generally more shy and reclusive than Red-footeds.  They avoid denning in holes that can flood, and often lay their thicker-shelled eggs on the ground instead of digging a nest.

As a rule of thumb, scientists say that reptiles with small, fine scales evolved more recently than those with heavier scales.  This, combined with the ranges and habitats used, would point towards the Red-footed being an offshoot of the Yellow-footed.

It is not always easy to tell these species apart without careful study.  Here are two excellent articles about this topic:

 

Distribution and Habitat

Range map

Red-footed Tortoise

These are found in much of the northern half of South America. Other than the population in Panama and part of Columbia, most of the range is to the east of the Andes Mountains to the Atlantic Ocean, from the Caribbean Sea south to the Tropic of Capricorn. They are found in southern Panama, northern Colombia, Venezuela, Guyana, Surinam, French Guiana, Brazil, Peru, Bolivia, Paraguay, and possibly the northern tip of Argentina. They are also found on many of the Caribbean islands, including the Lesser Antilles, Puerto Rico, the U. S. Virgin Islands, Grenada, Trinidad, and Tobago. It is unclear, in most cases, whether the tortoises are native, or were introduced by natives or Europeans [Vinke 2008, pp.38, 49-53].

Red-footed Tortoises are found in a variety of habitats, ranging from relatively dry savanna to full rainforest.  Their preferred habitat is a matter of debate, but the simple version is that the Yellow-footed Tortoise is most often found in the Amazon rainforest and the Red-footed Tortoise is found outside the basin [Vargas-Ramirez 2010].  A typical habitat in the northern part of their range is lightly wooded, dry savanna with plenty of small or temporary streams. The climate would be tropically warm and humid, similar to that preferred by Yellow-footed Tortoises [Vinke 2008, pp. 110-112].  A typical habitat in the southern half of the range would be more arid and temperate, resulting in scrub or thorny savanna areas, more like the habitat of the Chaco Tortoise (Chelonoidis chilensis) [Vinke 2008, p. 122].  Nonetheless, Red-footed Tortoises are also found in rainforests and other habitats.  More study is needed to better understand their ranges and population dynamics [Vanzolini 1994]

Yellow-footed Tortoises

Yellow-footeds are a more rainforest adapted species and are almost all found in the Amazon drainage basin around the Amazon River throughout much of the interior of northern South America. They are well-adapted to the darker, more humid forest floor where little of the food holds much nutrition and there is lots of competition for it. They share some locales with the more savanna-dwelling Red-footed, but the Red-footed
generally prefers openings, edges, grasslands, etc.

Red-footed Regional Variation

Species with large and varied ranges usually develop sub-species or regional types. Red-footed Tortoises have
long been thought to form three to seven groups that may be elevated to sub-species or even full species with more investigation [Pritchard 1984, pp.214-216]. Mitochondrial DNA research suggests that there are 5 distinct and recognizable types or clades that also seem to conform to natural barriers: Northern, Northeastern, Northwestern, Southern, and Eastern [Vinke 2008, pp. 72-76; Vargas-Ramirez 2010].

Names in parenthesis are geographical terms or local names added to try to minimize confusion.

Northwestern (Panamanian or morrocoy) Red-footed Tortoises

Northwesterns are found in southern Panama to the Andes in northeastern Colombia. The preferred habitat seems to be open forests to grasslands.

Their main distinguishing characteristics are carapaces that are more often dusty gray to coffee colored, with mostly yellow to orange scales on the limbs and a relatively patternless plastron. Some individuals are described as “bleached out”.

Northern (Colombian or wayapopi) Red-footed Tortoises

Northerns developed about 2.8 MYA (million years ago) and come from the region between the Andes and the Guiana Highlands in northern Colombia and eastern Venezuela. Preferred habitats in this region are not well-defined but probably are similar to Northeastern types.

They generally have pale yellow to lemon to light tangerine scales compared to the Northeastern Red-footed Tortoises  and may be more likely to have a vertically divided prefrontal scale between the eyes.

Northeastern (Guyanan, ‘common’ or wayamou) Red-footed Tortoises

Northeasterns probably split off about 2.2 MYA.  They range from the Guiana Highlands to the Atlantic through Venezuela, Guyana, Surinam, French Guiana, and the northern part of Brazil. Typical habitat is the greener areas of dry savannah.

They are the most commonly seen type in the pet trade or in photographs. The holotype specimen is from this region.

Southern (Gran Chaco, ‘giant’, or motelo) Red-footed Tortoises

Southerns were probably the first sub-group, developing approximately 4 MYA. They are from the Gran Chaco region of Bolivia, Paraguay, and parts of Brazil and Argentina. The primary habitats are drier, more temperate thorn and scrub forests, where they often find refuge in Giant Armadillo burrows.

They trend 5-10cm/2-4in longer than most Red-footed Tortoises, have browner or “dustier” carapaces, yellow to light red scales on the limbs, have mostly dark plastrons, and an enlarged scale or spur on the forelimb “elbows”. Males do not develop the pronounced indentations along the carapace that males from the northern regions do.

Eastern (Brazilian or japuti) Red-footed Tortoises

Easterns developed about 2.2 MYA and are from the central eastern to central southern region of Brazil, with the exact range and habitats not well known. Much of the area is rockier than most other ranges, as well as being drier and more temperate than the northern habitats. 

They look much like the southern type, although not as large and trending towards brighter reds. Many tortoises in this group show brilliant red coloration on the scales, especially the head, earning them the nickname of “cherry-head” in the pet trade.

Eastern types of Red-footeds (and probably Southern types as well) are different enough from the typical
Northeastern type to deserve their own page (See “Cherry-heads“)

Revised 8-21-2012 (C) Mark Adkins

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