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 they have been introduced on. 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 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.

Taxonomy and fossil history

Red- and yellow-footed tortoises go
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. We will also follow SSAR
conventions for captilization
. [Crother]

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‘ for 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, Cylindraspis,
Indotestudo,
Manouria,
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 has
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-Rameriz 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-Rameriz 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-Rameriz 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 marking 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.  [Pritchard
1984, 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’ 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 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-foots, reaching 20in/50cm routinely and have hit
28in/71cm, making them one of the largest mainland species. The colors
are 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’ are 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 cares are all based on the difference in habitat. Yellow-foots like subdued light, steady temps in the 85
oF/29oc
zone with high overall humidity, 95%+. They like warm rain and it may
help trigger eating and mating. Yellow-foots 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
are more recent developments than heavier scales. This combined with the
ranges and habitats used would point towards the red-footed being an
off-shoot of the yellow-footed.

It is not always easy to
tell these species apart without careful study. Here are two excellent
articles on 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, if 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
rain
forest. 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 rain
forest
basin and the Red-footed Tortoise is found outside the basin.
[Vargas-Rameriz
2010] A typical habitat in the northern part of their range is lightly
wooded,
dry savannah with plenty of small or temporary streams. The climate
would be
tropically warm and humid- similar to that preferred by yellow-foot
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 savannah
areas,
more like the habitat of the Chaco tortoise (Chelonoidis chilensis). [Vinke 2008, p. 122]
Nonetheless, red-footed tortoises are also found in rain forests 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 rain forest 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-Rameriz
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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