Overview

Distribution

Red-footed tortoises (Chelonoidis carbonaria) has a broad geographic range east of the Andes that extends from eastern Columbia through the Guianas, continuing south through eastern Brazil to Rio de Janeiro, and west to Bolivia, Paraguay and northern Argentina. They appear to be absent from all but the easternmost Amazon Basin. Red-footed tortoises are also native to Panama and western Columbian on mainland South America, and the island of Trinidad in the Caribbean. They have recently been introduced to other islands in the Caribbean.

Biogeographic Regions: neotropical (Introduced , Native )

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Continent: Middle-America Caribbean South-America
Distribution: SE Panama, Colombia (west of the Andes in Choco), east of the Andes in E Colombia, Venezuela, Guyana, French Guiana, Surinam, E Brazil (south to Rio de Janeiro; seems absent from almost all but the eastern parts of the Amazon Basin: Rio Grande do Sul, Goias etc.), Peru, E Bolivia, Paraguay, N Argentina, Trinidad, Virgin Islands (St. Croix); introduced to a number of Carribean Islands (incl. Providencia, Grenadine islands) Nicaragua (Great Corn Island)  
Type locality: "Habitat sub cognomine "Capitary" (?) ad flumen Amazonum," South America (cited in KING & BURKE 1989).
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Physical Description

Morphology

The carapace of red-footed tortoises ranges from dark-brown to blackish brown. Each scute contains a pale center called the areolae. Outer regions of each scute are golden-brown, and the edges tend to be dark-brown. The plastron can range from pale to a dark yellow, and the scales on the limbs and tail are enlarged and can range from yellow to dark reddish orange. Scales on the dorsal surface of the head have dark margins and are bright in color. Parietal scales are the brightest on the head, and frontal scales are typically more pale in comparison. Males are larger than females and have a more obtuse posterior anal notch. Females have an acute or rounded posterior anal notch and their xiphiplastron (the posterior-most scute) is not as heavily developed when compared to males. In males, the posterior edge of the xiphiplastron tends to form a thickened, nearly vertical free margin, whereas in females, it tends to be beveled inward and upward. Adults can reach 510 mm in carapace length.

Range length: 510 (high) mm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: male larger

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Ecology

Habitat

Chelonoidis carbonaria can be found in rainforests, dry thorny forests, temperate forests, and in savanna areas. It prefers heavily forested, humid habitats but avoids muddy areas due to low burrowing capacity of these habitats. This species is less common in forest clearings associated with palms, mangoes, and other vegetation.

Habitat Regions: tropical ; terrestrial

Terrestrial Biomes: savanna or grassland ; forest ; rainforest

Wetlands: marsh ; swamp

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Trophic Strategy

Chelonoidis carbonaria feeds primarily on fruit during the wet season and flowers during the dry season. Throughout the year, they also consume dead and living foliage, soil, fungi, stems, sand, pebbles, and carrion. Males consume greater amounts of fruit compared to females. Geocehlone carbonaria occasionally ingests sand, which has been hypothesized to act as an abrasive agent enhancing digestion of plants materials.

Animal Foods: carrion

Plant Foods: leaves; wood, bark, or stems; fruit; flowers

Other Foods: fungus; detritus

Primary Diet: herbivore (Folivore , Frugivore ); omnivore

  • Moskovits, D., K. Bjorndal. 1990. Diet and food preferences of the tortoises Geochelone carbonaria and G. denticulata in northwestern Brazil. Herpetologica, 46/2: 207-218.
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Associations

As frugivores, red-footed tortoises may be important dispersers of seeds of tropical plants such as figs and bromeliads. One study found that viable seeds of both types of plants were found in the feces of several red-footed tortoises in Brazil.

Ecosystem Impact: disperses seeds

  • Strong, J., J. Fragoso. 2006. Seed dispersal by Geochelone carbonaria and Geochelone denticulata in northwestern Brazil. Biotropica, 38/5: 683-686.
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Other than humans, there is no information available concerning predators specific to Chelonoidis carbonaria.

Known Predators:

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Life History and Behavior

Behavior

Chelonoidis carbonaria produces a series of clucks, which sound similar to those produced by domestic chickens. Clucks are primarily produced by males during courting or mating. Juveniles may also cluck or chirp and produce these sounds on a regular basis while foraging. Prior to clucking, juveniles stop foraging and bob their head while producing the sound. Little else is known of communication and perception in this species.

Communication Channels: acoustic

Perception Channels: visual

  • Campbell, H., W. Evans. 1972. Observations on the Vocal Behavior of Chelonians. Herpetologica, 28/3: 277-280.
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Life Cycle

At reproductive maturity, Chelonoidis carbonaria exhibits a central narrowing of the shell. In older individuals, the sides of the carapace expand, especially in females, and the abdominofemoral region becomes indented and slightly saddle-backed. The tail is longer and more distinct in males when compared to females. Males have a small opening between the carapace and plastron, which allows for movement of their heavier tail. Offspring sex is determined via ambient temperature during development.

Development - Life Cycle: temperature sex determination

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Life Expectancy

There is no information available regarding the average lifespan of Chelonoidis carbonaria.

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Lifespan, longevity, and ageing

Maximum longevity: 49 years (captivity)
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Reproduction

Chelonoidis carbonaria is polygynous, and males produce sounds and calls associated with distinct gular motions that are meant to attract potential mates and ward off competitors. Calls consist of a series of “clucks”, similar to those produced by chickens. Males compete for mates, and typically move their heads in a bobbing motion prior to wrestling. He who flips his competitor on his back gains access to the female and an opportunity to mate.

Mating System: polygynous

Most red-footed tortoises become sexually mature by 200 to 250 mm in length, which typically occurs around 5 years of age. They mate throughout the year in captivity, but nesting occurs from June through September. Females may nest several times during a season, depositing 2 to 15 eggs per clutch. Incubation times range from 117 to 158 days. Hatchlings have a carapace length ranging from 39 to 45 mm and weigh 22 to 30 g.

Breeding season: Red-footed tortoise mate throughout the year but nest from June to September.

Range number of offspring: 2 to 15.

Average age at sexual or reproductive maturity (female): 5 years.

Average age at sexual or reproductive maturity (male): 5 years.

Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous ; sperm-storing

In order to ensure successful egg production, female Chelonoidis carbonaria store substantial energy in the form of fat and sequester minerals in their bones for the formation of the egg-shell. During egg development, they feed on a nutrient-rich diet in order to maintain mineral deposits. Chelonoidis carbonaria lay their eggs in flask shaped nests that are about 20 cm deep in the ground. Prior to oviposition, females become restless and search for a good nesting area. Once oviposited, eggs are covered and there is no parental care. Hatchlings dig their way out of the nest and are immediately independent.

Parental Investment: pre-hatching/birth (Provisioning: Female)

  • Campbell, H., W. Evans. 1967. Sound production in two species of tortoises. Herpetologica, 23/3: 204-209.
  • Ernst, C., R. Altenburg, R. Barbour. 1997. "Geochelone carbonaria" (On-line). Turtles of the World. Accessed May 26, 2011 at http://nlbif.eti.uva.nl/bis/turtles.php?selected=beschrijving&menuentry=soorten&id=380.
  • Legler, J. 1963. Tortoises (Geochelone carbonaria) in Panama: distribution and variation. American Midland Naturalist, 70/2: 490-503.
  • Moskovits, D., A. Kiester. 1987. Activity levels and ranging behavior of the two Amazonian tortoises, Geochelone carbonaria and Geochelone denticulata, in north-western Brazil. Functional Ecology, 1/3: 203-214.
  • Spiess, P. 1997. "The Red-Footed Tortoise (Geochelone carbonaria), a South American Treasure" (On-line). Accessed March 27, 2011 at http://www.kingsnake.com/rockymountain/RMHPages/RMHredfoot.htm.
  • Wilkinson, A. 2010. Gaze following in the red-footed tortoise (Geochelone carbonaria). Animal Cognition, 13/5: 765-769.
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Geochelone carbonaria

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 1
Species With Barcodes: 1
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Conservation

Conservation Status

Chelonoidis carbonaria has not been evaluated by the International Union for Conservation of Nature (IUCN), however, many island populations are likely in serious decline as habitat loss and over hunting pose a serious threat throughout its geographic range. Chelonoidis carbonaria occurs in numerous wildlife reserves and national parks throughout its geographic range. Without current population estimates, it is difficult to predict the potential conservation and management needs for this species. The

US Federal List: no special status

CITES: appendix ii

State of Michigan List: no special status

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Relevance to Humans and Ecosystems

Benefits

There are no known adverse effects of G. carbonaria on humans.

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Red-footed tortoises are hunted for their meat throughout their geographic range.

Positive Impacts: food

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Wikipedia

Red-footed tortoise

Red-footed tortoises (Chelonoidis carbonaria) are tortoises from northern South America. They are medium-sized tortoises that generally average 30 centimetres (12 in) as adults, but can reach over 40 cm (16 in). They have a dark-colored loaf-shaped carapace (back shell) with a lighter patch in the middle of each scute (scales on the shell), and dark limbs with brightly colored scales that range from pale yellow to dark red. There are recognized differences between red-footed tortoises from different regions. They are closely related to the yellow-footed tortoise (C. denticulata) from the Amazon Basin. They are popularly kept as pets, and over-collection has caused them to be vulnerable to extinction.

Their natural habitat ranges from savannah to forest-edges around the Amazon Basin. They are omnivorous with a diet based on a wide assortment of plants- mostly fruit when available, but also including grasses, flowers, fungi, carrion, and invertebrates. They do not brumate but may aestivate in hot, dry weather.

Eggs, hatchling, and young tortoises are food for many predators but the main threats for adults are jaguars and humans. Population density ranges from locally common to very scarce due in part to habitat destruction and over-collection for food and the pet trade.

Taxonomy[edit]

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).[5]

 Lithograph of 'Testudo tabulata' from 1836 book Naturgeschichte und Abbildungen Der Reptilien by Heinrich Rudolf Schinz, illustrated by Karl Brodtmann
1836 illustration by Karl Brodtmann of Testudo tabulata from the book Naturgeschichte und Abbildungen Der Reptilien by Heinrich Rudolf Schinz

All turtles and 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 subgenera 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 generas: 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.[6] Many of these genera names are still debated; for example, there is no specific definition of Geochelone, and Chelonoidis is primarily used for geography rather than unique anatomic characteristics.[7][8]

The species name carbonaria 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. There are currently no subspecies of red-footed tortoise, although many believe the species has five or more variants that may be subspecies or even separate species.[9]

Description[edit]

Red-footed tortoises show gender, regional and individual variations in color, shell shape, and minor anatomic characteristics. Adult red-footed tortoise 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). There is often a high point over the hips and 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.

Plastron view of an adult male red-footed tortoise showing pale coloration and central darker markings, male tail and anal scutes, and plastron indentation
Plastron view of an adult male red-footed tortoise

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.[10]

profile of the head of a red-footed tortoise showing the squared off skull, red and dark colorations, and dark eye
Red-footed tortoise profile

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 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. There are fifteen to twenty 'teeth' or fine grooves 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 four claws on the forelimbs and five on the hind, but no visible toes. The forelimbs 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 gender, and lacks any sort of claw on the tip.[11]

Average adult sizes vary by region and gender, and 'giants' are often encountered. Red-footed tortoises average 30–35 cm (12–14 in) with males slightly larger overall. Red-foots of up to 45 cm (18 in) are fairly common and over 50 cm (20 in) are occasionally discovered. The largest known specimen was from Paraguay, was 60 cm (24 in) long, and weighed over 28 kg (62 lb)! It is unknown if the 'giants' represent diet availability, genetic issues, longevity, or other possibilities.[12]

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 to each scute. The marginals of very young red-footed tortoise 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.[13]

Sexual dimorphism[edit]

diagram showing the differences in the anal scutes and tails of female and male red-footed tortoises
Differentiating female and male red-footed tortoises

Male are slightly larger and more colorful overall. The carapace of males from north of the Amazon basic 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 90o angle) and the points are closer to the marginals in females.[14]

Distribution and habitat[edit]

Red-footed tortoises range from southeastern Panama to Venezuela, Guyana, Suriname, and Guiana in the north; down 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. 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.[15]

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 Netherlands Antilles, Trinidad, Tobago, Grenada, Barbados, St. Vincent, the Grenadines, Santa Lucia, Martinique, Dominica, Guadalupe, the Leeward Islands, the Virgin Islands, and Puerto Rico.[16]

Adult red-footed tortoise walking on a rocky outcrop in heavy vegetation
Red-footed tortoise in Barbados

The preferred habitat of the red-footed tortoise varies somewhat by region but generally includes fairly consistent seasonal temperatures near 30 °C (86 °F) that rarely get lower than 20 °C (68 °F) or over 35 °C (95 °F), 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.[17]

Regional variations[edit]

Various authors have divided the red-footed tortoise into different groups by anatomy and geography. Peter Pritchard recognized seven types,[18] but DNA research by Mario Vargas-Rameriz et al. have identified five genotypes.[19]

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 both 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 forelimb elbow.[20]

Northeastern variant[edit]

  • Description: This is the holotype of the species. Head and limb color generally light orange to red. Plastron is mostly pale yellow.
  • Range: Guiana Shield- Venezuela, Guyana, Suriname, Guiana, and northern Brazil.

Northwestern variant[edit]

  • Description: Similar to Northeastern variant but the carapace base color is grey, dark brown, or coffee rather than black. Pale plastron with central dark area resembling an exclamation point. Head and limbs are generally pale yellow to orange. The average size is slightly smaller than usual- 30–35 cm.
  • Range: Southeast Panama and Colombia.

North variant[edit]

  • Description: Similar to Northeastern variant with head and limb color generally pale yellow to light orange, rarely red, head and limbs often slightly different colors. The average size is slightly smaller than usual- 30–35 cm.
  • Range: Colombia, Ecuador, and Peru.[21]

South variant[edit]

Plastron view of a young 'cherry head' or eastern variant red-footed tortoise showing the dark pattern on most of the plastron
Plastron view of a young red-footed tortoise from Brazil, aka 'cherryhead'
  • Description: Carapace is often not quite black to dark brown, sometimes with light grey or whitish between the scutes. Plastron is mostly dark in a symmetrical mottled pattern. Size tends to be larger on average then Northeastern variants with the largest individuals found in this area. Forelimbs feature a slightly enlarged scale on the side of the 'elbow'. Adult males do not have the constricted waist, and females average a bit larger than the males.
  • Range: Gran Chaco- Bolivia, Paraguay, northern Argentina.

Eastern variant[edit]

  • Description: Carapace often has light grey or whitish between the scutes. Plastron is mostly dark in a symmetrical mottled pattern. Size tends to be smaller on average than Northeastern variants, also reaching sexual maturity at a smaller size. Forelimbs feature a slightly enlarged scale on the side of the 'elbow'. Head and limbs either yellowish or reds ranging to brilliant cherry-red.
  • Range: East to southeast Brazil.
  • Note: The red-headed type of this variant is often called a 'cherry-head' in the pet trade.[22]

Population features[edit]

Little information is available about population density or gender ratios. Many specimens are recorded from near research stations and cities, but that is almost certainly more due to the ease of finding them there than higher localized populations. They are considered one of the most common turtle species in many localities. When a dam was being built in the Edo region of Venezuela, several hundreds of the red- and yellow-footed tortoises were captured for relocation. Large numbers are also found in markets, confiscated at airports, etc.[23] On the other hand, there are very few records from Peru, Ecuador, Argentina and central Brazil. In the Guiana Shield region, there are islands of higher populations and stretches where few have been located.[24]

Debra K. Moskovits' noted the difficulties of counting tortoises that are often well-hidden, dug in, deep in burrows, etc. during her studies on the island of Maracas in Venezuela. She found that trained dogs discovered many that she would have not found on her own. Her studies showed a nearly balanced mix of 1.32 males per female, and 1.05 red-footed tortoise per hectare (2.4 acres) on the island, which she felt may be an underestimate due to the difficulty in finding the tortoises.[25]

Evolutionary history and fossil record[edit]

The Chelonoidis genus has two main sub-categories based on appearance and habitat- the carbonaria and the chilensis groups. The carbonaria group has the closely related red- and yellow-footed tortoises that clearly share a common ancestor. The chilensis group features the Argentine tortoise (C. chilensis), Chaco tortoise (C. petersi), and Galápagos tortoise (C. niger) which share similar habitats and a basic appearance but otherwise do not seem to be closely related. The relationship between the groups is unclear.[26]

There are several theories to explain the relatively small number of tortoise species in South America and the relationship between them, but the fossil record is not very complete. One long-held theory is that they came from Asia using the land bridge, then spread down through North America and shared ancestors with the gopher tortoises (Gopherus species). Another holds Geochelone ancestors floated over from central Africa, taking advantage of their ability to float, resist salt water, and go without food for extended periods.

DNA studies suggest that the carbonaria group may be related to the African hingeback tortoises (Kinixys species).[19] This suggests that they might have come from Gondwana before it separated into Africa and South America some 130 million years ago. One ancestral form from about 5mya, Chelonoidis hesterna (Auffenberg 1971), is thought to have lived in wet forests and split into two species in the Miocene with the yellow-footed tortoioses remaining in the deep forest and the red-footeds colonizing the edges of the forests and the emerging savannahs. As the climate and topography changed, groups of red-footed tortoises became physically separated and genetically isolated.[27]

Ecology and behavior[edit]

The red-footed tortoise's climate in the northern part of the range changes little day to day and rarely gets too hot for them, so the tortoises do not need to practice any form of dormancy and can often forage all day long. The tortoises in Moskovitz's study area were most active after 3:00pm while many species from warmer climes would be most active in the morning and evening. Tortoises from the southern parts of the range experience much hotter, colder, and drier conditions than most of the range and aestivate when food becomes scarce. They may eaestivate or brumate when the temperatures are low enough.[28][29]

Most species of tortoise spend much of their day inactive, and red-footed tortoises generally spend over 50% of the daylight hours at rest. They may rest for even longer after a large meal, with five to ten day stretches being common. One large specimen seems to have stayed in the same position for over a month. Resting tortoises barely move, allowing leaf litter to accumulate on them, and termites have built tunnels on the carapaces of resting red-footed tortoises.

Abandoned armadillo burrow showing a mostly over-grown depression in the soil surrounded by vegetation
Unused armadillo burrow in Brazil

They seek shelter in places that offer thermoregulation and protection from predators. Treefalls are a favored site, as are debris piles, burrows (especially those of the armadillo (Dasypodidae family) and agouti (Dasyprocta species)), hollow logs, holes, and heavy vegetation cover. They generally try to find tight-fitting resting places, and will occasionally 'wedge' themselves between roots and trunks but remain otherwise exposed. Burrows and holes are often flooded and the tortoises will rest in the water and mud with just their nostrils and eyes exposed. In warmer weather, they press up against moister, cooler surfaces in shelter areas. The tortoises show personal preferences with many individuals always seeking out a specific type of shelter.[30]

Shelters are often communal with as many tortoises as can fit in the space. Good shelters are so important, and visibility is so poor that the tortoises will leave scent trails that they or others can follow.[31] Some shelters are so heavily used by tortoises that there are clear trails in the dirt leading to them, even though individual tortoises may not return to a given shelter regularly.[32]

Besides communal shelters and scent marking, red-footed tortoises also show other signs of semi-social behavior such as lack of aggression at feeding sites, not protecting territory, and group feeding at fruit falls and carrion (although it is not unusual for one tortoise to block access or even try to make off with some of the food). Red-footed tortoises often follow each other, usually a smaller one following a larger and quite often males following males but all combinations are seen. Red-footed tortoises have also been observed following apparent scent trails laid by an individual a day or two earlier.[33]

Predators[edit]

Hatchling and young tortoises are at high risk of predation. Tegu lizards (Tupinambis species), ring-tailed coatis (Nasua nasua), and introduced rats and mongooses attack nests and eggs. Many predators take the young tortoises, including large lizards, snakes, crocodilians, and even large turtles; predatory birds such as the curassow (Crax species), guan (Penelope species), rails, cuckoos, and falcons; and mammals like cats (Felidae species), opossums, foxes, peccaries, and feral dogs.[34]

Other than humans, the main predator of the adult tortoises are jaguars (Panthera onca). Red-footed and yellow-footed tortoises seem to be a significant food source for jaguars in some parts of their respective ranges, such as Manú National Park in Peru. Jaguars will bite at the carapace and work at cracking or prying it apart to extract the soft tissues. Many tortoises show toothmarks from attacks that they survived, often on the hind end when they were otherwise protected in a burrow or shelter.[35]

Diet[edit]

Discussing the diet of the red-footed tortoise is difficult due to the wide variety of food it eats, the variety and seasonal availability of plants available across the extensive range, interpreting what field reports are trying to describe,[36][37] and because studying fecal pellets gives very different results than what the animals are observed eating.[38]

Forest-dwelling tortoises in the Chelonoidis, Indotestudo, Manouria, and Kinixys genera are omnivores with upper and lower intestines of about the same length, while herbivorous genera such as Gopherus and Testudo. have longer large intestines to digest fiberous grasses. Most omnivorous tortoises have no other specialized digestive structures, reflecting their generalized, flexible diet.[37]

The bulk of the diet is some sort of fruit or seed pod. Common fruits come from cacti (Opuntia), figs (Ficus), pehen (Acacia aroma), Spondias, Annona, Philodendron, bromiliad, and more. Up to five different kinds of fruits are often found in fecal pellets.[39][40] The entire fruit is eaten, and the seeds are passed and can germinate, giving red- and yellow-footed tortoises a significant role in seed dispersal.[41] Red-footed tortoises have been observed at the base of fruit trees, apparently waiting for fruit to fall.[42]

The rest of the diet includes grasses, leaves, flowers, roots, and shoots from a wide assortment of plants as well as fungi, live invertebrates (such as ants, termites, beetles, butterflies, snails, and worms), carrion, and feces (especially from foxes). Tortoises are often found at carcasses feeding until gorged, and occasionally eat small live animals such as snakes and rodents. Pebbles and sand are also often found in fecal pellets.

The diet changes based on season and availability. In the wet season it may be roughly 70% fruit, 25% fresh leaves and shoots, and the rest being fungi and animal food. The dry season sees 40% fruits, 23% flowers, 16% fresh leaves and shoots, and the rest fungi, moss, and animal food.[43]

Omnivorous tortoises will seek out foods high in calcium even if other foods are more readily available, and will even eat mineral-rich soil if they cannot get adequate calcium in the diet.[44]

Movement[edit]

Red-foot tortoises will forage over areas ranging from 0.63 to 117.5 hectares (1.6 to 290.3 acres) usually making a 'spiderweb' pattern centered around a good hide or a recent fruit fall. They generally move methodically at around 5 to 20 metres/hour (5.5-22 yards/hour), but can raise up on their long legs and move at up to 100 metres/hour (109 yards/hour) when they want. While they generally forage in zig-zag or looping patterns, they sometimes move 100 metres (110 yd) or more in fairly straight lines, often at a rapid pace. They show a marked preference for moving under medium to dense vegetation cover.[45]

Life cycle[edit]

All turtles and tortoises start as eggs. Red-footed tortoise eggs are roughly spherical and average around 5.0 by 4.2 cm (2.0 by 1.7 in) and weigh 50 g (1.8 oz) with two to seven eggs in a clutch, although the same female may lay multiple clutches near each other. The incubation period is 105–202 days with 150 being typical.[46]

Hatchlings use an egg-tooth to open the egg. They will stay in the egg or nest for several days. Hatchling shells are bent almost in half in the egg and will take some time to straighten out. The 3.6 by 6.3 cm (1.4 by 2.5 in) hatchling's carapace will be flat, somewhat creased from being folded in the egg, and have serrationed sides. Little is known of the daily activities or diet of hatchling wild tortoises.[47] Sub-adult tortoises grow quickly to reach breeding sizes- roughly 20 to 25 cm (7.9 to 9.8 in), depending on the average adult size of the regional variant.[48]

Illustration of red-footed combat by Albert Eckhout

The peak time for courtship and reproduction is the early wet season in April and May although it can happen at any time. Courtship noises and possibly scent cues seem to attract other tortoises to 'courting sites' under fruiting trees such as Genipa[49] When two tortoises meet about a meter apart, they will engage in some specific behaviors to identify the other. The first trigger is head and limb color- the bright red, orange, yellow, or white colors on the dark skin identifies the other animal as the proper species. Next, the larger tortoise will make jerky side to side head movements for two to four seconds. If both tortoises are males, one will either withdraw and retreat, or they may try to ram each other, trying to get their gular scutes under the other one, then pushing them several meters away as quickly as possible. The defeated tortoise is sometimes flipped onto his back in the process. The defeated tortoise will leave the area afterwards. Neither head bobbing nor ritual combat have been observed in tortoises south of the Amazon Basin, possibly due to the lack of yellow-footed tortoises in the area. Males mounting other males, and even females mounting either sex have been witnessed and are thought to show dominance.

Two mating red-footed tortoises, male perched on the carapace of the female, clasping at the sides, head arched over her
Red-footed tortoises mating in Barbados Wildlife Reserve

If the other tortoise is a female, she will move away and the male will follow, touching her carapace and occasionally sniffing at her cloaca. If the female stops, the male may either wait for her to resume moving or leave. Males make loud 'clucking' sounds during the chase. After trailing, the male mounts the female, his feet planted on the costals of her carapace, rams his anal scutes against her supracaudal, and makes a loud raspy 'bark'. If the female resumes walking, he may fall off and resume trailing. Females sometimes seem to intentionally use low limbs to knock males off. A receptive female will extend her hind legs and lift her plastron as the male plants himself on his own extended hind legs as he works to align their cloacas for insertion. The tail, scutes, and penis of the tortoise are designed to work around the awkwardness of the shell. The male often leans his head over her head and holds his jaws wide open making calls that get louder. He may bite her as well, sometimes quite aggressively. The shells can make loud clacking noises during the forceful thrusts. The female walks away after copulation, sometimes knocking the male off her.

The female will begin nesting five to six weeks after mating. Digging the nests is often difficult in hard soil. The female may urinate to soften the soil before using her hind legs to dig a chamber about 10 by 20 cm (3.9 by 7.9 in) in about three and a half hours. Inexperienced females often dig several partial nests, and even experienced females may abandon a nest they are working on and start another. When he nest is ready, she will lower her tail as deep into the nest as she can and deposit an egg every 30 to 120 seconds. She will recover the nest and tamp the soil down. Females get better at digging, covering, and camouflaging nests over time. After it is covered and hidden, she will often get a long drink of water then find a shelter and rest. Very rarely a red-footed tortoise will lay eggs on the surface, or within a patch of cacti.[50]

As with other tortoises, red-footed tortoises can reproduce most of their lives, although the number of eggs laid and the ratio of successful hatchlings improves as the tortoise matures, then drops off again as the tortoise ages. Because of the difficulty in determining the age of a wild tortoise, there is little data on longevity, although many live for thirty years or more in captivity.[51]

Conservation and relations with humans[edit]

The red-foot tortoise is considered vulnerable and is listed in CITES Appendix II, restricting international trade- although this does not offer protection within a country and smuggling still occurs in large numbers. Conservation parks and refuges, captive breeding farms in natural conditions, and increased captive breeding in other countries has helped, but they are still exported in large numbers- 35,565 from 2000–2005, mostly as pets and food.[52] The recorded exports do not include smuggling or other losses, which some estimate to be well over twice that number. They are considered especially at risk in places like Argentina and Colombia, and are considered more at risk than yellow-footed and Chaco tortoises.

They are widely used as food throughout their ranges, especially where other meats are limited. Their ability to go a long time without eating makes it easy to catch and keep them fresh for extended periods. The Catholic Church allows tortoises to be eaten on fasting days when most meats are forbidden such as Lent. 'Tortoise pie' (pastel de morrocoy, served in a tortoise shell) is a favorite food for those times, and large numbers of tortoises are exported just for that purpose. Even people living in countries with an abundance of available livestock enjoy wild game, such as tortoises, when possible. Hunting for food is so extensive that Colombia and some other countries import tortoises from neighbors.

Habitat destruction is another significant threat to the red-footed tortoise, and so many other species. They are also widely collected as local pets and their shells are sold as souvenirs.[53]

Captive care[edit]

Red-footed tortoises are popular pet tortoises around the world. They are relatively inexpensive, are a manageable size, have interesting personalities, and are colorful.[54] Pet tortoises should be purchased as 'captive bred' from a reliable breeder when possible to both help protect wild populations and to avoid internal parasites.[55]

Any reptile can carry Salmonella, so keepers should practice proper hygiene, such as washing their hands after handling the animals or their wastes. Dogs, even well-behaved dogs, often attack or chew on tortoises so great care must be taken if they are around.[56]

Housing[edit]

All tortoises should be housed outdoors when conditions allow. Outdoor pens should allow space for exercise, secure walls that are at least 1.5 times taller than the tortoise is long, and security from both predators and escape. Shelter and water should always be provided.[57]

Indoor housing is generally scaled to the size of the tortoise and needs to be secure and waterproof for this high humidity species, as well as offering adequate space. Aquariums and plastic tubs are often used for younger tortoises, while a 'tortoise table' (similar to shelf-less bookcase lying on its back), indoor mini-greenhouse, or large indoor pen can be used for larger tortoises or groups of tortoises.[58]

An indoor habitat should be lined with a substrate such as hardwood mulches (like cypress ), coconut coir, soil and sand mixes, or some combination. A hide and water dish are necessary, and live or silk plants also help.[59]

Environment[edit]

Heat, light, and humidity must be kept within proper guidelines for healthy tortoises. Red-foot tortoises are most active at temperatures from 27 to 30 °C (81 to 86 °F). A warmer area of 30 to 31 °C (86 to 88 °F) is recommended, and night temperatures can drop a few degrees lower. High levels of humidity should be available in some part of the habitat.[60]

Lighting should be low and diffuse or plenty of shade should be offered. Lights that emit UVB wavelengths are recommended to help the tortoise metabolize calcium correctly and help regulate the pineal gland if the tortoise will be indoors for extended periods.[61]

Captive diet[edit]

Pet tortoises should be allowed to forage in a well-planted outdoor pen whenever possible. The basic diet should consist of a variety of plants, vegetables and fruits with occasional meat; and be high in calcium and fiber, and low in sugars and fats. Fruits should be kept as whole as possible. Commercial tortoise pellets can be offered along with fresh foods.

The bulk of the diet should be leafy greens such as turnip or collard greens, dandelion, leafy or curly lettuces, endive, kale, cabbage, edible tree or plant leaves such as mulberry or hibiscus, lettuce mixes, parsley, grape leaves, etc.

Vegetables and fruits offer variety and other nutrients, but are a smaller part of the captive diet. Good choices would include: cactus pads and fruits, papaya, figs, mango, mushrooms, pumpkin, squash, melon, pineapple, strawberry, cucumber, hays and grasses (such as wheatgrass), corn, peas and beans, carrot, apple, pear, plums, and okra.

Meats form a very small part of the captive diet, and can include live bugs or invertebrates (especially slugs), baby mice or rats, chicken, egg, organ meat, lean beef, tuna or other 'oily' fish, or cat or dog food.

Calcium should be supplemented frequently in very small amounts. Other vitamins can be offered in very small amounts as well, but are best provided through a balanced, varied diet.[62]

Notes[edit]

  1. ^ a b Turtle Taxonomy Working Group [van Dijk , P.P., Iverson, J.B., Shaffer, H.B., Bour, R., and Rhodin, A.G.J.]. 2012. Turtles of the world, 2012 update: annotated checklist of taxonomy, synonymy, distribution, and conservation status. Chelonian Research Monographs No. 5, pp. 000.243–000.328, doi:10.3854/crm.5.000.checklist.v5.2012, [1].
  2. ^ Spix, Johann Babtist. 1824. Animalia Nova sive Species Novae Testudinum et Ranarum. Monachii: 53 pp.
  3. ^ Gray, John Edward. 1830. A Synopsis of the Species of the Class Reptilia. In: Griffith E. and Pidgeon, E. The Class Reptilia arranged by the Baron Cuvier, with specific descriptions. In: Griffith, E. (Ed.). The Animal Kingdom Arranged in Conformity with its Organization, by the Baron Cuvier, with Additional Descriptions of all the Species Hitherto Named, and of many not before Noticed. Vol. 9. Reptilia. Supplement. London: Whittaker, Treacher, and Co., 110 pp. [Part 26, published Dec 1830].
  4. ^ Wagler, Johann Georg. 1833. Descriptiones et Icones Amphibiorum. Tres partes cum XXXVI tabulis. Monachii: J.G. Cottae, 30 plates.
  5. ^ Vinke 2008, p. 27-29.
  6. ^ Crumly
  7. ^ Vinke 2008, p. 18.
  8. ^ Pritchard 1984, p. 204.
  9. ^ Vinke 2008, p. 24
  10. ^ Vinke 2008, p. 68.
  11. ^ Pritchard 1984, p. 207-210
  12. ^ Vinke 2008, p. 88-91
  13. ^ Vinke 2008, p. 70.
  14. ^ Vinke 2008, p. 82-84.
  15. ^ Vinke 2008, p. 38-47.
  16. ^ Vinke 2008, p. 47-53.
  17. ^ Moskovits 1985, p. 7-9.
  18. ^ Pritchard 1984, p. 214-216.
  19. ^ a b Vargas-Ramirez
  20. ^ Vinke 2008, p. 72-74.
  21. ^ Ebenhack, p. 7-10.
  22. ^ Vinke 2008, p. 74-76.
  23. ^ Pritchard 1984, p. 213.
  24. ^ Vinke 2008, p. 39-44.
  25. ^ Moskovits 1985, p. 41-42
  26. ^ Vinke 2008, p. 18
  27. ^ Vinke 2008, p. 101-106.
  28. ^ Moskovits 1985, p. 35.
  29. ^ Paull, p. 82.
  30. ^ Moskovits 1985, p. 130-132.
  31. ^ Moskovits 1985, p. 61-62.
  32. ^ Vinke 2003
  33. ^ Moskovits 1985, p. 66
  34. ^ Vinke 2008, p. 278.
  35. ^ Moskovits 1985, p. 49.
  36. ^ Vinke 2008, p. 151
  37. ^ a b Bjorndal
  38. ^ Moskovits 1985, p. 48.
  39. ^ Moskovits 1985, p. 113-115
  40. ^ Vinke 2008, p. 154.
  41. ^ Strong
  42. ^ Vinke 2008, p. 156.
  43. ^ Merchan
  44. ^ Vinke 2008, p. 152-155
  45. ^ Moskovits 1985, p. 123.
  46. ^ Pritchard 1984, p. 218.
  47. ^ Vinke 2008
  48. ^ Pingleton, p. 110
  49. ^ Moskovits 1985, p. 55-56.
  50. ^ Vinke 2008, p. 172-178
  51. ^ Pingleton, p. 11.
  52. ^ Vinke 2008, p. 298.
  53. ^ Vinke 2008, p. 272-278.
  54. ^ Pingleton, p. 3.
  55. ^ Pingleton, p. 23.
  56. ^ Pingleton, p. 6.
  57. ^ Ebenhack, p. 63.
  58. ^ Pingleton, p. 32-35.
  59. ^ Ebenhack, p. 57-61.
  60. ^ Pingleton, p. 65-73.
  61. ^ Ebenhack, p. 57.
  62. ^ Pingleton, p. 77-80.

References[edit]

Bjorndal, Karen A. (March 1989). "Flexibility of digestive responses in two generalist herbivores, the tortoises Geochelone carbonaria and Geochelone denticulata". Oecologia 78 (3): 317–321. doi:10.1007/bf00379104. 

Crumly, Charles (1982). "A cladistic analysis of Geochelone using cranial osteology". Journal of Herpetology (16): 215–234. 

Ebenhack, Amanda (2009). Redfoots and Yellowfoots; The Natural History, Captive Care, and Breeding of 'Chelonoidis carbonaria' and 'Chelonoidis denticulata' (Turtles of the World, Testudinidae, Number 3). Living Art Publishing. ISBN 0978755634. 

Merchan, Manuel; Ana M. Fidalgo, Cesar Perez (1998). "Biology, Distribution and Conservation of the Redfoot TortoiseGeochelone carbonaria". Reptilia (GB) 2: 30–38. 

Moskovits, Debra K. (1985). "The Behavior and Ecology of the Two Amazonian Tortoises, Geochelone carbonaria and Geochelone denticulata, in Northwestern Brazil". University of Chicago. PhD Dissertation. 

Paull, Richard C. (1997). The Great Red-foot Tortoise, Tortoises of the World Vol. 4. Green Nature Books. p. 82. ISBN 1-888089-33-4. 

Pingleton, Mike (2009). The Redfoot Manual; A Beginners Guide to the Redfoot Tortoise. Art Gecko Press. ISBN 978-1441494030. 

Pritchard, Peter C. H.; Trebbau, Pedro (1984). The Turtles of Venezuela. Contributions to Herpetology. Society for the Study of Amphibians and Reptiles. ISBN 0-916984-11-7. 

Strong, Joel N.; Jose M. V. Fragoso. "Seed Dispersal by Geochelone carbonaria and G. denticulata in Northwestern Brazil". Biotropica 38 (5): 683–686. doi:10.1111/j.1744-7429.2006.00185.x. 

Vargas-Ramirez, Mario; Jerome Maran, Uwe Fritz (2010). "Red- and yellow-footed tortoises, Chelonoidis carbonaria and C. denticulata (Reptilia: Testudines: Testudinidae), in South American savannahs and forests: do their phylogeographies reflect distinct habitats?". Organisms, Diversity and Evolution. 

Vinke, Thomas; Sabine Vinke (2003). "An Unusual Survival Strategy of the Red-footed Tortoise Geochelone carbonaria in the Chaco Boreal of Paraguay". Radiata (English edition) 12 (3): 21–31. 

Vinke, Sabine; Holger Vetter, Thomas Vinke, Susanne Vetter (2008). South American Tortoises (Chelonian Library Vol. 3). Germany: Edition Chimera. ISBN 978-389973-603-8. 

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