Chaco Tortoise

1 Overview

The Chaco Tortoise is a rather rare land tortoise. Perhaps because its color resembles the Sulcata but its price is much higher, it is not commonly seen. It is related to the red- and yellow-footed tortoises. A Yale study has suggested it may be the closest blood relative of the Galapagos tortoise (a claim still debated). It feeds mainly on wild grasses and leaves; reproduction is low, only 2–5 eggs per clutch, with an incubation of 4–12 months (a record 15 months). Taiwan had small imports that did not do well — about a third died within a year.

Chinese Name: Chaco Tortoise

Alias: Chaco tortoise, Bolivian tortoise, Patagonian tortoise

Latin Name: Chelonoidis chilensis (source listed it as Geochelone chilensis; the genus is now Chelonoidis, and ‘Chilean tortoise’ is a historical misnomer)

Classification: Chordata, Reptilia, Testudines, Testudinidae, Chelonoidis, Chelonoidis chilensis

Distribution: Southern South America (Argentina and Paraguay, also Bolivia and Brazil). Terrestrial. Inhabits tropical savanna, shrubland, or desert dry regions. Because it is very sensitive to humidity, dry hay or akadama soil is the best substrate. Although not hard to keep, it easily catches disease, so do not mix with other tortoises. Diet: grasses, succulents, or cactus. Max carapace 43 cm; tail tip has one large scale. Breeding: November to February, two laying events, 1–6 spherical or oval eggs, incubation 4 months to about 1 year. Difficulty: hard. Does not hibernate. Price: not well documented.

2 Physical Characteristics

Related to red- and yellow-footed tortoises; the Yale study suggests it may be the closest relative of the Galapagos tortoise. Juveniles closely resemble the Sulcata, only with a wider carapace and more upturned edges; with growth the color tends toward black. Based on region, size and color vary.

Size and form vary greatly. Two subspecies are described: ‘donosobarrosi’, larger and more oval, distributed more to the south; and ‘petersi’, smaller and more slender, to the north; today both share the name chilensis. In general it is moderate, about 20–40 cm; the yellow-brown carapace usually has few features, only dark-brown spots on clear growth lines. The head and legs are brown; the front legs have thick large scales, and the hind-leg base has coarse tubercular knots.

Sexing is hard: males are usually smaller and lighter, with only a longer thinner tail; males in the same habitat may have broader heads and brighter color, but their front-leg scales are dark brown while females’ are yellowish-brown. In nature females lay 2 eggs (sometimes 6) in February or March, with wild incubation seeming to need up to a year but only about 4 months captive. Juveniles have flat, round, nearly uniform brown carapaces. Because they are almost inactive in winter, they grow slowly and may need at least 12 years to mature.

3 Husbandry

The southern form matures over 30 cm, the northern about 25 cm; males have a distinctly concave plastron and are typically smaller than females. In the wild courtship is roughly November–December and laying January–March, 2–6 eggs, incubation over 250 days (sometimes a year or more), average lifespan around 80 years.

4 Habitat and Distribution

It lives in sparsely rainy, dry, shrubby tropical savanna and desert. Northern individuals shelter from winter cold in shallow depressions (‘tortoise beds’); southern ones dig burrows like gopher tortoises.

Also called the Chaco tortoise, named after its habitat — the Chaco plain from eastern Bolivia through Paraguay and Argentina. Its scientific name ‘Chilean tortoise’ is a geographic error: the Chilean population is tiny, and when Gray first found it in Mendoza in 1870 he mistook that for Chilean territory and misnamed it.

Mainly a grassland tortoise, in savanna, dry grassland (grassland, shrubland, dry forest), including plains and mountains. Climate varies with terrain; north is warmer, south cooler; northeast more humid, southwest drier. Winter average 5–25°C (south colder), summer 28–35°C; daily range south 5–15°C. Summer is December–March, winter June–August; no rainy/dry split, but south is drier. Southern forms in desert edges endure 40°C summers and below 10°C winters, migrating or burrowing — hence locally called the Argentine gopher tortoise.

5 Feeding

It feeds mainly on wild grasses and leafy vegetables, with a little fruit; it is one of the few tortoises that accept rabbit hay feed. Because it is very sensitive to humidity, dry hay or akadama soil is the best substrate.

In nature it eats hay, cactus, and other plants; in captivity feed lettuce and provide ample drinking water. Evolutionarily similar to the North American gopher tortoise and easily confused with it — the gopher has a nuchal scute, the Chaco does not. Both face over-collection and habitat loss; unless captive-breeding technique improves, beginners should avoid this tortoise.

Although not hard to keep, it easily catches disease, so do not mix with other tortoises. It also commonly develops pyramiding or overgrown beak, so control food portions and offer calcium blocks, cuttlebone, or unsoaked tortoise feed to wear the beak.