What does the future hold for these charming tortoises?
©1996 Melissa Kaplan and Tony Berke. Reptile & Amphibian Magazine, March/April 1996.
My first tortoise just sort of fell into my lap. Well, to be precise, she wet my lap. Since that rather inauspicious beginning, however, we have come a long way. She now makes the rounds of schools and education events where I patiently explain that no, she is not the mother of my desert tortoise yearlings. She is, I explain, a Chaco tortoise.
The Chaco tortoise (Geochelone chilensis) is a moderately sized tortoise native to the Chaco regions of Argentina and Paraguay. Their range extends from southwestern Bolivia east to western Paraguay, and from northwestern Argentina down into the northern part of Patagonia. Despite their species name, they are not found in Chile. Chacos are the smallest of the Geochelone tortoises, the largest of which includes the Galapagos tortoises. Chacos are related to the yellow-footed (G. denticulata) and the red-footed (G. carbonaria) tortoises.
Chaco habitat is dry, desert scrubland, savannas, thorn and scrub bush, and deciduous woodlands. In northern Patagonia, where winter temperatures range between 30 to 50 F (-1 to 10 C), they spend the winter in open burrow or pallets. Shallow burrows are used throughout the more clement months wherein the tortoises spend much of the day; winter burrows are deeper. There is some debate as to whether Chacos actually hibernate during the winter or merely spend the time in a semi-dormancy, waking periodically to move around, drink, void, even eating a bit before going back to sleep.
Their wild diet includes grasses, shrubs, fruits, and cactus pads. It is theorized that they may eat some carrion in the wild as they will sometimes take meat in captivity. As with much of the natural history of these tortoises, there remains much to be learned.
In captivity, their diet includes a wide variety of greens (75%), vegetables (15%) and fruits (10%), their dietary needs similar to other tortoises found in tortoises from similar regions: greens such as collards, kale, mustard, spinach, turnip; Opuntia, nopalis and prickly pear cactus; alfalfa, clover and other grasses; flowers such as hibiscus, nasturtium, geraniums, petunias, roses, violets; and weeds such as dandelion and mallow; vegetables such as green beans, squashes, turnip, parsnip, carrots, broccoli, corn, sweet peppers; cooked plain rice and other grains; fruits such as berries, figs, mangos, cantaloupe, papaya, apples (without seeds), and organically grown bananas with skin. Foods should be supplemented with calcium and multivitamin supplements, and drinking water should be available at all times. Chacos enjoy the occasional bath, with weekly soaking in bridge-deep water ensuring hydration and defecation.
As of 1988, the Chacos have been listed as "vulnerable" in the IUCN Red List of Threatened Animals due to the increasing pressure on the tortoise populations in Argentina. As yet, there is little information on the populations in Paraguay.
The primary threats facing the Chaco tortoises include the two most common facing other threatened populations: habitat destruction and the pet trade, with the biggest impact on wild populations being from the latter. Interestingly enough, although these tortoises are listed as threatened on Appendix II of CITES, very few are actually shipped out of the Argentina and Paraguay. While some 75,000 Chaco tortoises a year are captured for the Argentine pet trade, only 3,000 a year are exported to Chile, Denmark, Japan, Germany, the United States, the Netherlands and Uruguay. Of those sold within Argentina, it is estimated that 32% die in their first year in captivity. (Based on the survival estimates of box turtles shipped from the United States to Europe, one can assume similarly high mortality rates in those tortoises shipped out of the country.) There is some indication that the numbers collected and exported may in fact be higher, with lower numbers being reported in order to obtain legal documentation for the shipments.
The second biggest threat comes from the destruction of Chaco habitat. The burning off of ground vegetation leaving the Chacos to compete with domesticated goats for an ever decreasing amount of vegetation. The destruction of the habitat through burning and overgrazing makes it easier for these relatively small (8 in, or 20 cm) well-camouflaged tortoises to be found and collected. This results in the third big threat to these tortoises: they are all, especially the gravid females, highly prized for their flesh.
The habitat destruction due to agricultural expansion, competition with domestic goats, and the collection for pet trade and food has put a great strain on the remaining fragmented populations. After a certain point, they will not longer be able to sustain themselves.
Another factor affecting the overall Chaco numbers is their very low reproduction rate. Mating takes place during the warmer summer months of November and December, with generally two clutches laid of one to six brittle-shelled eggs laid sometime between January and March. Incubation is quite lengthy, ranging from 125 to over 365 days; according to one report, the eggs of one captive Chaco in Argentina hatched after 14-15 months.
A few months ago, I responded to a post in one of the newsgroups on the Internet from someone who was also looking for a mate for his Chaco. Thus Tony Berke and I 'met.' While to date our tortoises have not met, it was through our ensuing discussions that we decided to try to form a sort of clearing house for Chaco owners in the United States, providing information on Chacos available for breeding loans or trades.
Unfortunately, there was an underwhelming lack of response to the registry, aside from some people who wanted copies of the registry without actually joining it. So, the registry remains a dream, rather than a reality. If you are interested in trying to find a chaco to mate with yours, or are trying to buy or sell your chacos, contact your local chelonian and herpetological societies as well as major chelonian groups in other regions (such as the California Turtle & Tortoise Club, Chicago Herp Society's chelonian group, the New York Turtle & Tortoise Society). Contact information for such groups can be found linked to my Herp Societies page.
The above article differs slightly from the version published in Reptile & Amphibian Magazine,March/April 1996, 118-120.
Chaco Tortoises - Geochelone chiliensis (Chris Tabaka & Darryl Senneke)
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