Captive Breeding of the Chaco Tortoise (Testudo chilensis)
Juergen Rottman, Santiago Chile. Translated from the German by Andrea Henke
The Chaco tortoise, also known as the Argentinean tortoise, while not native to Chile, is still commonly offered here in Chile in the pet trade. The animals originate from different Argentinean locals: Mendoza, San Luis and Cordoba. Dr. Heinz Wermuth published an extensive article on this tortoise species in DATZ (Issue 2,1967)
The sexes of this species are difficult to differentiate. The male hasa a somewhat concave plastron; however, the curvature is very slight and hard to notice. Also, in the male, both the anterior scutes of the plastron (gular scutes) are thickened and rounded as they are used in mate combat. The epiplastron is thinner in the female with the growth rings visible in most cases.
My own Chaco tortoises hibernated for a considerable length of time, from May to September [southern hemisphere]. They hibernated outdoors under a leaf-pile. They dug a depression under the pile, using both fore and hindquarters. Several animals hibernated together, lying side by side. The outside air temperature during the winter dips a few degrees below freezing in these parts, which proves fatal to individuals who are not adequately sheltered. Caution needs to be taken when the animals are hibernated indoors, as they tend to dehydrate quickly. Insufficient hydration makes them susceptible to respiratory infections. My animals ate lettuce, cucumbers, cactus fruits, melons, apricots and other various fruits, while their favorite food item was cactus leaves [prickly pear?]
During the spring, I frequently observed copulation. My own tortoises only laid eggs during the fall; however, I observed egg laying during the spring and summer in specimens kept by other enthusiasts. Prior to egg-laying, the female would dig a 8 cm (3.2 inch) deep depression into which she would lay 2 to 4 white eggs. She would then carefully cover them with dirt. The eggs were laid next to one another, but occasionally one would lie on top of the others. The female is ready to lay another clutch of 2 to 4 eggs after about a week. My largest female laid 15 eggs in four different clutches during the span of one year. The following year, however, she laid only three clutches. This particular female weighted 2640 grams (5.78 lb.) and had a carapace length of 215 mm (8.6 inches) (ruler measurement). The eggs have a hard, rough, white shell and are either round or oval in shape. On average they massed 36.5 grams. The dimensions of 5 eggs were: 47x38 mm, 46x37 mm, 46x35 mm, 44x39 mm, and 42x40 mm. The oval eggs tend to be flattened, so that their circumference in the middle, depending where it was measured, varied within 3 mm. In the first year of attempted breeding, I left the eggs in the ground but they spoiled. In only one of the eggs did I find a 12 mm long embryo after 12 months. The following year I excavated the eggs and kept them in a tin can filled with sand over the winter. Once spring arrived, I prepared a box filled with sand. I placed the eggs 8 cm deep in the sand. In order to increase both humidity and temperature in the box, I covered it at a height of 10 cm with plastic sheeting, leaving a 10 cm wide opening for ventilation at one side. I moistened the sand every 10 days. The box stood outdoors in a sunny spot. After 5 months, a single tortoise hatched and made it to the surface. A second tortoise died shortly after hatching while still buried in the sand. It measured 44x44 mm, was 28 mm tall and massed 25 grams. Even though their native environment lies on the same latitude as my location in Chile, our summers ewe not warm enough.
The young tortoise hatched in the fall, 13 months after egg-laying. I had difficulty bringing her through the winter. She refused food. Even though I had placed two 75 watt light bulbs over her enclosure, she tended to be active only in the sun. Her condition after 4 months was serious: she refused food completely and her eyes and nose were sticky. I treated her with medicated eye drops (2% antibiotic solution) by moistening her head, neck, fore limbs, hind limbs and tail region with the solution. I repeated the treatment three times, after which her condition improved and she resumed feeding. During the spring and summer, she would drink water daily. Her diet consisted of lettuce and fruit, mainly apples. After 5 months (on Sept 30th) she massed 27 grams. On January 11th, she massed 34 grams, April 5th 80 grams. Her carapace was 65 mm (2.6 inches) long and 58 mm (2.32 inches) wide, with a height of 32 mm (1.28 inches). During May, she would only eat on sunny days which is normal behavior for a tortoise which hibernates.
The original German copy of this article is long gone, as is any reference of the journal in which this article first appeared, the photos, literature citations in the original article, and the date of the original publication.
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