Pancake Tortoise Breeding
Recently I wrote about the care and natural history one of the world’s most unique turtles, the pancake tortoise.Today I would like to add a note about breeding this species in captivity. In addition to the personal satisfaction you will gain from such endeavors, your efforts stand to contribute to what little we know concerning this creature. This is especially important for those species, such as the pancake tortoise, that face threats to their continued existence in the wild.
Pancake tortoise breeding programs in both zoos and private collections are plagued by the low fertility rates that are common among captive individuals. The fertility question in this species in perplexing, as it otherwise adjusts well to captivity- captive hatched animals are usually vigorous, and longevities of over 25 years are documented. Stress, which often results in reduced fertilities and complete lack of breeding, seems not to be a major factor here. This is, therefore, is an area where hobbyists can make important contributions.
Temperature and Humidity Requirements
In my and other’s experience, some species respond well, in terms of increased fertility, to temperature, day-length and humidity fluctuations that mimic those occurring in the animal’s natural range. A study of the prevailing conditions within this tortoise’s natural range may provide some answers. For example, pancake tortoises in some areas aestivate (become dormant) during the hottest, driest times of the year. We know that many temperate turtle species, such as the box turtle, Terrepene Carolina, exhibit decreased fertility if they are not give a hibernation period in captivity - perhaps some pancake tortoises require a hot, dry “season” followed by rains and cooler temperatures. By creating captive conditions that are in tune with those of southeast Africa, you may meet with greater success.
Obtaining Breeding Stock
As not all pancake tortoises aestivate (only those from certain parts of their range do so), it is very important that you determine, if possible, where your particular animals, or their parents, originated. More and more dealers and breeders are paying attention to their stock’s point of origin, so be sure to ask when you purchase or trade animals. This is a good rule to follow with all reptiles and amphibians – doing so will enable you to fine tune diets, heating, light cycles and other important processes that affect your pet’s health. Accurate locality data is also vital to the success of breeding programs. In some cases, mating same species animals from different parts of the range can have disastrous consequences. I am thinking here of a zoo-sponsored program that sought to reintroduce the ibex (a wild goat) to portions of its range in Europe. Ibex, all of the same species, were transported from mountain ranges in Italy, Spain and North Africa to suitable habitat in, I believe, northern Italy, and released. They adjusted well but females often gave birth in the dead of winter, and the young did not survive. It seemed that animals from different areas were distinct, genetically, and the resultant inter-breeding somehow disrupted the reproductive process. There are similarities among reptiles and amphibians - i.e. Carolina anoles, Anolis carolinensis, from south Florida cannot survive the occasional frosts that barely affect animals in the north of Florida. If you are serious about breeding animals and even possibly cooperating with conservation efforts, please do your utmost to determine locality data, and record it carefully
Dietary factors are also very important in the reproductive process. Many species change their diets, often quite dramatically, prior to coming into breeding condition. Field research reports are often a valuable source of information as to a species’ native diet, so keep an eye out for them when doing your research.
And now back to some specifics concerning our flattened friends. As with many tortoises, male combat often precedes mating, and seems to spur reproductive success in captivity. Unlike most tortoises, male pancakes get along fairly well in general, but should be watched when one shows interest in breeding. A bit of fighting should be allowed, but battling males should be separated when you are not present, just to be safe.
Females lay a single large, elongated egg per clutch (rarely 2) and may produce 3-4 clutches per year. Adults tortoises provided with a varied diet need vitamin /mineral supplementation only once each week in most cases, but during the breeding season supplements should be added to the females’ salad at each feeding (calcium is particularly important at this time). Be sure also that your UVB bulbs have been replaced within the time limits set by the manufacturer, so that your pets can utilize their dietary calcium. Mating occurs most often in January and February, and the eggs are deposited in July and August, but such can occur throughout the year in captivity. Incubation may take up to 300 days (range 99-300 days). The hatchlings average 1.6 inches in length, and, in contrast to the adults, have domed shells.
Egg Laying and Incubating
Pancake tortoises often deposit eggs right on the surface, or within shelters, so check frequently lest they be crushed by the female or other animals. None-the-less, it is important that you provide appropriate laying sites, as some tortoises may retain eggs, or become stressed, if unable to find a good laying site. A container of slightly moist sand covered by a domed shelter (i.e. cork bark), often does the trick. Some keepers have noticed that gravid (those with developing eggs) females tend to climb into flower pots and other elevated sites at egg laying time - perhaps in the wild they seek higher ground?
Handle any eggs that you discover gently and bear in mind that oil from your skin can clog egg pores - powder free latex gloves are a good idea. The eggs should not be turned when they are moved, and should be re-positioned in the incubator in the same position as they were found. A commercial reptile egg incubator is the way to go when seeking to hatch tortoise eggs. A mix of vermiculite to water at a ratio of 1:1 by weight is the standard, although some success has been had with a ratio of 1:3. To obtain a 1:1 mix, first weigh the vermiculite in grams and note this figure. For the water, you will need a graduated cylinder or measuring cup that is marked off in milliliters. Since 1 milliliter of water weighs 1 gram, the computation is easy (even for one so mathematically challenged as I!)- you are using 50 grams of vermiculite, add to it 50 ml. of water.
The substrate should be placed within a small Tupperware or similar container and the eggs half-buried into the substrate. Weigh the container, with substrate and eggs inside, and note this figure on the container's lid. Re-weigh once each week - any drop in weight is the result of evaporation, and should be made up by adding the appropriate amount of water (i.e. if the container weighs 1 gram less, add 1 ml. of water). In the past I have used unventilated containers (opening each day to oxygenate) with some success, but the current trend is to perforate the container to allow for more gas exchange. I would agree – especially as the eggs mature and the embryos require more oxygen - just remember to watch for water loss.
Incubation temperatures of 86-89 F have worked for me and others in hatching pancake tortoise eggs. As with those tortoise species that have been studied thus far, the sex of the hatchling is likely temperature dependent. In general, cooler temperatures produce more male tortoise hatchlings, while higher temperatures favor the development of females (the same rules do not apply to other reptiles). There is also a range at which both sexes will be produced, more or less in equal amounts, but I do not believe the exact limits of this range have been established for pancake tortoises. This is an area where pet owners can contribute greatly, so please be sure to write in with your discoveries.
There is some evidence that decreasing substrate moisture levels spur hatching, and that a nightly drop in incubation temperature (to 77 F) increases hatching success - further experimentation in this area is needed. Again, anything that you can learn will be of immense help to those interested in keeping and conserving this fantastic tortoise.
The details of 1 person’s success in breeding this species are given at:http://www.tortoisetrust.org/articles/pancake.htm