That Reptile Blog – Reptile, Amphibian and Exotic Pet Care and Information

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.

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.

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.

Amphibians and fish are highly susceptible to even minute amounts of foreign chemicals in their habitats. As such, their current population declines should serve as an important “early warning signal”, forecasting problems that will eventually affect other animals and ourselves.

An odd twist to this sensitivity issue among frogs is that an injection of gonadotrophin, a human growth hormone, brings many species into breeding condition. This discovery was a boon to captive breeding programs, as most frogs require the duplication of certain environmental cues – dry or wet seasons, for example – if they are to breed normally. However, things can easily go wrong – while using hormones to stimulate breeding, I and others have noted that some male frogs began to develop organs resembling ovaries.

Now, male frogs in the wild are being found to have inter-sex characteristics, including immature eggs within the testes. A recent Harvard University study found such characteristics in 21% of the male green frogs, Rana clamitans, in ponds in suburban Connecticut. It seemed that the affected frogs were more common in suburban than agricultural areas, but other studies have yielded opposite results. Similar reproductive system changes have been documented among catfish in Africa, sturgeon in the Mississippi and other fishes.

Pesticides, the herbicide Atrazine, and other chemicals commonly found in water and soil have been shown to affect sex hormone development, but much more research needs to be done.

There is a great deal of ongoing research in this important area – please read any related articles that you may come across and write in to share new information.

An article describing research into the effects of Atrazine on amphibians is posted at:http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1247376

Another amphibian that breeds in early spring is the strikingly marked spotted salamander, A. maculatum. Reaching 9 ¾ inches in length, these stout animals are jet black with yellow spots, and have been observed crossing snow during breeding migrations (I find them in ponds in southern NY in mid-March).

Amazingly, a species of green algae, Oophila amblystomatis, colonizes the spotted salamander’s globular egg masses. The algae most likely utilizes carbon dioxide and ammonia produced by the developing salamander embryos, and may in turn provide the embryos with oxygen (although the amount released is quite low). There is speculation that the algae may produce a growth factor that benefits the embryos, but more research is needed. In any event, experiments have shown that egg masses with this algae hatch faster, and with a higher survivorship, than do those lacking the algae. Conversely, algae growth slows markedly if the embryos are removed from the egg mass upon which it is established.

Spotted salamanders make interesting pets, and, while adapted to a burrowing lifestyle, adjust well to life above ground. Properly cared for, they can live for over 25 years. I will discuss them further in a future article.

More detailed information on this unique relationship is available at:
http://jeb.biologists.org/cgi/reprint/197/1/17.pdf

The robber fly, which is sting-less and tasty, closely resembles the unpalatable bumblebee. A southern toad, which had previously seen neither fly nor bee, was presented with a robber fly, which was promptly eaten. A bumblebee was then offered – the toad grabbed it, was stung, and spit out the bee. A subsequent bumblebee was refused. Then another robber fly was offered – and, its lesson learned, the toad backed away. To prove that the toad was still hungry, the researchers then provided a dragonfly, which was immediately eaten.

I am not aware of research concerning how long such lessons are retained – but my own experience offers some clues. I have long kept green frogs, Rana (Lithobates) clamitans in an outdoor pen, where I used ripe fruit to attract insects for them to eat. Year after year, I observed the same frogs to studiously avoid yellow-jackets and other wasps, while snapping up flies and beetles located close to the wasps. It would appear that they were stung at one point, and that the lesson lasted, as far as I can tell, for at least 6 years.

The book to which I referred above is one in the wonderful Life Nature Library series published by Time, Inc. Don’t let the publication dates fool you – they are packed with original observations and unique photos.