Breeding tortoises is all about patience (since they need to be several years old) and knowledge (since every species has specific needs and ways of doing things). There are, however, some general concepts that you should know.
To encourage breeding
As your tortoises approach sexual maturity, you can improve your odds of successful breeding by following a few basic recommendations.
- The tortoises are kept outside in a well-planted, spacious pen with an open ‘courtship area’ and good nesting opportunities- sandy pits at least six inches deep, located in sunny areas. They may not use them, but it often helps, especially if your soil is hard. See Tortoise Trust’s article for more on nest sites. (Nesting certainly can occur indoors, but takes room and planning to work. The Tortoise Trust article addresses this as well.)
- There is a breeding group with at least two males and more females than males. A ratio of 2:3 is the usual minimum. Some keepers suggest that breeding colonies should be built up to about 2:10-15, and when the numbers get larger, that another colony be started around two more males.
- Males and females are separated outside of mating season. It also works best if the males for a breeding group are kept together. A mix of a younger and older male often creates competition and improves results.
- The animals are healthy- a good diet, good weight, adequate UVB, etc. Breeding animals should also get more calories in their diet, while keeping an excellent calcium:phosphorous ratio.
- The females are large, with enough spacing around the anal scutes for egg passage. The best males often have deeply indented plastrons and very long tails.
Signals of courtship and breeding
It can be tough to distinguish aggression from courtship and domination challenges. Both sexes tend to get more active during mating season. Females often walk with their legs extended or hind end held high, males sniff at females or anything else that catches their attention. Males also tend to become more vocal and flash (display their penis) more often. These are signals that it is time to unite the males and females, or generally about mid-March for many species. (Note- a smart tortoise breeder will make sure they have a good, properly set-up incubator at this time. Otherwise, Murphy’s Law will kick in full force!)
Some species of tortoises, such as red-footeds, are so vocal in their mating that you can hear them some distance away- a good sign that courtship and mating is happening. Of course, seeing tortoises mate is another obvious sign!
Roughly a month after mating, females begin to build nests. They may build several practice or decoy nests, and even females that are not carrying eggs may build nests. Most species take pains to cover and camouflage the nests, Some, especially Manouria build rather large and elaborate nests of leaves and debris, while others, such as the yellow-footed, may just lay eggs on the top of the soil.
Look for signs of disturbed soil or active nests and mark them for later exploration, but do not disturb a nesting or egg-laying female, or a nest that is being guarded, again, like those of Manouria. You can always leave the nests alone and let things happen naturally, but because of risks from weather, predators, etc., most keepers prefer to dig up nests and move the eggs to an incubator.
If you need to move the eggs, carefully dig up the nest and mark the tops of the eggs with an ‘X’, and any identifying info you care to (date, mother’s name, etc.) Keep the ‘X’ up during all moves! Move them to a warm, humid incubator as quickly as you safely can. Return the nest to its original condition.