Second to diet....this is the subject that seems to raise the most questions. I will attempt to address all the questions and concerns that have been presented to me over the past 11 years.
Size: How big/old do they need to be in order to mate?
They seem to start mating at a small size. Males start at 4". From my experience these small males are not mature enough to be fertile. I have heard that females 4.5" can lay viable eggs. This seems to be the exception rather than the rule.
It appears that size is more of an issue than age. Most people that are having success with breeding have females that are over 6" and males over 5".
Here are some pictures to help: Male/Female pictures
The males have long tails that are kept tucked to the side (its long enough to reach over the leg). The tail has a "hook" on the end.
Females have much shorter tails...usually carried straight back.
Probably the most important aspect of breeding ( after being sure you have males and females that are the right size) is making sure the tortoises are well fed and healthy.
While success can be achieved with one female and one male, its much easier on the female if there are 2 or more females in the breeding colony. A good ratio is 1 male to 3 females.
While some feel hibernation is an absolute necessity, many are very successful in breeding these torts and producing fertile eggs without hibernation. For the first 5 years mine had viable clutches without hibernation and I haven't seen a change in the number of clutches or viability of eggs since I started hibernating my torts.
If the diet is good and the animals are old enough,
mating will occur. Most mating takes place the first
few weeks after they come out of hibernation. Males initiate
mating by circling the female and bobbing its head. He will
often bite the front legs of the female at times pulling off
(see the following pictures )
The females rarely seem interested and do their best to escape. When the male mounts the female he assumes an open mouth posture and squeals.
If the female was fertilized, within a month she will be ready to lay eggs. Some females will have multiple clutches. And (at least with mine) some won't lay eggs until the fall.
A suitable nesting area needs to be provided whether they are inside or outside. Outside a sloping, well drained sunny spot ideally with plants or rocks for her to hold onto while digging. My females like to nest at the base of a small pussy willow. Inside, you will need to provide a nesting box. A 6" deep Tupperware container filled with 50% sand/ 50% Bed-A-Beast works or garden loam works well. Provide a ramp of flat rocks .
When the female is ready to lay eggs, she will usually become very restless...pacing the perimeter of the pen (and constantly digging if kept indoors). She may stop eating for a few days to a week. Many will dig "test" nest or two.
Frequently indoors they will lay eggs in the open no matter how nice the nest box is.
As a rule the female is very particular about nest site selection. However once the eggs are laid she will take no further interest in her offspring.
They will lay 1-5 rather large eggs. Mine typically lay 2-3 eggs. The eggs weigh 16-30 g . For sequential pictures of egg development click here.
I like to have an incubator set up prior to egg laying. I use the Hovabator. Its fairly cheap and keeps a constant temperature. An accurate digital max/min thermometer is a must. It can take a few days to get the temperature right. Most recommend the temperature to be set between 29°C (84.2°F) and 35°C (95°F). I have personally found that temps over 32.22°C (90°F) results in less hatchings. I prefer 31.67°C (89°F). Sex determination is temperature dependent, with lower temps producing males and higher temps producing females. At 31.67°C (89°F) I get females. If the temps are too high shell deformities (such as extra scutes) will occur. In the past I have set the temperature to 30°C (86°F) and got a mix of males and females without deformities.
Before digging up the eggs, set up a Tupperware container big enough to hold the eggs( you can see some examples below). Fill it half way with moist vermiculite (available at garden centers). To moisten the vermiculite , mix with an equal amount of water by weight.
Once the eggs are laid, carefully dig them up being sure not to rotate or flip them. I use a soft lead pencil to mark the date and weight on the top of the egg. Bury it half way in the vermiculite and cover with a damp piece of paper towel or some strands of damp sphagnum moss. Put the lid on loosely. In the incubator I put a few open containers of water. This helps keep the temps stable and helps with humidity. If all goes well they should hatch in 8-12 weeks.
Between 2-4 weeks blood vessels may be visible when candling. Candling is shining a bright light through the egg. Its best done in a dark room. Be careful not to turn the egg. Click here to see how to candle eggs.
It can take up to 2 days for a hatchling to break out of an egg. They are oriented "sideways " in the egg and appear "folded" when they hatch. Many have visible yolk sacks and should be kept in the incubator until the yolk sack absorbs.
It can take 2 weeks or longer before they start eating. During this time they are living of the yolk reserves. I keep them in small Rubbermaid containers until they are actively feeding. If the weather permits I bring them outside during the day. I use 55 gallon Rubbermaid containers that are planted with weeds. The top is securely covered with hardware cloth and 1/2 is shaded.
©2000 Joe Heinen DC
Eggs and hatchling pictures of egg laying can be found here