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Nesting and Incubation (Red-footed)

Breeding Red-foot Tortoises:
Nesting and Incubating

By Carl D. May

[Editor's note: I have not bred any tortoises yet, so I have no personal experience. When I asked some friends to provide me a basic outline of what happens, Carl D. May, a well-known, respected, and experienced keeper wrote me a quick note that impressed me so much I made this page by pretty much just cutting and pasting his response. Thank you, Carl!

There are also a lot of questions about the age or size a Red-foot can start breeding at. The general consensus is that most of the Red-foots from the northern areas will begin laying healthy, viable eggs at about 9in/23cm, while those from the southern regions, like 'cherry-heads' start a bit smaller- 8in/20cm.

They can start to lay earlier, but this seems to result in smaller clutch sizes, fewer viable eggs, and/or a shorter breeding life. Like all tortoises, the earliest clutches are often small with fewer fertile eggs but things get better as the tortoise gets older and larger. ]


Pre-nesting behaviors
Sometime after breeding (6 weeks or more) a gravid female will begin to display a very characteristic behavior known as 'nest searching' or simply as pacing. This may go on for several days or even a week. Then again, some females only pace for a single day. 


During this time the female will drink more than usual but give little attention to food. Most noticeable though will be her wandering back and forth against a fence line or other barrier and a general restless demeanor. In the mid-afternoon she may start to dig a nest and may in fact nest on her first attempt. But very often a female (especially a younger female) will abandon that nest hole and then go rest for the night. But next day she will be right back at her pacing/nest search behavior. After seeing this display a few times it becomes obvious to most keepers.

Most of us watch for the female to start digging in the afternoon- although sometimes they will begin to nest in the mid-morning- and then keep an eye on her until she is finished. Eventually she will drop her eggs and spend quite a bit of time covering the eggs and obscuring the nest site. Then she wanders off in the dark and will sleep long into the next day... sometimes into the day after.


Nesting
The nesting process can take up to 6 hours from start to finish depending on the female and where she is nesting. There are some keepers who claim that the nesting female is in a 'trance' but this is pure nonsense- they are quite aware of what is going on around them but as they are rather busy, they give the impression of not paying attention. A nesting female can and will get spooked so keep away from her if possible and DO NOT take close-up photos with a flash!

Where I live there are raccoons and so I go right out and dig up the eggs, bring them inside for a gentle washing to remove the dirt and occasional feces that are on them. Then a date and number is written on the egg with some form of identification to specify what female the egg belongs to. Measurements are also taken at this time.


[Editors note: in another article, Carl May  mentioned that his Northern types of Red-foots often started to nest in late August/early September, then would nest roughly every month for a total of 4-5 nests. He also said that his Cherry-head (Brazilians) did not seem to follow as tight of a schedule.

Nest egg counts and egg sizes may vary by type of Red-foot with younger females laying fewer and smaller eggs. Andy Highfield mentions 3-15 eggs per nest as typical for Northern types with eggs of about 43x48mm (1.7x1.9in)]


Incubating
Since around 1980 I have used Hova-Bator chicken egg incubators ( GQF Hova-Bator Turbofan Egg Incubator: Increased Hatch Rate w/ Turbofan!Amazon link) exclusively to hatch my tortoise and turtle eggs. These Styrofoam incubators come with vent holes in the bottom so they must be plugged with silicone cement before use or else water will drip from the bottom all over your floor.

I have used both Perilite and Vermiculite as a medium for the eggs but I prefer Vermiculite as it is easier to keep uniformly moist over the many months the eggs are in the incubator. Whichever incubation medium I use I first soak it completely in water to get the dust off and hydrate it. Then the excess water is squeezed out and it is fluffed up to receive the eggs that I bury 3/4 of the way into the medium.

I set up the incubator BEFORE a female shows nesting behavior to give myself time to get the temperatures right. You don't want to be screwing around with a new incubator at the same time you need it for eggs. Temperatures ranging from 82.5 F to around 85.5 F (or around there) have produced the least amount of deformed hatchlings (with red-foot tortoises) while at the same time giving me a fairly decent sex ratio in the hatchlings. 

Red-foot eggs will take anywhere from 4 to 4.5 months to hatch but then this is not a hard and fast rule.

It seems strange but many keepers have found that eggs from the same clutch- and incubated right next to each other in the same incubator- can hatch many weeks apart. I once had an egg from a specific clutch that hatched after 4.5 months while the last eggs in that clutch took 7 months.

Egg Development
While a lot of breeders say that 'chalking' means the eggs are good I have found that sometimes even bad eggs will chalk after a couple of weeks. Eventually the eggs go from being translucent pink as when they are first laid, to a clean looking solid white.

You can candle the eggs for veins after a few weeks but I prefer to not handle them at all after they are in the incubator. If you really want to see if they are fertile then simply hold a small penlight up to the eggs without removing it from the incubator. Usually you can see a reddish pink interior with some veins inside the egg.
 
However, as the egg continues to mature and chalk up, you won't be able to see inside it any longer without hitting it with a really powerful light. You aren't helping the egg to hatch by doing this so again, don't mess with them.


 An egg that is about to hatch will appear very clean and white as I mentioned above. Sometimes you will see a small clear spot inside the egg that is the inner membrane of the egg shrinking away from the egg shell. This looks like a clear 'bubble' when a light is shone on the egg and it is a good idea to mist that egg heavily with water then. (See photo to the right)

Hatching
In the case of a hatching egg the neonate pops open a small hole in the egg shell and might stick its nose out for a day or two before doing much else. Typically, they pull their nose back into the egg and then turn and make another opening on the other side of the egg. Over the next day or two the neonate will make several more turns inside the egg and poke holes in the shell which results in the egg getting chipped in half along the midline. You will often see the neonate's bottom sticking out of one side of the egg while it is working on the opposite side with its egg tooth. DO NOT REMOVE THE HATCHLING AT THIS TIME. Unless it is bothering another egg around it, leave the new hatchling alone. It’s not a bad idea to mist the hatchling with dechlorinated water at this time to keep it from getting too dry as they sometimes do inside the unnatural environment of an egg incubator.

After a couple of days the neonate will begin to shuffle around a bit inside the incubator but they will still have a pretty big yolk sac so remove it and place it in a warm, damp place to finish absorbing the yolk sac. They will begin picking at food even then however and you have to be careful and make sure they don't start eating the incubation medium. For some reason, the white colored Perilite seems very attractive to neonate tortoises and I have seen them sitting inside their eggs and reaching their heads down to eat it while they still have a huge yolk sac left. Typically, these hatchlings produce little white piles as their first droppings. Never seems to hurt them though. 

After that, the work really begins as you now have all the anxiety of raising the babies!


Photo Credits
Nesting Red-footed Tortoise by Allegra Fung
Red-footed Tortoise eggs by Carl D. May
Egg showing membrane pulling away by Carl D. May


[Editor's note: This photo by Allegra Fung shows what is sometimes called the 'polar ice cap', another sign of a good egg.]


11-28-2011 (C) Carl D. May
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