Hatching Baby Turtle Eggs
Just the other day I discovered that one of my ornate box turtles has laid several eggs. This came as a big surprise since I'd assumed the turtle was a male. I'd been overwintering her inside because she refused to hibernate this year and the cold weather was rolling in. So I put her in a big, opaque plastic tub for a terrarium that contained potting soil as substrate and a water dish big enough to soak in and a shelter that consisted of a hollowed-out piece of log turned upside-down to form a little tunnel.
I noticed that this turtle spent a lot of her time sleeping insider her hollowed-log shelter, which is normal for overwintering inside. Then the other day I saw what looked like a partial egg lying in the potting soil outside of her shelter. It definitely was a soft-shell turtle egg that hadn't completely developed and had subsequently dried out. I picked up her shelter only to find four more eggs that she had laid within! Clearly my turtle had been busy fulfilling the urge to lay eggs.
Ornate box turtle eggs are pale and oval-shaped, and about 1.5 inches in length. Unlike the hard-shelled eggs laid by birds, these eggs are soft and leathery and must be handled with care. I immediately picked up the four that I found and transferred them to a small plastic container filled with soft potting soil. I set a plastic lid loosely on top. Then I misted the soil with distilled water and placed a folded-up paper towel over the eggs. The towel is to retain humidity and to prevent any water that might condense on the inside of the lid from dripping directly onto the eggs.
I probably should have an incubator for reptile eggs – but I don't since I'm not a reptile breeder and I tend to let my turtles handle their own egg-laying and hatching in their outdoor habitat during normal spring and summer months. Usually all you have to do in the outdoor scenario is provide several attractive-looking spots in their pen to tempt them to lay eggs. This involves providing level ground that won't get flooded during rainstorms, and making sure that the ground is soft enough for turtle claws to dig a burrow without much effort. Also you don't want any ant-hills located nearby because ants can eat the newly laid turtle eggs.
Indoors, however, an incubator comes in handy. Not having one, I put the plastic container of eggs in my bathroom and put the heating lamp on overhead. This raises the temperature of the room to a steady 80-degrees Fahrenheit, which I then need to maintain for the roughly two to three months it takes for the eggs to hatch.
Here is a summary of what to do:
- If your turtle lays eggs in her outdoor habitat, let her handle it.
- If you see turtle eggs in your turtle's indoor terrarium, you will want to remove them so the turtle doesn't trample them in her confined space. Handle the turtle eggs with care; they will be soft to the touch.
- Transfer the eggs to an incubator. If you don't have an incubator, put them in a small plastic sandwich container, nestling them in soft potting soil. Mist the soil with a plant-mister filled with distilled water. Put a folded paper-towel over the eggs to cushion them and set the lid of the plastic container loosely on top.
- Place the egg-container under a heat-lamp that you can leave on for the next roughly two months to maintain a consistent temperature. Use a thermometer to make sure you're not overheating the eggs.
- If you keep the temperature at 71-degrees Fahrenheit, the hatchlings will be males. At 79-degrees Fahrenheit, you'll get some males and some females. At temperatures between 80- and 88-degrees, the hatchlings will be females. If the temperature range dips below 70-degrees or above 90-degrees Fahrenheit, it could kill the embryos. 
- Eggs take anywhere between 75 days and 90 days to hatch. 
- Mist the eggs every day and check to see if they're still okay. It will be obvious if they're not: they will cave in, dry up, or rot.
 The Box Turtle Manual, Third Edition by Philippe de Vosjoli, Advanced Vivarium Systems an imprint of Bow Tie Press, Copyright 1992, 1998, 2003, ISBN 1882770714, page 37.