Though wild red-ear sliders incubate their eggs in the sand, hobbyists generally have better success rates when they dig up the eggs and incubate them artificially. You will need some type of incubator, an incubation medium, a quality thermometer and about two months of patience. By incubating them at different temperatures, you can even decide whether you want the eggs to produce males or females. Be sure to set up the incubator before you begin retrieving the eggs.
Setting Up the Incubator and Egg Box
An incubator is essentially a climate-controlled box. Hobbyists and breeders use a wide variety of sizes, styles and configurations -- some buy commercially produced units, while others construct their own. All have different pros and cons, but most types will work for slider eggs. Inside the incubator, you will place a small plastic container that holds the eggs and substrate. Some place the incubator’s temperature probe inside the egg box, while others prefer to leave the probe outside of the egg box. Drill a few very small holes in the box so that the container will have some air exchange with the incubator.
Most keepers use damp vermiculite inside the egg box, though others prefer peat or sand. While opinions on the optimum ratio differ, many keepers are successful with a 1:1 ratio of vermiculite to water by weight. A handy tip is to squeeze the vermiculite in your clenched hand -- it should be damp enough to clump, but not wet enough to drip.
Retrieving the Eggs
When ready to deposit their eggs, female red-ear sliders excavate a small chamber in dirt or sand. Inside, they deposit about 15 eggs before replacing the removed dirt, thus hiding and protecting the eggs. Allow the female to cover the hole and return to the water before removing the eggs. At this point, you will need to dig out the hole with your hands and remove the eggs. Remove one egg at a time, mark the top of it with a graphite pencil and then place it in the egg box. Bury each egg about half to three-quarters of the way, and be sure to keep the pencil mark pointing up.
Temperature Dependent Sex Determination
Like many other reptiles, temperature -- rather than genes -- determines the gender of hatchling red-ear sliders. Scientists call this phenomenon temperature-dependent sex determination. When incubated at or above 86 degrees Fahrenheit they usually become female, while those incubated below 81 degrees Fahrenheit become male. Clutches incubated at intermediate temperatures produce a mix of both genders. This characteristic allows breeders to maximize their efforts and develop breeding projects quickly by producing prodigious amounts of females.
Countdown to Hatching
The eggs may begin hatching after about 50 days, though some may take as much as two more weeks to develop. The exact duration of incubation varies with the temperature at which you incubate the eggs; higher temperatures result in shorter incubation times. Accordingly, females generally hatch faster because they develop in warmer environments. Turtles break out of their eggs by using their egg tooth, which will drop off soon after hatching. They may take a day or more to exit the egg completely. At this time, place them in a warm, clean habitat with a very shallow water dish. Sometimes, the hatchlings will retain part of their yolk sac, which you should leave intact until the turtle absorbs it naturally.
- California Turtle and Tortoise Club: The Red-Eared Slider, Trachemys Scripta Elegans
- RedEarSlider.com: Reproduction
- University of Michigan: Pond Slider
- Biology of Reproduction: Incubation Temperature Influences Sex-Steroid Levels in Juvenile Red-Eared Slider Turtles, Trachemys Scripta, a Species With Temperature-Dependent Sex Determination.