Leopard Gecko Breeding | Egg Laying and Incubation Part 2
Leopard Gecko Infertility
Poor nutrition, not male sterility, is the leading cause of infertile leopard gecko eggs. In all my years, I rarely have proven a male was the reason for infertile eggs. If you are experiencing the frustration of getting infertile/bad eggs, you must examine your feeding regime and make sure you provide a balanced vitamin/mineral supplement that has good levels of calcium and vitamin D3. Once adequate supplements are offered, it may only take 2-4 weeks for fertile eggs to appear. In females who are grossly deficient, it may take 2-4 months. Another cause of infertility occurs with virgin females who have not been exposed to a male at the right time or with females who have not been bred at least once a month. Hence, the care and management of females is paramount for high fertility and strong neonates.
Leopard Gecko Egg Incubation
The soft pliable eggs leopard geckos require high humidity and good air exchange compared to hard-shelled eggs. The leopard gecko egg gains weight by absorbing moisture from air and from contact with a moist incubation medium. If the medium is too wet, then an egg will swell to a degree leading to embryo death. A sure sign of such excess pressure is the formation of transparent areas in the eggshell often allowing attack by harmful molds.
Depending on the quantity of eggs involved, the most common containers used for incubation are plastic deli cups, shoe boxes, or large sweater storage boxes filled with 1.5 to 2 inches of Perlite, vermiculite, or a 50:50 combination of both. In the last few years we have switched to vermiculite over Perlite since it does not promote the buildup of deadly ammonia gas and decay as Perlite does. Whichever medium you choose, proper moisture is achieved by mixing six parts of medium to four parts of water (6:4) by weight, not volume. Many sources of information suggest a 50:50 ratio of medium to water, but we have found that it is better to have the medium a bit on the dry side. Breeders with years of experience can mix medium and water by touch, but when this mixture is actually weighed out it has been found that such a “feel” approach is closer to a 6:4 ratio when it comes to leopard geckos.
Do not reuse incubation medium, since it becomes contaminated from the fluids and residual yolk associated with the hatching process. More than one hobbyist has experienced the anguish of losing all their eggs in the hopes of being frugal.
Eggs can be buried or rest on top of the 1.5-2 inches of incubation medium depending on how much air circulation is allowed to pass into the plastic box. Place the eggs on their side and spaced at least ½” apart so if an egg goes bad during incubation it does not directly contaminate the eggs nearby. It’s a wise practice to check egg boxes weekly for spoiling eggs. The combined effect of heat, water, and a rotting egg can produce deadly ammonia gas, which is heavier than air and stays trapped in the surrounding medium and can kill viable eggs. Eggs that are adhered together should not be separated unless you have the experience to do so or if you need to place each egg in separate incubators to get the desired sex.
Your box of eggs must be covered with a secure lid. If you are lifting the lid weekly or have a lid that is not airtight then you will not need to add small air holes to the top or upper sides of your egg box. If you will not be checking the eggs weekly by opening the lid, you should drill or melt (using a small inexpensive soldering iron in a well ventilated area) air holes near the top edge of the box or lid before setting it up with an incubating medium or adding the eggs. If you see dents occurring in an egg after some days of incubation then your medium is either too dry or the egg is not viable. To moisten the medium after setup, it’s best to spray the inner sides of the egg container (not the eggs directly) four or fives times using a pistol-grip plant mister. With dented eggs, an extra measure is to bury them just beneath the surface of the medium and then spray a couple of times directly over the egg to give them an added boost of needed humidity. Viable eggs with such dents will take 1-3 days to become full once again.
Note that long-term exposure to temperatures below 74° F (23.3° C) will kill the developing embryos
If you don’t mind hatching all females, and don’t care about your geckos’ adult color, then you won’t necessarily need an incubator. You can merely set your egg container, described in the above section, in a room or on a shelf that experiences 76-82° F (24.5-27° C) and your eggs will hatch in 75-105 days. We have found that young whom were incubated for 65-80 days hatch larger than those emerging after only 33-40 days of incubation. Simple inspection of the short-incubation eggshells frequently showed the presence of significant amounts of unused yolk. Some of these short-incubation neonates hatch prematurely, but survive if handfed, suggesting that continuous temperatures of 90F are detrimental.
Note that long-term exposure to temperatures below 74° F (23.3° C) will kill the developing embryos. If in doubt about being able to provide adequate temperatures, get an incubator.
Remember, even if you are using an incubator you MUST still place your eggs in a proper egg container of moist medium, as described in this article above. Every week of the hatching season, beginners ask us why the eggs they placed in the incubator turned into raisins overnight. And in every instance, it is because they did not place a container of eggs in the incubator but rather merely placed the eggs loose, which afforded no protection from dehydration.