Authored by Ron Tremper, of Leopardgecko.com
Leopard Geckos | Incubators, and Incubation
In general the best location for placing a reptile incubator for leopard geckos is at a room temperature slightly lower than the minimum temperature you are striving for.
There is a wide range of bird egg and other incubators available from specialized companies, including reptile supply stores, on the Internet. These should be carefully evaluated, particularly if your goal is to produce leopard geckos on a large-scale. For most hobbyists in the United States, the small Styrofoam poultry egg incubators such as the popular Hova-bator® by Lyons, will prove affordable and readily meet their needs. Hovabators are available via our affiliate as well, just click the link Hovabator.
Unless one can afford to spend hundreds, or even thousands of dollars on an incubator that can both heat and cool, most simply provide an insulated box with a thermostatically controlled heating unit. Exo Terra has some new Reptile Incubators which both heat and cool for relatively inexpensive. New Digital Temperature Control Exo Terra Incubator.
This is important to remember, because these incubators will not maintain the desired temperature if placed in a location where the air temperature can exceed the desired incubation temperature. Thus, during heat waves, if one does not have air conditioning, there is the risk of overheating eggs and killing them. In general the best location for placing a reptile incubator for leopard geckos is at a room temperature slightly lower than the minimum temperature you are striving for. For most purposes comfortable room temperature will work fine.
The inexpensive Hova-bator® has a lever/dial which adjusts a very precise wafer type thermostat that turns the heater on or off, but it does not tell you at what temperature. The setting needs to be calibrated with the thermometer placed inside the unit. To incubate the eggs at the desired temperature, you will have to adjust the dial setting so that the heating unit turns off when the right temperature has been achieved and the thermometer readable through a clear window stays at the desired temperature.
To initially calibrate the incubator, place the thermometer and assuming heat is required, turn the dial a little past the point where you hear the click that indicates the heating unit is on and then wait at least a half hour, check the temperature again and adjust accordingly. Repeat the procedure until the thermometer indicates the incubator is maintaining the desired temperature. The calibration process can take an hour or more to complete. To facilitate things, there are currently on/off thermostats sold in the pet trade where you can plug the unit in and set the dial to the desired temperature, which will be maintained with the help of a thermometric probe placed in the incubator. Zilla makes just such a thermostat, Zilla Reptile Terrarium Heat & Habitat Lighting Temp. Controller,1000W.
Do refer to the thermometer inside the incubator to verify the accuracy of the setting. Another useful tool is an electronic digital thermometer with probe, (place probe in incubator and set to outdoor measurement) which will provide a continuous readout of the temperature inside the incubator such as the Indoor Outdoor Electronic Digital Thermometer and Humidity Sensor.
What to do in heat waves
If during a heat wave you are facing an emergency where the room is rising higher than what is safe for eggs, a quick solution is to add a small container with ice or a small ice pack inside the incubator. Replace as needed until temperatures return to normal.
The process of getting the best possible colors in females, from the genes present, requires that you keep the eggs at the “female” temperature for the first three weeks and then move these eggs to the “male” incubator for the duration
Researchers discovered some years ago that incubation temperature, not sex chromosomes, determines what sex a leopard gecko will be (Viets et al. 1993). More recently, researchers have shown that temperature can also affect pigmentation, behavior and even brain structure.
If eggs are incubated at 79° F(26° C) then 100% female geckos hatch. At temperatures around 85-87° F (29.5-30.5° C) you get close to an equal number of males and females, and at 90-91° F (32-33° C) mostly males are produced. Eggs incubated at 93° F (34° C) again produce primarily females. Worth noting is that both females incubated at temperature extremes (low and high) have a smaller percentage of fertilized eggs survive to hatching and that high temperature females have the lowest percentage of fertile eggs than other temperature group (Sakata and Crews unpublished data in Crews et al. 1998)
Keep in mind that a constant incubation temperature of 89-91° F (31.7-33° C) may increase embryo losses and that temperatures above 95° F (35° C) for more than 24 hours are lethal for developing eggs.
To determine the sex of leopard geckos (which is apparently done in the first three weeks of incubation) it is not necessary to maintain the determining temperature round the clock. To avoid thermal stress in newly developing embryos it is advised to expose eggs you want to be males to 90° F (32° C) for 12 hours a day and down to 85° F (29.4° C) for the remaining 12 hours each day. This can be accomplished by turning off your incubator with an inexpensive multi-setting wall timer. Another acceptable approach is to lock in the sex at the male or female temperature for the first 3-4 weeks of incubation and then let the eggs finish development at a continuous 84-87° F (29-30.6° C).
Temperature also affects the amount of melanin, which is responsible for black pigment, and other colors in leopard geckos, as well. Basically, at the male incubation temperature the lightest concentration of pigments in the skin and eyes occur. This stands out in particular in the three albino lines. One can easily understand how to get light-colored male albinos that are beautiful, but some moving of eggs is required to get “pretty” female albinos. The process of getting the best possible colors in females, from the genes present, requires that you keep the eggs at the “female” temperature for the first three weeks and then move these eggs to the “male” incubator for the duration. Albino females incubated at a constant temperature between 80-84° F (26.7-29° C) will hatch out being dark brown in color. Lavender albinos are not a product of genetics, but rather from an incubation temperature of 85-87° F (29.5-30.5° C).
Over time, selective breeding should produce lines of albinos that hold their color after hatching.
Even after incubation and hatching, manipulating temperature will have an influence on the phenotype of leopard geckos. Exposing leopard geckos of any morph to temperatures below 82° F (27° C) for more than 24 hours will cause dark skin pigments to be synthesized. For example young albinos raised at cooler temperatures can show varying amounts of dark brown and dirty yellow. I have found that it is not until an albino reaches 10 months of age that some individuals’ colors become permanently set. Over time, selective breeding should produce lines of albinos that hold their color after hatching.
With hypo tangerine leopard geckos, specimens that lack banding at warm temperatures may show light brownish tangerine bands when maintained at cooler temperatures. With morphs where darker color is more desirable, keeping them at the cooler end of the temperature requirements for this species can enhance their appearance, e.g. melanistic or ‘Midnight blizzard’. In conclusion, manipulating incubation and rearing temperatures can be an important tool for designers whose goal is to produce living art.