There are various reasons why owners would want to sex or determine the gender of their pet Leopard geckos. There are 4 ways to sex a Leopard gecko.
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Introduction to sexing a Leopard gecko
Sexing a Leopard gecko is fairly easy. From a gender point of view, all baby and most juvenile Leopard geckos will look exactly the same and can therefore only be accurately sexed from about 3 months of age. Sexual maturity in Leopard geckos (the age at which they can start to breed) is reached between 6 to 10 months of age. Larger, and adult Leopard geckos have a definitive sexual dimorphism (sexes are visibly distinguishable), but there are other ways to make an educated guess.
Not all Leopard geckos will show same-sex characteristics. Some Leopard geckos will have more gender identifying characteristics than others.
Leopard gecko sexing
The most accurate way to sex a Leopard gecko is by looking at the externally visible sex organs. They are situated next to the vent area on the underside of the tail base.
In male Leopard geckos, the area next to the vent towards the tip of the tail, there will be two visible bulges. These bulges are formed by the two hemi-penises. The middle of the two bulges will have an ‘hourglass’ appearance. Having no hemi-penises, female Leopard geckos will have no, or one slightly visible, bulge in this area.
Another fairly accurate way to determine the sex of Leopard geckos is by looking at the presence of femoral pores. Males will have a row of very distinctive femoral pores just in front of the vent. The rows often form a V-shape pointing to the head of the gecko. Leopard geckos with femoral pores can be accurately sexed as a male, but those without pores are not always female. A female Leopard gecko will almost always be without femoral pores.
A second, far less accurate way to determine the sex of a Leopard geckos is by looking at its body conformation. Generally, male Leopard geckos will have a broader head and will weigh more. Females might have broader/shorter bodies when compared with males.
Although an informed guess can be made by comparing the size of two Leopard geckos,
Temperature-dependent sexual dimorphism
Another way to make an educated guess on the gender of a Leopard gecko is by knowing the temperature at which it was incubated during the first 3 weeks after the egg was deposited. Leopard geckos have, what is called, temperature-dependent sexual dimorphism. This means that the temperature at which Leopard gecko eggs were incubated has an effect on the gender of the babies.
The male to female ratio is much higher at warmer average incubation temperatures (31-33 °C / 88-91 °F). More females will be born if the incubation temperatures were dropped to between 26 and 27 °C / 79 and 81°F during the first 3 weeks and then increased to a higher incubation temperature (31-32 °C / 88-90 °F) after that. A more-or-less equal amount of male and female Leopard gecko babies will be born when the eggs are incubated at temperates ranging from 29 to 30 °C / 85-87 °F. By controlling the incubation temperature, Leopard gecko breeders often manipulate the gender of the babies.