Authored by Ron Tremper Leopard Gecko
The Breeding Season
North of the equator, most reproductive leopard geckos experience a breeding season that begins as early as January and extends to late September with some geckos laying eggs into October. For individuals that are hatched late in a given year they may not start to cycle for egg-laying until April or May of the following year. Basically, a female that has attained proper body weight will begin laying at 9-10 months of age once introduced to a male.
How does one get eggs year-round? Many breeders are able to manipulate light cycle and temperature to induce separate groups of leopard geckos to begin laying at different times of the year, so that when one group is just finishing their season another group is just beginning. Also, it has been shown that certain related lines of leopards have a set pattern of reproduction different from the normal January to September season. For example, our complete colony of Tremper albinos all start cycling in September and begin laying in October each year without any environmental manipulation, while the unrelated, non-albino designers on the same rack system don’t start laying in earnest until January.
Many people ask, “Is it alright to breed fathers with daughters and brothers with sisters?” The answer is, yes. First, many reptile species live on small islands where genetic diversity has been limited for thousands of years, while others have isolated habitats or form colonies in the wild that exhibit varying degrees of “inbreeding” as the natural order of things.
If, however, you have breeding stock that exhibits obvious abnormalities in body, tail shape, eye configuration or other physical weaknesses, then inbreeding, commonly called line breeding, should be avoided since you will be passing on and likely increasing the rate of these defective traits.
By the time I had reached twenty generations of line breeding I noticed weaknesses in my colony that included a shortening of the tail in proportion to the body, lowered egg fertility and, when stressed, greater susceptibility to disease. Introducing a new bloodline consisting of three tangerine females into our group some years ago resulted in renewed vigor and the elimination of the problems. As a rule, it is recommended to outcross a leopard gecko line every 4-5 generations to ensure consistent good breeding results and the overall vigor of a line. The further you get from wild-caught bloodlines, the more important out-crossing becomes.
Beginners may not need any particular breeding plan and often don’t. There is nothing wrong with simply keeping a gecko singly or setting up a male and female and letting nature take its course. But please know that it is not true that a single gecko gets lonely and will do better if paired with a cage mate.
On the other hand, if you have begun to focus on breeding leopard geckos then you will need to keep careful records on parentage and crosses. This will require planning based on what color and pattern morphs you have, and identifying the ones you will need in order to achieve the desired outcomes. For example, if you consult the steps required to obtain leopard geckos that express three recessive traits, you will quickly realize that failure to keep careful records of genotypes at any stage in the process will greatly reduce the probability of ever obtaining valuable triple het foundation lines.