Tokay geckos are among the most recognisable and popular reptiles in the pet trade, celebrated for their vibrant colours and vocal nature. Despite their popularity and frequent breeding in captivity, many questions about how their early environment influences their development have remained unanswered.
A recent study published in the open-access journal Herpetozoa by Dr. Birgit Szabo of the University of Ghent has shed light on these critical factors, offering valuable insights that could transform how we care for these lizards.
When asked about what inspired this investigation, they explained:
“As a very popular pet, Tokay geckos are frequently bred in captivity. It was surprising to me how little we know about very basic environmental factors that can influence development. I am very passionate about improving captive conditions for reptiles and my study provides very important basic data.”
The research focused on both pre-natal factors, such as incubation temperature and humidity, and post-natal factors, specifically whether juveniles are raised in isolation or within a family group. Dr. Szabo monitored sixteen breeding pairs, tracking where females chose to lay their eggs and how the resulting thirty hatchlings grew over their first six months of life.
One of the most remarkable findings involved how temperature influences the sex of the geckos. Traditionally, Tokay geckos are understood to have a genetic sex-determination system with distinct sex chromosomes. However, the study revealed that higher incubation temperatures actually led to a higher proportion of male hatchlings.
Reflecting on this discovery, Dr. Szabo shared:
“I was most surprised about the effect of temperature on sex development. Tokay geckos are reported to possess sex chromosomes. Therefore, I did not expect that temperature would have an effect on sex development.
However, after consulting the literature I found that sex determination is quite labile in lizards, but this is a severely understudied area of research. So, I am quite excited to have found this effect and plan further research on this topic.”
Beyond sex ratios, incubation temperature also significantly affected developmental timing and physical size. Eggs kept at warmer temperatures had a shorter incubation period, yet they produced larger hatchlings with a greater snout-vent length. Interestingly, incubation humidity did not appear to have a noticeable impact on these physical outcomes.
The study also revealed that mother geckos actively chose nesting sites that offered warmer and less humid microclimates compared to other areas in the enclosure, demonstrating a preference for specific nesting conditions.
Managing such a detailed study was no small feat. Dr. Szabo noted,:
“The most challenging aspect was to set up the breeding and treatments after hatching. Tokay geckos are quite large lizards and need lots of space. Coordinating the different treatments under space limitations was quite the challenge.”
After hatching, the geckos were raised either alone or in family groups of varying sizes alongside their parents and siblings. Surprisingly, the post-natal social environment did not affect the young geckos’ growth, size, or body condition. Whether raised in isolation or in a busy family group, the juveniles grew at similar rates, suggesting that captive-bred Tokay geckos are highly adaptable in their early life stages.
These findings have direct implications for reptile husbandry, emphasising the need to provide captive reptiles with choices that replicate natural gradients. Dr Szabo remarked:
“A better understanding of the thermal and humidity requirements and preferences of reptiles is one of the most important aspects of the environment that is often suboptimal in active conditions.
I hope my research will highlight their importance and lead to improved enclosure design in the future.”
Ultimately, this study challenges long-held assumptions about reptile behaviour and social structures, proving that there is much more to these creatures than meets the eye. Dr. Szabo concluded:
“Reptiles are still viewed as asocial creatures but sociality exists in this animal group. Tokay geckos perform biparental care and protect both eggs and their offspring after hatching. Despite this knowledge, there is still much to learn about their social organisation especially in respect to welfare.”
Original source:
Szabo B (2026) The influence of the pre- and post-natal environment on Tokay gecko (Gekko gecko, Squamata, Gekkonidae) development in captivity. Herpetozoa 39: 217-228. https://doi.org/10.3897/herpetozoa.39.e165454
