Leopard geckos are popular pets that originate from the arid and semi-arid regions of Asia. While these reptiles have adapted to dry environments, they still require specific humidity conditions to remain healthy in captivity. Understanding the difference between the general ambient humidity and the localized moisture they need is paramount for any keeper.
The Optimal Ambient Humidity and Health Risks
The general, ambient humidity level throughout a leopard gecko’s enclosure should be kept relatively low, ideally ranging between 30% and 40%. This range closely mimics the dry conditions of their natural habitat. Consistent humidity levels above 50% or 60% can create an environment that promotes the growth of harmful bacteria and fungi.
When the air is consistently too moist, geckos become susceptible to respiratory infections (RIs), which manifest as labored breathing or mucus around the nostrils. High humidity also increases the risk of skin infections and fungal issues. Conversely, humidity that is too low, dropping below 30%, presents a different set of problems, primarily affecting the shedding process.
The most common issue from low humidity is dysecdysis, or stuck shed, where the old skin does not come off completely. This is particularly problematic around delicate areas like the toes and eyes. Stuck shed on the toes can constrict blood flow, potentially leading to tissue death and the loss of digits. Providing the correct ambient humidity prevents these common health complications.
The Essential Role of the Moist Hide
Despite the need for a dry ambient environment, leopard geckos require a high-humidity microclimate to facilitate a smooth shedding cycle. In the wild, they seek out underground burrows where moisture is naturally trapped. This localized high-moisture area must be replicated in the enclosure using a dedicated moist hide, which is a necessary component of their habitat.
The humidity level inside this specific hide should be significantly higher than the rest of the tank, ideally maintained between 70% and 80%. This concentrated moisture softens the old skin, allowing the gecko to rub it off easily and completely. A moist hide can be constructed from a simple plastic container with a smooth entrance hole cut into the side.
The container is filled with a moisture-retaining substrate, such as sphagnum moss, coco coir, or damp paper towels. The substrate must be kept damp, not soaking wet, to prevent the growth of mold or mildew. Placing this hide on the warm side of the enclosure encourages evaporation, which maintains the necessary high humidity level inside.
Monitoring and Maintaining Enclosure Humidity
Accurate measurement is the first step in controlling the moisture level within the habitat, making a hygrometer an important tool. Digital hygrometers are recommended over analog dial gauges because they provide more precise and reliable readings. The hygrometer probe should be placed in the main living area of the enclosure to monitor the ambient air, not inside the moist hide or directly on the substrate.
If the ambient humidity is too low, keepers can employ several methods to increase it slightly. Using a larger water dish or placing it closer to the heat source will increase the rate of evaporation. Lightly misting the enclosure walls or using a substrate that retains moisture, like a soil mix, can also provide a temporary boost.
Conversely, if the humidity is too high, the primary solution is to increase ventilation. Ensuring the enclosure has a screen top or adding extra screened vents allows moist air to escape and be replaced by drier air. Switching to a dry substrate, such as paper towels or slate tile, and moving the water dish away from the heat source will help to lower the overall moisture content.