While many animals hibernate in winter, lizards, like other reptiles, undergo a distinct process called brumation. This natural adaptation allows them to endure harsh environmental conditions when temperatures drop and resources become scarce, conserving energy until more favorable conditions return. Brumation is fundamentally different from mammalian hibernation.
Understanding Reptile Inactivity
Brumation describes a state of inactivity in reptiles, including lizards, during periods of cold temperatures or environmental stress. This differs from mammalian hibernation. Mammals are endothermic, meaning they internally regulate their body temperature, often lowering it to a stable, cooler level during hibernation. This allows them to enter a deep, continuous sleep where they do not need to eat or drink.
Lizards and other reptiles are ectothermic, relying on external heat sources to maintain their body temperature. During brumation, a lizard’s body temperature fluctuates with the cooler external environment. While their metabolic rate, heart rate, and respiration significantly decrease, they do not enter the same deep, continuous sleep as hibernating mammals. Brumating lizards may occasionally wake up to drink water, unlike hibernating mammals that can go much longer without food or water.
How Lizards Brumate
Lizards undergo specific preparations and physiological changes when entering brumation. Before brumation, they reduce or cease food intake to clear their digestive system. This prevents food from decaying in their gut during dormancy, which could cause illness. They also increase food intake beforehand to build fat reserves, providing energy during this period.
Once prepared, lizards seek sheltered locations to brumate, protecting them from extreme temperatures and predators. Common spots include underground burrows, rock crevices, caves, and spaces under logs or leaf litter. During brumation, their activity level is reduced, and they become lethargic, remaining still for extended periods.
Environmental Triggers and Species Differences
Environmental cues initiate brumation in lizards. Declining temperatures and shorter daylight hours are significant triggers, signaling to these ectothermic animals that it is time to enter dormancy. Changes in barometric pressure and reduced food availability also contribute. These external signals prompt physiological responses, including hormonal changes, preparing the lizard’s body for the inactive period.
The duration and necessity of brumation vary widely among different lizard species and geographical locations. Lizards in temperate zones with cold seasons undergo brumation periods. However, some species in warmer climates or near the equator may not brumate at all, or their brumation might be less defined due to more consistent conditions. Brumation also influences the reproductive cycles of some species. The cooling period can stimulate hormonal release, aiding in reproduction.