Lizards are ectothermic reptiles, relying on external sources to regulate body temperature. This poses a challenge when temperatures drop, especially in colder months. To survive harsh winter conditions, lizards employ specific strategies.
The Science of Winter Survival
Lizards in temperate climates commonly enter a state of metabolic dormancy known as brumation to survive winter. This process is similar to hibernation in mammals, but with distinct differences. During brumation, a lizard’s activity, feeding, and metabolism slow significantly, allowing them to conserve energy when external temperatures are too low for normal function. This survival tactic is triggered by environmental cues such as decreasing temperatures, shorter daylight hours, and reduced food availability.
While in brumation, a lizard’s metabolic rate decreases substantially. Unlike true hibernation, they remain semi-alert and may occasionally stir to drink water. They often rely on glycogen reserves in their blood for energy rather than solely on fat stores, which are more critical for reproduction later.
Choosing a Winter Hideaway
Lizards seek sheltered locations to enter brumation, providing insulation from freezing temperatures and protection from predators. Common sites include underground burrows, which they may dig themselves or utilize abandoned ones. Lizards also find refuge in deep crevices within rocks, under decaying logs, or beneath leaf litter.
Some species may even use hollowed-out tree stumps or find shelter in caves and old animal burrows. These chosen spots offer a stable temperature that remains above freezing, along with adequate moisture. The insulation provided by these shelters helps lizards survive the cold.
When Winter Ends
As winter transitions to spring, rising temperatures, increasing daylight, and barometric pressure changes signal the end of brumation for lizards. Lizards gradually become more active as the weather warms, with activity levels and appetite returning incrementally.
Upon emergence, their immediate needs include rehydrating and finding food, as they have gone without sustenance for months. They will bask in the sun to raise their body temperature, a necessary step to regain full activity. Following this period, lizards resume their normal behaviors, which include foraging for food and engaging in reproductive activities.
Not All Lizards Brumate
Brumation is a survival strategy primarily observed in lizard species inhabiting temperate climates where winters are distinct and cold. Lizards in these regions have evolved to cope with seasonal temperature fluctuations. However, not all lizards undergo this dormant period.
Lizards living in tropical or subtropical regions, which experience consistently warm temperatures year-round, typically do not need to brumate. Their environments do not present the same challenges of extreme cold or prolonged food scarcity that necessitate such a state of dormancy. While some tropical species might exhibit reduced activity during less favorable conditions, it is not a true brumation.