Thermoregulation, the ability of mammals to maintain a stable internal body temperature, is fundamental for survival. Many mammals, including humans, primarily cool down through sweating, where evaporating moisture dissipates heat. This mechanism helps regulate body temperature in warm conditions or during physical exertion. However, not all mammals cool themselves in the same manner, raising questions about how fur-covered species manage heat.
Squirrel Body Temperature Regulation
Squirrels do not possess widespread sweat glands across their bodies like humans for thermoregulation. While they have some sweat glands on their paw pads, these primarily aid in grip and scent marking, not significant cooling. Instead, squirrels employ a variety of physiological and behavioral adaptations to manage their body temperature during warm periods.
Panting is a common physiological response, allowing evaporative cooling from the respiratory tract. When squirrels pant rapidly, moisture evaporates from their mouths and airways, drawing heat away from their bodies. Vasodilation is another physiological mechanism, where blood vessels close to the skin’s surface, particularly in areas with less fur like their ears and tails, expand. This increased blood flow allows heat to radiate away from the body.
Squirrels also exhibit several behaviors to reduce their body temperature. A notable behavior is “splooting,” where a squirrel lies flat on its stomach with limbs outstretched on a cool surface, such as concrete or a shaded path. This posture maximizes contact, transferring heat from their less-furred underside through conduction. They also seek shaded areas and reduce physical activity during the hottest parts of the day, often becoming most active during cooler morning and late afternoon hours. Some squirrels may spread saliva on their forearms, where fur is thinner and blood flow is higher, to achieve some evaporative cooling, though this is less efficient than panting.
Signs of Squirrel Overheating
Despite their various cooling strategies, squirrels can still suffer from heat stress or overheating, which can become life-threatening. Recognizing the signs of an overheated squirrel is important. Behavioral indicators include lethargy, appearing unusually tired or slow, and disorientation, where the squirrel may seem confused or wobbly and have difficulty with coordination.
Physical signs of overheating can include excessive panting (heavy, rapid breathing) and increased salivation (drooling or foaming at the mouth). The fur may also appear damp. In more severe cases, a squirrel might exhibit uncoordination, seizures, or even collapse. If a squirrel shows these symptoms, offer a shallow dish of cool, fresh water from a distance in a shaded area. Do not handle the animal directly; instead, contact a local wildlife rehabilitator for guidance.