How Wildlife Keeps Cool in Hot Weather
Sadly, the Brood XIX periodic cicadas have completed their 13-year life cycle and will not been seen again until 2037, but the arrival of hot summer weather is greeted by the much less abundant but more familiar annual cicadas. Nicknamed “dog day cicadas,” these noisy bugs come out of the ground every summer and buzz during the hottest parts of the day.
The term “Dog Days” derives from ancient Greek observations of the star Sirius (a.k.a. the “Dog Star”) rising in the eastern sky along with the Sun during this time of year. It has since become synonymous with the hottest part of summer in the Northern Hemisphere. Dog day cicadas thrive in these sultry conditions, but many other animals, including us humans, require certain behaviors or adaptations to tolerate and persist in such hot weather.
Of course, we humans mostly avoid these stifling days by retreating into our air-conditioned homes and businesses, but when we must be outside our bodies keep us cool mostly by sweating. As we warm up, our sweat glands perspire and coat our skin with water that vaporizes and pulls much of the heat off our bodies and into the air – a process known as evaporative cooling.
Surprisingly, besides other primates such as chimps and gorillas, horses and hippos are the only other animals that sweat to cool off.
Perhaps the most bizarre (and kinda gross) heat-releasing technique is a specialized type of evaporative cooling known as “urohydrosis,” performed by a few bird species, most famously vultures. During hot weather, these birds actually pee and poop on their legs to cool off. Other birds such as herons, owls, and doves open their bills and rapidly vibrate their throat membranes (“gular flapping”) to expose the moist membranes and allow for evaporation, not unsimilar to the way dogs and cats pant for the same reason.
Many “cold-blooded” animals such as reptiles have no way to regulate their body temperatures within, so they must seek refuge from excessively hot weather like we often do, by simply getting out of it. Lizards and snakes, for example, retreat into burrows or crevices in the ground, or shelter under logs, leaf litter, or rocks. The term “cold-blooded” is misleading though, as some reptiles can operate efficiently with body temperatures reaching 150 degrees F!
Rabbits evolved long, large ears not for better hearing, but instead to help cool them off in hot weather. Rabbit ears have an extensive system of blood vessels that provide large surface areas for shedding heat. During hot conditions, these blood vessels will swell allowing for more contact to the air and thus greater heat loss. Not surprisingly, jackrabbits that inhabit scorching deserts have the longest ears of all.
Many animals individually cool off in hot weather simply by taking a dip in a stream or pond, but bees altruistically harvest water from such places and transport it back to the hive—and brood—bees that can’t access it themselves. Amazingly, foraging honeybees will spit-out and spread collected water droplets across the honeycomb and fan their wings to create a mist that cools the entire hive.
These are just but a few of the many interesting ways wildlife keeps cool during the dog days of summer. We humans also have many ways to cool off, some like sweating and jumping into a lake mimic behavior of other animals. Please be careful when outdoors in this summer’s heat and consider all the behavioral options we have to stay cool. Just don’t consider urohydrosis – pretty sure that’s illegal in Jasper County, at least publicly.
