As my grandmother always said, “Horses sweat. Men perspire. Women glow.” How do we avoid this sticky situation? Kids run through sprinklers and adults head for the air conditioning, but what do the birds do when the thermometer climbs? They don’t sweat they can’t take advantage of the A/C. However, that doesn’t mean they just sit there and bake, either.
Because birds have relatively high body temperatures—a Golden Kinglet’s temperature was measured at 111° F!—it’s critical that they avoid getting too warm. Many essential proteins begin to break down at temperatures just a few degrees higher, so overheating could easily be fatal. Thankfully, birds have all sorts of ways of beating the heat.
We know that many bird species migrate to avoid the cold of winter, but you can also interpret their journeys from the opposite viewpoint. Perhaps some birds migrate to avoid the heat of summer. Consider those species that head north to the boreal forest, or nest on the tundra surrounding the Arctic Ocean. Sure, there’s food in those northern latitudes, but it’s also substantially cooler.
When the highs are too high, Pete and I head to the mountains. So do some birds. For example, I only see Dark-eyed Juncos (right) at my feeders in the winter. As the weather warms, they head for higher altitudes, where we see them flitting through the forest underbrush.
Not all of us can leave town during a heat wave. Instead, we have lots of ways of staying at least somewhat comfortable. For example, we might head to the neighborhood swim club. Birds do the same, flocking to ponds and birdbaths for a cooling dip. Or, we might hop into the shower. Try setting up a misting sprinkler (those perforated hoses work well) and watch the local hummingbirds gather to zig and zag through the gentle droplets. Water sources also provide the birds a much-needed opportunity to rehydrate their parched bodies.
We might set up a fan. Birds can take to the sky. I’ve often envied a soaring hawk’s ability to enjoy the cooling breeze it rides.
Who doesn’t enjoy spending a sizzling summer day snoozing in the shade of a patio roof or tall tree? Birds are just as sensible, and will look for shady spots to while away a hot afternoon. The only thing missing is their tall glass of icy lemonade. This is a major reason why birding field trips start so early. By the time the day warms, the birds are taking it easy—and so should we.
Baby birds need shade too. The parents will spread their wings over their offspring, providing a parasol for those too young to leave the nest.
Even birds with no nests will spread their wings. In the cooler months, they do this to act as solar collectors, warming themselves. In summer, however, they lift their feathers and spread their wings as radiators, letting the breeze reach their skin to dissipate heat.
Earlier I said that birds don’t pant. That depends on how you define panting. Remember that birds have a different way of breathing than mammals do. (If this is news to you, check out my post on “Flow-through Ventilation.”) While ornithologists don’t call it panting, a bird can do something similar to move cooling air in and out of its throat—it will open its mouth and flutter its neck muscles in a behavior called “gular fluttering.” To an observer, it appears as if it’s trying to gargle!
Finally, studies have shown that in some species, individuals in warmer climates have larger bills than those living in more moderate areas. According to an article on the Audubon website,
In a study conducted on marsh sparrows in 2011, scientists found that bill size correlates to outside temperatures. Marsh sparrows with larger bills live in warmer climates, for example. The study noted that the tropical toucan also possesses a large bill, and has the ability to increase or decrease blood flow to its beak to either promote or prevent heat loss.
To a large extent, birds survive summer’s heat in the same way we all do—vacationing somewhere cooler, getting wet, staying well hydrated, catching the breeze, and hanging around in the shade.
Last week’s quiz bird is a Belted Kingfisher.