For the Birds Radio Program: Nighthawks: Gentle Spirits of the Night Sky
One of the familiar sounds of summer is the raspy “peent!” of nighthawks in the evening sky. These voracious insect-eaters swoop and dive, darting and weaving through the air as they chase and capture flying insects ranging in size from huge moths to the tiniest mosquitoes. Most of the year nighthawks spend their days sitting on a large tree limb, a fencepost, or the ground, quietly contemplating the world, but during migration and the nesting season they can sometimes be spotted catching insects even at high noon.
Nighthawks have a tiny beak, but it widens at the base to give them an enormous mouth. With their big nocturnal eyes, they watch for insects and fly straight at them with their capacious maw open, at high enough speeds that the bugs go straight down the hatch. When I handled injured nighthawks as a licensed rehabber, I quickly learned that virtually all adult males needed me to stroke their throat to help them swallow their food. It generally took weeks for a flightless nighthawk to regain the ability to swallow without this help. Adult females, who feed their nestlings by regurgitation, never lose the ability to use their throat muscles, and adapt much more quickly than males to feeding in captivity.
Nighthawks have a 24-inch wingspan, which is rather large relative to their two and a half ounce weight. In contrast, Blue Jays, which are two inches longer and significantly heavier, have only a 16 or 17-inch wingspan. The delicate hollow bones inside these long, slender wings may snap when dashed against a wire, but nighthawk wings are powerful enough to carry the birds from their breeding grounds in North America thousands of miles down to their wintering grounds as far south as Argentina, and back again come spring.
Before Europeans colonized America, nighthawks nested exclusively on the ground, on flat rocks or bare patches of gravelly soil, hardly even making a scrape before laying their two eggs. Once people started constructing buildings here, nighthawks started nesting on flat roofs covered with tar paper and stones, which not only look like bare ground, but also provide safe havens from many predators. Most large cities were built on lakes or rivers which provided a smorgasbord of emergent aquatic insects. Soon many nighthawks shifted their routine and started spending summer in the city.
Insects are drawn to lighted spaces, where they are both concentrated and easy to see, luring in nighthawks, too. One summer night in a restaurant parking lot I watched a pair of nighthawks hunting where floodlights illuminated a huge American flag. The birds managed to catch a host of bugs even as they evaded the flag whipping about in the stiff night breeze.
Of course, lights shining out from a moving automobile also attract and illuminate insects, but in this situation a two-and-a-half-ounce bird doesn’t stand much of a chance of surviving the first course. And when attracted to street lamps, nighthawks often crash into wires. Also, in their courtship ritual, male nighthawks plummet to the ground at high speed, making a loud booming sound as the rush of air vibrates their primary wing feathers. In the heat of passion, they sometimes don’t notice wires suspended in their airspace and frequently break their long, fragile wings. Because nighthawks are specifically adapted to catching flying insects, when one can’t fly, it is doomed. Their fatal attraction to lighted meals and deadly crashes into wires have contributed to the slow but steady decline of nighthawks during recent decades. Other factors include the burgeoning urban crow population, because crows are adept at taking baby nighthawks from rooftops, and pesticide use, especially in mosquito abatement projects which kill other aquatic insects, such as mayflies and stoneflies, decimating the nighthawk’s food supply.
Belying their macho name, nighthawks are not at all related to hawks, and though they are kin to owls, they are gentle and fragile cousins who couldn’t kill the tiniest mouse if their life depended on it. Considering that nighthawks have flat, delicate feet incapable of grasping, a soft, fragile mouth, absolutely no defenses against predators except flight, and a slow, erratic flight, one must assume that the many sporting teams who take nighthawks as their mascots are singularly poor on offense. But unlike cardinals and Baltimore Orioles, nighthawks are masters at one pertinent sporting skill. They can’t be beat when it comes to catching flies.