It never ceases to amaze me how our understanding of wildlife behavior can be turned on its head when unusual circumstances occur. The bull moose that wanders into town in search of a mate. The mountain lion that takes up residence under a house in Los Angeles. The ruffed grouse that follows a man around his property, even riding on the handlebars of an ATV. If you live long enough and keep your eyes open, you will surely be treated to all kinds of surprises.

Recently I witnessed some unusual bird behavior while fishing in western Montana.  We were in inflatable rafts, riding down the beautiful Blackfoot River, featured in the stunning Robert Redford movie, “A River Runs Through It.” Warm weather in mid-June triggered significant insect hatches at midday, offering great dry fly fishing for cutthroat and brown trout. As we ate lunch along the bank the air was full of beetles, flying ants, caddis, stoneflies and, in particular, the three-inch long salmon fly.

Fishermen love the salmon fly hatch because these huge insects are highly sought after by hungry trout, triggering wild top-water feeding activity. If you are fortunate to be on the water during the hatch and have the right dry fly to mimic the natural insect, it can lead to some epic fishing for large trout. But we also witnessed another feeding frenzy in the skies above the river.

For more than 30 minutes we watched five Common Nighthawks swooping and diving to gorge on insects, well outside the normal hours of activity for this secretive species. The birds were too far above us to see which insects were on the menu, but I’d wager that fat salmon flies figured prominently that day. It was quite an exhibition of flying and a reminder that most wildlife species are willing to break their normal behavior pattern when opportunity knocks.

Common Nighthawk (Chordeiles minor) is one of North America’s most unusual birds. Neither a hawk nor strictly nocturnal, this creature belongs to the nightjar family (Caprimulgidae), a group of aerial insectivores known for their crepuscular habits—being most active at dusk and dawn. Known historically by folk names like the “bullbat” due to its bat-like, erratic flight patterns and booming wing displays, the term “nighthawk” originated in old England as a generic term for nightjars and was first written in the King James Bible in 1611.  Common Nighthawk is a master of camouflage, an extraordinary aviator, and a vital component of healthy ecosystems across the Western Hemisphere.

It can be difficult to spot a roosting Common Nighthawk because of their plumage in a complex mix of black, gray, brown, and white. When you finally see the bird, it resembles a piece of mottled tree bark or a weathered stone. This cryptic coloration renders the Nighthawk nearly invisible when resting horizontally along tree branches, fence posts, or the ground. Measuring just nine inches in length with a wingspan of 20 to 24 inches, the bird is built for specialized flight.

On the wing, a Nighthawk’s identity is unmistakable. The bird possesses long, slender, sharply pointed wings marked by a bold, bright white bar across the primary feathers—a feature that flashes distinctly against the evening sky. Its tail is long and notched, and its head is broad and flat with large, dark eyes adapted for low-light vision. The male’s white collar and other coloration is brighter than the female, as is common with most species.

Perhaps its most surprising physical trait is its mouth. As you will see in the accompanying photos, the bill appears tiny and delicate from the outside.  When open, the mouth gapes wider than would seem possible for a small creature.  The mouth is surrounded with sensory rictal bristles, effectively serving as a wide net for scooping up flying insects in mid-air. This large mouth allows the bird to snatch insects flying at high speed, and to grab larger specimens like dragon flies.

The nightjar family contains roughly 80 species worldwide, with eight known in North America. The Common Nighthawk and the Eastern Whip-poor-will are confirmed breeders in Maine, while the Chuck-will’s-widow is now considered a rare vagrant species due to significant population declines. These fascinating birds suffer from an unfortunate nickname given to them over 2,000 years ago by the respected Greek philosopher Aristotle, who clearly knew much more about philosophy than birds.

Aristotle foolishly recorded a common misperception that nightjars flew into livestock pens at night to drink milk directly from goats’ udders, causing the animals to dry up or go blind. The Roman writer Pliny the Elder later reported the same “goatsucker” legend. Too late, scientists realized that the presence of nightjars around livestock was simply a matter of the birds targeting insects that swarmed around the animals. Those gaping mouths seemed capable of latching on to a goat’s teat and sucking milk, but of course this was wild speculation. The lack of milk in some goats was more likely caused by mastitis.

When the great Swedish scientist Carl Linnaeus created his modern biological taxonomy in the 18th century, he unfortunately enshrined the goatsucker myth into the nightjar family’s scientific name: Caprimulgidae (derived from the Latin capra, meaning “goat,” and mulgere, meaning “to milk”). As a member of Caprimulgidae, the Common Nighthawk inherits this historical moniker, even though it is entirely insectivorous, dining on a wide variety of prey such as moths, flying ants, beetles, caddisflies, Mayflies, stoneflies, and mosquitoes.

Common Nighthawks might be called “aerial vacuum cleaners” since they feed almost exclusively on the wing, using an impressive but erratic flight style that often resembles that of a giant moth or bat (or think of an F-18 fighter jet in combat). While most active during twilight hours, they may forage on overcast days or around bright artificial lights at night if food is readily available. At times of peak insect availability, a single Nighthawk might consume thousands of small flying insects in an evening.

The Common Nighthawk ranges from the boreal forests of Canada and Alaska down through most of the continental United States. The female is a minimalist in her nesting behavior, simply laying her two speckled eggs on bare ground. Her habitat preferences are defined by open ground and clear airspace for foraging. They may nest on gravel bars along rivers, forest clearings, sand dunes, rocky outcrops, or blueberry barrens.

The breeding season, running May through July, features an impressive courtship display similar to that of the American Woodcock. To attract a female and establish territory, the male flies high into the air, swooping erratically while uttering a sharp, nasal “peent” call. He then folds his wings into a steep dive and pulls up just above the ground. Air rushing through his stiff wing feathers produces a deep “boom” or “whoosh”.

The Common Nighthawk has been documented as making one of the longest migrations of any North American landbird. The birds that nest here may winter in Brazil or Argentina for a total roundtrip up to 11,000 miles. Nighthawks are social migrants meaning that in late August and early September they gather in large flocks—sometimes called “kettles”—numbering from dozens to thousands of birds. They forage while traveling, flying continuously during late afternoons and dusk to refuel on swarming insects.

Because adult Common Nighthawks are agile flyers and masters of concealment, adult mortality from predation is relatively low, though they are occasionally prey for fast-flying raptors such as Peregrine Falcons, Cooper’s Hawks, or Great Horned Owls. Their primary risk comes on the ground, where raccoons, skunks, foxes, gulls, snakes, and domestic or feral cats seek the eggs or flightless chicks.

The Common Nighthawk plays an interesting role in North American natural and cultural history. Tribes along the Connecticut River recognized the booming sound of the male’s courtship dive and named him the “Shad Spirit,” believing the bird was calling schools of shad upriver to spawn. Before legislation protected the birds, Nighthawks were shot in vast numbers during fall migration simply for sport. Because of the misnomer “hawk,” farmers also targeted them, believing they posed a threat to poultry.

Wikipedia offers that in the western US, folks once referred broadly to all the nightjar species as “bugeaters.” Nebraska’s nickname once was the “Bugeater State” and their vaunted football team was known as “The Bugeaters” before sportswriter Charles Sherman in 1899 wisely suggested the use of the current name, the “Cornhuskers.”

During the late 19th and mid-20th centuries, as cities expanded, Nighthawks adapted to the new landscape. They colonized urban areas by nesting on flat, gravel, and tar roofs. City streetlights and illuminated billboards provided abundant nighttime insect hunting grounds, making Nighthawks a familiar sight in suburban and urban skylines across North America. The passage of the Migratory Bird Treaty Act of 1918 ended hunting, allowing populations to recover somewhat in the early 20th century.

Sadly, their story in the last 100+ years has been one of widespread decline. Long-term data from the North American Breeding Bird Survey indicates total populations have dropped by more than 50% to 70% since 1970. The birds are designated as Threatened or a Species of Special Concern (SSC) in Canada and numerous U.S. states included Maine.

While changes in roofing technology have been a factor, the biggest issue is the precipitous drop in insect populations due to pesticide use and pollution. Habitat loss and fire suppression means there are fewer open clearings and natural burn areas for nesting. Nighthawks are also prone to resting on warm road surfaces and foraging along open highways, resulting in collisions with vehicles.

The Maine Nightjar Monitoring Project was launched in 2017 to monitor Maine’s two nightjar species. Each year, volunteers conduct surveys along routes through nightjar habitat at dusk and again on moonlit nights. I look forward to the pending publication of the most recent Maine Breeding Bird Survey results to see what is happening with these fascinating birds.

The Common Nighthawk is a noteworthy symbol of evolutionary adaptation—a bird that bridged natural ecosystems and our cities. Its twilight acrobatics, flashing white wing bars, and echoing wing-booms remain iconic hallmarks of summer evenings. Protecting this species requires preserving open natural habitats, reducing pesticide dependency, and adopting bird-friendly urban design to ensure these extraordinary migrants thrive for generations to come.

If you like Ed Robinson’s writing, check out his two Nature Notes books! Click here for more information.