Late into a warm, moonlit evening in June, your casual stroll may be enriched by the melodies of nature: the lingering peepers, the trills of American toads, a few early crickets, the late song of a Hermit Thrush, and maybe even the hoots and squawks of a Barred Owl. But your evening, fading into one of the year’s shortest nights, may also introduce you to the haunting sounds of some “crepuscular” birds, those that are most active through dusk and before dawn.
Whip-poor-will or Whip-poor-won’t?
For 10 years I have participated in a decidedly discouraging nocturnal bird survey in June. The Vermont Center for Ecostudies, based in Norwich, conducts excellent scientific studies of the distribution, habitats, and populations of Vermont bird species of concern, based on volunteer observers. Following VCE’s protocols and tracing the same route each year, I have sought the voice of the Eastern Whip-poor-will, a bird well known by name and familiar in our past, but my survey each year has failed to hear that persistent “whip-poor-will, whip-poor-will, whip-poor-will, whip-poor-will.” There are accounts of their presence on my route but not in my exasperated ears. I’ll try again this year.
The Whip-poor-will (Antrostomus vociferus) is widely distributed in eastern North America but scarce in some habitats. They prefer dry, open woodlands with no underbrush. Throughout their range, they are heard, but seldom seen, active at night but quiet and still during the day. Their handsome brown, buff, and gray markings make perfect cryptic camouflage in the dry leaf litter where they spend the daylight hours. With no nest other than the dead leaves, their two eggs and hatchlings are just as secretive as the adults. The “Whips” feed on flying insects, a particular challenge at night, but the dim light of dusk and dawn is enough for their foraging of moths and beetles on the wing. In a remarkable synchrony of adaptive phenomena, the Whip-poor-will chicks usually hatch during the cyclical weeks of waxing partial moonlight, about 10 days before the full moon, extending nighttime foraging for the demands of their young family.
Whip-poor-wills belong to a bird family known as the Nightjars. This name refers to their nocturnal habits and the jarring sounds of their voices, but the scientific name for this family is the Caprimulgidae, Latin for “goatsuckers or goat milkers” an ancient name based on thousands of years of myth. The widespread belief was that these night birds with tiny bills but gaping mouths fed at goat udders and caused the nanny goats to go blind.
Today, their familiar names simply echo their calls. This family of nocturnal insectivores is represented in all continents except Antarctica. Among the Whip-poor-will’s relatives is the Chuck-will’s-widow, a nocturnal insectivore of the southeastern states, this one calling his name in a loud four-syllable voice. Another is the small Common Poor-will of the western states, an exceptional species – the only bird known to go into a form of hibernation or torpor during periods of chilly weather. The Poor-will speaks its name in a sotto voce (soft voice).
The (Un)Common Nighthawk
Another “Goatsucker” shows up in Vermont for the summer when flying insects are abundant. This is the Common Nighthawk (Chordeiles minor), not a hawk at all. The Nighthawk is seen in the sky at dusk, gracefully hawking flying ants, moths, and others that may be drawn to artificial lights. They are shaped like sleek falcons. On warm evenings watch for them, identified by their white wing slashes and graceful flight in the evening sky over open spaces. Nighthawks forage above farms, grasslands, beaches, deserts, treetops, and even cities. They announce their presence at dusk with a nasal, mysterious “peent” call that is repeated frequently. The males also announce their availability with a startling “boom” or “roar” made by their wing feathers as they plummet acrobatically.
Nighthawks nest on the ground on remote beaches, gravel patches, and waste areas. For several decades, they found flat gravel rooftops in urban areas to be ideal nest sites, with city lights attracting their preferred food nearby. More recent sheet metal and rubber membrane roofs are less enticing as they get very hot in sunlight a danger to nestlings and a contribution to the decline of this species.
Modern Caprimulgidae in Decline
Both of our local “Goatsuckers” – Whip-poor-wills and Common Nighthawks – have mouths adapted for gathering in flying insects on the wing, and eyes that have a tapida lucidum, a reflective surface that amplifies faint light on the retina. Because of their crepuscular and nocturnal habits, these species need not be colorful, but male “Whips” and Common Nighthawks do flash white feathers to secure their identities. Male Whip-poor-wills have a white throat patch and white outer tail feathers; Common Nighthawks of both sexes have their distinctive white wing slashes.
Sadly, both species, with their eerie nighttime voices and specialized adaptations, are declining in numbers for a host of reasons: probably the most random is the widespread use of toxic insecticides; habitat loss is another problem, and climate change disrupts inter-specific synchronies for avian food supplies. These two have become species of concern at all levels throughout Eastern North America. For this reason, should you hear “whip-poor-will, whip-poor-will, whip-poor-will, whip-poor-will” or a few “peents” of Common Nighthawks discussing their social foraging, please let me know, including date, species, and location. email: firstname.lastname@example.org
Two other creepy crepuscular bird voices but more common are those of the American Woodcock, whose frequent “peents” and tinkling voices in aerial display are supplemented by shuddering wing sounds, and the ghostly “woo, woo, woo , woo, woo, woo” of the Wilson’s Snipe flight sounds are generated by their fanned tail feathers in aerobatic swoops and dives. These are who show up when I’m out to encounter Whip-poor-wills calls on every survey.
For an introduction to these night sounds, you may want to listen to these two videos:
Whip-poor-will calls: https://www.youtube.com/watch?v=_HNAp_BPf9E
Common Nighthawk calls: https://www.youtube.com/watch?v=9qpsyjmda5Q