Common Nighthawk and Whip-Poor-Will

Wildlife Note — 55 LDR0103 CommonCommon NighthawkNighthawk andand Nighthawk Whip-Poor-WWhip-Poor-Willill By Chuck Fergus The common nighthawk and the whip-poor-will than 50 insect species have been reported as prey, in- belong to Family Caprimulgidae, a group of nocturnal cluding flying ants, June bugs, mosquitoes, moths, may- and crepuscular birds also known as the nightjars; 80 spe- flies, caddisflies, wasps and grasshoppers. Nighthawks cies are found around the world. Nightjars have large drink on the wing, skimming the surface of lakes and heads and eyes and exceedingly wide mouths, used as streams. They do not fly during heavy rain, strong winds scoops for catching insects in midair. Their long wings or cold weather. and large tails contribute to a buoyant, maneuverable The call is a loud, nasal Peent which, according to flight. Their legs are short, and their feet are small and one source, resembles the word “beard” whispered loudly. weak. Most spend the day resting on the ground or roost- As part of his breeding display, the male also makes a ing in trees, perched lengthwise on limbs. “Nightjar” booming sound, which is produced by air rushing through seemingly refers to the birds’ nocturnal habits and the his primary wing feathers after a sudden downward flex- jarring or grating aspect of their vocalizing. The night- ing of the wings while diving. Years ago, while camping jars are also known as “goatsuckers,” from an erroneous at a back-country site in the Badlands National Park in belief that the birds use their expansive maws to steal South Dakota, I sat enraptured by nighthawks “boom- milk from goats and other livestock. ing” above the prairie through the extended twilight of a June evening and on into moonlit night. Common Nighthawk (Chordeiles minor) — The Chordeiles minor has a large breeding range, from name “nighthawk” is a misnomer, as the bird is not re- the Yukon Territory to Labrador and south to Florida, lated to the hawks and it flies mainly at dawn and dusk Texas and Central America. The birds nest in open fields, rather than at night. A nighthawk is about nine inches gravel beaches, rock ledges, burned-over woods, grass- long, with a wingspread of almost two feet; individuals lands and flat graveled roofs of buildings such as schools weigh from two and a half to three and a half ounces. and grocery stores. The female nighthawk does not build The flight pattern is bouncy, erratic, full of twists and a nest; she lays her two eggs directly on the ground. The turns. Nighthawks spend the summer in many cities and laying period peaks around the first of June. Nighthawk small towns across the state. During late summer eve- eggs are creamy or pale gray, dotted with brown and gray. nings many people see flocks of nighthawks flying high The female does most of the incubating (the male may above towns and farmland, but few have gotten a close spell her at times), and the eggs hatch after about 18 look at the birds. The plumage is a mix of dark gray and days. Nestlings are “semi-precocial”: their eyes are open brown. The long wings have a crook about halfway out and they are able to move from side to side after hatch- and then taper to a point. The tail has a white band; white ing. Females may feign injury to draw predators away brightens the chin and throat; and a white “bandage” on from the nest. Both parents feed the chicks by regurgi- each wing is clearly visible from below. tating insects to them. At around 18 days, young night- Unlike whip-poor-wills, which sit in wait and then hawks make their first flights. They can fly capably by 30 sally forth to catch individual insects, nighthawks remain days, and by 50 days they are fully developed. Night- on the wing for extended periods, flapping, gliding, stall- hawks raise only one brood per year. They are among the ing and swerving as they chase and catch prey. Their bat- earliest breeding birds to leave Pennsylvania, commenc- like flight has earned them the nickname “bullbat.” More ing their southward migration in August. The average life span of a common nighthawk is or early May, when males arrive from the south; the call- estimated at four to five years; banded birds as old as ing continues through June and dwindles in July. Whip- nine years have been recovered. Since the 1960s the poor-wills call mainly at dawn and dusk, and they go on number of breeding and migrating nighthawks has fallen and on. A friend of mine who lived on our road, upon noticeably. This decline may stem from indiscriminate hearing a whip-poor-will start up outside his house, use of pesticides, increased predation, or changes in habi- counted for four consecutive minutes, recording 55, 56, tat, either in the northern breeding range or in the south- 56 and 57 repetitions. He noted the time, then sat read- ern wintering area, which includes South America, about ing. The bird kept singing, without changing position or which little is known. In Pennsylvania most nesting takes tempo, for 91 minutes. Figuring an average of 56 calls place on building roofs in urban areas, with nighthawks per minute, he arrived at a total of more than 5,000 whip- seemingly abandoning traditional rural nesting sites. poor-wills. The calling attracts females. Whip-poor-will court- Whip-Poor-Will (Caprimulgus vociferus) — The ship involves head-bobbing, bowing and sidling about whip-poor-will lives in moist woods across the eastern on the ground. The female lays two eggs on the ground and southern United States. It is about the size of a com- in dry open woods, often near the edge of a clearing. Most mon nighthawk, but its wingspan is not as great and its egg-laying occurs between mid-May and mid-July. The wings are broader and more rounded. On each side of eggs are off-white, speckled with tan, brown or lilac; they the bill, a vertical row of hair-like bristles flares toward blend in with the dead leaves, as does the adult that in- the front: the bristles funnel insect prey into the gener- cubates them. Several times I have almost stepped on ous mouth. The plumage is a mix of camouflaging browns. whip-poor-wills incubating or brooding. In one case the Both sexes have a white neck band, and the male has incubating bird was a male. On another occasion the white outer tailfeathers. adult, a female, flew directly at my face, then fell to the Whip-poor-wills perch on branches or sit on the ground and tried distracting me by feigning an injury. ground or along roadsides, where the birds’ eyes gleam The reproduction of whip-poor- red or bright orange in the wills may correlate with the lunar glare of automobile head- cycle: males sing longer on moonlit lights. This “eyeshine” is nights, and hatching may occur caused by a reflective layer at when the moon is waxing, on its way the back of the retina called to being full, so that the increased the tapetum. The tapetum light makes foraging easier for the amplifies small amounts of light adults, which must now feed nest- by passing them back through the lings as well as themselves. The retina a second time. Whip-poor-wills eggs hatch after about three weeks fly up to catch moths, mosquitoes, gnats, of incubation. Parent birds feed June bugs and crane flies. The sit-and-wait their young by regurgitating crushed foraging strategy is less energy-expensive Whip-Poor-Will insects. The fledglings first fly about than the common nighthawk’s in-flight forag- 20 days after hatching. Whip-poor-wills ing and may be what allows whip-poor-wills to arrive ear- begin leaving the Northeast in August and September, lier on northern breeding grounds and to survive peri- with stragglers into October. The species winters in the ods of cold weather and low prey availability. Its soft southeastern states, in areas where the related chuck- feathering lets a whip-poor-will fly almost as quietly as will’s-widow (Caprimulgus carolinensis) breeds in summer. an owl and helps the bird intercept moths, many of which (The chuck-will’s-widow withdraws to Central and South can detect, through tympanic membranes, sounds of po- America in winter.) Some whip-poor-wills migrate to tential predators. Whip-poor-wills take sphinx moths, Central America and the West Indies. noctuid moths and the big silk moths: cecropia, tuna and Whip-poor-wills reach their greatest numbers in polyphemus. young brushy forests; abandoned farms, sometimes called The whip-poor-will is named for the male’s repeti- “whip-poor-will farms”; and woodland edges, where rank tive nocturnal calling. The “whip” is sharp, the “poor” plant growth promotes insect populations. The birds hunt falls away, and the “will” — the highest note in the se- in forest clearings and around water, orchards and gar- quence — is a bullwhip snapping in the night. The call dens. In Pennsylvania the population remains strongest carries about half a mile. Listeners close to the calling in the Ridge and Valley Province in the southcentral bird may hear a soft knock sound before each repetition. counties. The whip-poor-will does not adapt well to ur- In Pennsylvania whip-poor-wills start calling in late April banization; the growth of suburbs and cities has eliminated this Wildlife Notes are available from the species from much of south- Pennsylvania Game Commission eastern Pennsylvania.

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