Chapter D: B. Burrows, in some notes sent to Major Bendire (1895) says (1)

“During the winter the birds may be flushed from the dense thickets in the bottom lands, but as the nesting season approaches they leave these close retreats and seek more open ground.”

Mr. Sennett (1878) says of their haunts: “I saw them occasionally, singly and in pairs, about the thickets and open chaparral, and once in the canebrakes close to the woods.” Again (1879) he says: “They breed in the more open places among the cactus and scattered bushes along with _O. texensis_--Texas Nighthawk. On dark days I flushed them from thickets in the chaparral, or from copses near the bottom lands on the edges of the woods.”

_Nesting._--Mr. Sennett’s nests “were found in open brush, on the bare ground. One of them was partly concealed by the branches of a low bush 6 or 8 inches from the ground.”

Mr. Burrows wrote to Major Bendire (1895): “I have never found the Pauraque nesting in the dense thickets, where they hide during the winter. They seek the more open ground, the high, level spots near the river, or up some arroya, among scattering bushes and pear cactus, but never on the rocky hills, where the Texan Nighthawk is frequently found. In one instance a nest was found at the edge of a cultivated field. The eggs are placed on the bare ground, with no attempt at nest building, and usually at the foot of a clump of bushes. The bird, when flushed from the nest, quietly darts off and drops to the ground but a short distance away.”

Dr. James C. Merrill (1878) writes: “On the 15th of May, 1876, I found a set of eggs near camp at Hidalgo, and on returning in about fifteen minutes to secure the parent, who had disappeared among the thickets, I found that she had removed the eggs, although they had not been touched.”

_Eggs._--The pauraque lays two very handsome eggs, quite unlike the eggs of any other species in the family. They vary in shape between oval and elliptical-oval, with a decided tendency toward ovate or elliptical-ovate, one end often being slightly more pointed than the other. The shell is smooth, with little or no gloss. The ground color varies from “light ochraceous-salmon” to “pinkish buff”. Some eggs appear to be nearly immaculate, but in most cases they are more or less evenly covered, some sparingly and some profusely, with small blotches, spots, or dots of pale “clay color,” pale “cinnamon,” or, more rarely, with deeper shades of “cinnamon-rufous”; often there are underlying blotches or spots of “ecru-drab” or “light cinnamon-drab.” Occasionally the markings are concentrated around the larger end, but usually they are quite evenly distributed.

The measurements of 50 eggs average 29.80 by 22.36 millimeters; the eggs showing the four extremes measure =35.10= by 23.10, 31.50 by =24.64=, =27.18= by 20.57, and 28.96 by =20.32= millimeters.

_Young._--In his unpublished manuscript on the birds of the Caribbean lowlands of Central America, kindly lent me, Alexander F. Skutch devotes considerable space to his studies of the care and feeding of the young of the local race of the pauraque (_Nyctidromus albicollis albicollis_). As the habits of the different races of this species probably do not differ materially, it seems pertinent to include here some of his remarks on this subject. He says that “during the day male and female take turns on the eggs, relieving each other every two or three hours. The male is usually found incubating in the early morning. At night, I have found only the female covering the eggs.” Other species of goatsuckers have been reported as moving their eggs to a place of safety after being disturbed, but he found no evidence that this species does so, saying: “I have given pauraques all kinds of incentives to move their eggs to a safer place, but they have never shifted their positions even a few inches as a result of my interference. The case was quite different when I moved the eggs from the spot which the birds had selected as their nest.” In this case, he had moved the eggs twice, once only a few inches and once a foot away from an area infested by fire ants; but each time the parents moved them back again to their chosen spot; the result was that, as soon as the eggs began to hatch, the chicks were destroyed by the ants. He did not see how the eggs were moved; probably they were pushed along with the feet and body, as the nighthawk has been seen to do.

Both parents took turns in brooding the young throughout the day, relieving each other at intervals of two or three hours, as they did on the eggs. As the young were fed in the dusk or deeper darkness of evening, it was only after several trials that he was able to see the performance clearly. He writes: “It was dark now, but at the critical moment I pushed the button of a powerful flashlight. The mother was resting on the ground in her customary position, looking toward me with eyes that shone like rubies in the beam of light. The little ones stood on tiptoe in front of her, their necks stretched up, bringing their heads on a level with her mouth. One was being fed while the other waited impatiently for its turn. Though her _mouth_ was so big she could easily have swallowed her nestling whole, her little _bill_ was inserted into its widely open mouth, just as with a hummingbird, and with distended throat and convulsive movements of the body she regurgitated into it the insects she had captured. When she had given sufficient to the first one, she paused with head erect, clearly much alarmed by the light, but the second continued its silent importunities and the parent yielded despite her fears, feeding it in the same manner. Then she went off to hunt more insects.

“Presently one of the parents entered the thicket again, but instead of going to the youngsters it settled on the ground behind the blind, fully 20 feet from them, and began the low croaking-clucking call, which draws them as the magnet draws the floating needle. The two- and three-day-old bantlings drew themselves up and began hopping bravely toward the voice, peeping as they went through the darkness. Directly in their path was a young banana plant, which I had felled in clearing a place for the blind. The large, slippery leaves lay in a tangled mass that loomed above them; the Alps formed no more insurmountable obstacle to the advance of Hannibal’s army than this confusing barrier to the young pauraques. Dauntless as the renowned Carthaginian, they pushed resolutely onward, lured by the continued calls. I completely lost sight of them in the obscurity, but for many minutes their weak cries emerged from the dark mass. At length they descended victorious into the plains of Italy, and henceforth their path, although not free from obstacles, was comparatively easy. Finally they found a haven beneath their parent’s sheltering wings.”

On this and previous occasions Mr. Skutch discovered that the young pauraques were perfectly capable of locomotion, even at an early age, in response to warning calls from their parents. He saw no evidence that the adults ever carried them in their capacious mouths, as other species of the Caprimulgidae have been reported to do, or assisted them to move in any other way. He says that “during the day male and female take turns on the eggs, relieving each other every two or three hours. The male is usually found incubating in the early morning. At night, I have found only the female covering the eggs.”

_Plumages._--The downy young pauraque is as unique among the Caprimulgidae as are the eggs. It is completely covered with fine, soft down, leaving nothing exposed but the tip of the bill and the feet. The colors are rich and contrasting; the forehead, crown, and nape are “pinkish buff”; the lores, cheeks, and auriculars are “mikado brown”; the back and rump are “sayal brown,” with a central band of “pinkish buff”; the chin and throat are pale “pinkish cinnamon,” and the remainder of the under parts are “pinkish buff.”

Ridgway (1914) describes a female nestling, not yet fully grown, as follows: “General color of upper parts pale brownish gray, very minutely vermiculated or stippled with darker; pileum and scapulars with scattered roundish and subtriangular small spots of black; interscapular region clouded or blotched with black; under parts light grayish buff, narrowly barred with dusky on chest, more broadly barred with the same on throat, breast, and sides, the abdomen and under tail-coverts immaculate; thighs uniform light fawn color; remiges and rectrices (not fully grown) apparently as in adult female.” Of a young female, fully grown, he says: “Primaries and rectrices as in adult female; pileum spotted, instead of streaked, with black, the spots mostly of broadly triangular form; back also heavily spotted, or blotched, instead of streaked, with black; scapulars without buff margins; barring of under parts much less sharply defined, less dark in color; throat band light dull buff, barred with blackish.”

Mr. Sennett (1888) says of the young male: “White wing-patch of male mixed with buff; white on tail not so sharply defined, nor does it extend so near to base as in mature birds. The outer tail-feathers are barred and streaked with brown and buff. White throat-patch smaller and barred sparingly with black and buff. In this immature stage the sexes are not easily determined aside from the difference in the white tail-patches; in the males the white on second feather from outside is never less than 2.5 inches long, while in the females the corresponding patch is about one inch in length.”

The above descriptions evidently refer to the juvenal, or first plumage, which is largely replaced in summer, July and August, by a first winter plumage. In this the contour plumage is much like that of the adult, the spots on the crown and back being replaced by streaks; but the juvenal wings and tail are retained; the sexes are much alike in this plumage but can always be distinguished by the amount of white in the tail.

I have seen birds in this plumage in October, December, and March, from which I infer that it is worn until the first postnuptial molt the following summer. Mr. Sennett (1888) thought that “at least two years must elapse before the perfect plumage is attained”; but it seems more likely that the first postnuptial molt produces a plumage that is practically adult, except for some dusky mottling on the tips and edges of the white tail feathers, and some buffy intrusion of the white wing patch, which may indicate that the full purity of these white areas is not attained at the first postnuptial molt.

Dickey and van Rossem (1938) say: “Young birds which have assumed the postjuvenal plumage may be distinguished from adults by the narrower, more pointed, and usually impurely colored tail feathers and by the buffy edgings and mottlings on the tips of the primaries. The juvenal primaries which are worn until the bird enters the second fall (first annual) molt, are from 5 to 10 mm. shorter than those of adults. Males, at least, breed the first spring as shown by dissection of several specimens. The annual molt of adults takes place in August and September.”

There are two distinct color phases in the adult plumage, a gray-brown phase and a tawny phase, mainly recognizable in the coloration of the upper surface. Ridgway (1914) says of the former, “pileum, hindneck, and interscapular region grayish brown,” and of the tawny phase, “general coloration of upper parts much more tawny or ochraceous, the general color of the pileum varying from fawn color to mars brown or russet.”

_Food._--Bendire (1895) says that “the food of Merrill’s Pauraque, like that of the rest of the _Caprimulgidae_, consists mainly of night-flying insects, such as moths, beetles, etc. The crop of a specimen shot by Mr. H. P. Attwater, near Rockport, Texas, was filled with fireflies, _Photinus pyralis_?”

On several occasions, Mr. Burrows (Bendire, 1895) observed a pauraque “perched upon the extremity of a low, dead limb, or on the top of a bush. At these times I found that the bird was watching for food, and at intervals would leave the perch, dart off a short distance as if in pursuit of an insect, and as quickly return, in very much the same manner that the Whip-poor-will is accustomed to do. I believe that these birds are strictly insectivorous; but I have never made an examination of the stomach except in one instance. The stomach of this bird, killed in January, showed parts of the feet and wings of beetles and other insects.”

Three stomachs examined by Cottam and Knappen (1939) contained parts of ant lions, stink bugs, soldier bugs, locusts, click beetles, tiger beetles, ostomid beetles, twig borer, carrot muck beetle, long-horned beetles, and traces of butterflies, moths, bees, or wasps. Beetles made up 89 percent of the whole food.

_Behavior._--Mr. Burrows (Bendire, 1895) writes:

During the daytime the birds were commonly found on the
ground at the foot of a growth of bushes or among fallen
branches, and I have occasionally found them perched,
nighthawk-fashion, upon a low branch not more than a foot
from the ground. When closely approached, they dart quickly
forward in a zigzag course, dropping as suddenly to the
ground. This flight is short, usually not more than 50 or
80 feet, and when settled they commonly remain perfectly
quiet until again flushed. They have a peculiar way of
turning or facing about as they strike the ground, so that
they can better watch the approaching danger. They lie so
close that it is with great difficulty that they can be
detected, unless the spot is carefully marked. In a number
of instances, where the bird seemed to feel that it was
observed, I have had them go through a peculiar bowing
movement, resembling that of the Burrowing Owl, except that
the body is raised from its completely prostrate condition.

The pauraque has a relatively longer tarsus than our other members of the goatsucker family; hence it is more active on its feet. Dr. Frank M. Chapman (1896) observes: “I was surprised to learn how rapidly these birds can run. On one occasion two lit within a few feet of me when it was light enough to distinguish their movements. They crouched close to the earth, sometimes running quickly and with unexpected ease for a few steps, then turned their heads sharply from side to side as though looking for insects. They would also spring suddenly fifteen feet into the air to catch a passing insect.”

_Voice._--Dr. Merrill (1878) writes: “Their notes are among the most characteristic night sounds of the Lower Rio Grande, and are constantly heard at evening during the summer months. They consist of a repeated whistle resembling the syllables _whew-whew-whew-whew-whe-e-e-e-e-w_, much stress being laid upon the last, which is prolonged. The whole is soft and mellow, yet can be heard at a great distance. The preliminary _whews_ vary somewhat in number, and late in the season are often omitted altogether.”

Mr. Burrows wrote to Major Bendire (1895): “At the approach of the breeding season and as early as the middle of March the peculiar whistle of the Pauraque becomes general, and along the lower Rio Grande, where they are common, it may be heard on all sides. * * * The birds begin to call as the dusk of evening comes on. The commonest call is a long-drawn ‘ko, whe-e-e-e-e-w’, much prolonged, and raised to a high pitch toward the last. This is repeated often and with great energy, and on a still night may be heard at a long distance. At other times the first syllable is omitted. Again it is varied by a repetition of the first syllable, as ‘ko, ko, ko, ko-whe-e-e,’ the first syllables repeated deliberately, and the last not so long-drawn and suddenly cut short.” He also refers to a short _put, put_ note, resembling one of the notes of a wild turkey.

The name of the pauraque is said to have been derived from a fancied resemblance to one of its notes; the same is true of its Mexican name, cuiejo.

_Winter._--The pauraque is a permanent resident in southern Texas and farther south, and even as far north as the Nueces River. Mr. Burrows found it “to be fairly common” during the winter and spring of 1894. He met with it during the winter in Starr County, southern Texas, and says: “When the nesting season is over the birds remain quiet, and their peculiar whistling note is not heard with regularity, and yet, on very warm nights during each of the winter months, I have occasionally heard them. During the winter the birds may be flushed from the dense thickets in the bottom lands.”

DISTRIBUTION

_Range._--Southern Texas and northeastern Mexico; not regularly migratory.

The range of Merrill’s pauraque extends =north= to southern Texas (Refugio County and Aransas County). =East= to Texas (Aransas County, Corpus Christi, Rio Hondo, and Brownsville); eastern Tamaulipas (Aldama, Altamira, and Tampico); and Veracruz (Mirador and Jalapa). =South= to central Veracruz (Jalapa); and Puebla (Metlaltoyuca and Tehuacan). =West= to southeastern Puebla (Tehuacan); western Tamaulipas (Santa Leonor and Rio Cruz); and Texas (Lomita, Neuces County, San Patricio County, and Refugio County).

Closely allied races of this bird are found in Central and South America.

_Egg dates._--Mexico: 9 records, March 22 to June 22.

Texas: 66 records, March 5 to June 26; 33 records, April 15 to May 16, indicating the height of the season.

CHORDEILES MINOR MINOR (Forster)

EASTERN NIGHTHAWK

PLATES 29–33

CONTRIBUTED BY ALFRED OTTO GROSS

HABITS

The nighthawk, because of its piercing calls and the extraordinary evolutions and gyrations of its flight, attracts many persons, even the casual observers who ordinarily pay no special attention to birds. A bird so unique and striking, one that during its breeding season plays such an important role in our experiences out of doors, is destined to be the recipient of many common names.

Long before the white man came to America the nighthawk was well known to the Indians, and we find it taking a prominent place in their myths and traditions. Apparently the notes of this bird appealed most, since the names chosen by the various tribes were usually graphic allusions to the calls or to the characteristic booming noise heard during the courtship season. To the tribes along the Connecticut River this booming was the sound of the Shad Spirit announcing to the shoals of shad, about to ascend the river, of their impending fate. The nighthawk was known to the Seminoles of Florida as “Ho-pil-car.” In the Milicite Indian Natural History there is the name “Pik-teis-k wes,” and according to W. W. Cooke (1884) the Chippewas not only had the name “Besh-que” for the nighthawk but recognized it as a species distinct from the whippoorwill, to which they gave the name “Gwen-go-wi-a.” That the Chippewa Indians differentiated these two species is all the more remarkable when we recall that this distinction was confused by Catesby and the American ornithologists of the next 50 years who followed him. It was Alexander Wilson who first noted that they were distinct species.

When the first European settlers came to our coast they compared the nighthawk and the whippoorwill with the nightjar of their old homes, and hence we find this name in the earlier ornithological writings used as a synonym for the American bird. In certain districts of England and Scotland the nightjar is called the goatsucker, a name that originated from the queer superstition that this bird with its enormous mouth sucked the teats of goats. Like the name nightjar the name goatsucker also crossed the Atlantic, as is manifested by such names as long-winged goatsucker and Virginia goatsucker to be found in the older books and papers dealing with American birds. The name goatsucker is still applied to the order and family but is seldom used today in designating the species.

In parts of the United States, especially in the South, nighthawks are known as bats, since the birds are usually seen at dusk when their erratic flight resembles somewhat that of the common mammal. This resemblance linked with the bellowing or booming sound produced by the wing feathers during the courtship plunge has given source to the commonly used name bullbat. Audubon (1840) used the synonym Virginia bat and stated that the French Creoles of Louisanaknew the nighthawk by the metaphorical French name “crapau volans,” or flying toad. In the Bahamas, as well as in certain localities of America, a common local name is “pick-a-me-dick,” a crude imitation of one of its notes. The name mosquito hawk was well earned by one individual that, according to the Biological Survey, had eaten 300 mosquitoes. Other names sometimes applied to the nighthawk but less frequently than some of those previously mentioned are pisk, pork and beans, will-o’-wisp, burnt-land bird, and bird hawk.

The commonly accepted name nighthawk probably originated because of the bird’s resemblance to the smaller hawks when observed in flight. However, it has sometimes proved to be an unfortunate choice, since to the layman it suggests a bird of the true hawk type. This name on occasions has been a source of trouble to an innocent bird as illustrated in the following cases. According to B. H. Warren (1890) the Pennsylvania Game Commissioners, in their interpretation of the Scalp Act of 1885, took the stand that they were obliged to allow bounty on all nighthawks because they were known as hawks. Mr. Warren also states that there is a somewhat prevalent idea that nighthawks are destroyers of young poultry, the name doubtless having given origin to the absurdity. The following clipping taken from the Portland (Maine) Press is another example of the way the name has misled well-meaning persons. “The Press building acquired a new claim to distinction yesterday as the haunt of wild fowl when janitor Phillip Ward, upon making an ascent to the roof, discovered two hen hawk’s eggs there. Apparently some bird of the genus so despised by farmers had found the top of Portland’s skyscrapers the right kind of a nesting place, and had laid her plans to hatch a few juvenile hen hawks up there. Janitor Ward’s unexpected arrival put an end to such plans, however, and farmers may rest assured that the breed of distasteful birds who pillage their chicken yards is two the less.” Arthur H. Norton, director of the Portland Society of Natural History, investigated the story and found the victim to be an innocent nighthawk. Adverse criticisms of the name nighthawk have been numerous but the name although inappropriate is destined to persist.

_Spring._--The vanguard of the nighthawks in the spring migration reaches Florida and the Gulf States about the middle of April. There have been March arrivals reported, but these are exceptional. Large flocks, some of them numbering thousands of individuals, have been seen during May. Many of these southern records may be representatives of the southern form, _Chordeiles minor chapmani._

It is not necessary to search the isolated retreats away from the habitations of man for the first nighthawk arrivals. In fact, they are more likely to appear in the midst of our populous cities and towns, where they may be seen flying high above the graveled roofs that later are to be the scene of their nesting activities.

_Courtship._--The courtship of the nighthawk is an ardent and amorous performance on the part of the male. He may be seen at twilight or early dawn uttering his sharp _peent_ calls as he flies in wide circles sometimes hovering or soaring in the air high above the proposed nesting site. At more or less regular intervals he swoops down often within a few yards of his mate. Just as he seems about to dash into the ground he makes an abrupt upward turn, the vibrating primaries producing the well-known boom. After these preliminary aerial performances the male alights on the ground or graveled roof near the resting passive female. He now stands on his feet instead of resting his body on the ground. His tail is widely spread like a fan and wagged from side to side while the body is given a peculiar rocking motion. The throat is frequently puffed out, displaying a large white patch, which is ordinarily concealed when he is at rest. Synchronized with the throat distension is the uttering of guttural croaking notes. In producing these notes the bird holds the beak tightly closed, so that the throat membrane is distended by the pressure of the air emitted from the lungs. Under these conditions the sound waves originating at the syrinx beat against the tense membrane, producing notes of a striking and peculiar resonant quality. These notes are not uttered under ordinary conditions and constitute a very important part of the courtship.

The female, as far as outward manifestations are concerned, does not seem to be at all impressed by these extraordinary antics. The male at times in seeming desperation flies directly over the female uttering a sharp _peent_. He may then circle the female several times but even to this she seems unmoved. At times, when he approaches too near, the female will take a short flight, alighting a few yards away. The male follows and the performance described above is repeated. Eventually the courtship terminates in copulation.

The aerial evolutions of the male, including the downward plunges and “booming,” are continued throughout the nesting period, but after the young are hatched his effervescent energies are directed in part to securing food for his offspring. With regard to the courtship of the nighthawk, Charles W. Townsend (1920b), who gave the subject of the courtship of birds careful study, stated: “The rapid headlong plunges of the nighthawk may be classed as a display of motion, a form of the dance. Incidentally, and perhaps accidentally at first, a loud booming sound is produced by the rush of air through the wing feathers. This instrumental music is now the important feature, although the dance is by no means a negligible one.”

_Nesting._--The nesting site, according to the procedure of a pair of nighthawks studied by me at Brunswick, Maine, is chosen by the female. A banded female returned to the same nesting site on the graveled roof of the high school building for four successive years, although the males, during at least two seasons, were different individuals.

The nighthawk is solitary in its nesting habits, though there have been instances where the nests of this species have been placed very near together, approaching a gregarious tendency. For example, E. A. Samuels (1872) states that on “a ledge of rocks back of the settlement known as Wilson’s Mills, which seemed a favorite breeding-place for these birds, and, in the space of every four or five rods, a female was sitting on her eggs.” B. H. Warren (1890) writes that he has found several nighthawks breeding within a few yards of each other. A similar case of this kind was noted at Gardner, Maine, where five pairs of birds nested in a very restricted area of an old deserted dock. I am inclined to believe that the existence of a good nesting site rather than a social tendency is the more important factor in causing these birds to nest in proximity. In general, each pair of birds has a relatively large nesting territory, which is vigilantly guarded. I have never noted any marked tendency of the birds to flock together until after the nesting season prior to and during the migrations.

The nests of the nighthawk located on the ground are found in a diversity of situations as far as the surroundings are concerned. It prefers gravel beaches or open barren areas of rock or soil unobstructed by tall shrubbery or trees. It never builds a nest in the seclusion of a forest. In regions where forests abound it nests in places where vegetation is sparse or preferably where forest fires have left a barren waste. C. F. Batchelder (1882) found the nighthawk frequenting burnt lands in the region of the upper St. John River near Fort Fairfield, Maine, and it has also been found to be common in the burnt lands of the Restigouche Valley, New Brunswick. R. W. Chaney (1910) found a nest in a burnt-over area near a partly burned log in Mason County, Mich. I found three nests of the nighthawk in a burnt-over area near the Biological Station, Douglas Lake, northern Michigan, and C. E. Johnson (1920) saw two young on a scantily moss-covered and stick-strewn rock outcrop in Lake County, Minn., in a district previously burnt over. It has been noted that in regions that have been burnt over the nighthawk population increases; hence the burning of timber land, which is so destructive to many species of birds, is not a hindrance but possibly an aid to the general welfare of the nighthawk.

The nighthawk has also been found to breed in cultivated areas. I. E. Hess (1910) noted its nesting in plowed fields in central Illinois, and T. G. Gentry (1877) states that old stubble fields are frequently selected as nesting sites. H. J. Rust (1911) has reported the western nighthawk in cornfields in Idaho and California. The Texas nighthawk, according to Sharp (1907), is a common inhabitant of the vineyards of San Diego, Calif., where the eggs are placed on the ground under or near the vines. Nests have also been found in potato fields and even in gardens near the houses of man. C. B. Ressel (1889) reported the eggs of the nighthawk placed upon the loose soil thrown up by the woodchuck (_Marmota monax_), indicating that barren places even though they are composed of loose soil may be preferred to sites covered with vegetation, twigs, or other debris.

In Virginia, according to H. H. Bailey (1913), the nighthawk often departs from its usual ground nest to a place on a stump, fence rail, or tops of drifts formed on the islands off the Virginia coast. Nests on stumps have been reported from various localities. I have found nests on the flat surface of top rails of fences in central Illinois; one of these nests was 8 feet from the ground. V. Max Kemery (1925) reports an unusual nesting site between the rails on a railroad track that was in daily use. The bird would fly when the cars or engine approached but returned as soon as the train had passed. Another unique nesting place that has come to my attention is an old robin’s nest located in a tree near Farmington, Maine. This nighthawk, according to Mr. Jewell (1908), nested in this unusual site for five successive years, the tree being destroyed by fire at the end of that time.

The nighthawk in increasing numbers is availing itself of nesting sites provided by the graveled roofs of our cities and towns. In certain sections of the country this tendency is so marked that nighthawks are now seldom seen remote from graveled roofs during the nesting season, according to Lynds Jones (1909). The chimney swift, a not distant relative of the nighthawk, long ago forsook its primitive nesting sites in hollow trees, and today we no longer associate them with such places. Occurring simultaneously with the destruction of the giant forest trees was the erection of chimneys in connection with the homes of civilized races. The chimney swift, deprived of its original nesting site, was quick to make the radical but necessary change. Doubtless this adaptability to a changing environment has been an important factor in the preservation of the species. Chimneys have been used in America for centuries, but the graveled roof on which the nighthawk builds its nest is a comparatively recent development. It was not until the middle of the nineteenth century that the mansard and the flat type of graveled roofs were introduced. It was not long after these first roofs were built that the nighthawks discovered the possibilities of a new and admirable type of nesting site. As early as 1869 W. P. Turnbull wrote that the nighthawk was often seen high in the air above the streets of Philadelphia and that their nests were frequently found on the roofs of the warehouses of the city. Louis A. Zarega (1882) reported finding them breeding on a roof on the north side of 71st street, Philadelphia, in June 1882. In 1870 and 1871 Dr. T. M. Brewer (1874) found a number of instances of this bird nesting on the flat mansard roofs of Boston, and a few years later it was discovered nesting on the flat roofs of Montreal, Canada, by William Couper (1876). In 1879 a pair of the birds built a nest on a roof in the heart of the city of Cleveland, Ohio, and a few years later E. Sterling (1885) observed three pairs nesting on a slate roof of a large building near his study. Since 1880 there are innumerable records of nighthawks that have deserted the rural districts to take up their residence in the city. Today roof-nesting sites of the nighthawk seem no more unusual than the nests of the chimney swift built in our sooty chimneys. It is difficult to determine the factors that have been instrumental in this radical change, for unlike the case of the swift’s hollow trees, there are just as many rocky knolls, pebbly beaches, and barren fields as there were prior to the appearance of the flat-roofed buildings. Although certain insects such as flies and mosquitoes are abundant about our cities I do not believe that the food supply has an important bearing on this question, as has been maintained by certain observers. Even in the small country villages, wherever there are graveled roofs there is the usual quota of nighthawks. In these villages the environment, as far as food for the nighthawk is concerned, is not different from regions isolated from civilization.

W. E. Saunders (1917) states that the young after their first flight often land on the ground and he asks the question: “What chance of survival is there for a young nighthawk on a city street or vacant lot?” Mr. Saunders believes that the nighthawk has steadily decreased in numbers since the bird has taken up its abode in the city and states further that immigration is the only thing that keeps up the city population. To the contrary my observations of the past 25 years in Maine indicate that the birds are not only maintaining but are increasing their numbers. Furthermore, the mortality of the birds that nest on roofs is much less than among those that choose nesting sites on the ground. In the latter place the birds are constantly exposed to the ravages of predatory animals including the cat. In the country hundreds of young birds meet with a tragic end without any of us being the wiser, while in the city such cases are more likely to be brought to our attention. On the city roof there is freedom from natural enemies. In the study of a large number of nighthawk families I have noted relatively few young that left the nesting roof prematurely, and it has been a common experience to see them return to the roof many times after the initial flight. One bird, the account of which is related in a subsequent division of this paper returned to the roof every day until it went south on its migration at the age of 52 days. Many of the birds that nest on the roofs are never disturbed by human beings during the entire nesting period, and under such circumstances the young do not leave the security of the roof until they are able to fly well. It is obvious that the young of parents that nest on roofs are the ones most likely to survive, and they in turn will nest in similar situations the following seasons. It seems reasonable to suppose that after the habit is established natural selection and heredity play an important part in the general departure from the old to the new nesting environment.

No attempt is made by the nighthawk to construct a nest, and no materials are added to those already present on the nesting site chosen by the birds. The eggs may be in a slight depression, but no material is excavated or removed by the bird except that incidentally shoved aside by the incubating bird.

_Eggs._--Normally two eggs are laid, and there is seldom a departure from this number. In a letter dated January 20, 1936, F. W. Rapp, of Vicksburg, Mich., writes that he found a nest of the nighthawk containing three eggs on May 22, 1889.

The eggs are elliptical-ovate or elliptical-oval, one end being slightly smaller than the other. The shell is strong, closed grained and moderately glossy. The ground color varies from pale creamy white to shades of cream olive-buff and olive-gray. The eggs are marked and speckled with shades of slate, black, drab, smoke and lilac gray, and tawny-olive, and some of the eggs have shades of pearly gray, lavender, and plumbeous. In some eggs the markings are fine and uniform in size, almost obscuring the ground color; in others they are less numerous but larger and more prominent. There is an endless variation in the details of the markings and colors, but the eggs in general exhibit a coloring that blends effectively with their surroundings.

The average measurements of 81 eggs in the United States National Museum are long diameter 29.97, short diameter 21.84 millimeters. The largest egg of the series measured 33.53 by 22.86 and the smallest 27.68 by 20.57 millimeters. The average capacity of nighthawk eggs, according to Walter Hoxie (1887), is 0.448 cubic inch.

The eggs do not necessarily remain in the position in which they are first laid, especially when the nesting site is on a comparatively level surface such as that provided by graveled roofs. During the period of incubation of two nests under daily observation, the eggs were gradually moved for a distance of 5 to 6 feet. This shift in position comes about by the habit of the female pulling or pushing the eggs under her breast, thus moving them a short distance each time she settled on the eggs. As the direction of the bird’s approach was more or less constant, the eggs were moved in the same general direction. This resulted in a distinct trail being formed, giving an appearance that one would expect to see if a giant snail had traveled over the graveled surface and forced the larger pebbles to one side. B. H. Warren (1890) writes that the eggs of a nighthawk in one instance were moved 200 feet by the bird, which carried them in her mouth. I have never been able to verify this extraordinary behavior of a nighthawk transporting an object as large as an egg in its mouth.

The following experiment is of interest as it suggests an interpretation of the manner in which a nighthawk locates its eggs. One evening when the female nighthawk was away feeding I moved the eggs to a place on the graveled roof about 6 feet from their original position. When the bird returned she alighted in the accustomed place and waddled up to the spot where she had left the eggs. No eggs being there, she went by a few inches, turned around, and recrossed the spot. This was repeated several times, and finally much bewildered she flew away. The eggs were in plain view yet were not discovered. Fearing she might desert her nest, I returned the eggs. In about 10 minutes the female returned, alighted in the usual position and without hesitation went directly to the eggs. This experiment was repeated on this and other birds with essentially the same results. It is evident that some factor such as a hypothetical sense of location or orientation is important, whereas sight plays a minor role for the nighthawk in locating its eggs. The same factor is probably important to the nighthawk in finding its way over thousands of miles during migration and its ability to arrive punctually not only in the same State and the same town but to the identical nesting site.

_Incubation._--Both the male and female have been reported as sharing the duties of incubation. George H. Selleck (1916) states that the male nighthawk incubated the eggs during the daytime, whereas the female took charge of the nest at night in the case of a pair of birds he observed at Exeter, N. H. Dr. A. A. Allen (1933) states that the male takes his place on the eggs in the evening while the female is away feeding. Forbush (1927) states that both male and female share in incubation. On the other hand, J. H. Bowles (1921), who made an intensive study of the nighthawk, records only the female incubating the eggs. T. G. Gentry (1887) states that incubation “is the exclusive labor of the female” but that the young are cared for by both parents. It is evident, if the above statements are all true observations, that there is considerable individual variation in the behavior of the male in regard to incubation. In my own intensive studies of several pairs of nighthawks that nested on graveled roofs at Brunswick, Maine, I have never seen the male incubating the eggs. In the case of one nest under daily observation the birds were subject to study day and night by a relay of observers for a considerable part of the incubation period. The same held true for a pair of nighthawks studied in northern Michigan. Furthermore, visits made to numerous nests revealed in those cases that only the female was incubating the eggs, although the male was often very near to the female or to the eggs. My observations agree with the statement of Gentry that the female does all the incubating, but the male in most instances assists in caring for the young.

The behavior of the birds in relation to the nest and eggs and correlated with the time of day, the weather, environmental conditions, and the activities of other birds can be illustrated by field notes taken on June 20, 1921. These notes are representative of observations taken throughout the nesting season. The nest under consideration was located on the graveled roof of a two-story high-school building at Brunswick, Maine, a village of about 7,000 inhabitants located on the Androscoggin River. There are numerous giant elms and other shade trees along its streets, and the spacious yards and gardens present an environment attractive to a large number of birds. The times given throughout the following notes are eastern daylight saving:

June 20, 1921. 2:50 a. m. Cloudy, moon hidden by clouds, clear near the eastern horizon where the stars shine brightly. Entered the blind on the roof at 3 a. m. Female incubating the eggs. Her eyes were wide open when viewed with the flash light.

3:20 a. m. The female has been quiet during the past 20 minutes but has now shifted her position and is facing northeastward directly toward the first faint light of dawn. (Daily observations revealed that the nesting bird usually faced the sunrise in the morning and the sunset in the evening. In other words, she oriented herself toward the source of light preceding the times she anticipated leaving the nest to feed. It became evident through repeated experimental tests that her leaving the nest was considerably influenced by the factor of the intensity of light.)

3:24 a. m. The male gives a loud _peent_ call as he awakens on his perch in the elm tree. (The elm stands in the school yard and some of its branches extend over the roof wall. The male’s favorite perch was on a large horizontal limb just above the level of the roof. When he was through with his activities in the morning or evening he usually retired to this limb. He generally perched lengthwise on this limb, but it was not rare for him to depart from the conventional nighthawk position and perch crosswise to the limb.)

3:40 a. m. Light growing brighter in the east, the female can be seen without the use of the flashlight. She sits with her eyes closed, but from time to time she opens them, then raises her head and peers around, as if testing the intensity of the light prior to her leaving the nest.

3:42 a. m. The male nighthawk alights on the roof and gives a sharp _peent_ call, followed by a series of guttural _awk-awk-awk_ notes.

3:44 a. m. The male shifts his position to the roof wall but continues the guttural calls, each time displaying his conspicuous white throat patch.

4:04 a. m. The male leaves the roof wall and alights on the graveled surface within 8 inches of the female. He utters a single sharp _peent_ note, then continues with the striking guttural _awk_ calls. The female shows no outward signs of being impressed by the ardent attentions of her mate.

4:08 a. m. The male leaves the roof but soon returns and is joined by a second male. Female leaves her nest and flies toward the males, and all leave under great excitement, uttering sharp, piercing calls. The female lent a hand in driving away the strange male.

4:10 a. m. The female returns and pulls her eggs beneath her in the usual manner.

4:14 a. m. The male alights on the roof about 30 feet from the nest and utters a series of _awk_ calls in rapid succession, as if much excited as the result of his combat.

4:30 a. m. The male is chasing a strange nighthawk and, as he pursues he utters a series of _yap-yap-yap-yap_ calls in rapid fire succession, a note I have not heard before.

4:33 a. m. The male is now going through his hair-raising dives and producing the so-called boom notes, which to me resemble _swo-o-o-onk_, with the accent on the last syllable.

4:46 a. m. The sun has not yet risen. The male nighthawk flies to his perch in his favorite elm tree, and thus end his activities for the morning.

9:00 a. m. The nighthawks have been quiet since 4:46 a. m. For the greater part of the time the female has been motionless, with her eyes closed, but at intervals she opens her eyes wide in response to some unusual disturbance. She did not leave to feed, as is usual for her to do each morning.

9:10 a. m. The female shifted her position and turned her eggs. I left the blind at 9:15 a. m. and my place was taken by student observers, who took notes in relays until my return in the evening. They reported no activity on the part of the male. He remained on his perch in the elm throughout the day. The female did not leave the nest but merely shifted her position slightly from time to time in adjusting her eggs. When the heat was excessive she panted vigorously in order to adjust her body temperature.

7:30 p. m. When I arrived at the roof the sun was shining on the nesting female. Her eyes were opened as I approached the nest but were again closed after I had entered the blind.

8:05 p. m. The first _peent_ call of the nighthawk is heard from the male nighthawk, perched in the elm tree near the school building, where he had retired at 4:46 a. m.

8:09 p. m. Male leaves his perch in the elm. Simultaneously another nighthawk appears from the elms farther down the street.

8:46 p. m. The male alights near the nesting female.

8:47 p. m. The female, facing toward the western sky, opens her eyes wide and turns from side to side. With this preliminary action repeated several times, she leaves the nest. The male remains within a few inches of the nest but makes no attempt to incubate the eggs. He merely serves as a guard while the female is away.

8:48 p. m. The male leaves the roof for a moment, uttering the sharp _peent_ calls, and then returns to take up his position near to the nest.

8:50 p. m. The female returns to the nest after being away only three minutes. The male was quiet while on the roof alone, but as soon as the female returned he started his guttural notes.

8:58 p. m. The male takes leave without any ceremony and flies to his perch in the elm tree.

9:01 p. m. The female leaves the nest quietly.

9:22 p. m. No nighthawks have been seen or heard during the past 20 minutes. The female unannounced returns, after her quest for food, to brood her eggs for the remainder of the night.

Activities began again at 3:14 a. m. the next day, and the program was in all essentials similar to that recorded for June 20. Although a large series of such observations were made the male never was seen to incubate the eggs, but he regularly visited the nesting female each morning and evening. Sometimes, especially in very cloudy weather, the male left the elm tree during the day and flew about uttering the usual _peent_ calls. He was never seen on the roof during the middle of the day.

The female was always faithful to her task regardless of a parching sun or torrential downpours of rain. At one time the thermometer placed on the graveled roof reached 130° F., although it was only 98° F. in the shade on the street level. At such times her enormous mouth was wide open, and she panted incessantly. The female’s presence was needed to protect the eggs from the excessive heat fully as much as it was to supply warmth during the cool evenings when the temperature sometimes dropped as low as 45° F. If the female should leave her eggs when the temperature rises as high as 130° F. the embryos inside of the eggs would be killed in a few minutes.

It was common for the heat to melt the tar beneath the gravel so that it oozed to the surface of the pebbles. Milton Goff (1932) relates an interesting experience of a nighthawk that nested on a school roof at Rockford, Ill. One of the two eggs became firmly embedded in some tar melted by the sun. The female was unable to move the egg after nine desperate attempts made during the course of two hours.

_Young._--In 1922 the nighthawks arrived at Brunswick, Maine, on May 15. On June 3 the first egg was laid and was marked No. 1. It was not incubated the first day. On June 4 the second egg was laid at 11:05 a. m. and marked No. 2. The laying of the second egg was observed. It was seen when it first appeared and watched until it emerged from the cloaca two minutes later. The egg was moist at first but quickly dried in the warm air, after which the female turned around and tucked it under her breast. Incubation began immediately after the second egg was laid.

On June 23, 1922, egg No. 1 was pipped at 8:30 a. m. and at this time the peeps of the confined embryo could be heard distinctly. At 11:00 a. m. the chick had emerged. The egg shells of the first egg were removed about noon. The female took them in her beak and dropped them during flight at a point about a hundred yards from the building. Egg No. 2 was pipped at 2 p. m., and at 3 p. m. portions of the shell were broken away. The female seemed little concerned about the first chick but lavished all her attentions on the unhatched bird. At times she elevated her body, peered at the egg, and responded to the calls of the embryo with an assuring note. She frequently rocked her body over the egg as if to assist in removing the shell. At 6 p. m. the shell was cracked latitudinally and soon thereafter the cup of the larger end was slightly lifted. At 6:30 p. m. the young was completely freed from the shell, which broke away in two parts. As the shell membrane dried the two cups closed again forming a complete empty shell case. At this time the first young was being brooded while the second, in a wet bedraggled condition, awkwardly and weakly wavered its head beneath the bill of the female. The faint peeping notes uttered by the youngster were answered with guttural purring notes of the proud and triumphant mother. After the down of the second youngster was dry it joined its fellow under the breast of the mother. The egg shell was not removed until the following morning. The incubation period for this set of eggs was definitely established to be 19 days.

The next day the female attempted to brood the young continuously. One of the young, however, persisted in its attempts to break away from parental care in spite of the warning notes of its mother. In one instance the mother dragged the one young under her body until within reach of the unruly youngster, which was quickly and violently tucked under her breast with something of an attitude of rebuff.