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.
On the second day the young frequently appeared in the open and at
such times often pecked at the mother’s beak as if recognizing it
to be the door of a well-filled cupboard. The young had not yet
been fed, as they were still dependent on the yolk provided by the
egg and stored in their bodies at the time of hatching. The female
remained with the young throughout the day, whereas the male did
not make his appearance until 8:50 in the evening. He announced
his arrival with a sharp call as he landed on the roof. His call
was immediately answered by the female, whereupon he made his way
to the nest and without ceremony or delay delivered the first food
received by the young.
I was not prepared to see the male feed the young because the
male of the preceding summer (another individual) never assisted
in the care of the young. This striking difference in individual
behavior emphasizes the point that it is not safe to generalize on
observations of a single individual.
The next morning the female was brooding her young, and being
accustomed to my daily presence she allowed me to reach under
her breast to remove the young without exhibiting the least bit
of fear. A female nesting on another roof when visited for the
first time scooted away hurriedly, fluttered helplessly on the
roof, enacting a perfect imitation of a crippled bird, a ruse to
attract my attention away from her young. When I followed her she
quickly flew away. On subsequent visits this bird stood her ground,
elevated her wings in an upright position, and hissed at me in
defiance of my approach.
The following notes are from observations made of the young that
were hatched on the high-school roof the preceding year (1921).
The female of that year was the same bird that nested there in
1922. The identity of the female was established by banding and
also by a slight deformity of the maxilla, the tip of which was
broken off. The males of the two broods were different individuals.
The young were fed during the early morning before sunrise and
again in the evening after sunset. During the heat of the day, when
the temperature frequently went soaring above 110° F., the young
kept well concealed under the breast of the brooding bird in close
contact to her abdominal air sacs. When the temperature was less
torrid the young peeked their heads through the feathers and often
came out entirely. At such times they sometimes amused themselves
by picking at the mother’s beak and rectal bristles. If the
annoyance became too great the female would thrust her head beneath
her breast. The young then proceeded to pick at the feathers of her
crown and nape.
The female left the nest regularly about 8:30 p. m. (daylight
saving time) to obtain food for herself and young. In the case of
this brood the female delivered all the food required by the young.
The food was delivered by the process of regurgitation. The beak
of the female was thrust well into the large and widely distended
mouth of the young when the transfer of food was made. After
feeding, the adult brooded her young in the earlier stages of their
development.
For the first three days the young remained near the spot where
they had been hatched, but on the fourth day after a heavy rain
they had moved to a slightly raised portion of the roof, which
was free from excessive dampness. The female never left the young
during a rain at this stage of their growth, even if it meant
depriving them of food. The male regularly visited the roof early
in the morning and again in the evening throughout the breeding
season, but he was never seen to deliver food to the young. The
male was usually stationed on the roof when the female was away
and thus served as a watchdog in her absence. More than once
he was called upon to chase away a strange nighthawk that had
inadvertently alighted in his territory on the high-school roof.
On the fifth day (June 29) the young had wandered to the southern
end of the building where the shadow of the roof wall protected
them from the direct rays of the burning sun. The heat during the
middle of the day was frequently excessive. On July 7, when the
young were 13 days old, a thermometer placed on the gravel of the
roof registered 140° F. The heat was too much for one of the young,
which succumbed and was found dead near the middle of the roof.
Its fellow nestling, hidden in the shadow of the roof wall and
behind a clay ventilating pipe, escaped death but was in a serious
condition. A sponge soaked with cold water was placed near the
youngster, whereupon it ignored its parent to enjoy the comfort
provided by the cool sponge. This act probably aided the survival
of the young nighthawk through the remainder of the record-breaking
hot day.
As the nighthawk grew older he became very aggressive and
pugnacious and never hesitated to pester his mother whenever he
was hungry. At times he seemed mischievous. It was not a rare
experience to see him crouch under his mother’s breast and then by
standing up quickly and rigidly topple his mother so that she was
forced to extend her wings to keep from falling over. During the
period of the rapid growth of the wing feathers the youngster was
continually extending and stretching his wings as if to relieve the
uncomfortable feeling caused by growing pains.
When the young nighthawk was three weeks old he was able to make
short flights from one place to another on the gravel roof. At this
stage of his growth he had become so large that it was difficult
for the female to cover him adequately while brooding. This was
strikingly demonstrated on the evening of July 17, when he was
23 days old. The mother had left him alone on the roof while she
was away on her regular evening search for food. It was so cool
and damp that the young bird uttered notes that clearly indicated
discomfort. I placed him in a woolen bag, and this, combined with
the warmth of my hands, was very satisfying, as indicated by his
change to notes of contentment. He remained there in comfort until
his mother alighted on the roof and gave the characteristic call
note, announcing supper. The little nighthawk struggled out of
my bag and ran directly to his mother to be fed. After he was
gorged with insects, the female attempted to brood him, but to
her apparent dismay he rushed back to the woolen bag, clearly
recognizing that I could do a much better job at brooding.
On July 19, when the nighthawk was 25 days old, I discovered that
he was no longer solely dependent on his parent for food. I found
him busily engaged catching some white moths that had collected
about a drain pipe of the roof. He was flying this way and that,
catching the moths with great delight. As I sat there watching I
chanced to pull a small handkerchief from my pocket, whereupon
he dashed at the white object with the ferociousness of a tiger.
Evidently to the nighthawk this was some giant moth large enough to
provide for an entire meal.
The female now made frequent attempts to entice the young bird away
from the roof by first offering food but flying away before it was
delivered. The youngster would follow her in extended flights but
invariably returned to the roof.
On July 24, when the bird was 30 days old, the female was
photographed with the young for the last time. Thereafter she
forsook her offspring for a roost in the nearby elm tree. She then
visited the roof only for short intervals at feeding times. On
each successive day the young bird took longer and longer flights,
and each day I anticipated it would be my last opportunity to
photograph and to observe him. Much to my delight he continued to
return, seeming to enjoy my companionship.
On August 15 he left with the other nighthawks of the vicinity on
their migration to the south. This unusual experience of having the
bird return to the roof gave me an unprecedented opportunity to
make a continuous set of daily observations and measurements of a
nighthawk living under normal natural conditions up to the time it
was 52 days of age. By this time the growth of the juvenal plumage
was completed and exchanged in part for the first winter plumage.
_Plumages._--On the first day the young are able to stand upright
and are very active from the time of hatching. The eyes are open,
iris bluish black; skin darkly pigmented darker above than below;
bill “pale mouse gray”; tarsus and toes brownish drab. Down present
on both dorsal and ventral parts of the body. Down of the ventral
tracts pale gray shading to “pallid neutral gray” on the belly;
chin gray, malar stripes and patch on the throat “dark mouse gray,”
approaching black. Upper parts mottled and marbled, made up of
patches of pale gray and “dark mouse gray.” In the region of the
nape and scapulars the down has a distinct “pale olive-buff” tint.
At the base of the beak the down has a tinge of buff. A circular
area about the anus, the outer part of the shanks, and fore arm
have patches of darker colored down. Patterns of dark and white
vary considerably in different young. The average length of the
down on the various parts of the body varies as follows: Crown 9,
base of bill 4, region over eye 6, throat 12, belly 15, wing 11,
and region of anus 8 millimeters.
On the third day the color of the bill has changed to a “deep
neutral gray,” and the tarsus and toes become a dusky drab. Down
at the base of the beak, scapular region, and irregular patches of
the back has faded from the colors present in the day-old chick to
a “tilleul buff.” Iris is now a clear brown instead of the bluish
black of the freshly hatched chick.
At the age of 10 days the tarsus and toes are “deep Quaker drab,”
bill “dark neutral gray,” eyelids “light neutral gray.” Exposed
portions of the eyes are noticeably greater. Down of the back much
worn and matted down, the feather papillae in the region of the
crown, wing coverts, scapulars, and rump now more conspicuous than
the down. The tips of the feathers of the back are unsheathed and
exhibit a black and cinnamon color. The color pattern of the back
is completely lost since the appearance of the feather papillae
and their unsheathed tips. The papillae of the tail feathers are
only 8 millimeters long and as yet do not show through the down.
The feather papillae of the head and tail are the last to unsheath.
In chicks 13 days old the “pinkish cinnamon” of the tips of the
feathers of the dorsal tracts has faded to a “pinkish buff,” and
some of the feathers approach a “tilleul buff.” Freshly unsheathed
feathers of the crown are “pinkish cinnamon.” Black markings have
faded to a “fuscous-black” or “dusky neutral gray”; yellowish
color of the breast feathers of the younger stages now faded to
gray tinged with yellow. The juvenal plumage is rapidly replacing
the natal down in all parts of the body. The yellowish-gray breast
feathers are barred with “dusky neutral gray.” As previously noted,
one of the two birds died from exposure to great heat at this time
and the remaining descriptions are based on one bird.
At the age of 15 days the down is ragged in appearance but is still
prominent on the breast, sides of the head, wing coverts, and
region of the tail. The down is worn off the feathers in the region
of the crown and scapulars. Feathers of all tracts of the juvenal
plumage are partially unsheathed. When the young are handled there
are numerous particles of the feather sheaths that scale off. The
wings exhibit a marked development. The tips of the under tail
coverts recently unsheathed are ivory colored. The down persisting
at the tips of the feathers comes off with the slightest pull. The
pupil of the eye appears bluish black and the iris has changed to a
“Van Dyke brown.”
When 17 days old the sixth primary has now proceeded with
unsheathing so that the white patch is 13 millimeters in extent.
Tarsus and toes are “blackish plumbeous,” bill is a “dusky purplish
gray,” eyelids are “dark olive-gray”; otherwise the markings are
similar to those of the 15-day-old bird.
When 20 days old a relatively small amount of down remains, but
a few filaments can be seen on the tips of some of the crown
feathers, sides of neck, and breast. Feathers of the wings are
growing fast and are so heavy from the large amount of blood and
large sheaths that the wings rest on the surface of the roof,
the bird being unable to support them. The wings are frequently
outstretched, apparently to relieve the uncomfortable sensation
produced by rapid growth of the feathers. Bristlelike feathers now
appear around the base of the beak. The fifth primary is grown so
that the white patch is beginning to unsheath, and the base of the
fourth primary shows white area on sheath, which is destined to
form part of the white patch on the wing of the fully grown young.
The white on the sixth primary made its first appearance in the
17-day-old chick.
At this age the crown is “dusky neutral gray” or black, the
feathers tipped, barred, and spotted with “vinaceous-buff”; some
of the tips approach “avellaneous.” The feathers of the upper parts
are dark, or dusky, neutral gray variously mottled with shades of
gray and “avellaneous” many of the feathers tipped with “pinkish
buff.” Auriculars “light cinnamon-buff” and black, tipped with
lighter shades. Primaries and secondaries blackish warm gray,
some of the feathers having an olivaceous-black appearance. All
the remiges are tipped with “tilleul buff” or “vinaceous-buff.”
Some of the secondaries and inner primaries spotted with
“vinaceous-buff.” Coverts of primaries unspotted “blackish mouse
gray” or black. Coverts of secondaries spotted with “tilleul buff”
and “vinaceous-buff.” Lesser wing coverts variously mottled with
colors mentioned above. Feathers of the breast barred with “dark
mouse gray” and shades of gray and white. Throat and chin with a
crescentic band of feathers, which are barred with dark gray and
white, the white predominating. Band of feathers along the edge of
mandible extending below the eyes to the auriculars “neutral gray”
and marked with “vinaceous-buff.” Under tail coverts “cartridge
buff,” narrowly barred with black. Middle of the belly a heavy mat
of down. Eyelids “light olive-gray,” tarsus deep metal gray.
At 25 days the down has been lost, except that of the middle of the
belly and small patches on the legs above the heels.
At 28 days the colorings are about as described for the 20-day-old
chick, but the colors are subdued and faded because of exposure
to the intense sunlight. The down is now entirely replaced by the
feathers of the juvenal plumage. Although the outer primaries
are only partially unsheathed, the young bird is capable of long
flights and frequently leaves the roof, but invariably returns.
At 30 days the secondaries and the primaries, except the outer
ones, are now unsheathed. The barred feathers lining the wings are
now in process of unsheathing.
At 35 days the prevailing color of the upper parts is
olivaceous-black, glossed with greenish, but this base color is
very much broken by irregular markings, spotting, and marbling of
buffy gray and whitish; many of the larger spots approach a light
vinaceous-buff, which is especially evident on the crown. Spots of
the crown are larger than those of the back. The throat patch now
is clear white, an indication of its sex.
At 40 days, all the primaries except the outer two are completely
unsheathed. The white patch of the second to fifth unsheathed, that
of the first is 11 millimeters.
The bird, although able to fly as well as an adult, returned to
the roof each day and allowed me to make daily measurements and
weighings without the least resistance. It never attempted to run
or fly away when I approached to pick it up. When I arrived on the
roof wall it gave a series of calls, which seems to be a sign of
recognition. The bird placed before me in a natural sitting pose
measured 187 millimeters from the tip of the bill to the tip of the
wings. Distance from level of the crown to the board on which it is
seated is 90 millimeters. Tip of tail to front of toe in natural
position 150, and tip of folded wing to toe 165 millimeters.
The bird at this age is very active and vivacious and captures all
its own food. It offers no difficulty for me to capture it for
measurements and poses perfectly for photographs.
On Monday, August 15, there was a great flight and departure of
nighthawks, and after that date the nighthawk was seen no more.
Presumably it went southward on its migration. The bird was 52 days
old, and I had an unexcelled opportunity to observe the bird up to
the time of the completion of its growth.
The completed juvenal plumages of both sexes is similar to that
of the adult female except that the throat patch is not so well
defined; in some it is replaced by blackish and buffy bars. The
barring of the underparts is more extensive and the coloration in
general is paler than that of the adults. There are whitish tips on
all the primaries.
The postnatal molt has already been described in detail under the
account of the young. There is a partial molt that does not include
the wings and tail in September. There is a partial or complete
prenuptial molt in spring when the young attain the plumage of the
adult. The adults have a complete postnuptial molt before they
return for their nesting activities the following year. I have not
been able to ascertain the time of the postnuptial molt.
Albinistic phases of plumage, in which there is an absence of dark
pigment, may appear in any species of birds. W. A. Strother (1886)
reports a perfect albino taken at Lynchburg, Va.
_Food._--The nighthawk is insectivorous in its eating habits. Since
the major part of the insects it destroys are destructive to useful
vegetation or are otherwise adverse to human welfare, the nighthawk
ranks high in the list of birds beneficial to man.
The nighthawk captures the insects chiefly during its flight. The
birds sweep up in their capacious mouths all types of insects from
the large moths and beetles to the tiniest of flies and mosquitoes.
Some of the stomachs examined have contained no less than 50
different species of insects, and some of the smaller insects are
at times represented by thousands of individuals.
One of the most conspicuous elements of the food is flying ants.
In the examination of 87 nighthawk stomachs, the United States
Biological Survey reports that ants comprised nearly one-fourth
of the total food eaten by the birds. In 24 of the stomachs the
number of ants ranged from 200 to 1,800, and in all the stomachs
examined there were not less than 20,000 ants (Beal, 1897). In
the stomach of a nighthawk that met with accidental death at
Brunswick, Maine, on August 20, 1925, there were 2,175 ants.
The mass and weight of these insects were so great that they
constituted a serious handicap and probably a factor in the bird’s
untimely ending. Charles Drury (1887) obtained a specimen in August
that contained 320 insects, chiefly winged ants. W. L. McAtee
(1926) found more than one hundred carpenter ants (_Camponotus
herculeanus_) in one nighthawk stomach. In most all instances the
ants captured are the mating winged individuals, which fly in
immense swarms during the late summer. These ants are killed at a
time when they are preparing to propagate their kind, and hence the
death of every female means the destruction of thousands of the
next generation.
According to examinations of the United States Biological Survey
(Beal, McAtee, and Kalmbach, 1916) beetles comprised one-fifth
of the food eaten by 87 nighthawks examined. May beetles, dung
beetles, and others of the leaf-chafer family were in greatest
numbers. Beal (1897) reported finding the remains of 34 May beetles
(_Phyllophaga_) in a single nighthawk stomach, in another 23, and
in a third 17. In the stomach contents of one specimen no less
than 17 species of beetles were identified. Chester Lamb (1912)
reports that all nighthawks collected by him had eaten enormous
quantities of beetles. Thomas G. Gentry (1877) reports eight
species of beetles in food examined by him. McAtee (1926) reports
various leaf chafers, sawyers, wood borers, bark beetles, weevils,
and plant lice in the food eaten by nighthawks in the course of
his study of the relation of birds to woodlots in New York State.
In the examination of hundreds of droppings of nighthawks obtained
from various nesting sites chiefly at Brunswick, Maine, a large
percentage of the identifiable remains consisted of parts of
various species of beetles.
Nighthawks, especially in the Middle West, have been known to eat
a considerable number of grasshoppers and locusts. According to
Ernest Harold Baynes (1915) seven Nebraska specimens were found to
have eaten 348 Rocky Mountain locusts; five specimens collected in
Indiana reported by A. W. Butler (1898) had eaten 9 grasshoppers,
19 beetles, 23 Heteroptera, and 4 Neuroptera. B. H. Warren (1890)
reported that grasshoppers were an important element of the food
eaten by nighthawks collected in Pennsylvania. F. E. L. Beal (1897)
states that one nighthawk contained the remains of 60 grasshoppers.
A male killed on July 7, 1882, was reported by Everett Smith (1883)
to have “an ichneumon fly, a black cricket, about twenty small
grasshoppers, and many small, hard insects” in its crop.
Flies, plant lice, and mosquitoes frequently form an important
element of the food of the nighthawk. A nighthawk examined by the
Biological Survey had eaten more than 300 mosquitoes, and E. H.
Forbush (1907) reports finding 500 mosquitoes in the stomach of one
bird. McAtee (1926) reports that he found 650 plant lice in the
stomach of a single nighthawk. Phoebe Knappen (1934) found stone
flies in 21 nighthawks. The insects were chiefly adults but also a
few larvae, nymphs, and eggs were present.
In the South various observers have noted that the nighthawk is
an important factor in the control of the cotton-boll weevil. F.
H. Herrick (1901) writes of a nighthawk that had been feeding on
fireflies; the wide open mouth of an adult observed feeding its
young was brilliantly illuminated like a spacious apartment all
aglow with electricity. F. H. Carpenter (1886) relates a unique
experience with nighthawks that darted at the artificial flies
on his line when he was casting for trout. It is not an unusual
experience to see nighthawks after dusk flying about electric
lights of city streets (Knowlton, 1896) or about campfires of
remote districts where they capture myriads of insects attracted by
the lights.
During the migration nighthawks frequently fly near the ground and
at such times may take advantage of any insects that appear in
their path. During an afternoon late in August I observed a flight
of several hundred nighthawks near Urbana, Ill. As I sat in a car
alongside a large meadow I noticed that the birds were ravenously
feasting on grasshoppers. Some of the birds lingered long enough to
capture half a dozen of the insects before passing on to make place
for other nighthawks in the migrating procession. A. Dawes DuBois,
of Excelsior, Minn., relates a similar experience he had in the
vicinity of Salt Creek, Logan County, Ill., as follows: “At dusk
on the evening of May 22, 1913, as I walked along a cloverfield,
we witnessed an assemblage of nighthawks in pursuit of low-flying
insects. They skimmed over the clover like swallows; and their
dusky forms were so numerous that they seemed to be weaving an
intricate pattern in the gray twilight. They were so intent on
their bountiful repast that they paid no heed to our presence, but
sometimes darted past us only a few feet away.”