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American Crow
Corvus brachyrhynchos
[Eastern Crow]
Contributed by Alfred Otto Gross
[Published in 1947:
Smithsonian Institution United States National Museum Bulletin 191
(Part 2): 226-257]
It has been aptly stated that if a person knows only three
birds one of them will be the crow. The crow, if we include all
the five subspecies, is widely distributed over the greater part
of the North American Continent. Throughout this area this
familiar bird is instantly recognized by anyone who sees it.
Because of its striking coal-black plumage, its large size, its
unusual adaptability, its extreme cunning and apparent
intelligence, its harsh garrulous notes, and its habit of
frequently appearing in the open, it has become one of the best
known of our American birds. The common name crow is universally
applied, and I know of no English local synonyms for it. Even
before white man came to America it was well known to the Indians
and every tribe had its name for this bird, which was such a
conspicuous creature of their environment.
Unfortunately the crow has a questionable record as far as his
relations to human interests are concerned. No bird has been the
subject of more heated controversy than the crow, and none of our
birds have been more violently persecuted by man. In spite of
incessant persecution the crow has been able to outwit his human
adversaries by its unusual intelligence and instinct of
self-preservation, to the extent that it has been able to maintain
its existence in all parts of its wide and diversified range. For
this the crow commands our admiration.
Spring.--A few crows winter in
northern New England, but the majority of them are found farther
south during the season of extreme cold weather. The first
arrivals of the spring migration reach Maine during February, but
it is not until the latter part of the month or the first week of
March that they become common. Low (1934), in connection with
banding operations at the Austin Ornithological Research Station
on Cape Cod, Mass., has collected data that suggest that three
populations of crows may be found there as follows: permanent
residents, breeding birds that winter to the south, and northern
breeders that either winter or migrate through the region.
Determinations of sex ratios at roosts by Hicks and Dambach
(1935) indicate that the migration of the sexes may differ in
range and extent. Certain of our populations of crows undergo a
relatively short migration, but banding operations conducted in
Oklahoma by Kalmbach and Aldous (1940) prove that many of the
crows wintering in that state migrate to the Prairie Provinces of
Alberta, Saskatchewan, and Manitoba, a flight of more than a
thousand miles. One crow shot at Meadow Lake, Saskatchewan, at
latitude 54o N. had traveled 1,480 miles and another at
Camrose, Alberta, 1,435 miles from their winter home in Oklahoma.
Out of 714 crows banded, 143 recoveries were obtained. Of 65 crows
recovered during the nesting season, 49 were from the Prairie
Provinces. It is obvious that many of the returns recorded in the
states north of Oklahoma were on their way to or from the Canadian
breeding grounds. The results obtained by Kalmbach and Aldous not
only give us definite information concerning the extent of crow
migration but are important in their relation to the value of the
extensive control measures undertaken in Oklahoma.
Crows have been used for important experimental work concerned
with different phases of migration. William Rowan, proceeding on
the hypothesis that the migrating stimulus is a physiological one
originating in the gonads or sexual organs, experimented on
various birds, but chiefly the crow. The crows were confined in
outdoor aviaries at Edmonton, Alberta, and exposed to temperatures
as low as 44o F. below zero, but from the first of
November until early January they were subjected to an
ever-increasing amount of light, supplied by electric bulbs. In
this way they were artificially subjected to light conditions that
approximated those of spring. At the close of this period it was
found that the gonads had actually attained the maximum
development normally associated with the spring season. Control
crows not subjected to the light treatment showed no development
of the gonads. The birds, both the light-treated individuals and
the controls, were marked, banded, and then liberated. By means of
radio and other publicity, the cooperation of hunters was
solicited for the return of the bands. While bands from eight of
the experimental crows were returned from the north and northwest
(two of them from a point 100 miles northwest of the point of
liberation), an equal number were recovered from the south and
southeast, thus to some extent nullifying the experiment. This
work does indicate that the stimulus that initiates migration is a
physiological one, and it is assumed to be a hormone produced by
the interstitial tissue of the reproductive organs.
Courtship.--Edward J. Reimann in
correspondence writes of the early courtship of crows he observed
in the vicinity of Philadelphia, Pa. On March 8, 1940, he saw
crows paired at most of the nesting localities along the Pennypack
Creek. In some of these places two or three birds and at times
four or five, what he supposed to be males, were seen chasing a
female in courtship. Late in March the crows were rather noisy as
he passed through each prospective territory. At some places
courting was still going on where small groups of crows milled
about the trees. Males chased the females, courting them while
performing aerial gyrations of diving and wheeling. It was
apparent to Reimann that the birds were pairing off, were claiming
their nesting territory, and were about to drive their unwanted
rivals from the scene.
Charles W. Townsend gave the subject of courtship of many birds
serious and careful study, and no one is better qualified than he
in the recording and interpretations of their performances. The
following account is based on his observations of crows at
Ipswich, Mass. His published account (1923) in part is as follows:
Courtship in birds is expressed in three ways, namely in
display, dance and song. . . . The courtship song of the Crow
consists of a rattle, a quick succession of sharp notes which have
been likened to the gritting of teeth. That this is a courtship
song and not merely one of the bizarre expressions of this
versatile bird, is shown conclusively by its association with
courtship display and dance. Like all bird songs it is commonest
in the spring, but may occasionally, as in the case with many bird
songs, be heard at other times, especially in the fall of the
year, when it is explained by the "autumnal recrudescence of
the amatory instinct." Although the song is generally given
from a perch, it may also be given on the wing, constituting a
flight song, although there is no other difference in the
character of the two songs.
The whole courtship of the Crow varies somewhat, but the
following description of this act, seen under favorable
circumstances, is fairly typical. A Crow, presumably the male,
perched on a limb of an oak tree, walked towards another and
smaller Crow, presumably the female, that seemed to regard him
with indifference. Facing the smaller one, the male bowed low,
slightly spreading his wings and tail and puffing out his body
feathers. After two bows, he sang his rattling song, beginning
with his head up and finishing it with his head lower than his
feet. The whole performance was repeated several times. The song,
such as it was, issued forth during the lowering of the head. . .
.
During the love season, fights by rival Crows are common.
Each bird tries to rise above the other in the air, and, with
noisy outcry, each attacks the rival. Sometimes their struggles
are so violent that the birds come to the ground, where they
continue their fight and sometimes roll over together in their
efforts, all the time voicing their wrath.
On the other hand, one may sometimes chance upon the loving
actions of affianced couples. More than once I have seen one of a
pair that were sitting close together in a tree, caress the other
with its beak and pick gently at its head. The mate would put up
her head to be caressed, and I have been reminded of billing
doves.
Later Townsend (1927) made further observations which he
elaborated upon as follows:
Spending the nights in an open lean-to in my
"forest," at Ipswich, I found myself listening every
morning to the courtship song of the Crow close at hand, and, on
May 3, 1926, I discovered from my bed that a pair had their nest
in a white spruce twenty-five yards from me, so that I was able to
watch them closely. At about four-thirty every morning I awoke to
the rattling song of the Crow, and I often saw one flying about in
irregular circles, singing and chasing another. Both alighted on
trees, especially on a spruce, from time to time. The song was
given in the air and from a perch, and once I heard it given as a
whisper song. I also heard for the first time at the end of the
rattle a pleasing sound which suggested the cooing of a Pigeon or
the note of a cuckoo clock, but softer and more liquid. It was
usually double--I wrote it down 'coi-ou' or a single 'cou'--and
generally repeated several times, although sometimes given only
once. These soft sounds, which I heard many times when the bird
was near, generally followed the rattle, but were often given
independently. When the bird was perched, he bowed and puffed out
his feathers at the time of their delivery as during the rattling
song. The cooing was also given in the air and on one occasion, I
saw a bird drop slowly down with wings tilted up at an angle of
forty-five degrees, singing as he fell. The rattle song was once
given fifty-four times in succession, followed by a series of 'cous.'
The female was at times very importunate, calling slowly
'car car' like a young bird begging for food. If the male
approached, the calling would become more and more rapid and end
exactly as in the case of a young bird in a gurgle or
gargle--'car, car, car, cowkle, cowk!e, cowkle.' After mating the
male would fly to the next tree and call loudly 'caw-caw' several
times. Occasionally the loud 'wa-ha-ha-ha' was given. An
examination of the nest made at this time showed three heavily
incubated eggs.
Nesting.--In northern New England
and the Maritime Provinces the vast majority of the crows nest in
coniferous trees and those that I have examined have ranged 18 to
60 feet from the ground. Of 22 nests observed in Maine, 12 were in
pines, 6 in spruces, 3 in firs, and only 1 in a hardwood tree, an
oak. A nest containing six eggs found on May 20, 1936, near
Brunswick, Maine, is typical. It was in a large pine located near
the center of a 10-acre grove. The nest was built close to the
trunk of the tree and was supported by three good-sized horizontal
branches at a point 42 feet from the ground and approximately 30
feet from the top of the tree. The foundation of the nest was made
up of branches and twigs of oak, beech, and pine, the largest ones
were one-fourth to three-eighths of an inch in diameter and 10 to
16 inches in length. The nesting bowl was made up of smaller twigs
interwoven with strands of bark. The soft compact lining was
entirely of finely separated fibrils of bark, which apparently
were shredded by the birds before being placed in position. The
foundation of nesting materials measured 22 by 26 inches, the
depth of the nest from the upper rim to the base was 9 inches, and
the rim of the nest proper was 12 inches in diameter. The interior
of the nesting cup occupied by the bird was 6 by 7 inches and its
depth 4 1/2 inches.
All the nests of the crow are substantial and well built; they
are crude in general external appearance but always delicately and
warmly lined. The main departure from the type described above is
the nature of the materials used in lining the nesting bowl, a
difference somewhat dependent on their availability. Different
nests may be lined with moss, reed fibers, grass, feathers, twine,
rags, wool, fur, hair, roots, seaweed, leaves, and similar
materials.
The crow seems to prefer coniferous trees not only in the
northern sections of its range but even in the south where such
trees abound. In states where hardwood trees predominate, they are
more frequently selected as nesting sites. T. E. McMullen, who has
made extensive observations on the nesting sites of 227 crows in
Pennsylvania, Delaware, and New Jersey, reports finding 112 nests
in oak trees, 62 in other species of hardwood including 13 in
maple, and 11 in beech trees. The remaining 43 were in coniferous
trees, 24 in pine, 17 in cedars, and 2 in hemlocks. The above
nests varied from 10 to 70 feet in height from the ground, but the
majority exceeded 25 feet. Edmund J. Reimann writes that he has
found nests in Pennsylvania that were built at a height of 100
feet from the ground.
In the agricultural areas of the Middle West, where there is a
lack of large trees, crows resort to second-growth timber and
shrubs of various kinds. In central Illinois favorite nesting
sites are the Osage-orange fences. These hedges, abundantly armed
with thorns, offer excellent protection, even against the prowling
naturalist who may wish to examine the nests.
The crow is adaptable in the choice of its nesting site. In the
western Canadian provinces there are numerous instances where the
crow has nested on the ground either from choice or because of the
lack of trees. Ferry (1910) found a crow's nest at Quill Lake,
Saskatchewan, that was situated on the ground at the forks of the
dead branches of a fallen and nearly burned up weather-bleached
poplar tree. At Regina, Saskatchewan, Mitchell (1915) found a
crow's nest on the ground between wild-rose bushes; others were
placed on clusters of rose and low bushes just a few inches
above the ground. On June 13, 1935, Aldous (1937) found two crow's
nests built on the ground along the shore of Lake Manitoba.
Another nest containing three eggs was found in the tules over the
water, and a fourth nest was built on marshy ground among the
reeds. In the latter two cases there were trees and brush in the
vicinity, and apparently these situations were a matter of choice
on the part of the birds.
Horning (1923) cites an unusual experience with a nest that he
found at Luscar, Alberta. "We found a crow's nest in a willow
thicket about ten feet from the ground, on May 28, 1922. The
situation surprised us, as the Crow usually builds very high. and
there were high trees within a few hundred yards. We thought that
the presence of an abundant food supply, in the shape of a dead
cow, within twenty-five yards may have been the reason for the
choice of nesting site. We cut down the nest, which contained
three eggs, newly laid, and photographed it, leaving it not more
than two feet from the ground, and inclined at an angle of about
55 degrees. We removed the eggs. . . . Judge of our surprise, on
re-visiting the nest on June 1 to find four new eggs. . . . It
seemed to us very unusual for the Crows to re-occupy the nest
especially when so close to the ground and at such an angle."
Occasionally crows select sites that are an extreme departure
from the usual situations. Harold M. Holland in correspondence
states that a pair nested in the hollow of an old stub located in
a wooded tract in Knox County, Ill. They nested in this place for
at least three seasons in preference to other numerous apparently
suitable locations offered by the surrounding woods. Potter (1932)
states that a pair of crows remodeled the top of a disused magpie
habitation.
Bradshaw (1930) comments on unusual nesting sites he found in
Saskatchewan as follows: "In many treeless sections of the
prairie, such as Big Quill Lake, crows have been found nesting on
the cross-arms of telephone poles. In such cases one usually finds
nearby a marsh well-stocked with ducks, coots, rails, grebes, and
other marsh-loving birds. Probably the easy available food supply
is the principal factor for the crow locating in such areas. . . .
"The most unique nesting site of the crow encountered was
one found on the top of a chimney of a country church, between the
towns of Pense and Lumsden." On the same road a pair of crows
built their nest in a chimney of an abandoned house. In both
cases, however, there were plenty of trees that the crows might
have chosen for their nests.
Dr. S. S. Dickey, who has made extensive observations of crows
in Pennsylvania during the nesting season, contributes the
following observations made of the procedure of nest-building:
"The female descended into the underwoods or would move along
branches of the trees to masses of twigs. She would take one of
them into her beak, twist it loose from its fastenings, and hurry
with it to the site she had chosen for her nest. At first she
tended to drop sticks en route, or else would proceed awkwardly in
placing them in a fork or crotch. She dropped many sticks, causing
a veritable heap of rubbish near the base of the nesting tree.
Finally after many trials she managed to arrange a loose array of
sticks in the base of the fork. Most of the work was done in the
morning hours between 7 and 11 o'clock. Thereafter she appeared to
weary and would fly away in company with the male in search of
food. Late in the afternoon and shortly before dusk she proceeded
again to work on her nest. The walls grew consecutively from
coarse sticks and twigs to finer materials. She added mud, strands
of rope, rags, corn husks, mats of dry grass, roots, moss and weed
sterns, and strips of bark from various kinds of trees. The rim
was nicely rounded off with strips of grapevine bark. The interior
of the deep wide cup was tightly lined with inner bark fibers,
pads of hair, fur, wool, and green moss. It required approximately
12 days to complete the nest after the first sticks had been
placed.
"If bad weather conditions prevailed, several days would
elapse before the first egg was deposited, although in one nest an
egg had been laid in spite of the fact that the edge of the nest
was encrusted in snow. During fair warm weather eggs were found in
the nest a day or two after the nest had been completed."
Although not mentioned by Dr. Dickey, it has been noted by many
observers that both male and female take an active part in the
building of the nest as well as sharing in the incubation of the
eggs.
Eggs.--The number in a complete set
of crow eggs is usually four to six, but in some cases there are
only three and in others as many as eight or nine. Macoun (1909)
reports an unusual set of ten eggs. In the latter instances it is
probable the large number of eggs are the product of two birds, as
it has been observed that two females in addition to the male have
shared a single nest. Bendire (1895) has given us an excellent
description of the eggs of the crow based on a wide experience and
the study of large numbers of specimens. His account is as
follows:
"Crows' eggs are rather handsome, and vary greatly in
shape, size, color, and markings; the majority may be called
ovate, but both short and rounded ovates, and elliptical and
elongated ovates are also found in a good series. The ground-color
varies from malachite and pale bluish green to olive green, and
occasionally to an olive buff. The markings usually consist of
irregularly shaped blotches and spots of different shades of
browns and grays. In some specimens these are large, and
irregularly distributed over the egg, usually predominating about
the larger end, leaving the ground color clearly visible. In
others again the markings are fine, profuse, and evenly
distributed, giving the egg a uniform dark olive-green color
throughout."
Bendire gives the average measurements of 292 eggs in the
United States National Museum as 41.40 by 29.13 millimeters or
about 1.63 by 1.15 inches. The largest egg of the series was 46.74
by 30.78 millimeters, or 1.84 by 1.21 inches; the smallest 36.07
by 25.91 millimeters, or 1.42 by 1.02 inches.
Sometimes eggs of abnormal size have been found. G. Ralph Meyer
collected a set of eggs in which one egg measured 2.00 by 1.25
(50.8 by 31.8 millimeters), much larger than the largest egg in
the large National Museum series. One or more eggs dwarfed
in size have been found in sets in which the other eggs are
normal, but these usually prove to be sterile.
There are a number of reported cases of erythristic crow eggs,
in which there is present an excessive amount of red pigment. In
correspondence William Rowan, of Edmonton, Alberta, informs me
that he has two sets of erythristic eggs that he obtained from
central Alberta. They were laid by the same bird in successive
years, and he states further that this same type of egg has been
found in the same nest for seven successive years. Mr. Rowan
believed that these eggs were unique and represented the first
recorded case of erythrism in crow's eggs. However, there are
published descriptions of so-called abnormal red-colored eggs that
are undoubtedly cases of erythrism. Following are a few that have
come to my attention. Bendire (1895) states as follows: In an
abnormal set of five eggs, presented by Dr. A. K. Fisher to the
United States National Museum collection, four have a pinkish buff
ground color, and are minutely speckled with fine dots of ecru
drab resembling somewhat in general appearance a heavily marked
egg of the American Coot. . . . In another specimen, presented by
Dr. Louis B. Bishop, the ground color is salmon buff and this is
blotched with pinkish vinaceous. The entire set of six eggs was
similarly colored. Sage, Bishop, and Bliss (1913) mention six
pinkish eggs of a set obtained near New Haven, Conn., on May 8,
1884. Jacobs (1935) describes a set of five eggs he found May 1,
1934, in a nest located in a willow tree near Waynesburg, Pa., as
follows:
Throughout the whole set there is not the slightest
suggestion of the usual greenish-drab shades. The shell, held to
the light, appears a rich cream-white such as seen in the eggs of
the Eastern Sparrow Hawk, and on the whole, resembles in
coloration eggs of the latter collected on the same day. The
smallest egg is less thickly marked and contains sparingly
scattered hold patches of mauve and maroon purple, which tints are
brought out by the brick-red laid over varying shades of lilac and
lavender, the majority of them all on the smaller half of the
shell. It is a beautifully spotted egg with brick-red, mauve and
maroon purple about equally apportioned and equalling the amount
of lilac and lavender shades which are untouched by the reddish
pigment.
The ground color of the four eggs originally rich
creamy-white with lavender blendings in paler underlays is heavily
mottled over with brick-red giving the shells a uniform rich
vinaceous appearance, over which are diffused blotches of strong
vinaceous-cinnamon blending into the underlays. Thus we have, in
these five crow eggs, specimens appearing like huge Cactus Wren
eggs but the general red shade is really stronger than that of the
wren's eggs.
Incubation.--The incubation
period of the crow is 18 days. One brood is reared each year, but
in the southern part of the nesting range two broods each season
are not unusual. Both male and female may take part in incubation
and both share in the care of the young. Macoun (1909) reports a
nest in which both birds were sitting on the eggs at the same
time. The cavity of the nest was much larger than usual. There
were five nearly incubated eggs in the same stage of development,
indicating that these birds were male and female rather than two
females. Occasionally three crows may be seen about the nest, but
because of lack of sexual differences of plumage it is difficult
to determine whether they represent cases of polygamy or
polyandry. There is indirect evidence, however, that two females
may be concerned. There are a number of cases on record where two
sets of eggs were found in a nest that hatched on different dates.
Jung (1930) found a crow's nest on June 15, 1928, in Alberta,
Canada, that contained three eggs and one young about a week old.
When the nest was visited the next day a fourth egg had been
added. Three crows were seen about the nest and it is apparent
that two of them were females, both of which were contributing
eggs to this communal nest. In other cases three crows were
concerned with a single nest, which contained a normal set of eggs
hatching on the same date. Here, it is probable, two males were
involved.
Young.--The young when first hatched
are pink or flesh color and scantily clad with tufts of grayish
clove-brown on the head, back, and wings. At five days of age the
eyes are open and the exposed parts of the skin have acquired a
brownish-gray color. At 10 days the principal feather tracts are
established by the rapidly growing feather papillae. At this stage
they assert themselves by loud clamorings for food, and the
presence of a nest may be revealed by their incessant calls,
especially as they grow older. When the young crows reach the age
of 20 days many of the contour feathers are unsheathed, presenting
a dull black color. Tufts of down still cling to the tips of these
juvenal feathers, especially in the region of the crown. The eyes
are a dark blue-gray, the scales of tarsus and toes are grayish
black, the upper mandible or maxilla is black, and the lower
mandible is pale yellow or horn color streaked with gray. The
lateral basal portions of the gape are yellowish orange. At this
age tufts at the base of the bill are developed.
After four weeks most of the feathers are completely
unsheathed. The young at this stage also show a marked change in
behavior especially in regard to a human visitor. Before this time
they were passive but now exhibit fear and offer resistance at
being handled or lifted from the nest. At this time they may stand
on the rim of the nest or even leave to nearby branches of the
tree where they are fed by the adults. In the course of another
week they are capable of leaving the nest and making their initial
flight. If disturbed they may leave the nest before reaching the
age of five weeks.
Plumages.--The young in the
completed juvenal plumage are dark grayish black above, with the
under parts somewhat duller in tone; the wings and tail are black
with violet and greenish reflections; iris bluish and the bill and
feet grayish black.
The first winter plumage is acquired by a partial postjuvenal
molt, which involves the body plumage and wing coverts but not the
rest of the wings or the tail. The young in this plumage are
similar to the adults, but the feathers show less gloss and the
majority of the specimens have a greenish hue. The under parts are
of a duller black, the belly with a dull slaty cast. The first
nuptial plumage is acquired by wear, the feathers becoming
brownish and worn by the end of the breeding season. The adult
winter plumage is acquired by a complete postnuptial molt. The
sexes are alike in plumages and molts. All parts, including bill,
legs, feet, and claws, are deep black. The plumage of the body has
a distinct metallic gloss of violet, and the wings are glossed
with bluish violet and greenish blue; iris brown.
Albinism is common in the crow, judged from the more than 25
reported cases that have come to my attention. Since an albino
crow offers such a striking contrast to the normal plumage, and
because crows are more readily observed than the more secretive
species, there are many reports of albinism. A few of the more
interesting cases are cited below.
In the Bowdoin College collection there is a female crow
collected at Yarmouth, Maine, that is pure white, including the
bill, feet, and claws. The iris of this specimen was pink and so
the bird was a pure albinistic type. Two albino crows taken from a
nest near Portland, Maine, in 1910 were mounted by J. A. Lord, a
taxidermist in Portland. An albino crow was seen at South China,
Maine, for a period of several weeks during August 1930. F. A.
Stuhr, of Portland, Oreg., reported having four live crows that
were taken from a nest in Lane County, Oreg. Three of them are
almost entirely white, showing only slight black colorations on
the primaries and secondaries and at the base of the bill. The
iris of these birds is brown, but the feet and tarsus are nearly
white. Fleming and Lloyd (1920) report that two albino crows were
taken from a nest 9 miles north of Toronto on June 29, 1908.
Both birds were grayish white, the eyes blue-gray, the feet lead
black, and the beak horn color. Harry Piers (1898) reported a
partial albino collected near Halifax, Nova Scotia. His
description is as follows: "Its general color was brown,
darker on the throat, cheeks and belly; scapulars and feathers of
back margined obscurely with whitish; primaries mostly whitish;
tertials white; tail feathers light reddish brown margined with
whitish on outer edge; legs, bill and iris brown." Several
crows similar in coloration to the one described by Piers but with
certain variations have been reported by other observers.
Warne (1926) cites a very unusual case of a pet crow that after
five years suddenly acquired white feathers in each of its wings;
when the wings were spread, about half of the area was white.
Previous to this time they were black. Albinism is a hereditary
character, and why white feathers would replace black feathers
after five years is difficult to explain.
Longevity.--We have relatively
few records on the longevity of the crow. Banding of the birds has
not been conducted in sufficient numbers or for a long enough time
to yield definite results, but the following four banding returns
are of interest: A crow banded as a nestling in Saskatchewan in
July 1924 was shot five years later in July 1929 only a mile and a
half from the place of banding; one banded at Garden Prairie,
Ill., was shot five years later at Marengo, Ill., on March 25,
1934; one banded at Richmond, Ill., on May 28, 1927, was shot
seven years later in Kenosha County, Wis., on March 13, 1934; and
one banded at Lundar, Manitoba, on May 1, 1926, was shot seven
years later in Grant County, S. Dak., on April 2, 1933.
Kalmbach and Aldous (1940) are of the opinion that relatively
few crows in the plains area live more than four years. This
supposition is based on the rapid decrease in the number of
returns during the years following the release of the birds. Out
of 143 returns of 714 crows banded, 76 were received the first
year and 47, 12, and 8 (first six months) in the successive years.
All were reported killed, which emphasizes the intense persecution
the crow receives from the hands of the gunner. It is possible,
state these authors, that the number of returns for the crows
banded might have been greater were it not for the fact that, in
their winter home, many are killed in bombings under conditions
not conducive to the recovery of the bands.
Crows kept in captivity have lived spans of life exceeding 20
years, but it is doubtful if many individuals in nature ever
approach that age.
Food.--Few ornithological problems
have been of greater widespread controversy than the economic
status of the crow. It is an omnivorous feeder and readily adapts
its food habits to the changing seasons and available food supply.
Its food varies so greatly that isolated observations may be very
misleading unless the food habits are considered from the
standpoint of the entire population through all seasons of the
year. If one is biased it is relatively easy to find abundant
evidence either for or against the crow. It is no great wonder
that this bird has been the subject of heated debate between the
conflicting interests of those who wish to destroy and those who
would protect this species with no thought of control. The
advocates of either side of this question are probably sincere,
but what we need is a common-sense solution of the problem,
combining the interests of both factions. Only the thoughtless
shortsighted person desires to have the crow completely
exterminated, and the overzealous conservationist should submit to
a reasonable control of a species when large numbers prove
destructive to man's best interests.
The resourcefulness of the crow is vividly indicated by the
fact that the Biological Survey identified 650 different items in
the food eaten by 2,118 crows collected in 40 states and several
Canadian provinces. According to Kalmbach (1939), "about 28
percent of the yearly food of the adult crow is animal matter and
consists of insects, spider, millipeds, crustaceans, snails, the
remains of reptiles, amphibians, wild birds and their eggs,
poultry and their eggs, small mammals and carrion. About
two-thirds of the animal food consists of insects, chief among
which are beetles and their larvae and Orthoptera (grasshoppers,
locusts, and crickets), each group constituting more than 7
percent of. the food of the crow, and comprises the essential
beneficial feature of the food habits of the species.
The numbers of insects eaten vary with the season. For example,
few May beetles are eaten early in spring, but by April they
constitute 5 percent of the food and in May, at the peak of
abundance of May beetles, they comprise nearly 21 percent of the
bird's diet. Likewise, the monthly increase in grasshoppers from
May to September is shown in the crow's food, in which these
insects constitute respectively by month 4, 6, 14, 19, and 19
percent of the food taken.
At the time of outbreaks of such insect pests the crow becomes
a valuable agent in their control and herein lies the chief
benefit to the farmer. Examples of isolated cases revealed the
presence of 85 May beetles in one stomach, 72 wireworms in
another, 123 grasshoppers in another, and 438 small caterpillars
in a single crow's stomach collected in Michigan. In central
Illinois I have seen large flocks of crows following the plow,
where they were devouring great numbers of grubs of the
destructive May beetle. It is also a common experience to see them
digging up the grubs in the pasturelands where these pests were
abundant. Alexander (1930) states that in Kansas the early spring
crows eat enormous numbers of grubs and cutworms, which are very
destructive to wheat in that state.
Nestling crows require even greater quantities of insect food
than do the adults. One brood of four examined by the Biological
Survey had eaten 418 grasshoppers and another brood of seven had
eaten 585 of these insects; one individual had taken the record
number of 143 grasshoppers. Of 157 nestlings obtained in Kansas,
151 had been fed grasshoppers. Caterpillars, always a favorite
source of food for nestling birds, were present in more than a
third of the 778 nestling crow stomachs examined.
The insect food of the crow is one of the strongest points in
its favor and should be given proper consideration in judging the
economic status of the species. The crow is an enemy of gypsy and
browntail moths, but it has been observed that new colonies of
moths often form about the nests of crows, indicating that these
birds may serve as an agent in the spread of these pests.
Unfortunately the food of the crow is by no means restricted to
insects, and among the bird's less admirable traits is its
destruction of eggs and young of other species of birds, a habit
that has placed the crow on the black list of many both sportsmen
and bird lovers. However, these depredations, in many instances,
have been greatly and perhaps willfully exaggerated in articles
advocating the destruction of the crow, which have appeared in
many sporting columns of newspapers and magazines. The
examinations by the U. S. Biological Survey reveal that only about
a third of 1 percent of the animal food of the adults and 1.5 per
cent of the food of nestlings is derived from wild birds and their
eggs, and only about one in every 28 crows and one in every 11
nestlings had eaten such food.
The percentage of such food, as would be expected, runs higher
in crows that inhabit the proximity of nesting waterfowl.
Examinations of adult crows collected in such situations in the
prairie provinces of Canada show that they had eaten four times
the quantity of other birds and their eggs, and the young six
times the quantity eaten by crows collected in the United States.
On the basis of frequency of such predation in Canada the adult
crow is ten times and the nestling crow six times as bad as their
fellows in the United States. This pronounced record of bird and
egg destruction in Canada was due primarily to the fact that the
birds collected were taken in close proximity to nesting
waterfowl, almost to the exclusion of any obtained in agricultural
sections.
Observations on the Lower Souris Refuge in North Dakota in 1936
and 1937 showed that the crow is not an outstanding hazard to
waterfowl there. Only 1.7 percent of the 351 nests studied in 1936
were destroyed by crows, while in 1937 the birds preyed upon 3.4
percent of the 566 nests under observation. Even with the latter
rate of loss, the crow on this refuge is at present considered to
be a minor hazard to waterfowl.
Many independent observers have reported the destruction of
eggs and young of both game and song birds, and there is no doubt
that the crow at times is guilty of serious depredations. Baker
(1940) reports the destruction of a colony of 1,500 little
blue herons and 3,000 snowy egrets nesting in an island of timber
known as "Live Oaks" on the coastal prairie, 9 miles
south of Waller, Tex., by about 40 crows that inhabited the
section. On Great Duck Island, off the coast of Maine, where I
studied a colony of black-crowned night herons for an entire
season, the crows destroyed 27 of the 125 nests under observation.
During the season of 1940 crows proved to be a serious menace to
the eider ducks nesting on Kent Island, Bay of Fundy, where
Bowdoin College has established a bird sanctuary and scientific
station. On this island the crows had the habit of carrying their
booty to certain convenient places to be devoured. At one such
rendezvous I counted 37 eider-duck eggs and 24 herring-gull eggs
and in another 22 eider-duck eggs and 28 of the gull eggs. Crows
have been reported as carrying an entire egg in their beaks, but
at Kent Island the egg was usually punctured by a thrust of the
beak. On several occasions we observed them carrying off the downy
nestlings. In August I found a place where there were more than a
dozen juvenal gulls that had been killed and partially eaten,
presumably by the crows. Certainly in sanctuaries such as
"Live Oaks" and Kent Island, where a special effort is
being made to preserve certain species of birds, the control of
the crows is necessary, as it is when they become too abundant in
the vicinity of nesting fowl, such as in the Prairie Provinces of
Canada.
Depredations on poultry have been reported. For example,
Mousley (1924) states that he saw 16 young chickens carried away
by crows. Numerous reports have been published citing instances
where crows have killed and eaten various species of small birds,
and even birds as large as the partridge have been killed and
eaten.
Such depredations, though they may call for certain measures of
control, in no way warrant the total destruction of a species that
has been shown to be beneficial to man's interests at other times.
In the case of poultry means of protection can be readily
improvised.
Of interest but of lesser economic importance is the
consumption of small mammals, crustaceans, mollusks, amphibians,
snakes, and carrion. Eifrig (1905) found the crop of a crow filled
with earthworms. Along the seacoast, especially during the winter
months, mollusks constitute a most important element of the food.
It is a common practice of the crow to carry clams, scallops,
mussels, or sea-urchins to a considerable height to let them fall
on the rocks to be broken and thus enable them to secure the
edible contents, a habit shared by other birds, notably the
herring gull.
Along the New England coast, especially in Maine, I have seen
groups of crows on the mud flats at low tide, where they were
feeding on the myriads of invertebrates that abound there. I have
also seen them feeding on dead fish left behind by the tide, and
at one time seven crows were taking their turns at the carcass of
a dead seal. It is not unusual to see them thrusting their beaks
into the mud to secure what seemed to be a Nereis, a marine
annelid worm, much after the fashion that robins retrieve
earthworms from our lawns. F. H. Kennard on July 15, 1923, saw a
young crow foraging on his lawn for earthworms. For over an hour
he and others observed the crow pulling up the worms. After they
were pulled out the crow would stand on the worm and cleanse it
with its bill before swallowing it. Brewster (1883) relates an
experience of crows eating 20 good-sized trout that had been
hidden in a spring. The farmers along the Maine coast complain
that crows as well as gulls are a nuisance in removing fish placed
on their fields as fertilizer. Ball (1938) reports similar damage
in the Gaspe' region, and other complaints have come from New
Brunswick and Nova Scotia.
When hard pressed crows may resort to all manner of means to
obtain food. For example, Isel (1912) has seen crows enter the
business district of Wichita, Kans., to feed from garbage pails
back of restaurants; Crook (1936) has observed crows feeding on
car-killed animals, including dogs, cats, chickens, opossums,
pigs, and even skunks; Guthrie (1932) states that crows prize a
dead snake as much as a living one; Anderson (1907) reports that
in Iowa crows frequent the slaughterhouses to feed upon the waste
of slaughtered animals; Scott (1884) observed crows feeding on a
carcass of a dog while the temperature registered 14o
below zero. These cases serve to emphasize the role played by
crows as scavengers. They also attest the omnivorous feeding of
crows and their extreme resourcefulness in securing a livelihood
under adverse conditions. Such adaptability insures the success of
any species in spite of persecution.
According to Kalmbach (1920) vegetable matter forms nearly 72
percent of the adult crow's yearly food, and over half of it
consists of corn. Of 1,340 adult crows collected in every month of
the year, 824 (over 61 percent) had fed on corn. During April and
May, when the corn is sprouting, corn constitutes about a third of
the food, and at the harvest in October it supplies over half of
the crow's diet. The damage by the crow is chiefly to sprouting
corn, corn "in the milk," or when the ripened grain has
been stacked in shocks. Of the three, the second seems to be the
most serious. It is not so much the corn the crow actually eats at
this time but the subsequent injury resulting from water entering
the ears from which the husks have been partially torn that makes
the loss so important.
In 1938 the United States Biological Survey made a special
investigation of the crow damage to grain, sorghums, and Indian
corn growing on 210 farms comprising 39,797 acres in Grady County,
Okla. The results reveal that Oklahoma has a winter crow
population of between three and four million. The damage to grain
sorghums was appraised at 3.8 percent and to Indian corn 1.7
percent. The loss of these crops in Grady County alone for the
year was estimated to be $18,370.
On the basis of this investigation the Biological Survey
concluded that in southwestern Oklahoma there may be need of
measures of control. This situation is now being met by the
systematic bombing of the roosts. The case of the crow in Oklahoma
is qualified by the statement that in some of the wheat-raising
sections of Oklahoma the wintering crows are a benefit.
It was concluded that the crow problem, though serious to
sorghums and corn in some counties, is not of sufficient magnitude
in the State as a whole to demand combined State and Federal
action for its solution. Kalmbach (1920) writes that in the
Northwest States, where corn is not raised extensively, wheat
replaces corn in the crow's diet. The damage is especially severe
at the time wheat is sown or is sprouting. Oats and buckwheat are
also occasionally eaten, but the larger part of these grains
represents a waste product.
"Apples and almonds are less frequently injured; while the
aggregate losses to beans, peas, figs, oranges, grapes and
cherries are not important. Fruits of the various sumachs,
poison-ivy and poison-oak, bayberry, dogwood, sour gum, wild
cherries, grapes, Virginia creeper and pokeberry" are also
common ingredients of the food. "The mere consumption of wild
fruit by the crow involves nothing of economic importance,"
but the "digestive processes destroy practically none of the
embryos of the seeds, and crows act as important distributors of
certain plants, some of which, as poison-ivy and poison-oak, are
particularly noxious.
The indigestible parts of the crow's food, such as bones,
teeth, fur, and hard seeds, are regurgitated in the form of
pellets as is customary with such birds as hawks and owls. An
examination of these pellets gathered at crow roosts reveal
interesting elements of the food eaten by any such crow
population. Townsend (1918) collected several hundred pellets from
a crow roost located in Essex County, Mass. These pellets amounted
in bulk to 662 cubic centimeters of material after they were
broken up into their composite parts. The examination of this
material by E. R. Kalmbach, of the Biological Survey, revealed 13
kinds of insects and 7 other invertebrates including Melampus,
Nereis, Mytilus, and Littorina. Among the vertebrates
there were fish, bones and scales of a snake, shells of hen's
eggs, four meadow mice, a star-nosed mole, two short-tailed
shrews, and large fragments of bone. There were seeds and parts of
no less than 20 plants, of which the following are of special
interest: 10,000 seeds of bayberry, 2,300 seeds of poison-ivy and
species of sumac, 360 seeds of cranberry, and varying numbers of
seeds of juniper, smilax, winterberry, grape, and nightshade.
There were also very small quantities of wheat, barley, corn,
buckwheat, and seeds of pumpkin or squash, apple, and pear. These
results again emphasize the omnivorous feeding habits of the crow
as well as its resourcefulness during adverse winter conditions.
It is important to know not only what the crow eats but also
how much it eats to enable us to form a complete picture of the
economic status of the species. Forbush (1907) made careful
records of the food eaten by captive crows, which throw
considerable light on this problem. He found that two well-grown
crows fed 20 to 25 ounces of food a day just maintained their own
weight, but less than that amount was not sufficient. When the
quantity of food given the birds was largely reduced there was a
corresponding reduction in their weight. He concluded that young
crows, when fledged absolutely require a daily quantity of food
equal to about half their own weight and will consume much more
than this to their advantage if they can get it. When this amount
is multiplied by the number of crows in an entire population the
results are impressive. Experiments on the time required for
assimilation of food revealed that from the time of eating to that
when the undigested parts of the food were emitted average 1 1/2
hours. It is not only what they eat at a single time, but it must
be remembered that the average crow gorges no less than eight to
ten full meals a day. Hicks and Dambach (1935) found that the
average weight of the filled stomachs of 75 adult crows was 36.6
grams and that their food contents averaged 11 grams.
The following interesting experience submitted in
correspondence by R. Bruce Horsfall reveals how we may unwittingly
condemn the crow when the facts are not clearly understood. Mr.
Horsfall bought a farm near Redbank, N. J., where he planted five
acres in corn and ten acres in asparagus. He noted that the lower
end of his field, where the crows were present each day during the
early morning hours, yielded no harvest. Mr. Horsfall immediately
jumped to the conclusion from published accounts of crow
depredations on farm crops that these birds were responsible for
his loss. Without further investigation the crows were shot and
the bodies left there as a warning to others. After a number of
crows were killed an examination of the stomach contents revealed
a mass of greenish liquid filled with cutworm heads, black
beetles, and other undigested materials. On the following day a
visit was made to the fields in the early morning hours at about
the time the crows were accustomed to be present. Great numbers of
cutworms were found before they dug into shelter for the day. Mr.
Horsfall thereupon decided to welcome his much-maligned friends
and he had reason to regret his past hasty judgment. He placed
ears of corn on the ground and left the fields to the crows. They
recognized the change of attitude, returned in numbers, cleared
the field of cutworms, and rewarded the owner by giving him a full
yield. Since this experience Mr. Horsfall has been a staunch
friend of the crow.
Forbush (1927) relates a similar experience of Gardner Hammond,
of Marthas Vineyard, Mass. "Mr. Hammond owned great pastures
where many sheep grazed. He told me once that he had offered a
bounty of fifty cents each for Crows, as the birds had already
killed about 200 of his newly born lambs, and that the native
hunters under the stimulus of this bounty had killed nearly all
the crows about the Squibnocket region. Notwithstanding my
objection he continued to offer the bounty, although he expressed
some fear that the expense would leave him bankrupt. About three
years later he hailed me one day to see if I could determine what
had destroyed the grass in his pastures. The grass was dead,
having been cut at the roots by white grubs which had increased so
rapidly after the destruction of the crows that they had already
ruined a large part of the pastures. The offer of a bounty was
withdrawn and the pastures gradually recovered."
Charles P. Shoffner, associate editor of the Farm Journal
of Philadelphia, sent a questionnaire regarding the economic
status of the crow to the readers of the journal who are scattered
all over the agricultural districts of the United States. The
results of this questionnaire are interesting, since they present
a cross section of public opinion of a group of citizens most
vitally concerned in the problem. Some of the replies were copied
directly from the reports of the Department of Agriculture or
other sources, but 9,731 were selected as being apparently based
on personal observation or opinion. Among these 1,801 were in
favor of the crow and 7,829 against him. Of the latter, 7,573
replies charged damage to crops, 6,937 to poultry, 4,112 to young
pigs, sheep, rabbits, etc., 6,796 to song birds, and 6,493 to game
birds. As Mr. Shoffner truly says, due weight must be given to the
fact that reports were solicited by mail and it would be natural
for farmers who had suffered serious damage to write their
disapproval, while those who had suffered little or no loss would
not trouble to do so. The interesting point is that so many
persons defended the crow.
The conclusions of the Journal were:
1. The Crow wherever found in large numbers is injurious to
farmers from March to December.
2. Where Crows are numerous they should be reduced in
numbers and this should be done under active cooperation of State
or National Agricultural Authorities. The Crow need not be
exterminated.
3. The good Crows do by eating insects does not compensate
for the damage done by eating eggs and young of other birds.
4. In acting as scavengers, Crows carry disease; farmers
should bury or burn at once all dead animals.
There is a great difference in local conditions. In the West
crows are a serious menace, while in parts of the East they are
neutral or actually beneficial. Of the conclusions arrived at by
the Farm Journal, those who have studied the economic
relations of the crow will take exception to conclusion No. 3.
(For further comment on this questionnaire, see The Auk,
vol. 43, pp. 140-141, 1926.)
Behavior.--The crows return to
their roosting place early in the afternoon. The flight then is
high and quite direct. Various estimates have been made of their
speed in flight. Crows have been known to keep up with trains
running at the rate of 60 miles an hour, but the speed determined
by Townsend and others indicates that under ordinary conditions it
seldom exceeds 20 to 30 miles an hour. If this rate is correct
then a crow during sustained flight of a 10-hour day would cover
only about 250 miles. Ducks, according to Lincoln (1939), travel
400 to 500 miles in the same period.
Townsend (1905) in writing of his experiences with crows in
winter at Ipswich, Mass., records some interesting incidents as
follows: "Hearing a great outcry among a party of Crows one
day at Ipswich, I saw several swooping down to within a few feet
of a fox. Reynard seemed not a whit disturbed, and carried his
brush straight out behind as he sauntered along. . . . I have
heard them make a virtuous outcry over a couple of innocent hares
that were running through the dunes.
"Tracks show that it is a common habit for Crows to drag
their middle toe in walking and sometimes all three front toes are
dragged. Again, tracks of the same or other Crows show that the
toes are lifted up without any dragging. I have seen Crows hop,
and have found evidence of that in the sand. In landing from the
air, their tracks show it is often their habit, to bound or hop
forward once with feet together, before beginning to walk."
Some observers have stated that the crow in flight carries its
feet extended backward, but F. H. Kennard, in some unpublished
notes, records an observation made under favorable conditions. He
was very near a crow that was silhouetted against the snow as it
took flight. It raised its legs, after dangling them straight,
directly up under and flew off with the closed claws showing as
two lumps barely projecting from the feathers of the lower breast.
The feet of the crow are not well adapted for grasping, and
their appearance would not at all suggest that they are
prehensile, yet these birds do at times carry fairly large objects
by means of their feet. At Kent Island I saw a startled crow grasp
an eider duckling in its claws and transport it to cover in a
thick growth of spruces. Chamberlain (1884) observed crows
carrying two young of a brood of robins in their claws, and
Kneeland (1883) has seen crows carrying fish heads and other
objects too large and too heavy to be conveniently carried in the
bill yet too precious to be left behind when food is scarce, as it
often is during the winter. Chamberlain also saw a pet crow seize
a partially eaten ear of boiled corn in its claws and fly away
with it when accosted by a barking dog. Fred J. Pierce (1923), in
an article entitled "A Crow that Nearly Looped the
Loop," presents the following interesting observation:
"I noticed a Crow flying overhead carrying an article in his
feet that looked like a mouse or something of that sort. This Crow
wanted to transfer the morsel to his bill, and in trying to do so
bent his head underneath him so far that he lost his balance and
barely escaped overturning in the air. This must have surprised
him considerably, but he was a determined Crow and shortly tried
it again with no better success. He was continuing his vain
efforts when lost to view, but as his unsteady flight had brought
him very near the ground, he doubtless alighted, where his object
was accomplished with much less danger to his equilibration."
The adult crow is very wary and suspicious of man, an
instinctive behavior for self-preservation that has been acquired
through generations of experience. Yet crows taken from the nest
at the proper time have become pets that have exhibited the
greatest confidence in their companionship with human beings.
There are innumerable instances on record in which crows have
proved to be interesting and entertaining pets.
Lorenz (1937) has pointed out that a young bird, when reared
under artificial conditions, will invariably react to its human
keeper in exactly the same way that it would have reacted, under
natural conditions, to birds of its own species. He has also
stated that the period of acquiring this imprinting is confined,
in some species, to a very definite and often astonishingly brief
period, and that certain actions of the bird for the remainder of
its life depend on the imprinting during this crucial period.
Cruickshank (1939) in testing out the statements of Lorenz,
contrasts the behavior of two crows that he kept as pets. The
first was taken from the nest when it was only two weeks old. It
was raised in his home with great attention and soon reacted to
him and his wife as it would have to its own parents if left in
the wild. The crow followed them about, fluttering its wings and
excitably begging for food. After it had learned to fly it paid no
attention to local wild crows or to other human beings about the
camp, but would single out Mr. Cruickshank or his wife and follow
them everywhere. The food-begging act was performed for them only.
The appearance of either of them or the sound of their voices was
sufficient to start its begging. In various other ways this pet
crow showed that it had thoroughly accepted its human foster
parents and rejected all others. The other crow, obtained a few
years before, had been taken on the day it left the nest. Though
kept in isolation for the ensuing two weeks this crow never
accepted Mr. Cruickshank in any way. His appearance never released
the begging act, and the bird was always interested in the calls
of nearby crows. At the first opportunity it flew off into the
woods and never returned. This individual evidently had been
obtained at too late a period. The imprinting had already taken
place, and even close attention and strict isolation did not
initiate a reverse.
The above experience readily explains the varying success
persons have had in attempting to make pets of crows. Many have
written about their pet crows, but one of the most detailed
accounts is presented by Norman Criddle (1927), who had four crows
that he obtained near Treesbank, Manitoba, on June 19, 1926. These
birds exhibited considerable fear when first obtained, and it was
necessary to feed them by force, but after a day they strongly
exhibited the begging reactions. They greeted his approach by
enthusiastic cries for food and their fear of man had vanished.
Later, when able to fly, they were allowed to roost among the
trees, but in the morning they collected around the feeding cage
and his approach was always greeted with enthusiasm. They would
alight on his head and shoulders as readily as on any other perch.
During the day the crows devoted much of their time collecting and
hiding objects of various kinds. As they grew older, berries and
other food were hidden with the definite object of using it later
when hungry. One of the crows would alight on its foster parent's
shoulder, pull out the pocket handkerchief, deposit a throatful of
berries, and then carefully shove the hankerchief back into place
on top of them. The love of destructiveness became a dominant
trait. Newspapers and brightly colored flowers in the garden were
pulled to small bits, and other objects were similarly treated.
When a pan of water was provided they soon took to bathing,
although they had never experienced water before. Bathing and
playing in the water became a regular pastime. Sometimes, after
flying to Mr. Griddle's shoulder, they would playfully pinch his
ear or run their beaks through his hair. One of them repeatedly
tried to dislodge the button from his cap. Each of the crows was
different in its personality and details of behavior. Mr. Criddle
presents a multitude of experiences indicating that these crows
performed just as they might have done toward their own kind if
left in nature.
Pet crows are known to possess unusual ability to articulate
the words and imitate the sounds of the human voice. They readily
master such simple words as "mama," "papa,"
"hello," "howdydo," and others, and human
laughter is often imitated to perfection. This presents the
question as to how the crow is able to articulate and imitate so
well. We should not expect to find the tracheal syrinx and its
controlling muscles to be well developed in a bird that is not
recognized for its ability to sing. To the contrary, the crow has
a complete set of voice muscles. It is these muscles that give
parrots and certain passerine birds such a variety of vocal
modulations, so that they can mimic other birds or even the human
voice. Hence it is not at all surprising that crows exhibit this
unusual ability of imitation.
Pet crows are known to be very adept at learning and to meet
new and previously inexperienced conditions. Coburn (1914) has
proved this ability experimentally. He found that crows learn very
quickly to distinguish the correct exit door when placed in a dark
box from which there were translucent and lighted exits, each of
the same area and light intensity but of different shapes. In this
way it was shown that they distinguished with very little practice
between a circle, a triangle, a square, and a hexagon. In this and
other tests the experimenter was convinced that the crow's
reputation for brains is quite deserved, and that Henry Ward
Beecher was correct when he said that if men could be feathered
and provided with wings, very few would be clever enough to be
crows!
Voice.--The crow does not excel in
its musical ability, but it has a great versatility in its voice.
It has an interesting repertoire of many calls and notes, which
serves it well in its interrelations with its fellows. It also has
superior imitative faculties, and captive crows have exhibited
unusual aptitude in learning new calls. Even human laughter is
imitated, at times so appropriately uttered that it is difficult
to think of it as mere coincidence.
The calls and notes have been subject to diverse
interpretations; hence several representative authors have been
quoted to present a better-rounded concept of them. Hoffmann
(1904) states: "Besides the ordinary caw, and the many
modifications of which it is capable, the crow utters commonly two
other striking notes. One is a high-pitched laugh, ha-a-a-a-a-a;
the other a more guttural sound like the gobble of a turkey, cow
cow cow." Knight (1908) interprets the various calls of
the crow as portraying signals that have a distinct meaning to
their fellows:
When a band of crows is feeding one or two are generally
posted as sentinels and a 'caw c-a-a-w' of warning from these is
sufficient to make all seek safety. Their call 'caw-caw' is
uttered in varied tones and different accents so that it is
capable of meaning a great many things from alarm to satisfaction,
and one acquainted with their ways can usually tell just what they
are saying in a general way. For instance I have never failed to
correctly judge from their excited and confused cries that they
had an owl penned up somewhere and were engaged in 'mobbing' it to
their satisfaction. The alarm 'caw' uttered sharply and quickly,
which means 'look out' is well known to about everybody who has
ever seen a Crow. Their prolonged cries of distress when their
home is menaced should be easily recognizable. The prolonged
'car-r----------a----------c-------k' of a love sick individual in
spring, uttered in various tones and drawn out into prolonged
gurglings, though somewhat like the call of the young for food is
still quite different.
Forbush (1927) writes:
Some Crows, if not all, are capable of producing unusual,
tuneful or pleasing sounds. As an example of the unusual let me
refer to an individual that I heard early one morning on Cape Cod
repeating for over an hour syllables like 'clockity-clock,
clockity-clock'; while as showing the musical attainments of the
species mention may be made of a Crow that I saw on the banks of
the Musketaquid, August 10, 1906, which uttered a series of
exceedingly melodious, soft, cooing notes unlike any others within
my experience. In the same locality on July 14 a young Crow
remarked very plainly 'aaoou, cou, cou, cou, aaaou, coucoo.' On
October 20, 1903, I heard and saw a Crow give an excellent
imitation of a whine of a dog. . . . I have heard from Crows a
varied assortment of notes, some of which apparently were
imitations, such as the cry of a child, the squawk of a hen, or
the crow of a young rooster. The cooing notes mentioned above were
similar to sounds uttered by the male in courtship. At this
season, also, the male has a peculiar cry which may be an attempt
at song and has been represented by the syllables 'hollow-ollo-ollo.'
Townsend (1923) gives the following account of the calls of the
crow:
There are many other words in the Crow vocabulary than the
simple 'caw,' and I find a number of them recorded in my notes.
Many are common and familiar sounds of the countryside, and their
recognition is always a pleasure. First, one may consider the
modifications of the 'caw.' Of these, 'orr, orr,' are common, as
well as 'ah, ah,' the latter delivered at times as with a great
feeling of relief. Again, the note may sound like 'gnaw, gnaw,'
delivered with a nasal inflection and in a taunting manner.
On the other hand the notes may lose all semblance of the
typical 'caws,' and rapidly repeated and wailing 'kaa, wha, wha,
wha, kaa, wha, wha, wha,' may be heard, or, as I have written at
other times, 'ou, ahh, ahh, ahh.' Again, a loud and cheerful 'ha,
ha, ha,' may be heard, suggestive of one of the calls of the
Herring Gull. A despairing, 'nevah, nevah,' is not uncommon.
Occasionally one may hear a loud 'cluck.' One of the most
extraordinary combinations of Crow notes that I have ever heard
was emitted near my house at Ipswich early one April morning. The
bird called 'chuck-chuck, whoo-oo,' and then 'cawed' in the
ordinary manner, repeating the formula in this order several
times. Its significance was hidden.
The conversational notes of a small group or family of Crows
are always entertaining, and the observer is impressed with the
extensiveness of their vocabulary and with the variations in their
feelings. At times the notes are low and confidential, pleasant
and almost melodious, if I may use that word here; again they are
raucous and scolding, bursting at times into a veritable torrent
of abuse. In the same way, in human conversations, one may, even
without understanding the words, be able to interpret the meanings
and motives involved. [See under Courtship for
additional notes.]
Allen (1919) has called our attention to the time rhythm, which
he attributes to a well-developed esthetic sense of the crow. He
has noted that the caw notes are not only in triplets but
at times they give four caws in groups of two (2-2); again
he noted that the bird cawed 2-1 a large number of times in
succession and on other occasions 2-1-1. The time was so regular
that he could detect no variations. The length of the several
notes and their pitch and quality were uniform, the rhythm being
all that differentiated the phrase from other performances of the
crow.
Allen does not believe the series of combination of calls
represents a code of signals, nor does he believe them to be
purely mechanical and involuntary, but he thinks the crow takes
delight in the rhythm and variety of his utterances. He asks the
question, "Is he not, in a limited way, a true artist, a
composer as well as a performer ?"
Wright (1912), in a study conducted at Jefferson Highlands in
the White Mountains, N. H., determined the order and manner in
which summer resident birds within range of hearing awoke and
voiced themselves. According to Wright the crow is a comparatively
late riser, as it ranks twenty-fourth among the common birds in
time of voicing itself. Fourteen records show that the earliest
times at which a crow was heard to call were 3:35 and 3:36 a.m.
The average time of the first call was 3:44 a.m. The variations of
the crow's awakening was only 21 minutes on 14 occasions, ranging
in date from May 27 to July 9, and covering ten seasons. Wright
concluded that the crow was one of the most regular in awakening
of the common birds he observed.
Enemies.--The crow is recognized
as an enemy of certain species of birds, especially in the
destruction of their eggs and young, but it is itself in turn
preyed upon by hawks and owls. Horned and snowy owls have been
seen to capture and kill crows, and the remains have been found in
the stomach contents of others. Likewise remains of crows have
been found in the stomach contents of red-shouldered and
red-tailed hawks and goshawks, and probably the crow falls a
victim to other species of the larger hawks. Even the smaller
species of hawks may sometimes exhibit a daring inclination to
tackle a crow. White (1893) relates an experience in which the
small sharp-shinned hawk was seen to attack successfully a crow on
Mackinac Island, Mich. Sutton (1929) found the crop of a Cooper's
hawk, killed near Shippensburg, Pa., packed with feathers and
flesh of a crow. According to the observer a second Cooper's hawk
was seen to fly up from the spot where the first was killed, and
nearby among the weeds was a partly eaten and fairly well plucked
crow, the flesh of which was still warm. Dr. Sutton, although
admitting he is unable to prove the case, believes that one or
both of the hawks killed the crow.
It is well known that even smaller birds, notably the kingbird,
may harass a crow and make its existence very uncomfortable.
Currier (1904) in an account of crows observed at Leech Lake,
Minn., writes: "One pair in particular had our sympathy. They
had a nest full of young in a scrub oak standing alone out on the
marsh, where several pairs of Kingbirds, and thousands of Redwings
were breeding. Every time a Crow made a move it was pounced upon
by from two to a dozen of the smaller birds and forced to light
for a time. The Yellow-heads would also join in at times, but they
were not so persistent. The Redwings seemed to be the worst."
I have seen crows that have chanced to enter seabird colonies
viciously and violently attacked by terns.
That crows are never on good terms with predaceous birds,
especially owls, is evidenced by the great commotion aroused among
the crows whenever an owl is discovered. Fortified by numbers,
they exhibit great audacity and may harass an owl for hours at a
time. In fact, the presence of an owl may frequently be revealed
by the cawing and behavior of the crows at such times.
Their antipathy for owls is so great that they may be lured by a
stuffed owl placed by a gunner who wishes to destroy them. For the
past 15 years I have had several live horned owls in a large
flight cage in the backyard of my home in Brunswick, Maine. Almost
every morning during the spring migration, flocks of crows ranging
from a dozen to 25 or 30 alight in the surrounding trees and
awaken the entire neighborhood by their haranguing calls. The
crows alight on top of the cage but the least movement on the part
of the owls sends them scampering to the tree tops under loud
protests. Seeking renewed courage the crows descend again and
again to repeat the performance. This goes on in spite of the fact
that it is in the midst of a thickly settled portion of the town.
Crows, as well as other birds, fall as victims of flesh-eating
mammals. Errington (1935) in his study of the food of midwest
foxes, reports that crows are eaten by them.
Wilson (1923) reports a case in which a crow was attacked by a
large snake, but such instances are probably rare.
Among mammals, the crow's greatest enemy is man. Since the
economic status has been questioned thousands of crows have been
killed by poisoning, shooting, and especially by bombing the
populous roosts. A few are killed on the highways by automobiles.
No comprehensive study of the diseases of the crow has been
made to my knowledge, but as has been shown in the case of other
species of birds, disease is probably an important factor in the
life of the species.
Mitchell (1929) reported an epidemic of tuberculosis in crows
of western Ontario, where he conducted experiments to see if
infection is likely to be carried to other animals. Eaton (1903)
has given us a detailed report of an epidemic of roup in the
Canandaigua crow roost in Ontario County, N. Y., during the winter
of 1901-2. Eaton estimates that at least a thousand crows
succumbed to the disease in that region alone. Dr. Fox (1923) in a
pathological examination of 16 crows, found cases of tropidocerca,
occasional intestinal cestodes, and a few filaria.
Dr. E. B. Cram (1927) lists five internal nematode parasites
found in the crow. Three of these are found in the proventriculus,
the glandular part of the stomach, and the other two in the
trachea, or lungs. The parasites are as follows: Acuaria
cordata (Mueller), found in the wall of the proventriculus;
the males range from 10 to 11 and the females 22.5 to 40
millimeters in length. Microtetrameres helix Cram, found in
the walls of the proventriculus; the males of this small worm are
4.9 and the females 1.2 to 1.3 millimeters in length. Tetrameres
imispina (Diesing), known only from the female, which is 3
millimeters in length; this parasite is found also in the
proventriculus. Syngamus trachea (Montague), occurring as
adults in the trachea and bronchi and as larvae in the lungs;
immature worms have been found in the peritracheal tissue and air
sacs; the males are 2 to 6 and the females 5 to 20 millimeters in
length. Syngamus gracilis Chapin, found only in the
trachea; the males are 3 to 3.3 and the females 8 to 11
millimeters long.
Harold Peters (1936) lists three lice and one tick as common
external parasites of the crow. The lice are Degeeriella
rotundata (Osborn), Myrsidea americana (Kellogg), and Philopterus
corvi (Osborn) and the tick is Haemaphysalis
leporis-palustris Packard. A different species of tick and two
species of mites have been found on the southern crow. The tick is
Amblyomma americanum (Linnaeus), found in a crow from South
Carolina, and the mites are Liponyssus sylviarum (Canestrini
and Fanzago) and Trouessartia corvina (Koch), found on
crows collected in South Carolina and Florida, respectively.
But by far the worst enemy of the crow is man. Where crows are
numerous, especially in their winter roosts, enormous numbers are
killed by bombing with dynamite. As one example of this, Dr.
Walter P. Taylor tells us that in Collingsworth County, Tex., on
April 7, 1937, bombs were exposed in a shinnery clump to kill
crows. There was one stick of dynamite to each bomb, and the bombs
were connected with wires, so that they could be fired
simultaneously. Sixty bombs were set off at the first discharge,
at which it was estimated that 40,000 crows were killed; at the
second shot, 120 bombs were set off, killing nearly as many more.
Other bombing operations are mentioned under "Roosts."
Roosts.--During the summer crows
associate only in pairs at their isolated breeding places, but in
fall they exhibit a marked gregarious inclination, and birds from
many miles of territory congregate in immense roosts comprising
thousands, sometimes tens and even hundreds of thousands, of
individuals. These roosts are not only made up of the birds
breeding in the region but the flocks are augmented by birds that
have migrated from nesting grounds located farther to the north.
In New England there is a marked tendency for the crows to move
from inland areas to roosts established near the coast. Food is
the primary factor involved in this shift; whereas the feeding
grounds in the interior become covered with snow and ice, the
seacoast provides an uninterrupted food supply that is replenished
with every flow of the tide. Even the severe winter weather does
not drive the hardy members from the roosts established in the
dense coniferous forests that fringe the coast. Most of the roosts
in northern New England are comparatively small, however, and one
must go farther to the southward before meeting with aggregations
of unusual size.
Townsend (1918) has presented a vivid account of a crow roost
that contained approximately 12,000 individuals, located in the
thickets and hardwoods on Castle Hill near Ipswich Beach, Mass.
Following are extracts from Dr. Townsend's paper, which portray in
detail scenes similar to those many others have experienced.
In the short winter afternoons the Crows begin their flight
to the roost long before sunset. By three o'clock or even as early
as one o'clock, especially in dark weather and in the short
December days, this bed-time journey begins, while in the latter
part of February the flight is postponed until half past four or a
quarter of five. From every direction but the seaward side the
Crows direct their course towards the roost. Three main streams of
flight can be distinguished: one from the north, from the region
of the Ipswich and Rowley "hundreds,"--the great
stretches of salt marshes that extend to the Merrimac River,--a
second from the west and a third,--apparently the largest of all,
broad and deep and highly concentrated,--from the south.
It was the last of these rivers that on a cold December
afternoon with a biting wind from the northwest I first studied. .
. . It was an impressive sight. About 3 o'clock the Crows began to
appear, singly and in small groups, beating their way in the teeth
of the wind towards the north. In flying over the estuary of the
Castle Neck River they kept close to the water as if to take
advantage of the lee behind the waves; over the land they clung to
the contour of the dunes. As we walked among these waves of sand
the Crows often appeared suddenly and unexpectedly over the crest
of a dune within a few feet of us. Silently for the most part,
except for the silken rustle of their wings, they flew over in
increasing numbers until it was evident that they were to be
counted, not by hundreds, but by thousands. Many of them alighted
on the dunes to the south of the roosting place; sand, bushes and
stunted bare trees were alike black with them. Others assembled on
the bare hillside to the east. About sunset a great tumult of
corvine voices issued from the multitude,--a loud cawing with
occasional wailing notes,--and a black cloud rose into the air and
settled in the branches of the bare trees to the west of the
roost. From here as it was growing dusk they glided into the
evergreens for the night.
The last day of the year 1916, I spent with Dr. W. M. Tyler
in the dunes. The wind was fresh from the northwest,--the
temperature was 15 o Far. at 6 :30 a.m., 18 o
at noon and 20 o at 6 p.m. As early as one
o'clock in the afternoon a few Crows were seen struggling north
over and close to the surface of the dunes. Others were noticed
flying high and towards the south. This southerly flight came from
over Castle Hill to the north, passed the roost and continued on
over the dunes. At half-past three some of these birds, which were
apparently turning their backs on their usual night's lodging
place, met with a large company coming from the south and all
settled together in the dunes about two miles south of the roost.
Some of the birds coming from the north, however, settled in the
bare fields by the roost, and their numbers here were augmented by
a stream from the west. This concourse on the hillside set up a
great tumult of cawings just before four o'clock. At five minutes
after four the united multitude of northerners and southerners
rose from their meeting place in the dunes and flew low to join
their noisy brethren on the hillside. This river of black wings
from the south was a continuous one and it was joined just before
its debouch on the hillside by the stream from the west. The river
from the north had split into two layers: the lower flying
birds came to rest on the hill,--the higher flying ones favored by
the strong northwest wind, continued on their way south,
notwithstanding the great current that was sweeping north below
them. They joined their comrades in the dunes and retraced their
steps. No signs of starvation and impaired vigor in these
unnecessary flights, or in the game of tag in which two or more of
the birds at times indulge!
The pace is now fast and furious. The birds are anxious to
get within touch of the roost before it is dark but none have yet
entered it. At 4:15 p.m., 135 birds pass in a minute from the
south alone on their way to join the concourse on the hillside. A
little later this southern river becomes so choked with birds that
it is impossible to count them. From our point of vantage in a
spruce thicket on the hill we can see that this flock stretches
for two miles into the dunes and it takes them four minutes to
pass. The speed of flight, therefore, must be roughly about thirty
miles an hour. At 4:15 p.m. the sun sets, but in the yellow glow
of the cloudless sky the birds can be seen pouring by from the
west and south. The bulk of the stream from the north now comes to
rest on the hillside for only occasionally can a crow be seen
flying to the south over the heads of the southern stream.
At 4:35 p.m. Dr. Tyler and I again counted the southern
stream for a minute as they flew silently between us and the
lighthouse. One of us counted 160 the other 157 birds, so it is
probable that our counts are fairly accurate. This constant
watching of the black stream from the south against the white
lighthouse produced in both of us a peculiar optical illusion. The
lighthouse and dunes seemed to be moving smoothly and swiftly from
north to south!
At 4:37 p.m. a great cawing arose from the hillside and a
black cloud of birds rose up, some to enter the roost, others to
subside on the hillside. It was evident that the birds from time
to time had been diving into the roost. At 4 :40 p.m. it was
rapidly growing dark and the tributary streams were evidently
dwindling. Only 50 went by the lighthouse in a minute. Five
minutes later it was nearly dark and only a few belated stragglers
were hurrying to the concourse on the hill.
At 4:45 p.m. Dr. Tyler and I walked around to the north of
the roost and although we could see nothing in the darkness we
could hear the silken rustle of wings and feathers as the Crows
were composing themselves for the night's rest among the branches
of the trees. The babble of low conversational notes that went up
from the company suggested the sounds of a Night Heronry although
'cawings' and 'carrings' were interspersed with the 'kis' and 'uks'
and 'ahhs.' . . .
In the dim light we could make out that the hillside field
between the roost and the sea was still blackened with birds that
were continually rising up and entering the trees. Some of them
perched temporarily on the bare tops of the hard woods where they
were visible against the sky. The noise and confusion were great.
It would seem as if the roost was so crowded that the birds had to
wait their time for a chance to get in and that a constant
shifting of places and crowding was necessary before the Crows
could settle in peace for the night. Hence the prolonged varied
conversation; hence the profanity.
It was an intensely interesting experience, this observation
of the return of the Crows to their night's lodgings, and one
wished for eyes all about the head, well sharpened wits to
interpret and a trained assistant to take down notes. . . .
At the full of the moon on the sixth of January I visited
the roost at 9 p.m., a time when all well regulated Crows should,
I had supposed, be sound asleep. As I approached the roost much to
my surprise I heard distinct sleepy cries like those of young
herons, and when I reached the edge of the roasting trees there
was a tumultuous rush and bustle of Crows flying from tree to tree
and overhead. Strain my eyes as I would only occasionally could I
catch sight of a black form, although the air was brilliant with
the moonlight and the reflection from the snow. I turned back at
once as I had no desire to disturb the birds' slumbers but it was
evident that many, even at this late hour, had not settled down
for the night.
The morning flight from the roost takes less time than the
evening return. As I approached it in the semi-darkness at 6:25
a.m. on January 7, a distant cawing could be heard and a minute
later nine Crows were seen flying off to the south, and three
minutes later, nine went off to the west. At half past six, after
a great uproar of 'caws' and 'uks,' occasional rattles and wailing
'ahhhs,' a broad stream boiled up from the roosting trees and
spread off towards the west, obscurely seen in the dim light
except when the birds stood out against the beginning red glow in
the east or against the light of the setting moon in the west. As
I stood concealed on the hillside among a grove of spruces, the
Crows passed over my head, noiselessly except for the silken swish
of their wings, fully a thousand strong. Then no more for over
five minutes although the tumult in the roost continued in
increasing volume. At 6:40 the roost boiled over again, but the
birds spreading in all directions soon united into a black river
that flowed over the dunes to the south. The settings of this
black stream were the white sand dunes and the luminous glow in
the east which had become a brilliant crimson fading to orange and
yellow and cut by a broad band of pink haze that streamed up to
the zenith. The morning star glowed brightly until almost broad
daylight. The sun rose at 7:14. At 7 I entered the roost and
hurried away the few hundred remaining birds some of whom were in
the bare tops of the hardwoods ready to depart, while others were
still dozing in the evergreens below.
Nuttall's Ornithology (1832) gives an account of two roosts on
the Delaware River in Pennsylvania. One of them was on an island,
near Newcastle, called the Pea Patch, a low flat alluvial spot,
just elevated above high-water mark, and thickly covered with
reeds. The crows took shelter in the reeds and at one time during
the prevalence of a sudden and violent northeast storm accompanied
by heavy rains, the Pea Patch Island was wholly inundated in the
night. The crows apparently made no attempt to escape, and were
drowned by thousands. The following day the shores for a distance
of several miles were blackened by their bodies.
Stone (1899) states that the crows that inhabited Pea Patch and
the neighboring Reedy Island were estimated at 500,000.
Another famous crow roost is one located in Brookland, near
Washington, D. C., which accommodates practically all the crows
that feed in the vicinity. Oberholser (1920) estimated that this
roost contained 200,000 birds. A very large crow roost was located
at Arlington, Va., across the Potomac from Washington. Dr. W. B.
Barrows estimated that 150,000 to 200,000 crows came to it every
night during the winter of 1886-87.
Widmann (1880), in connection with an account of a crow roost
located on Arsenal Island opposite the southern part of St. Louis,
writes: "As early as August they begin to flock in, first by
hundreds, then by thousands, and in December hundreds of thousands
sleep there every night. The roar they make in the morning and
evening can be heard for miles around, and the sight of the influx
of these multitudes in the evening is something really
imposing." Later Widmann (1907) in writing about this roost
stated: "All through fall and in moderately cold weather in
winter, the Crows spent the nights perched ten to fifteen feet
above the ground in the willow thicket of the island, but when the
cold weather became intense they deserted the willows entirely and
spent the nights on the snow-covered sand bank in front of the
willow thicket and exposed to the fierce northwest and north wind.
When they had gone in the early morning, every bird had left an
imprint of its body in the form of a light depression in the snow
with a hole in front made by the bill and a few heaps of excreta
on the opposite side, showing the bird had spent all night in that
position, always with the head turned toward the wind, letting the
wind sweep over its back, but keeping the feet from
freezing."
Although crows are very resourceful in combating the adverse
weather conditions of winter, extreme subzero temperatures have
been known to play havoc with them at the roosts. J. W. Preston
wrote Bendire (1895) of a roost of 40,000 crows located near
Baxter, Iowa, in which many of the birds died of starvation during
the cold winter of 1891-92 because they were blinded from the
freezing of the corneas of their eyes. Likewise, Ridgway in Science,
February 10, 1893, p. 77, mentions the sufferings of the crows in
a roost near Washington, D. C. He states that many had their eyes
frozen, which was followed by the bursting of the organs and the
consequent death of the birds from starvation.
Crows have probably evolved the habit of congregating in roosts
for mutual protection, but in the present day, since the verdict
concerning their relations to man's interests in certain states
has been pronounced against them, thousands of individuals are
killed by man at the very roosts where they sought refuge against
danger. Imler (1939) states that 26,000 birds were killed by the
bombing of a large crow roost near Dempsey, Okla., on December 10,
1937. The Game and Fish Commission bombed another roost at Binger,
Okla., on December 6, 1938, killing 18,000 crows. Frank S. Davis,
inspector for the Illinois State Department of Conservation,
killed 328,000 crows in roosts near Rockford, Ill., with the use
of festoons of dynamite bombs. This wholesale slaughter was given
great publicity, appearing with photographs in the issue of Life
for March 25, 1940. Numerous roosts throughout the winter range of
the crow in the Middlewest and South have been dealt with in a
similar manner. In addition to shooting and bombing, poisons also
have been employed. This unprecedented destruction of bird life
has been received with both commendation and violent criticism.
Some of the larger roosts numbering hundreds of thousands of
individuals provide us with one of the most spectacular scenes of
bird life. It is indeed unfortunate that departments of
conservation find it necessary to destroy them.
Winter.--Along the New England
coast winter is one of the most interesting seasons for a study of
crows. At this time they are more numerous than during summer,
since the snow-bound conditions of the interior bring them to the
tidal shores, where there is a more accessible and constant food
supply. They may be seen leaving the roosts early in the morning,
often before sunrise, in groups of two or three to a dozen or 20.
At this season they seem to lead an aimless kind of existence,
meandering here and there, flying low over the mud flats or open
fields in a persistent search for food. Sometimes their wanderings
take them long distances, going hither and thither until a carcass
or other food supply is located. At all times they are alert and
suspicious, always proceeding toward food with caution, often
alighting on convenient vantage points to carefully inspect the
surroundings and to make sure no harm is in store for them.
Finally an individual more audacious, perhaps hungrier than the
others, approaches to test out the situation. If he succeeds in
escaping harm the others quickly join him in active competition to
gorge themselves. At such times one bird may act as a sentinel to
give warning in the event of approaching danger.
Edward J. Reimann in correspondence concerning crows seen in
winter in the vicinity of Philadelphia, Pa., writes: "Crows
in winter, especially when ice has formed in the waterways, will
be found frequenting the low flats of streams and creeks left bare
by the low tide. They can be seen congregated in immense flocks
feeding on the seeds of arrow-arum (Peltandra virginica).
When the rivers are full of drift ice, crows seem to take a
particular delight in perching on the cakes and traveling up and
down stream with the tide. On some occasions crows were seen to be
eating fish frozen in the ice"
American Crow*
Corvus brachyrhynchos [Eastern
Crow]
Contributed by Alfred Otto
Gross
*Original Source: Bent,
Arthur Cleveland. 1947. Smithsonian Institution United
States National Museum Bulletin 191 (Part 2): 226-257. United
States Government Printing Office
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