In one or another of its geographic races the common crow[44] (fig. 16)
breeds in great numbers throughout the States east of the Plains and
from the Gulf well up into Canada, while in less abundance it is found
in California and in the Northwestern States. During the colder months a
southern migratory movement brings most of these birds within the borders
of the United States, and at about the latitude of Philadelphia and
southern Illinois we find them congregating nightly in roosts. Farmers
dwelling in the vicinity of such roosts frequently suffer losses to
shocked corn.
[44] _Corvus brachyrhynchos_.
In fact, none of our native birds so much concerns the average farmer of
the Eastern States as the common crow. Many of our present criticisms
of this bird, as its pulling sprouting corn, feeding on ripening ears,
damaging fruits of various kinds, destroying poultry and wild birds,
and disseminating diseases of live-stock, were common complaints in the
days of the early colonists. Many of the virtues of the crow, now quite
generally recognized, also have been matters of record for many years. In
recent times, however, scientific study of these problems, including the
examination of the stomachs of hundreds of crows secured in every month
of the year and under a variety of conditions, has enabled us to render a
much fairer verdict than was formerly possible.
The crow is practically omnivorous. During spring and early summer any
form of insect life seems to make a desirable item in its diet, and in
winter when hard pressed nothing in the animal or vegetable kingdoms
which contains a morsel of nutriment is overlooked.
The insect food of the crow, which comprises about a fifth of its yearly
sustenance, does much to atone for its misdemeanors. Grasshoppers,
May beetles and their larvæ (white grubs), caterpillars, weevils, and
wireworms stand out prominently. In 1,340 stomachs of adults examined
these highly Injurious forms comprised over 80 per cent of the insect
food. Grasshoppers are naturally taken in greatest abundance late in the
season. September being the month of largest consumption, when they form
about a fifth of the total food. May beetles and white grubs are eaten
in every month, but occur most prominently in May. In June caterpillars
are a favorite food, and weevils of various kinds are taken in varying
quantities throughout summer and fall. About half of the remaining
20 per cent of insect food is composed of beneficial ground beetles,
ladybirds, predacious bugs, and parasitic wasps, and related forms, the
rest consisting of neutral or injurious forms. Numerous instances are on
record where fields badly infested with white grubs or grasshoppers have
been favorite resorts of crows, whose voracity has resulted in a material
suppression of the pest. When the amount of food required to sustain the
individual crow is considered, the work of these birds appears all the
more important Single stomachs containing upward of 50 grasshoppers are
not uncommon. Thus in its choice of insect food the crow is rendering an
important service to the farmer.
[Illustration: Fig. 16.--Crow. Length, about 19 inches.]
In the other animal food of the crow are several items of the utmost
economic importance. Spiders are taken in considerable numbers in May and
June, but the yearly total is a little over 1 per cent of the food. In
early spring crawfish are eagerly sought, and other aquatic food, as fish
and mollusks, lend variety to the crow's bill of fare the year round.
In the consumption of toads, salamanders, frogs, and some snakes, which
together compose a little over 2 per cent of the yearly food, the crow is
doubtless doing harm. Small rodents occurred in the stomachs collected
nearly every month, but it Is often difficult to determine whether small
mammals found in birds' stomachs were taken alive or found dead.
From its carrion-eating habits the crow has been unfairly criticized as
a disseminator of live-stock diseases. While this may be to some extent
just, the fact that there are many other important carriers which lie
largely beyond our control, shows that we must seek final relief only
through the strictest methods of sanitation.
The nest-robbing habit of the crow, long a serious criticism, is verified
by stomach analysis. Of the 1,103 crows examined, 47 had fed on wild
birds or their eggs, and the eggs of domestic fowls were found somewhat
more frequently. The crow's habit of rummaging about garbage piles may
explain much of this latter material.
Of the vegetable food, corn, which is eaten every month, is the most
important item and forms about 38 per cent of the diet. Much of this,
however, must be considered waste, since over 60 per cent of it is
consumed from the first of November to the end of March. During the
periods when corn is sprouting and when in the "roasting-ear" stage the
crow is eating this grain at a rate considerably less than the yearly
average, and the months of smallest consumption are July and August. At
times, however, the damage to corn becomes a serious problem, and were
it not possible to make use of such deterrents as coal tar upon seed
corn there would be little friendship for the crow in some sections of
the East. The "pulling" of corn is a trait most prevalent in small-field
areas. Wheat and oats suffer similar damage at times, especially in the
Northwestern States, where these grains predominate. About the only
safeguard to ripening grain is the constant use of powder and shot or the
scarecrow.
Various kinds of cultivated fruits are also eaten, and local damage
to such crops as apples, melons, peas, beans, peanuts, and almonds is
occasionally reported. In long, rigorous winters, the crow, like other
birds, resorts to the fruit of numerous wild plants, as dogwood, sour
gum, hackberry, smilax, and the several species of sumac and poison ivy.
Damage to the eggs of poultry may be reduced to a minimum by careful
housing of lasting hens, and the farmer can protect his sprouting grain
to a large extent by the use of tar-coated seed. It will be well also
to keep the crow within reasonable numbers on game preserves and public
parks where it is desired to encourage the nesting of smaller birds.
While legal protection is not needed for so wary an individual as the
crow, it seems well, where local conditions have not aggravated some
particular shortcomings of the bird, to allow it to continue the good
services gendered to man in the destruction of noxious insects.