The crow in its relation to agriculture : Is it a farm pest?

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THE CHOW IIT ITS HELATIOB TO AGRICULTURE
Farmers Bulletin 1102

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Farmers' Bulletin 1102 United States Department of Agriculture,

THE

IN ITS RELATION TO

AGRICULTURE

IsItaFarmflest?

/~,

THE GROW is best known by the unfavorable
reputation it has acquired in the cornfield. No-
torious also are its raids on the poultry yard, its
depredations on wild birds, and its attacks on crops
other than corn.

Less heralded, however, but no less important to
the farmer, is the crow's warfare on insect pests.
Insects supply about one-fifth of its J"ood, and those
preyed upon include some of the worst pests with
which the farmer has to contend — grasshoppers,
caterpillars, and white grubs and their parents, May
beetles.

From the evidence at hand the crow's merits and
shortcomings appear about equally divided. While
it would be unwise to give it absolute protection, and
thus afford the farmer no recourse when the bird is
doing damage, it would be equally unwise to adopt
the policy of killing every crow that comes within
gunshot.

Much of the good the crow does can ill be spared,
and the damage it inflicts may be materially lessened
by proper measures against such birds as prove to
be a nuisance.

Show this bulletin to a neighbor. Additional copies may be obtained free
from the Division of Publications, United States Department of Agriculture.

Contribution frojn Jije.Bji{ea&i of Biological Survey

'•'.': J& A-: 1$£JJ5QF, Chief
Washington; D; G. •' ^ August, 1920

THE CROW IN ITS RELATION TO AGRICULTURE.

E. R. KALMBACH, Assistant Biologist.

Distribution and abundance

Life history

Economic status

Animal food

Insects

Spiders, fishes, reptiles, etc_
Wild birds and their eggs_

Poultry and their eggs

Mammals

Carrion and the distribu-
tion of live-stock dis-
eases

Vegetable food

Corn

Other grains

CONTENTS.

Page.

4

5

7

7

7

10

10

10

11

Economic status — Continued.
Vegetable food — Continued.

Other crops

Wild fruits

Distribution of seeds

Summary of food habits

Protection of crops and poultry.

Frightening devices

Deterrents

Scattering grain

Poisoning

Trapping

Shooting

Destroying nests

Summary

Page.

12
13
13
13
15
15
16
17
17
19
19
19
19

JT IS DOUBTFUL whether any other bird is of
as great economic importance to the farmer of the
eastern United States as the crow. In food
habits it is practically omnivorous ; it takes any-
thing from the choicest poultry and the tenderest
shoots of sprouting grain to carrion and weed
seeds, many of which offer at best but a morsel
of nourishment. The fact that no less than 656
different items have been identified in its food
gives some idea of the bird's resourcefulness and
its potentiality for good or harm. Some of the
complaints against the crow are well-nigh tradi-
tional, while a few of its beneficial habits have long been matters
of common knowledge. Irreconcilable differences of opinion regard-
ing the crow's worth have often been the rule among residents of a
community, and it has been only recently that sufficient information
has been assembled from most parts of the bird's range to allow a
thorough study of its habits.1

1 For a comprehensive treatise on the economic status of the crow based on the exami-
nation of the food contained in 2,118 stomachs, see Bulletin No. 621, U. S. Dept. Agr.,
"The Crow and Its Relation to Man," by E. R. Kalmbach, 92 pp., 2 pis., 3 figs., Feb.
16,1918. ?Hkr '• •"* .'/-UVS-."

3

434990

Farmers' Bulletin 1102.

DISTRIBUTION AND ABUNDANCE.

Although the crow is so well known to farmers in the Eastern
States that one would hardly suppose it could be confused with other
birds, considerable uncertainty in identification exists in regions
where it is scarce or where its range overlaps that of closely related
species. Ordinarily little distinction is made by the residents of the
South Atlantic coast between the common crow and the fish crow —
a bird of quite different habits ; and the same lack of distinction is
shown by the average individual of the northwest coast, where the
northwestern crow, also a maritime species, mingles with the com-
mon form. In the Southwest the small white-necked raven is fre-
quently called a crow, and in some other parts of the West even the
larger ravens have been similarly misnamed.

There are within the borders of the United States three species of
crows. By far the most abundant and widely distributed form is the
common crow.1 This bird, with its three closely related varieties, the
Florida crow,2 the southern crow,3 and the western crow,4 occupies a
range comprising practically all of our country east of the Rocky
Mountains, as well as sections in the Northwest and along our west-
ern coast as far as southern California. It also is found locally in
parts of Arizona and New Mexico. The other two species are
smaller and of maritime habits. The fish crow,5 whose notes are not
greatly different from those of the young of the common crow,
occupies a narrow strip along the Atlantic and Gulf coasts from
Connecticut to Texas, and is seldom found more than twenty miles
from salt water. Its counterpart, the northwestern crow,6 which
some authorities consider simply a subspecific form of the common
crow, occupies the Pacific coastal region from Puget Sound to
southern Alaska.

The wrhite-necked raven,7 inhabiting the arid and semiarid sections
of Texas and southern New Mexico and Arizona, is the raven most
frequently confused with the crow. This bird's slightly greater
size, the white bases of the feathers of its neck, and its restricted
range, however, serve to identify it. The northern raven,8 found
along our northern boundary and at higher altitudes farther south,
and the common raven,9 present in numbers in the States west of
the Great Plains, may be distinguished by their greater size and by
their discordant notes, which possess none of the lusty, open-throated
quality of those of the crow.

In this bulletin the name " crow " has been used to cover the four
forms of the common crow, including the close relatives, the Florida,
southern, and western crows.10 The food habits of all these are es-

1 Corvus brachyrhynchos braohyrhynchos. e Corvus caurinus.

2 Cofvus brachyrhynchos pascuus. 7 Corvus cryptoleucus.

3 Corvus brachyrhynchos paulus. s Corvus corax principaUs.
* Corvus brachyrhynchos hesperis. 9 Corvus corax sinuatus.

B Corvus. ossifragu*. 10 Corvus brachyrhynchos, four subspecies.

The Crow in Its Relation to Agriculture. 5

sentially the same, differing only to an extent occasioned by the vary-
ing character of the food supply in the different parts of the area
covered by their combined ranges. In some of the Western States,
where the crow appears only as an occasional breeder, it has little
economic significance, as in Nevada and the greater parts of Arizona,
New Mexico, Colorado, Wyoming, Utah, Idaho, and parts of Wash-
ington and Oregon. It can be considered only locally abundant in
California. The western parts of Texas, Oklahoma, Kansas, and

FIG. 1. — Young .crows nearly ready to leave the nest.

Nebraska support very few crows; and in large areas of Montana,
North Dakota, and South Dakota, and in the Gulf States of Florida,
Alabama, Mississippi, and Louisiana crows are not common. Based
on the average yearly abundance, the crow exerts its greatest eco-
nomic influence in the States along the Atlantic coast north of North
Carolina and in the central and upper Mississippi Valley.

LIFE HISTORY.

The nest of the crow is built at heights varying from 20 to 60 feet,
and during the breeding season it is usually well concealed from be-
low by foliage. Sometimes it is placed in the dense top of a pine, but
oaks and elms of the river bottoms, and, in the West, cotton woods are
equally acceptable. The nests are rarely found in deep forests. In

6

Farmers' Bulletin 1102.

the East the hilly and partially wooded sections of New Jersey, New
York, and Pennsylvania seem to meet nesting requirements ; in Ohio,
Indiana, and Illinois the low fertile river bottoms are especially at-
tractive ; and farther west the limited tree growth confines the breed-
ing activities of crows to the neighborhood of streams.

Crows raise one brood of from 3 to 7 young (see fig. 1). In the
Southern States the young may be found in the nest as early as the
middle of March and farther north correspondingly later, so that
along our northern border they may be present as late as July. The
nestling life lasts about three weeks. For some time after the brood
of the year has left the nest, in July, August, and September, crows
may be found in family parties or in small, loose flocks of 10 or a

FIG. 2. — Location of crow roosts known to have been occupied in the winter

of 1911-12.

dozen, securing much of their food from grasshoppers and ripening
corn.

While crows are more or less clannish, even in the nesting season,
their gregarious habit is most highly developed during the colder
months, when, often by thousands, they resort to their nightly roosts.
This flocking is of considerable economic significance in that it re-
sults in the gathering together of large numbers of birds possessing
some injurious habits. In the latitude of Washington, D. C., their
roosts are well established by the end of September, and by midwinter
their combined southerly migration and gregarious habits have
brought together in a comparatively small area the bulk of the
crow population of North America. From October to March the
States lying in the area between Connecticut and Iowa and south to

The Crow in Its Relation to Agriculture. 7

Virginia and Oklahoma harbor crows in extremely large numbers,
and damage often results in places where crops are left in the fields
until late in fall. On the accompanying map (fig. 2) are recorded
crow roosts known to have been occupied in the winter of 1911-12.

ECONOMIC STATUS.

What a bird eats or does not eat is the first question to be answered
in an inquiry into its economic status. To determine with accuracy
the various items entering into its diet nothing has been found more
reliable than the examination of stomach contents. In the case of the
crow such examination has been made of an excellent series of 2,118
stomachs, collected in 40 States, the District of Columbia, and several
Canadian Provinces. Of these stomachs 1,340 were of adult crows
and 778 of nestlings.

ANIMAL FOOD.

About 28 per cent of the yearly food of the adult crow consists of
animal matter. In this are found insects, spiders, millipeds, crus-
taceans, snails, the remains of reptiles, amphibians, wild birds and
their eggs, poultry and their eggs, small mammals, and carrion.

INSECTS.

Over two-thirds of the animal food, or about a fifth of the whole
diet of the crow, is composed of insects, and these include many of
the most destructive pests with which the farmer has to deal. The
crow is primarily a terrestrial feeder. Its share of insects, there-
fore, is made up almost exclusively of species found on or near the
ground, or those which it secures from beneath the surface by turn-
ing over sticks, clods of earth, or dung. The latter is a common
method of feeding employed diligently by the crow from early
spring to the beginning of autumn, when the usual crop of grass-
hoppers furnishes a more accessible supply of food.

Beetles of various kinds constitute about 7.5 per cent of the crow's
annual food. They are a promiscuous lot, some beneficial, some neu-
tral, and others, which comprise the major portion, highly injurious.
Among the injurious are May beetles and their larvae, white grubs;
also click beetles, weevils, and some of the ground beetles which have
vegetarian food habits. Orthoptera, including grasshoppers, locusts,
and crickets, form about an equal quantity (7.33 per cent), but
the damage this order of insects inflicts far exceeds that done by the
various beetles eaten. The short-horned grasshoppers especially are
destructive, and, while these insects have never been such serious
pests in the Eastern States as in some parts of the West, the annual
toll taken by them throughout the country amounts to many mil-
lions of dollars. In August and September grasshoppers form

Farmers' Bulletin 1102.

The Crow in Its Relation to Agriculture.

0

nearly one-fifth of the crow's food. Caterpillars form about 1.5 per
cent of the diet of the adults; nestlings, however, eat nearly four
times as much. Other insects, as bees, wasps, ants, flies, and true
bugs, are taken in only small quantities, and the economic problems
involved are not important.

The numbers of the various insects eaten during different months of
the year are often indicative of their period of abundance. Early in
spring, for instance, few May beetles or other scarabseid beetles are
eaten; but, beginning in April, they form about 5 per cent of the
crow's food, and in May the presence of the annual crop of May
beetles is indicated by the extraordinary percentage of 20.99. Like-
wise the monthly increase of grasshoppers from May to September
is shown in the crow's diet by the approximate percentages of 4, 6, 14,
19. and 19, representing the proportion of these in the food taken.
The height of the caterpillar season also is indicated by the ap-
proximate percentages of 1, 3, 6, and 2, for the months of April, May,
June, and July, respectively.

TABLE I. — Monthly percentages of the principal food items of the adult crow.

Kind of food.

Jan.

Feb.

Mar.

Apr.

May.

June.

July.

Aug.

Sept.

Oct.

Nov.

Dec.

Av-
erage.

May beetles, etc
Ground beetles
G rasshopper s

0.18
.07
.51

1.19
.10
1.14

1.04
.26
56

4.98
2.30
1 84

20.79
5.54
4 29

10.06
3.24
5 83

4.47
2.13
14 04

5.26
1.76
19 14

0.91
2.31
19 24

0.54
.14

8 68

0.77
.74
10 73

1.17
.19
2 07

4.28
1.56
7 34

Caterpillars

.18

.41

1.36

1.13

2.71

6 41

1 95

.62

2 12

1 19

30

39

1 56

Miscellaneous insects.
Carrion

.35
8.95

2.01
2.45

1.36
2.66

4.47
5.24

6.44
2.13

10.41
1.48

11.26
.29

8.29
.95

3.06
2.69

.96
.32

1.62
1 44

.67
2 37

4.23
2 58

Other miscellaneous
animal matter
Corn

4.70
51.95

3.67
43.19

8.81
36.85

14.13
35.28

10.56
33.26

9.55
20 53

10.14
9 13

3.38
17 96

1.99

29 60

2.46
54 33

3.14
63 93

6.32
65 00

6.57

38 42

Other grain

7.00

9 74

34 22

20 90

8 43

10 20

20 22

22 80

8 33

7 08

2 67

89

12 70

Cultivated fruit
Wild fruit

2.55
19.76

3.42
19.57

.26
10.65

2.74
5 06

.91

3 49

14.12

7 28

9.31
14 05

5.79
13 67

1.66
25 82

2.40
90 50

.07
12 94

1.36
14 75

3.74
13 96

Weed seeds and rub-
bish

3 80

13 11

1 97

1 93

1 45

89

3 01

38

2 27

1 40

1 65

4 82

3 06

The size and the voracious appetites of crows make these birds
especially valuable in times of outbreak of one or another of the insect
pests upon which they feed. In the stomach of a crow collected in
April were the remains of 85 May beetles, and these formed less than
half the food; in another were 72 wireworms; and in a third were
fragments of 123 grasshoppers. Twelve birds in a series collected in
Manitoba had fed on grasshoppers at the average rate of 57 each,
and one crow secured in Michigan had eaten 483 small caterpillars.
Nestling crows, whose rapidly growing bodies require even greater
quantities of insect food than the adults, often excel their parents in
the good work of insect destruction. One brood of 4 had consumed
418 grasshoppers, and another brood of 7 had made away with 585
during a few hours before they were collected. Of a total of 157
nestling crows secured in Kansas in 1913, 151 had been fed on grass-
hoppers. Caterpillars, always a favorite source of food for nestling
172161°— 20 2

10 Farmers' Bulletin 1102.

birds, were present in over a third of the 778 nestling-crow stomachs
examined.

Summing up, it may be said that the character of the insect food
of the crow leaves little to be desired and becomes the strongest argu-
ment in the bird's favor. While fully applicable to the adult birds,
this statement is doubly true of the nestlings, whose rapidly growing
bodies require enormous quantities of such readily digestible food
as is furnished by soft-bodied insects.

SPIDERS, FISHES, REPTILES, ETC.

In the other animal food of the crow are items that reflect some
of the bird's less-admired habits. The aggregate consumption of
spiders, millipeds, crustaceans, mollusks, fishes, and carrion may be
considered as having a slight influence for good, but the destruction
of beneficial toads, frogs, and small snakes is against the bird. For-
tunately, however, the quantity of such material eaten is small,
slightly more than 1 per cent of the yearly food.

WILD BIRDS AND THEIR EGGS.

Because of its depredations on small wild birds and its destruction
of the nests and eggs of larger game species, the crow has received
the condemnation of bird lovers and sportsmen. While stomach
examination has, to an extent, verified this accusation, it has at the
same time disproved extravagant statements. About a third of 1
per cent of the annual food of adult crows and 1.5 per cent of that
of nestlings is derived from wild birds and their eggs, and about 1
in every 28 adult crows and 1 in every 11 nestlings examined had
eaten such food. In the case of the nestlings, however, this ratio
gives an exaggerated idea of the work done, as in many instances
several members of a brood had fed on parts of the same victim. A
mitigating circumstance in connection with the destruction of the
eggs of wild birds lies in the fact that most of it is done during the
nesting ssason of the crow — a time early enough in the year to
allow the species attacked to lay a second set of eggs that will 'be
little molested by crows. Nevertheless, on game farms and preserves,
and in suburban districts where it is the desire to foster small birds,
the crow population must be held in check.

POULTRY AND THEIR EGGS.

The crow's depredations on poultry and their eggs are governe
largely by local conditions. The proximity of a crow's nest
taining a brood of voracious young, the accessibility of some
ticular poultry yard, and the overdevelopment in certain individual
crows of this obnoxious habit, are factors accountable for most of
the losses to poultry raisers from crows. Reports of striking simi-

The Crow in Its Relation to Agriculture. 11

larity often come from localities widely separated, while circum-
stances diametrically opposite have been reported from neighboring
farms. Food of this sort forms an extremely small part of the annual
diet of the crow, less than 1 per cent (0.57) of the adult's and 1.6
per cent of the nestling's. As in feeding on wild birds, the crow's
visits to the poultry yard are most frequent during the period when
it has young to feed ; as a consequence, successful protective measures
undertaken in May, June, and July will reduce to a minimum the
crow's depredations on poultry.

MAMMALS.

In feeding on mammals the crow supplements the good work of
hawks and owls by tending to hold in check rodent pests. Such
food forms 1.6 per cent of the diet of adult crows and 8.8 per cent
of nestlings. Their favorite mammal food consists of young cotton-
tail rabbits. While the crow does molest such live stock as young
lambs and swine, this is only an occasional habit when the bird is
hard pressed for food. Fortunately such work is not common and
the aggregate loss of this kind is negligible.

CARRION AND THE DISTRIBUTION OF LIVE-STOCK DISEASES.

As a carrion feeder the crow ably supplements the good work of
the turkey buzzard, especially along river banks and tidal flats,
where dead fish furnish a supply of animal matter much needed
during winter. But, from its carrion- feeding habits, the crow has
been accused of being a potent agency in the transmission of live-
stock diseases, especially hog cholera. No doubt the transmission of
this disease by the crow is within the range of possibilities, either
by the carrying of virus attached to its feet, bill, or other parts of
its body or possibly by the depositing of infected excreta after the
bird had fed on the body of an animal that had died from the dis-
ease. However, by the immediate burying of the dead bodies of dis-
eased animals and the employment of rigid sanitary measures in out-
breaks of this kind, the incentives which usually attract these birds
may be eliminated. It is well to add that many other agents in the
spread of such diseases, including dogs, cats, and innumerable in-
sects, are as potent in the dissemination of bacteria as are crows.
All of these can be made innocuous by thorough methods of sanita-
tion, while the extermination of the crow would eliminate only one
of many means by which such diseases are transferred.

VEGETABLE FOOD.

CORN.

Vegetable matter forms nearly 72 per cent of the adult crow's
yearly food, and over half of it consists of corn. In November, De-

12 Farmers' Bulletin 1102.

cember, and January this grain forms over half the diet, but most of
it is waste, gleaned from scattered unharvested ears. During the
sprouting season of April and May, corn constitutes about a third of
the food, and at the harvest in October it again supplies over half.
Of 1,340 adult crows collected in varying numbers in every month
of the year, 824 (over 61 per cent) had fed on corn.

It is the belief of some farmers that the depredations on this
grain in sprouting time are due largely to the nestlings' desire for
the soft, germinating kernel. Stomach analysis has disproved this,
and has showed that corn formed less than an eighth of the young
crow's food, one-third the quantity taken by the adults during ap-
proximately the same time. Injury to this crop may be either to
sprouting corn, to corn " in the milk " or in the " roasting-ear " stage,
or when the ripened grain has been stacked in shocks. Of the three,
the last form of injury is the least serious; the pulling of sprouting
corn sometimes results in heavy losses, but fortunately such damage
may be reduced by the use of deterrents; the damage to corn in
the roasting ear is the most vexatious form of damage to this grain
of which the crow is guilty. It is not so much the corn the crow
actually eats at this time, as it is the subsequent injury resulting
from water entering the ears from which the husks have been
partially torn, that makes such attacks among the most serious with
which the farmer has to contend.

OTHER GRAINS.

Of the smaller grains, which together form about an eighth of the
food of the adult crow, wheat is the favorite. This was present in
227 of the 1,340 stomachs examined, and it apparently takes the
place of corn in the crow's diet in regions where corn is not raised
extensively. Stomachs collected in the Northwest illustrate this.
When attacks upon wheat are made in sowing or sprouting time, the
depredations of a single crow, limited only by a most ample gizzard,
may be of considerable consequence. Oats are eaten much less fre-
quently than wheat, and when it is considered that oats are readily
available at all times of the year in horse droppings, the quantity of
this grain in the diet of the crow need not much concern the farmer.
Injury to kafir corn (sorghum) in autumn has been reported from
Kansas and Oklahoma, usually in the vicinity of roosts, where many
thousands of crows congregate and feed over a comparatively small
area day after day during fall and winter. Buckwheat also is oc-
casionally eaten, but by far the largest portion of it is waste.

OTHER CROPS.

A number of other crops are subject to damage by crows. In
Southern States, depredations on ripening watermelons have some-

The Crow in Its Relation to Agriculture. 13

times resulted in heavy losses. Apples, peanuts, pecans, and almonds
are less frequently injured ; while the aggregate losses to such crops as
beans, peas, figs, oranges, grapes, and cherries are insignificant.

WELD FRUITS.

Only about 14 per cent of the adult crow's sustenance is at present
derived from wild fruits and nuts, a source whence it originally ob-
tained all of its vegetable food. This part of its diet is secured from
a variety of sources, but chiefly from acorns and chestnuts. Fruit of
the various sumachs, poison ivy and poison oak, bayberry, dogwood,
sour gum, wild cherries, grapes, Virginia creeper, and pokeberry are
also common ingredients in the food.

DISTRIBUTION OF SEEDS.

The mere consumption of wild fruit by the crow involves nothing
of economic importance, but as its digestive processes destroy prac-
tically none of the embryos of the seeds, the bird acts as an important
distributor of certain noxious plants, as poison ivy and poison oak.
In this work, however, it is only supplementing the activities of the
many other native birds which feed on these seeds, often to a greater
extent than does the crow. Furthermore, as most of these seeds are
eaten by the crow during the winter, a large part of those regurgi-
tated are deposited at their roosts, often in dense stands of timber,
where the chances for sprouting are poor.

TABLE II. — Percentages of the principal food items of the nestling crow.

17.44

3.90

2.59

14.60

2.61

5.34

1.88

9.68

1.78

7. 04 1. 57

6.22

I

o

2.61

3.95

11.91

4.58

SUMMARY OF FOOD HABITS.

The crow's consumption of insects presents the strongest argu-
ment in the bird's favor. About a fifth of its diet is secured from
the insect world, and among the pests it destroys are some of the
most troublesome with which the farmer has to contend. Many of
the insects it eats are taken early in spring, when their life cycles
are at the lowest ebb and when their destruction results in the greatest
good.

Conspicuous among such food items are May beetles and their de-
structive larvae, white grubs, of which the crow is an effective enemy.
In its consumption of grasshoppers the crow probably renders man
its greatest individual service, and in regions where these insects are

14

Farmers' Bulletin 1102.

abundant their nymphs form the principal insect food of the nest-
lings. Other creatures in the destruction of which the young exceed
the adults include caterpillars and spiders. The latter, however, are
predacious and to a great extent beneficial.

The crow's feeding on reptiles and amphibians is on the whole not
to the best interests of man. but fortunately the highly beneficial
toads are found in the food less frequently than the more aquatic
frogs and salamanders. In feeding on the eggs and young of small

If

II

FIG. 4.— Food of nestling crows. The proportions of the various elements are represented by the rela-
tive sizes of the sectors. In Table II the same information is presented in percentages.

insectivorous and game birds the crow commits a serious offense, and
in the vicinity of game farms and preserves the bird must be held in
check if other species are to exist in concentrated numbers. This
offense is mitigated somewhat by the fact that most of the depreda-
tions on eggs occur early enough in the season to permit the raising
of a second brood at a time when there is little or no danger from
the crow. The molesting of poultry is an injurious habit against
which protective measures are effective under any but the shift-by-

The Crow in Its Relation to Agriculture. 15

itself method of caring for fowls. A little attention to the screening
of young chicks and the suitable housing of setting hens will obviate
most losses of this kind. In its feeding on small mammals, its
annoyance of young live stock, and its consumption of carrion, the
crow has tendencies about equally divided between good and bad.
The accusation that it is a dominant factor in the distribution of
live-stock diseases has little substantiating evidence.

Of the vegetable food, corn is the principal item. It is the crow's
staff of life and furnishes over 38 per cent of its annual sustenance.
In the consumption of this grain the bird comes in most frequent con-
flict with the farmer. Much of the corn eaten, however, is secured
from October to March, when waste grain necessarily forms a large
part of the supply. Deterrents, as coal tar, on the seed have lessened
losses to sprouting grain, especially in small isolated fields, but, when
" in the roasting ear," the corn crop is subject to annoying and de-
structive attacks by the crow, difficult to prevent. The crow also
levies a certain toll on small grains, as wheat and sorghums ; melons
are subject to attack and even cultivated fruits at times are damaged.

The offenses of which the crow has been accused outnumber its
good deeds, but this does not mean that they are equal in importance.
Many of the crow's depredations may be lessened or entirely pre-
vented by protective measures, while in its preying on insects it does
work that can ill be spared. An overabundance of these birds is not
to the best interests of the farmer, but, on the other hand, extermina-
tion of the crow would result in taking away a most effective enemy
of certain insect pests. Consequently the instituting of control meas-
ures is justifiable locally where the birds are taking more than a fair
share of the crops in return for good services rendered, while in other
sections where crows occur in normal numbers they may better be
allowed to exist unmolested.

PROTECTION OF CROPS AND POULTRY.

FRIGHTENING DEVICES.

It is not necessary to describe in detail the many well-known de-
vices employed as "scarecrows." The time-honored straw-stuffed
human effigy is the one most frequently used, though often it fails to
accomplish its purpose. Various unusual objects, as pieces of shining
tin moving in the wind or glass bottles hung about fields, windmills
operating a noise-producing mechanism, newspapers placed on the
ground, twine stretched about and across fields from poles stationed
at intervals around them, as well as bodies of dead crows hung in
conspicuous places, have been successful in some instances. Poultry
yards especially have been protected from the ravages of crows by
strands of cord stretched across at intervals and at a height of 6 or 8

16 Farmers' Bulletin 1102.

feet from the ground. One or another of these methods has met with
varying success on occasion, but sometimes none will produce the de-
sired results. None can be considered infallible.

DETERRENTS.

Coal tar. — Experience has shown that damage to corn and other
grains at sprouting time may be lessened by special treatment of
the seed. While the application of deterrents to the seed grain has
disadvantages, in that it involves additional labor at planting time,
tends to retard germination in periods of dry weather, and can not
be considered an absolute cure, the measure of success of many farm-
ers who have in this manner secured relief from crow depredations
warrants a description of the methods used.

One of the most successful deterrents is coal tar, a cheap by-product
in the manufacture of illuminating gas, which may be secured at
gas works or at some paint shops. It is a dark, heavy liquid of
about the consistency of thin molasses and emits a strong, gassy
smell for some time, even after the grain treated with it has become
thoroughly dry. When used in the quantities here recommended,
coal tar in no way injures the germinating qualities of the seed.
This important qualification is not possessed by certain other sub-
stances, sometimes recommended as crow deterrents. Experiments
conducted by the writer also have shown that in periods of normal
rainfall germination is but slightly retarded by the coal-tar treat-
ment, though in periods of drought the retardation may be several
days.

Coal tar should be used in the proportion of about a tablespoonful
to half a bushel of seed grain, the grain having been previously
heated by the application of warm water, and then drained. A con-
tinued stirring of the grain will eventually result in an even coating
of tar. The seed may then be spread out on a dry surface or may
be dried by the application of an absorbent medium, as ashes, land
plaster, or powdered earth. When thoroughly dry it may be used in
a planter.

Deterrents are commonly used by farmers of the North Atlantic
States and to a lesser extent by farmers of the South Atlantic States.
In the extensive corn-raising regions of Illinois, Missouri, and Iowa,
corn is seldom tarred, probably because it is planted on so large a
scale that losses to the individual farmer are less severe.

Bed lead. — Another substance used as a deterrent is red lead. This
appears to have been used first in Europe, where it met with con-
siderable success. The grain is first given a thin glue size, and is
then drained and dusted with red lead until well colored. Though
this process has been used but little in this country, its success in
deterring birds in Europe warrants a further trial here.

The Crow in Its Relation to Agriculture. 17

Other deterrents. — A few years ago the Kansas State Agricultural
College Experiment Station conducted a series of experiments on
seed grain to ascertain the usefulness of certain deterrents against
burrowing animals. Incidentally the effect of these various sub-
stances upon the germinating powers of the seed was investigated.
In his report on this work, Theo. H. Scheffer * says in part that kero-
sene, crude petroleum, copperas, crude carbolic acid, fish oil, and
spirits of camphor, when used in sufficient quantity or strength to
impart an odor to the corn, seriously injure the germinating powers
of the grain ; and that to treat the seed with any of these substances
in such small quantity or dilute form as not to injure the germ is a
waste of time, for the slight taste or odor imparted is soon dissipated
in contact with the soil.

Similar experiments2 conducted by B. M. Duggar and M. M.
McCool, at the Agricultural Experiment Station of Cornell Univer-
sity, indicated that of a number of substances employed, turpentine
emulsion and an anilin oil solution seriously affected germination.
Such substances should be carefully avoided.

The manufacture of deterrents for use on seed grain has been
undertaken on a moderate scale in this country, and a few articles
of this nature also have been imported. Most of these appear to use
coal tar or closely related products as a base; one at least contains
a copper salt and is a poison ; while the merit of one imported deter-
rent appears to be based on the fact that the treated seed is a brilliant
blue. None of those tested by the writer has had any harmful effect
on the seed ; but there is no evidence that any of these manufactured
substances is superior to coal tar as a deterrent when the latter im-
properly applied.

SCATTERING GRAIN.

Many farmers have had considerable success in protecting their
sprouting crop by spreading broadcast over the fields a quantity of
grain previously softened with water. This the birds take, leaving
untouched that which has been planted. It has been found that a
comparatively small quantity sacrificed in this way during the short
period of a week or 10 days when spouting corn is subject to damage
has often prevented loss to the growing crop.

POISONING.

Though the crow would be a most difficult bird to eradicate over
any considerable area by a campaign of poisoning — a fact due largely
to the bird's wariness — such a method has been found an effective
means of protecting crops. When once a flock of these birds have

1 Kansas State Agr. Coll. Exp. Sta., Circ. 1, p. 3, Apr. 28, 1909.

2 Cornell Univ. Agr. Exp. Sta., Circ. 6, pp. 14-16, May, 1909.

18 Farmers' Bulletin 1102.

learned through the loss of one or several of their number that a
certain area has been baited with poisoned food they are inclined
to avoid it for some time at least. In conducting such operations,
however, local regulations governing the distribution of poison must
be scrupulously observed, and as there is always an element of danger
connected with the distribution of poison about thickly settled re-
gions, its use should be limited and judicious.

Corn is the bait usually employed in poisoning crows, and it is
generally prepared by simply steeping the grain in a strong strych-
nine solution. If made, however, according to the following direc-
tions it will kill more quickly and its effectiveness will last for a
considerable time when exposed to weather:

Corn 20 quarts

Strychnine (powdered) 1 ounce

Starch 2 tablespoonfuls

Water 1$ pints

Put the starch and strychnine in the water and heat to boiling, stirring
thoroughly after the starch begins to thicken. Pour this mixture over the corn
and stir till every kernel is coated. The seed may then be spread out and dried.

Experiments conducted in Klickitat County, Washington, demon-
strated that where crows are troublesome to green almonds, relief
may be secured by using these nuts as bait, prepared by splitting and
inserting a quantity of a strychnine-saccharine mixture of about the
size of a kernel of wheat. The poison mixture is composed of 8 parts
of strychnine alkaloid and 1 of saccharine. The poisoned nuts are
then placed in bare spots, two or three under each tree. While such
a limited number of baits appears to be wholly insufficient to meet a
situation where a flock of several thousand birds settle down on an
orchard of a few acres, the results secured thus far have been most
satisfactory. In attacking an almond crop, crows will first alight in
the tree tops, knock down a few nuts, and then go to the ground to
feed on them. For this reason conspicuously placed poisoned baits
of this kind are almost certain to be taken, and as a few crows killed
or seriously affected by the poison will suffice to make others shun
the area, protection has been secured by one treatment that lasted a
week or 10 days. By this means almond crops that in previous
years had suffered losses sometimes totaling 100 per cent were but
slightly damaged.

A successful bait has also been prepared by the use of partially
blown hens' eggs into which a small quantity of strychnine has been
injected. This has been effective in stopping the raids of the poultry
and egg stealing crow. It should always be placed on the tops of
straw stacks, in artificial nests erected on poles, or in inclosures from
which poultry and all farm animals are barred. Strychnine may
even be conveyed by meat or carrion used as baits, but-the difficulty

The Crow in Its Relation to Agriculture. 19

in keeping such baits away from domestic animals is great ; they may
be used to best advantage in winter, when crows are hard pressed for
food.

TRAPPING.

Trapping at times has brought relief where other methods have
failed. No wholesale reductions in the number of crows has ever
been accomplished by this method, but when a few birds have been
trapped and their dead bodies have been left exposed in the fields,
their relatives are inclined to shun the immediate vicinity. Crows
have been secured mainly in steel traps carefully baited with hens'
eggs.

SHOOTING.

The unusual wariness of the crow has limited the effectiveness of
firearms in reducing its numbers. However, these birds are inclined
to shun those areas where the shotgun is frequently used. The use
of crow decoys and crow calls has been resorted to with such success
in attracting the birds within gunshot that these articles are now
placed on sale by extensive dealers in sporting goods. A mounted
specimen of an owl placed in a conspicuous position and within easy
gunshot of the concealed hunter has also been used successfully in
attracting numbers of crows to a point where they can be shot.

In eradicating objectionable winter roosts of crows, attacks on
several successive nights by a number of men with firearms will
frequently cause the birds to move on. Cartridges loaded with
black powder are better than those containing smokeless, as the re-
port is more deafening. When once a roost has been removed,
vigilance must be employed for some time thereafter to keep it from
being reestablished. In places where the discharge of firearms was
inadvisable, Roman candles shot among the roosting birds have
brought about the desired results, and on one occasion bunches of
firecrackers thrown up into the tree tops caused the crows to seek a
more peaceful community.

DESTROYING NESTS.

In sections where woodlands are close to farmyards containing
exposed nests and young chicks, the destruction of a few crows'
nests will greatly lessen depredations on poultry. The success of
this measure lies in the fact that most of the crow's raids on the
poultry yard are prompted by its desire to secure food for its young.

SUMMARY.

The crow is a bird whose size, ability to survive under diverse en-
vironments, and almost omnivorous food habits make it capable of
doing both serious harm and extensive good. The influence of the race
as a whole for good and harm appears to be about equal. Local

20

Farmers' Bulletin 1102.

conditions, however, greatly affect its economic status, and for this
reason hasty judgment as to its worth should not be rendered, lest
the bird be persecuted in sections wliere it is actually aiding the
farmer. This bulletin has aimed to point out briefly the benefits to
man from the crow's food habits, as well as the ways in which the
bird may do harm. Indiscriminate killing is not warranted, and
even in areas where the crow, is doing harm preventive measures
will often put a stop to the nuisance and allow the bird to continue
what good work it may be doing on insects. Among the preventive
measures are —

(1) The use of coal tar or other deterrents on seed grain.

(2) Scattering grain over fields where the crop is just sprouting.

(3) Stretching twine about and across fields from poles stationed
at, intervals. A network of such strands is often effective in pro-
tecting poultry yards.

(4) The use of frightening devices and the hanging up of the
dead bodies of crows in conspicuous places.

In places where more drastic measures are necessary the killing
even a few crows will intimidate others and these will usually shi
the area for some time. Such procedures include—

(1) The use of poison (strychnine) in places where this is per-
mitted by law. Corn and hens' eggs are the most effective baits.

(2) Trapping by means of steel traps, carefully concealed anc.
baited with hens' eggs.

(3) Destroying nests — a measure that will most irequently put a
stop to the poultry-raiding activities of a pair of crows which have
their nest near by.

(4) Shooting — the hunter being aided by the use of a crow call
and, where possible, also by a mounted owl placed conspicuously

a pole. Several night attacks by a number of men equipped wii
shotguns will frequently remove objectionable winter roosts.

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UNIVERSITY OF CALIFORNIA LIBRARY