THE ECONOMIC VALUE OF BIRDS
Wild birds are now generally protected by law. Wander where you will
through every province of Canada, and almost every nook and corner of
the United States, you will find that the lawmaker has been there
before you, and has thrown over the birds the sheltering arm of
prohibitory statutes. Legislators are not usually supposed to spend
much energy on drafting and enacting measures unless it is thought that
these will result in practical benefit to at least some portion of
their constituents. Legislative bodies are not much given to
appropriating hundreds of thousands of dollars annually for the
enforcement of a law which is purely sentimental in its nature. It is
clear, therefore, that our law makers regard the wild bird life as
{102} a great value to the country from the standpoint of dollars and
cents.
_Destructiveness of Insects._--If we go back a few years and examine
certain widely read publications issued by the United States Department
of Agriculture, we can understand more fully why our legislative bodies
have regarded so seriously the subject of bird protection. In one of
the Year Books of the Department we read that the annual loss to the
cotton crop of the United States by insects amounts to sixty million
dollars. We learn, too, that grasshoppers and other insects annually
destroy fifty-three million dollars' worth of hay and that two million
dollars' worth of cereals are each year eaten by our insect population.
In fact, we are told that one-tenth of all the cereals, hay, cotton,
tobacco, forests, and general farm products is the yearly tax which
insects levy and collect. In some parts of the country
market-gardening and fruit-growing are the chief industries of the
people. Now, when a vegetable raiser or fruit grower starts to count
up the cost of {103} his crops, one of the items which he must take
into consideration is the 25 per cent. of his products which goes to
feed the insects of the surrounding country.
Not all insects are detrimental to man's interests, but as we have just
seen the Government officially states that many of them are
tremendously destructive. Any one who has attempted to raise apples,
for example, has made the unpleasant acquaintance of the codling moth
and the curculio. Every season the apple raisers of the United States
expend eight and one-quarter million dollars in spraying, to discourage
the activities of these pests. In considering the troubles of the
apple growers we may go even farther and count the twelve million
dollars' worth of fruit spoiled by the insects despite all the spraying
which has taken place. Chinch bugs destroy wheat to the value of
twenty million dollars a year, and the cotton-boll weevil costs the
Southern planters an equal amount.
_Plagues of Insects._--Every now and then we read {104} of great
plagues of insects which literally lay waste a whole section of
country. History tells of these calamities which have troubled the
civilized world from the days of Pharaoh to the present time. During
the summer of 1912 there was a great outbreak of army worms in South
Carolina. In innumerable millions they marched across the country,
destroying vegetation like a consuming fire. In the year 1900 Hessian
flies appeared in great numbers in Ohio and Indiana, and before they
subsided they had destroyed absolutely two and one-half million acres
of the finest wheat to be found in the Middle West, and wheat land
dropped 40 per cent. in value.
Closing this Year Book, with its long tables of discouraging
statements, we may find more cheerful reading if we turn to another
Agricultural Department publication entitled, "Some Common Birds and
Their Relation to Agriculture; Farmers Bulletin number Fifty-four." We
need peruse only a few pages to become impressed with the fact that our
Government Biological Survey has made an {105} exhaustive and
exceedingly thorough investigation of the feeding habits of the wild
birds that frequent the fields and forests. The reports of the
economic ornithologists herein given are almost as surprising as the
sad records given by the entomologists in the Year Book. We learn that
birds, as a class, constitute a great natural check on the undue
increase of harmful insects, and furthermore that the capacity for food
of the average bird is decidedly greater in proportion than that of any
other vertebrate.
_Some Useful Birds._--Most people who have made the acquaintance of our
common birds know the friendly little Chickadee, which winter and
summer is a constant resident in groves of deciduous trees. It feeds,
among other things, on borers living in the bark of trees, on plant
lice which suck the sap, on caterpillars which consume the leaves, and
on codling worms which destroy fruit. One naturalist found that four
Chickadees had eaten one hundred and five female cankerworm moths.
With scalpel, tweezers, and microscope these moths were examined, {106}
and each was found to contain on an average one hundred and eighty-five
eggs. This gives a total of nearly twenty thousand cankerworm moth
eggs destroyed by four birds in a few minutes. The Chickadee is very
fond of the eggs of this moth and hunts them assiduously during the
four weeks of the summer when the moths are laying them.
The Nighthawk, which feeds mainly in the evening, and which is equally
at home in the pine barrens of Florida, the prairies of Dakota, or the
upper air of New York City, is a slaughterer of insects of many kinds.
A Government agent collected one, in the stomach of which were the
remains of thirty-four May beetles, the larvae of which are the white
grubs well known to farmers on account of their destruction of potatoes
and other vegetables. Several stomachs have been found to contain
fifty or more different kinds of insects, and the number of individuals
in some cases run into the thousands. Nighthawks also eat
grasshoppers, potato-beetles, cucumber-beetles, boll-weevils,
leaf-hoppers, and numerous gnats and {107} mosquitoes. Surely this
splendid representative of the Goatsucker family deserves the gratitude
of all American citizens.
Among the branches of certain of our fruit trees we sometimes see large
webs which have been made by the tent caterpillars. An invading host
seems to have pitched its tents among the boughs on all sides. If
undisturbed these caterpillars strip the foliage from the trees.
Fortunately there is a bird which is very fond of these hairy
intruders. This is the Cuckoo, and he eats so many that his stomach
actually becomes lined with a thick coating of hairs from their woolly
bodies. The Baltimore Oriole also is fond of rifling these webs.
Another well-known bird that helps to make this part of the world
habitable is the Flicker. It is popular in every neighbourhood where
it is found and is known by a wide variety of local names, over one
hundred and twenty-five of which have been recorded. Golden-winged
Woodpecker some people call it. Other names are High-holder, Wake-up,
{108} Walk-up, Yellowhammer, and Pigeon Woodpecker. The people of Cape
Hatteras know it as Wilkrissen, and in some parts of Florida it is the
Yucker-bird. Naturalists call it _Colaptes auratus_, but name it as
you may, this bird of many aliases is well worthy of the esteem in
which it is held. It gathers its food almost entirely from the ground,
being different in this respect from other Woodpeckers. One may flush
it in the grove, the forest, the peanut field, or the untilled prairie,
and everywhere it is found engaged in the most highly satisfactory
occupation of destroying insect life. More than half of its food
consists of ants. In this country, taken as a whole, Flickers are very
numerous, and the millions of individual birds which have yet escaped
the guns of degenerate pot hunters constitute a mighty army of
destruction to the _Formicidae_.
Let us not forget that any creature which eats ants is a decided boon
to humanity. Ants, besides being wood borers, invaders of pantries,
killers of young birds, nuisances to campers and barefoot {109} boys,
care for and perpetuate plant lice which infest vegetation in all parts
of the country to our very serious loss. Professor Forbes, in his
study of the corn plant louse, found that in spring ants mine along the
principal roots of the corn. Then they collect the plant lice, or
aphids, and convey them into these burrows and there watch and protect
them. Without the assistance of ants, it appears that the plant lice
would be unable to reach the roots of the corn. In return for these
attentions the ants feast upon the honey-like substances secreted by
these aphids. The ants, which have the reputation of being no
sluggards, take good care of their diminutive milch cattle, and will
tenderly pick them up and transport them to new pastures when the old
ones fail. Late in the summer they carefully collect all the aphid
eggs that are obtainable, and taking them into their nests keep them
safe during the winter. When spring comes and the eggs hatch, the ants
gather the young plant lice and place them on plants. It may be seen,
therefore, that the Flicker {110} by digging up ants' nests and feeding
on the inhabitants has its value in an agricultural community.
_The Question of the Weed Seeds._--The work of the Chickadee, the
Nighthawk, the Cuckoo, and the Flicker is only an example of the good
being done by at least two-thirds of birds in the United States, and
most of the remainder are not without their beneficial qualities. When
the coming of winter brings a cessation of insect life, many birds turn
to the weed patches for food. Especially is this the case with the
various varieties of native Sparrows.
No one has yet determined just how many weed seeds one of these birds
will eat in a day. The number, however, must be very great. An
ornithologist, upon examining the stomach of a Tree Sparrow, found it
to contain seven hundred undigested pigeon-weed seeds, and in the same
way it was discovered that a Snow Bunting had taken one thousand seeds
of the pigweed at one meal.
[Illustration: Cuckoo, Raiding a Tent of Caterpillars]
Mr. E. H. Forbush, the well-known Massachusetts naturalist, frequently
amuses himself by {111} observing the birds near his house as they feed
on the millet seed that he provides for them. Speaking of some of the
things he saw here, he says, "A Fox Sparrow ate one hundred and three
seeds in two minutes and forty-seven seconds; another, one {112}
hundred and ten in three minutes, forty-five seconds; while still
another Song Sparrow ate one hundred and fifty-four in the same length
of time. This Sparrow had been eating for half an hour before the
count began and continued for some time after it was finished." It is
readily seen that thirty seeds a minute was below the average of these
birds; and if each bird ate at that rate for but a single hour each day
it would destroy eighteen hundred seeds a day, or twelve thousand six
hundred a week. Some day the economic ornithologists under the
leadership of Professor F. E. L. Beal, America's leading authority on
the subject, may give us a full and exhaustive account of what the
various birds do for us in the way of keeping down the great scourge of
grass and weeds with which the farmers have to deal. In the meantime,
however, we may bear in mind that enough evidence already has been
accumulated to prove that as destroyers of noxious weed seeds the wild
birds are of vast importance.
[Illustration: Farallon Cormorants and White Pelicans on a Government
Bird Reservation in southern Oregon.]
_Dealing with the Rodent Pests._--In addition to {113} weeds and
insects, there is yet another group of pests, some representatives of
which may be found in every neighbourhood. It is composed of rabbits,
ground squirrels, prairie dogs, mice, and the like. They all possess
long front teeth for gnawing, and constitute the Order of Rodents.
Some species destroy fruit trees by gnawing away the bark near the
ground, others attack the grain stacked in the field or stored in the
granary. As these little sharp-eyed creatures are chiefly nocturnal in
their habits, we seldom see them; we see only the ruin they have
wrought. In some of the American ports incoming vessels are
systematically fumigated to kill the rats for fear they may bring with
them the bubonic plague. In April, 1898, while engaged in field
natural history work in Hyde County, North Carolina, I found the farms
along the north shore of Matamuskeet Lake were overrun by swarms of
large brown rats that burrowed in the ground everywhere, and coming out
at night wrought havoc and destruction on the farm lands. The whole
country was up {114} in arms and the farmers were appealing for State
and Federal aid to help them rid the land of this terrible scourge. In
short, the rodents, as a class, are regarded as decidedly detrimental
to the interests of mankind.
[Illustration: Screech Owl and Its Prey]
_The Terror That Flies by Night._--Among the chief enemies of rodents
in North America are the nineteen species of Owls, untold numbers of
which are abroad every night searching through fields and forests for
just such creatures as these. The digestive processes of Owls are such
that the hard, indigestible portions of their food are disgorged in the
form of balls and may often be found beneath their roosting places.
One of our most odd-looking birds is the Barn Owl. Being nocturnal in
its habits it is rarely seen unless one takes the trouble to climb into
unfrequented church towers, the attics of abandoned buildings, or
similar places which they seek out for roosting purposes. Some years
ago the naturalist, Dr. A. K. Fisher, discovered that a pair of Barn
Owls had taken up their abode in one of the towers {115} of the
Smithsonion Institution building. He found the floor thickly strewn
with pellets composed of bones and fur which these birds and their
young had disgorged. He collected two hundred of these {116} and took
them to his laboratory. A painstaking examination showed that they
contained four hundred and fifty-three skulls. Here is his list made
out at the time: two hundred and twenty-five meadow mice, two pine
mice, twenty shrews, one star-nosed mole, and one Vesper Sparrow. It
is plain to be seen that great good was accomplished in the community
by this pair of Owls and their young, for the evil effects of the
rodents in life must have far overbalanced the good service of the one
useful Vesper Sparrow.
_A Seldom Recognised Blessing._--There are some large predatory birds
which destroy the lives of many game birds and others of the weaker
species. On game farms, therefore, an unpleasant but necessary task is
the shooting or trapping of Hawks and Owls. At first thought it might
seem best to wage a war of absolute extermination on these offenders,
and some game-keepers urge that this should be done. Personally I am
opposed to any such course of action, one reason being that this would
not {117} necessarily forward the best interests of the game birds it
is desired to serve. So important and yet so unexpected is the
ultimate effect of the activities of predatory creatures that in a
state of nature I am convinced the supply of game birds is increased
rather than decreased by being preyed upon. Like all other creatures,
birds are subject to sickness and disease, but by the laws of nature it
appears that they are not designed to suffer long. Their quick removal
is advisable if they are to be prevented from spreading contagion among
their fellows, or breeding and passing on their weakness to their
offspring. Sometimes the Hawk, dashing at a covey of game birds, may
capture one of its strongest and healthiest members, but the chances
are that the afflicted member, which is not so quick on the rise or is
a little slower on the wing, is the one to be taken. Just as some
savages are said to put to death the incompetent and unfit, so do the
laws operate which govern wild life. If, therefore, we should destroy
all the Hawks, Owls, wild cats, foxes, skunks, {118} snakes, and other
predatory creatures, it is an open question whether in the long run our
game birds would be the gainers thereby.
Some time ago I visited a large game farm in one of the Southern
States, where for several years the owner had been engaged in raising
English Ring-necked Pheasants. The gamekeeper stated that there were
about six thousand of these brilliantly coloured birds on the preserve
at that time. He also pointed with pride to an exhibit on the walls of
a small house. An examination showed that the two sides and one end of
this building were thickly decorated with the feet of Hawks, Crows,
Owls, domestic cats, minks, weasels, and other creatures that were
supposed to be the enemies of Pheasants. Two men were employed on the
place to shoot and trap at all seasons, and the evidences of their
industry were nailed up, to let all men see that the owner of the big
game farm meant to allow no wild bird or animal to fatten on his game
birds.
A year later I again visited the same preserve and {119} found great
lamentation. More than five thousand Pheasants had been swept away by
disease within a few weeks. Is it going too far to say that the gunmen
and trappers had overdone their work? So few Hawks or Owls or foxes
had been left to capture the birds first afflicted, that these had been
permitted to associate with their kind and to pass on weakness and
disease to their offspring until the general health tone of the whole
Pheasant community had become lowered. In the end five-sixths of the
birds had succumbed to the devastations of disease.
All birds have their part to play in the great economy of the earth,
and it is a dangerous experiment to upset the balance of Nature.
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