, 1921-12-01

thrashers seek their insect prey on or near the
ground woodpeckers, nuthatches, titmice, and
chickadees closely search the trunks and limbs of
trees; vireos and warblers scan the leaves and
probe the flowers; and hycatchers and swallows
sweep their prey from the air itself. Every few
minutes all day long the hungry young must be
fed; and that they are well fed their rapid growth
attests. The quantity of insects they and their
parents consume is enormous Not only orchards
benefit by the good work of birds. but gardens,
berry patches, and plowed and newly sown fields
as Well. While fields actually grown to tall crops
are less freely visited. all crops are helped to some
extent, and practically every farm pest has its
bird enemies,
? To learn exactly how and to what extent birds
are aids to agriculture, horticulture, and forestry,
the biological survey has been making a scientific
study of their food habits ever since Its establish
mept IN 1885. Its Investigations are carried on In
both the field and laboratory. All that can be
learned out of doors by direct observation and by
study Of the available food supply is valuable, but
there is a surer way of finding out what a bird
eats, namely, to look into its stomach. 1t has
been repeatedly demonstrated that the nature OF
the food and feeding habits of birds Is such that
II is impossible to arrive at definite results by di-
rect observation. ON the other hand, the examina-
tIon in the laboratory of the contents of the stom-
ach gives Information that is definite, exact, and
indisputable.
From the percentages and the economic value
OF the food items, the utility of a bird can be
closely estimated. The biological survey is then
able TO how II should be treated.
: In the United States are found more than 500
distinct kinds of birds of 80 families, of which 20
families are classed as waterfowl, Z as shorebirds,
4 as upland game birds, 3 as birds of prey, and 80
as land birds.
The upland game birds comprise such familiar
groups as the quail, grouse. %ptarmigan, wild tur-
keys, wild pigeons, and doves. The last two, while
usually harmless, sometimes damage crops to an
extent which requires that they be controlled, and
economically they deserve less consideration than
the turkey, quail. and grouse. These three kinds
Of birds have feeding habits which are helpful to
agriculture. They may be hunted, but their num-
bers should not he reduced below the normal pop
ulatlon for each type of country.
Hawks and owls, though not closely related.
may be considered together on account OF the sim
ilarlty Of their feeding habits. Feeding chiefly up
on living animals smaller than themselves, natur-
ally they sometimes prey upon some of the domes-
ticated kinds, particularly poultry. This has given
them a bad reputation with farmers. so long estab-
lished as to amount to traditional prejudice. Sci
entifc investigation Of their habits shows that only
a few species Of hawks and only one owl feed chief
ly, or even largely, upon birds. and therefore to
any great extent upon poultry. The birds of prey
regarded as chiefly Injurious include the sharp
Skinned, Cooper, and duck hawks. the %goshawk, and
the grent horned owl. The great horned owl, which.
like most of Its relatives. feeds at night, gets only
poultry that is improperly exposed, and when pre-
vented from doing this, It's habits are largely bene-
fetal.
The remaining species of hawks and owls, more
than 500 In all, have useful habits. They feed on
"A great variety OF rodents aud have n tremendous
effect In controlling the numbers Of these pests.
Their staple food consists for the most part Of
meadow mice, but 1t Includes also many other de
structlve rodents, such as rabbits. ground squlr-
rels, prairie dogs, pocket gophers. and house rats
and mice.
The barn owl Is one of the most useful Of the
birds Of this group. It's food IL ensily studied by
examination of the pellets, made of the hair and
bones Of Its victims. which accumulate about its
roost In G15 bafn-owl pellets collected In Wash.
ington, d. c. were found the remains OF Lilo