2 COMMON BIRDS OF TOWN AND COUNTRY 
in the field, and the result is a large 
amount of invaluable data illustrative of 
the economic relations of many kinds of 
birds. This storehouse of information 
has been largely drawn upon in the fol- 
lowing pages. 
OUR COUNTRY IS PARTICULARLY FORTU- 
NATE IN THE NUMBER AND 
VARIETY OF ITS BIRDS 
It would be strange indeed if our land, 
with its vast extent of territory, its diver- 
sified landscape, its extensive forests, its 
numerous lakes and streams, with its 
mountains, prairies, and plains, had not 
been provided by Nature with an abun- 
dant and diversified bird life. As a mat- 
ter of fact, America has been favored 
with a great variety of birds famed both 
for beauty and for song. America also 
possesses certain families, as the hum- 
mingbirds and wood-warblers, the like 
of which exist nowhere else in the world. 
In considering the many kinds of 
birds in the United States from the prac- 
tical side, they may not inaptly be com- 
pared to a police force, the chief duty of 
which is to restrain within bounds the 
hordes of insects that, if unchecked, 
would devour every green thing. To 
accomplish this task successfully, the 
members of the force must be variously 
equipped, as we find they are. Indeed, 
while the 1,200 kinds of birds that inhabit 
the United States can be grouped in fam- 
ilies which resemble each other in a gen- 
eral way, yet among the members of the 
several families are marked variations of 
form and plumage and still greater vari- 
ation of habits, which fit them for their 
diversified duties. 
As the bulk of insects spend more or 
less time on the ground, so we find that 
more birds are fitted for terrestrial serv- 
ice than for any other. Our largest bird 
family, the sparrows, is chiefly terres- 
trial, and although its members depend 
much upon seeds for subsistence they 
spend no little share of their time search- 
ing for insects. They are ably aided in the 
good work by the thrushes, wrens, certain 
of the warblers, and many other birds. 
Another group is of arboreal habits, 
and plays an important part in the con- 
servation of our forests, the true value 
of which we have only recently learned 
to appreciate. So many insects burrow 
into trees that a highly specialized class 
of birds —the woodpeckers — has been 
developed to dig them out. The bills, 
tongues, feet, and even the tails of these 
birds have been cunningly adapted to this 
one end, and the manner in which this has 
been done shows how fertile Nature is in 
equipping her servants to do her bidding. 
The bark of trees also forms a favorite 
shelter for numerous insects, and behold 
the wrens, nuthatches, warblers, and 
creepers, with sharpest of eyes and slen- 
derest of bills, to detect our foes and to 
dislodge them from crack and cranny. 
The air is full of flying insects, and to 
take care of these there are the swallows, 
swifts, and nighthawks, whose wings and 
bodies are so shaped as to endow them 
with the speed and agility necessary to 
follow all the turns and windings of their 
nimble insect prey. 
The whip-poor-wills, swift of wing and 
with capacious mouths beset with bris- 
tles, attend to the night-flying insects 
when most birds are asleep, while the 
hawks by day and the owls by night sup- 
plement the work of other birds and have 
a special function of their own, the de- 
struction of noxious rodents. 
Thus every family of birds plays its 
own part in the warfare against insects 
and other foes to man’s industry, and 
contributes its share to man’s welfare. 
Birds would fall far short of what they 
accomplish for man were they not the 
most active of living things. It is curious 
that the group of vertebrates which live 
the fastest—that is, have a higher tem- 
perature and a more rapid circulation 
than any other—should be related by de- 
scent to a family of such cold-blooded 
creatures as the reptiles and_ lizards, 
which often go without food and hiber- 
nate for considerable periods. Very dif- 
ferent is it with birds. Few realize the 
enormous quantity of food required to 
sustain the energy of these creatures, 
most of whose waking hours are spent 
in a never-ending search for food. 
BIRDS CHECK RAVAGES OF DISEASE- 
CARRYING INSECTS 
In satisfying their own hunger birds 
perform an important service to man, for 
notwithstanding the fact that the acreage 
