BIRDS—THEIR MIGRATIONS AND SOJOURNINGS. 
235 
their departure is evidently from no inability to 
endure without inconvenience a much greater 
degree of cold than they usually experience. 
They always leave warmer weather in the fall 
than they find in the spring. Individuals of 
species which leave early for the south will 
sometimes remain during the winter if by any 
means they may find food ; some species of the 
same family remain while others go southward, 
and finally resident birds will sometimes make 
irregular migrations if they can obtain more 
abundant supplies. 
Swallows and bobolinks, for instance, make 
their appearance in the upper valley outlie Hud¬ 
son about the last of April, and leave late in Au¬ 
gust. September—perhaps October—is milder 
than May, and we can not attribute their de¬ 
parture to the cold. And representatives of 
various species which leave early for the south, 
especially robins, may be found at any time 
during the winter under the dense cover of ever¬ 
greens, where they grow on protected hill-sides, 
and the ground thickly laid with fallen tresses 
of white pine and hemlock, while the shingle¬ 
like boughs shut out the severest snows. I 
have known larks, which are among the very 
wildest of our summer birds, to remain all win¬ 
ter about barn-yards, when the cattle were not 
stalled as now, and the feeding ground was more 
extended. On one occasion, when we were im¬ 
proving a fine flax-day in February, an old lark 
with a heart upon the breast almost as perfect 
as that within, while scratching and burrowing 
in a heap of chaff, was pounced upon by a large 
hen-hawk; but the prey being somewhat ob¬ 
scured the aim was not fatal. A lively scuffle 
followed in the chaffheap, and for a time it 
seemed the old adage would be falsified; but 
the old lark was tough and vigorous, and finally 
slipped away, and then, mounting up as only a 
freed lark can, she struck off in a straight line, 
looking back over either shoulder alternately, giv¬ 
ing an indignant and terrified “yirp,” “ yirp,” 
with every successive jerk of her wings. 
This hawk—the noblest bird of our woods 
now that forests and eagles are gone—does not 
leave at the approach of winter. You may see 
him on one of those clear still mornings which 
usually follow a snow-storm, perched on the hor¬ 
izontal limb of an oak, and, if you have'no gun, 
you may come near enough to catch his expres¬ 
sion as he turns his clear gray eye down upon 
you. I once shot one of them after a long 
snow-storm in mid-winter, when, being sorely 
pressed by hunger, he was feeding on a carcass 
placed as a bait for the crows. The other spe¬ 
cies, down to the little sparrow-hawk which 
builds in the hollows of trees, though having as 
much endurance as he, and a habitation some¬ 
what suited to winter, all finding their prey 
among migratory birds, with them, now as in 
the time of Job, “ stretch their wings toward 
the south.” 
Some species of the hawk family migrate ir¬ 
regularly in flocks, or rather collections. I saw 
a remarkable instance of this last October. A 
cluster of about sixty, so high that they appeared 
like swallows, were wheeling in graceful lines, 
and diving through and through among one 
another, but still all moving in one direction, 
toward the northwest. I have seen other in¬ 
stances when they passed over more directly 
and consecutively, but also at a great height. 
Other instances of much larger numbers have 
been mentioned, but such are not frequent. Old 
hunters used to regard them as “ signs,” and 
tell of a vast host before the war of 1812. There 
is indeed something ominous in their silence and 
unusual manner, and we may remember that, 
from having seen six vultures, Romulus took 
heart and built a city. The whistle of the 
hawk when sailing in the upper air always 
comes down to us plainly, though from a great 
height, because of its clearness, but on these 
occasions they are always silent. Birds of the 
hawk family follow the migrations of birds on 
which they prey, and when they had appeared in 
these collections wild pigeons had been numer¬ 
ous in the adjacent woods. In the instance 
mentioned of last autumn pigeons had appeared 
in great numbers on the white oaks; attracted, 
not by the acorns, of which they are so fond, 
but by a species of caterpillar which* sheared off 
every leaf, leaving whole forests as if passed over 
by a fire. But the caterpillars had disappeared, 
and with them the pigeons and the hawks were 
a hunting-party in pursuit. 
The pigeon flies much more swiftly than the 
hawk, and is safe unless the latter comes un¬ 
seen and gets fairly above, and even then, in 
open flying, it can easily get out of danger. 
But in such cases fear often fails to lend wings. 
I have seen a hawk get above a pigeon by com¬ 
ing suddenly upon him, and the poor bird, low¬ 
ering gradually to avoid the clutch, was pressed 
to the very ground and caught, in a life-struggle 
of five hundred yards. A sparrow-hawk poun¬ 
cing upon a flock of blackbirds may have his 
pick if his aim is sure; but if he miss the whole 
flock are in the air above him, and find it pas¬ 
time to keep the vantage. So with the doves 
and their traditional enemy. The hawk can no 
more overtake his prey in fair flight than a lion 
can catch an antelope. Some pf the falcons 
are swift flyers ; but birds of prey in their flight 
are bold and silent rather than swift, and de¬ 
pend upon strategy more than speed. 
The rearing of their young is the great mis¬ 
sion of migratory birds in their summer home ; 
and to this fact we must look for. an explana¬ 
tion of the phenomena of migration and sojourn. 
This is the only use they make of our summer. 
They come and build when food for their young 
is ready, and leave when it is no longer suita¬ 
ble for that special purpose. That food con¬ 
sists almost entirely of worms and insects—the 
tender worms which feed on the juices of the 
early leaves. The putting forth of vegetable 
life is very rapid and the sole work of early 
spring. The long warm summer adds nothing 
to the length of the stem or to the number or 
size of the leaves. Its work is to mature. The 
