78 FRIENDS OF OUR FORESTS 
warblers go only to the West Indies. The 
worm-eating, myrtle, magnolia, chestnut- 
sided, black-throated green, hooded, blue- 
winged, Nashville, orange-crowned, pa- 
rula, palm, and Wilson’s warblers, and 
the chat, go no farther than Central 
America, while many species spend the 
winter in South America, including some 
or all the individuals of the black and 
white, prothonotary, golden-winged, Ten- 
nessee, yellow, cerulean, bay-breasted, 
black-poll, Blackburnian, Kentucky, Con- 
necticut, mourning, and Canada warb- 
lers, the redstart, oven-bird, and both the 
water-thrushes. Nearly all the warblers 
of the western United States spend the 
winter in Mexico and the contiguous por- 
tions of Central America.” 
VAST NUMBERS SUCCUMB 
The northward journey in spring, away 
from the land of sunshine and plenty to 
the land of uncertain spring weather, is 
another matter. Probably if all birds 
that habitually abandon the north and 
winter in the south were to nest there, 
their quota, added to the number resident 
in the tropics, would be too great for the 
means of subsistence. 
Nevertheless, birds are not forced away 
from their winter quarters by inclement 
weather or impending famine, but by the 
subtle physiological change which warns 
them of the approach of the mating sea- 
son and fills them with new desires, 
among which is the compelling one of a 
return to the spot where they first saw 
the light, or where they reared last sea- 
son’s brood. 
Whatever the cause, the birds are not 
discouraged by the many and great perils 
that attend migration, and vast numbers 
every year succumb to them. Storms, 
especially off-shore storms, constitute the 
gravest peril, and there is abundant evi- 
dence that millions of birds are annually 
blown out to sea to find watery graves. 
Perhaps no family suffers more in the 
aggregate than the warblers. Thinly 
feathered, delicately organized, highly in- 
sectivorous, they are exposed to unusual 
dangers while birds of passage to and 
from their nesting grounds. 
It is a matter of common observation 
that every few years in some given lo- 
cality, perhaps embracing a region of con- 
siderable size, a particular species of 
warbler or other bird suddenly becomes 
rare where before common. After a sea- 
son or so, though sometimes not for years, 
the equilibrium is reéstablished and the 
numbers are as before. ‘These changes 
very probably are the visible signs of 
migration catastrophes, the result of the 
sweeping away of a migration wave, com- 
posed of one or of many species, in the 
path of some sudden storm. 
Again, many of us have witnessed the 
dire effects of a prolonged rain and sleet 
storm in spring, when thousands of luck- 
less migrants find only too late that they 
have prematurely left the warmth and 
plenty of their tropical winter refuges. 
Under such circumstances thousands of 
migrants perish from the combined effects 
of cold and starvation, and among them 
are sure to be great numbers of warblers. 
ECONOMIC VALUE OF WARBLERS 
From the esthetic point of view, our 
warblers, as a group, occupy a high and 
unique position. They also occupy no 
uncertain place in the list of our useful 
birds. Preéminently insectivorous, they 
spend their lives in the active pursuit of 
insects. They begin with the eggs, prey- 
ing upon them whenever and wherever 
found, and continue the good work when 
the egg becomes the larva and when the 
larva becomes the perfect insect. 
They are especially valuable in this re- 
spect because of the protection they lend 
to forest trees, the trunk, bark, and foli- 
age of which they search with tireless 
energy. Their efficiency is vastly in- 
creased because the many different spe- 
cies pursue the quest for food in very 
different ways. While some confine their 
search chiefly to the trunks and large 
branches and examine each crack and 
crevice in the bark for eggs or larve, 
others devote their energies to the twigs 
and foliage, scanning each leaf and stem 
with eager eyes. Still others descend to 
the ground and examine the rubbish and 
grass for hidden prey, while nearly all 
are adept at catching insects on the wing. 
Each species, however, has a method 
of its own, more or less unlike that of its 
fellows, and each excels in some specialty. 
Not only does the group as a whole spe- 
