456 
ECONOMIC RELATIONS OF OUR BIRDS. 
not, in one or more stages of their existence, become a prey to them. And this 
division of labor which birds have assumed, in the face of the profusion of life 
from which they may choose their food, is conclusive evidence to me that the 
power which tliey exert over the abundance of insect life is far from being inap¬ 
preciable. The utility of birds as a whole, judged by that of a particular species, 
without reference to the points under consideration, would undoubtedly lead to 
an unfavorable, but equally false conclusion. What we need to aim at in regu¬ 
lating the bird-fauna of agricultural districts, is to make it combine, in sufficient 
abundance, all of those species which do peculiar but important work. We 
need, in fact, to adopt those divisions of labor which nature has been so long 
in working out, and perhai^s without modification, except so far as changing 
conditions and industries make it necessary that new relations should be estab¬ 
lished. 
To expect the Robin, with an unlimited abundance, to do the work of the 
Kingbird and Pewee, or that these birds can do the work of the Vireos, is ab¬ 
surd. Neither can the slow-winged and short-fiighted Pewee and Kingbird, 
although they are fly-catchers, be expected to do what the Swallows are able to 
accomplish with their long, swift, gyratory and zig-zag flights. Each species 
has fitted itself by long practice for its own peculiar work, and does it more 
effectually than another species can. Viewed in this light, it is evident that 
some birds, even though they may be somewhat destructive to particular crops, 
must, nevertheless, be protected, simply because they do an important work 
which other birds do not. 
The Baltimore Oriole has been consigned to extirpation because it is somewhat 
destructive to grapes, destroying at times, it is said, more than it needs to eat; 
and yet this bird does an important work, which, so far as I have observed 
among bii’ds, is peculiar to itself. It is that of feeding upon leaf-rollers in the 
larval state. These are a large and destructive group of moths. They infest 
nearly all our fruit trees, our strawberries and cranberries, as well as many of 
1 the trees of the forest. Those which do not infest the fruit protect themselves 
either by folding one side of a leaf over them, or by. tying a number of leaves 
securely together, thus forming a strong house in which they feed secure, I fear, 
from the majority of birds. But the Oriole has learned their habits, and, with 
its strong bill, is able to demolish their houses and devour the inmates. I have 
seen a whole family of these birds working together in a grove devouring leaf- 
rollers, and making such a noise as to lead me to suspect at first that some large 
animal was stripping the leaves from the trees. Pi’of. J. H. Comstock informs 
me that he has seen the same bird thrust its head through the web of the tent- 
caterpillar, and eat the larvae which courted security within. 
When a bird which is injurious does a' special work, that work must be an 
imi)ortant one in order that it may be urged as a reason for protecting the bird. 
The tent-caterpillar, although it is veiy destructive, is easily and completely 
under our direct control. Its tent makes it so conspicuous that it cannot be 
overlooked, while every worm in a colony may be easily removed at once and 
destroyed. When it is said that this evil sometimes becomes so great that even 
the best farmers have despaired of counteracting it, tlie statement only speaks 
disparagingly of the energy and shrewdness of the farmers. It is not in the 
destruction of such pests as these that birds render their greatest service, but 
rather in the destruction of those that are small, though prolific, of those that do 
not betray their existence until after their hurtful mission is performed, and of 
those that feed singly and do not congregate under tents for a season of rest 
and security. 
