26 THE AU DU BON Bir PEsiais 
named. The densest bird population anywhere recorded is near Washing- 
ton, D. C., where a careful count showed, in 1915, one hundred and thirty- 
five pairs of forty species on five acres. [wo city blocks, well furnished 
with trees, in the city of Aiken, S. C., harbored sixty-five pairs on ten acres. 
These high figures show the important results which will follow from 
careful protection and encouragement of birds.” 
On the basis of these surveys, we may estimate that there are about two 
wild birds per acre in the State of Illinois. “This would make almost 
70,000,000 birds in the state. This great army of servants goes forth each 
morning in search of insects and grass and weed-seed for their daily food. 
Their days are filled with unending effort to satisfy their appetites. That 
they do a real service to agriculture, no one who studies the question can 
doubt. To get a fair estimate of the service they render requires intensive 
study. 
Before we calculate the value of birds, let us get some picture of the 
insect problem. It is well to keep in mind that “insects comprise fully 
fourth-fifths of the animal kingdom. Nearly 400,000 species have been 
named and described, and several millions are probably in existence.” Of 
the losses due to insects many estimates have been made. A statement was 
made by the United States Department of Agriculture that the total loss 
to the farmers of the United States is approximately a billion dollars annu- 
ally. his is a conservative estimate. Some of the heavier losses caused by 
insects are as follows: 
Fruitstrees (eta oe eee $ 65,000,000 
Forest trees... ht Shai ae ee 100,000,000 
Cottons 2s ce A a 250,000,000 
Wheéatiy ch. GS nor cee Bae Aa ane eee 150,000,000 
Corn Jet. at en ee 100,000,000 
Vegetables... 5-3 Se eee 120,000,000 
Hayes ger bi gic te ere nt, eee nS 60,000,000 
Wiiscellaneous (inc. sprays yn eee 155,000,000 
Estimates of such losses are only approximate, as additional yields may 
bring down prices to offset much of these losses, but based on current prices 
they may be taken to represent a fair value of produce consumed annually 
by insect pests. 
Let us now estimate, if we may, just what relation birds sustain to this 
great host of insect life. On this subject we have definite figures from 
many sources. Weed observes that certain species visit the nest during the 
height of the brooding period, over 400 times daily, and take, each time, 
from 5 to 50 insects, or up to 400 insect eggs. 
In the Yearbook for 1928, United States Department of Agriculture, 
we find the following: “To illustrate the destructive capacity of birds, it 
may be mentioned that from 3,000 to 5,000 insects have been found in a 
