OUR LARGEST STANDING ARMY: THE BIRDS. 
Bv Clarence Moores Weed. 
NK of the re- 
sults which the 
study of in- 
sects has re- 
peatedly ver- 
ified is that, 
as a rule, the 
greatest dam- 
age to culti- 
vated crops is done by those species 
of insects or other animals that fluc- 
tuate greatly in numbers. Nearly all 
the insect pests of first importance, 
like the army worm, the canker 
worm, the Hessian fly, and many 
others, are sometimes so scarce that 
they are not noticed, while at others 
they become overwhelmingly abun- 
dant. 
Any agency which tends to estab- 
lish an equilibrium in their numbers 
and thus to prevent their undue in- 
crease is a beneficent one. The 
birds are the creatures to whom we 
most naturally turn for help of this 
sort, and in this brief paper I wish to 
call attention to some remarkable 
investigations undertaken to deter- 
mine whether in the presence of an 
extraordinary outbreak of a given 
insect the birds vary their food ra- 
tions by taking unusual numbers of 
the species in question. If they do, 
evidently they assist in reducing the 
pest to its normal limits; if they do 
not, they neglect an opportunity for 
usefulness. 
It need scarcely be stated here that 
xxv- 22 
one of the strongest arguments for 
the protection of birds must be found 
in definite scientific studies of their 
food. If we can prove that the birds 
are absolutely essential to the suc- 
cessful production of crops we have 
an argument which must appeal 
forcefully even to the most practical 
of the so-called practical men. 
A few years ago a large apple or- 
chard in central Illinois was severely 
attacked by canker worms. As a re- 
sult of their depredations a consid- 
erable part of the orchard had the 
appearance, at a little distance, of 
“having been ruined by fire.” To 
determine whether the birds of the 
region were exerting themselves to 
check this outbreak, Prof. S. A. 
Forbes visited the orchard for two 
successive seasons, shooting each 
time a number of birds of the vari- 
ous species present. The stomach 
contents of these were afterwards 
carefully examined. From the pub- 
lished record of the results (Bulletin 
Illinois vState Laboratory of Natural 
History) I have made the following 
summary : 
Nine robins had eaten only animal 
food, of which canker worms formed 
twenty per cent., cutworms twenty- 
eight per cent., and vine chafers 
fourteen per cent., making a total of 
sixty-two per cent, for these three 
groups of insects. Eleven per cent, 
of the remainder consisted of click 
beetles ( Elaieridce ) . Fourteen cat- 
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