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THE CONDOR 
Vol. XIII 
were collected. It was found that “birds of the most varied character and habits, 
migrant and resident, of all sizes from the tiny wren to the blue jay, birds of the 
forest, garden, and meadow, those of arboreal and those of terrestrial habits, were 
certainly either attracted or detained here by the bountiful supply of insect food 
and were feeding freely upon the species most abundant. That thirty-five percent 
of the food of the birds congregated here should have consisted of a single species 
of insect is a fact so extraordinary that its meaning cannot be mistaken.” Professor 
Forbes also found that the same percentage of other caterpillars had been eaten by 
the birds in the orchard as had been eaten by birds taken in other localities and 
that the cankerworm ratios had apparently been added to those of other caterpillars. 
Fig. 67. DEKoniATBm SNOW BRUSH (Ceanothiis cordulatits) , the resuet oe The 
WORK OF THE earvae OF Eugoniu californica. photograph taken 
NEAR SISSON, SISKIYOU COUNTY, CAEIFORNIA, AUGUST 24, 1911 
The most prolonged series of studies of the relation of birds to insect out- 
breaks was that by Professor Samuel Aiighey, who for thirteen years studied the 
extent to which birds fed on the Rocky Mountain locust or grasshopper during the 
periodic outbreaks of that insect. His tabulated results show that birds of every 
description from the pelican to the tiny hummingbird fed to a very large extent on 
the grasshoppers. 
The relation of birds to the army worm , which is one of the best known of 
the periodical pests, has received some investigation at the hands of the economic 
ornithologist. Professor B. H. Warren, the state zoologist of Pennsylvania, mak- 
