Nov., 1911 
REI.ATION OF BIRDS TO AN INSECT OUTBREAK 
203 
ant about Sisson. Flocks containing hundreds of individuals were often seen 
feeding on the meadow-land or on the stubble fields. They seemingly paid no at- 
tention to the hordes of butterflies but busied themselves searching for vegetable 
food. Stomach examination showed a considerable quantity of oats and other 
seeds, probably waste picked up in the stubble fields. A very small percentage of 
the food was made up of small ground beetles and grasshoppers. 
Most of the Bullock orioles {Icterus bulhcki) seen were feeding on huckle- 
berries or other wild fruit. Eighty-two percent of the food in the stomachs ex- 
amined was made up of wild fruit, mostly huckleberries and elderberries. The 
only animal food found consisted of wild bees. 
The commonest sparrows were English sparrows (Passer domesticiis) in 
town. Brewer sparrows (Spizclla brezveri) in the weed patches, and thick-billed 
fox sparrows ( PassercJIa iliaca megarhyucJui) in the brush. The English sparrow 
appeared to be feeding entirely on weed seeds as did also the Brewer sparrows. 
The stomachs of three Brewer sparrows were filled wdth weed seed and a few small 
beetles. The fox sparrow appeared to be largely a vegetarian also, for 96 percent of 
the food in two stomachs was composed of weed seeds. Parts of two ground 
beetles formed the only animal food. The stomach of a mountain song sparrow 
{Melospiza nielodia inoiitana ) two cutworms, one iinidentified larva, 
one beetle larva, and one small bee. 
A bird of the brush, the green-tailed towhee {Oreospiza c/ilonira) , was found 
to feed largely on small beetles and seeds, for the two stomachs examined were 
filled with these kinds of food only. 
Only two species of woodpeckers w^ere available for examination. As most of 
the members of this family feed very largely on larvae it seems probable that their 
use as checks would be most noticeable when the larvae were abundant. The one 
stomach of the woodpecker most likely to feed on the butterfly, the red-shafted 
flicker ( cafcr collaris), failed to show any Engoiiia califoruica. Two 
flickers, feeding on the ground, were watched for twenty minutes, but the}^ paid 
no attention to the many butterflies. They walked along searching the ground care- 
fully for some sort of food, in all probability ants. The stomachs of two white- 
headed woodpeckers (Xcnopicus alboJarvatiis) were filled wdth vegetable matter, 
doubtfully identified as fungus, aud a few beetles. 
Blue-fronted jays {Cyaiiocitta stellcri frontalis^ were often seen either climb- 
ing to the top of a fir or sailing from the tip top of one tall tree to a lower one. 
Only once w'as one seen feeding on the ground. Five Eiigouia califoruica were 
found in one of the two stomachs examined. The other contained a number of 
large green larvae. It seems natural that a bird with the varied diet of the jay 
should turn to this particular form of insect food when it became available. 
A western bluebird {Siaiia mexicana occidentaiis) , perched on an old stump 
in a small grassy pasture, was watched for half an hour. It flew to the ground, 
caught a white moth, flew back to the stump and proceeded to tear it to pieces and 
eat it. During the next fifteen minutes it repeated the operation four more times, 
having within twenty minutes destroyed five moths. Butterflies were very abund- 
ant, but the bluebird appeared to prefer the smaller moths to the larger butterflies. 
Two stomachs were available for examination. One contained a number of small 
beetles and the other two grasshoppers. 
Large flocks of western robins ( Pianesticns migratoriiis propinguus) could 
be found wherever wild fruit wms abundant. Especially was this true where 
huckleberries w'ere common. The flocks were made up largely of juveniles. An 
examination of thirteen stomachs gave evidence that their food at that particular 
