SPARROW FAMILY. 73 
up so that recognition is impossible. A few stomachs contained a 
vegetable food that could not be identified, perhaps some large seed 
broken up and discolored. Two stomachs containing this substance 
were those of nestlings 12 days old. One was entirely filled with it, 
but the other contained 75 percent of caterpillars. 
SUMMARY. 
There are probably few birds that do so little harm as the willow 
goldfinch. Its animal food, though small in quantity, is composed 
entirely of harmful insects. It eats no fruit and practically no grain. 
Most of its food consists of the seeds of noxious or neutral plants. Its 
food habits commend the bird, as much as its bright plumage and 
fine song. 
GREEN-BACKED GOLDFINCH. 
(Astragalinus psaltria hesperophilus.) 
The green-backed goldfinch (Pl. VI) occurs over most of California, 
except the mountains and the deserts, and is one of the most abun- 
dant birds. It is a lover of the orchard and garden, and delights to 
linger along the roads and in weed patches. Its favorite feeding 
grounds are in open pastures, where the bur thistle (Centaurea 
melitensis) grows, a plant specially adapted to the wants of the gold- 
finch, for it throws out from the roots short seed-bearing stalks that 
bear seed, while the rest of the plant is making growth and getting 
ready to produce the main crop. The goldfinches know where these 
seeds are, and apparently get every one of them. Next in favor is the 
groundsel (Senecio), which grows in orchards, and on the unripe seeds 
of which the goldfinches feed to repletion. In the investigation of 
the food of this bird 476 stomachs were examined. They were taken 
in every month, and are well distributed, Animal food amounts to 
1.7 percent and vegetable food to 98.3. 
Animal food.—Animal food was contained in 50 stomachs, all 
taken in the four months from June to September inclusive, except 
one, which was taken in November. This stomach contained 20 per- 
cent of some insect food, apparently flies. In one stomach taken in 
September beetles formed 1 percent of the contents. No other trace 
of a beetle was found. A small wasp or bee was identified in one 
stomach, also taken in September. It amounted to 2 percent of the 
contents and was the only hymenopterous insect found. Cater- 
pillars amount to only a small fraction of 1 percent, and were con- 
tained in 2 stomachs, one taken in June and the other in July. 
The great bulk of the animal food was made up of Heme z 
the form of plant lice. These were found in 46 stomachs ay UL 
through the four months from June to September inclusive, ae 
more than half of them were taken in August. One stomach was 
