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 1 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 (Centaur ea 

 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 Hemiptera in 

 the form of plant lice. These were found in 46 stomachs distributed 

 through the four months from June to September inclusive, though 

 more than half of them were taken in August. One stomach was 



