BLACK-HEADED GROSBEAK 63 



their corresponding coverts are renewed at this time; other changes 

 in the bird's appearance are by wear. Males in the first nuptial 

 plumage may be readily distinguished by their brown wings, brown 

 or brown-and-black tails, and the fact that the top of the head retains 

 traces of coronal stripe. Adult second-winter plumage is acquired by 

 a complete molt involving wings, tail, and the entire body plumage; 

 it is probably complete by October. At this time the black head, 

 wings, and tail of the male, the latter with the conspicuous white 

 blotches on the two outer pairs, are assumed. This plumage is 

 essentially similar to the nuptial plumage which is acquired by the 

 wearing off of the pale feather edges of head and upper parts." 



Food. — For his report on the food of the black-headed grosbeak, 

 Prof. F. E. L. Beal (1910) examined the contents of 225 stomachs. 



These stomachs contained about 57 percent of animal matter to 43 of vegetable. 

 The animal matter is composed of insects and spiders, with a few traces of ver- 

 tebrates. Insects, such as beetles, scales, and caterpillars, constituted nearly 

 53 of the 57 percent of animal food. 



Of the animal food, beetles are the largest item. They were found in 190 of 

 the 225 stomachs. Of these, predatory ground beetles (Carabidae) were found in 

 16 stomachs, and ladybird beetles (Coccinellidae) in 2. To offset the destruction 

 of these useful insects, the 12-spotted diabrotica, which often does serious injury 

 to fruit trees, was found in 109 stomachs. Many weevils were found, and great 

 numbers of several species of leaf beetles (Chrysomelidae) . To this family 

 belongs the notorious Colorado potato beetle, which at one time seemed likely 

 to ruin the potato industry of the East. * * * When the potato beetle finds 

 its way into California, as eventually it undoubtedly will, the black-headed 

 grosbeak is the bird most likely to become its active enemy. 



Hymenoptera in the form of bees and wasps with a few ants aggregate less 

 than 2 percent. A worker honeybee was found in one stomach. Scale insects 

 amount to 19.83 percent, or practically one-fifth of the whole food. Most of 

 these were the black olive scale (Saissetia oleae), but a few were the plum and 

 prune scales {Lecaneum corni and L. ■pruinosum) . So persistently are scales 

 eaten by this bird that they were found in 142 of the 225 stomachs, or 63 percent 

 of all. ♦ * * 



Caterpillars, pupae, and a few moths aggregate 7.7 percent. * * * Pupae 

 or larvae of the codling moth were found in 26 stomachs, one stomach containing 

 the remains of 29. Flies, grasshoppers, a few other insects, spiders, and mis- 

 cellaneous creatures make up something more than 1 percent. 



Of the vegetable food, he says : 



Cultivated fruit amounts to 23 percent of the grosbeak's food for the six months 

 that it stays in the North. * * * Cherries appear to be the favorite fruit, 

 as they were contained in 42 stomachs. Figs were identified in 24 stomachs, 

 blackberries or raspberries in 23, strawberries in 2, apricots in 1, and prunes 

 in 1. * * * During cherry season these birds were almost constantly in the 

 trees eating cherries. They do not appear to attack apricots, peaches, and 

 prunes so extensively, but they feed freely on figs later in the season. Black- 

 berries and raspberries are taken whenever possible, but mostly in July and 

 August, after cherries are gone. * * * The only wild fruit identified was the 



