96 BIRDS OF CALIFORNIA AFFECTING FRUIT INDUSTRY. 



greater extent than brood 1, although only 1 day older. Brood 4 

 was composed of 4 nestlings about a week old. They had been fed 

 on animal matter to the extent of 96 percent to 4 percent of vegetable. 

 The animal food was divided as follows: Beetles 67.6 percent, Hyme- 

 noptera 3 percent, caterpillars 2 percent, scales 20.7 percent, and 

 eggshells 2.7 percent. The vegetable matter consisted of hulls of 

 seeds and rubbish. The increase in beetles and other hard food and 

 the decrease in caterpillars in the diet of this brood, as compared 

 with the younger ones, is very marked. Brood 5 contained 3 young, 

 estimated to be 8 days old. These had been fed entirely on animal 

 food, made up of the following elements: Beetles 82 percent, Hyme- 

 noptera 10 percent, scales 6.3 percent, larvse 3.3 percent, insects' 

 eggs 1.7 percent, and spiders 2.7 percent. Another increase in the 

 hard elements of the food over the last is seen here, although the 

 difference in age is presumed to be only a day. 



Observations were made upon the feeding of nestling grosbeaks, 

 but the results are not remarkable. A nest of 3 young, estimated to 

 be about 3 days old when first seen, was watched for one-hour periods 

 for several days. The number of feedings varied from 2 to 4 per 

 hour. In this respect the grosbeaks much resemble the California 

 towhee. Like that bird they evidently collect a lot of food and then 

 supply all the nestlings by regurgitation. 



SUMMARY. 



In summing up the economic status of the black-headed grosbeak, 

 the fact that it eats a considerable quantity of orchard fruit can not 

 be ignored. That this fruit is taken from the ripening crop on the 

 tree is also true. This, however, is the sum total of the grosbeak's 

 sinning. It eats but few useful insects and practically no grain. To 

 offset its fruit eating, it eats habitually and freely the black olive 

 scale, the codling moth, and the 12-spotted diabrotica, three pests of 

 California fruit culture. Comparatively few complaints have been 

 made against this bird by orchardists, and its depredations are not 

 believed to be serious. Should it ever become so plentiful as to cause 

 serious loss, no attempts should be made to destroy the bird, but at- 

 tention should be directed to devices for protecting the fruit, thus 

 leaving the bird to continue its good work in the destruction of insects. 

 So active an enemy of insect pests as is this grosbeak can not well be 

 spared, especially in view of the possibility of an invasion of the 

 State by the Colorado potato beetle. a 



a For further information on the food of the grosbeak, see Bull. 32, Biological Sur- 

 vey, Food Habits of Grosbeaks, by W. L. McAtee, 1908. 



o 



