FOOD OF NESTLING EOSEBBEASTS. 55 



hopper season the data indicates at least a well-defined tendency of 

 the bird to neglect them. That it does not actually dislike grasshop- 

 pers there is sufficient proof, for John Bachman wrote to Audubon " 

 that a caged Specimen " ate grasshoppers and crickets with peculiar 

 relish," and Samuel Aughey " examined two specimens collected dur- 

 ing one of the historic invasions of the Rocky Mountain locust, each 

 of which " had about a dozen of locusts in its stomach." 



Comparatively little weight, however, attaches to these instp-nces, 

 since the conditions were unusual. It is worthy of note^ that the 

 closely related blackheaded grosbeak similarly neglects grasshoppers. 

 Four rosebreasts fed upon this class of insects, '2 securing the pe- 

 culiar shield-back grasshoppers, in one case to the number of 6, 

 which composed 85 percent of the stomach contents, while the other 

 2 birds had eaten an ordinary grasshopper and an orthopterous in- 

 sect not identified. 



The small quantity of animal matter not yet detailed comprises 

 spiders and their egg-sacs, which were eaten by 3 grosbeaks, and 

 insect eggs and a fly by 1 each. Only 1 bird of this species had 

 eaten a snail, which indicates that the rosebreast cares less for this 

 kind of food than does the cardinal. , 



Mineral Matter. 



Mineral matter, estimated in relation to the entire stomach con- ■ 

 tents, averaged 6.3 percent. Besides the ordinary sand and fine 

 gravel, fragments of fossil corals and crinoids had been utilized for 

 grinding material. 



Nestlings. 



Of the total. number of birds only 4 were young still being fed 

 by their parents, but, as usual among species whose diet is mixed, 

 the proportion of animal food to vegetable is much greater in the case 

 of fledglings than of adults. These 4 young rosebreasts consumed 

 78 per cent of animal and 22 per cent of vegetable matter. The 2 

 that were out of the nest were more highly vegetarian, one having 

 eaten 85 per cent of plant substances. The latter were a berry of 

 ■ rough-leaved dogwood, some blackberries, of which 45' pits were pres- 

 ent, and a few other seeds. Of the animal food consumed by the 

 4 young birds, caterpillars compose 20 percent, among them being 

 the larvae of sphinx moths, most of which are injurious to agricul- 

 ture. Almost 25 percent- is composed of beetles of various families, 

 including bronzy wood-borers, click-beetles, and leaf -beetles. Repre- 

 senting the last family are the species Melasoma lapponica, which 

 injures willow and cottonwood windbreaks, and that noted pest the 



"Audubon, J. J., Birds of America, III, 1841, p. 211. 



» First Ann. Kept. U. S. Ent. Comm., 1878, App. II, p. 32. 



