44 U.S. NATIONAL MUSEUM BULLETIN 237 pakt i 



that of rose-breasts and the lower mandible the same color as the rose- 

 breast; the upper mandible of the younger bird is darker but not quite 

 so dark as that of the adult black-head ; the lower mandible the same 

 as that of the rose-breast. The molt of neither is complete on this 

 date. 



"I might add here that the molt of both the black-headed and rose- 

 breasted grosbeaks begins about the middle of January and takes 

 about 4:% months to complete." 



Myron Swenk (1936) summarizes the knowledge of hybridization 

 between rose-breasted and black-headed grosbeaks in the Missouri 

 Valley, and David A. West (1962) made a detailed study of those 

 hybrids where their ranges overlap in the Great Plains. 



Food. — In his exhaustive report on the subject, W. L. McAtee 

 (1908) gives the following summary: 



Examinations of 176 stomachs of rose-breasted grosbeaks show that the food 

 is composed of animal and vegetable matter in almost equal parts, the exact 

 proportions being 52 and 48 percent, respectively. Of the portion of the diet 

 gleaned from the plant kingdom, 5.09 percent is grain, 1.37 garden peas, and 

 19.3 wild fruit. * * * 



Wild fruit is greatly relished, but cultivated fruit is not damaged, and although 

 budding is practiced to a certain degree practically no harm results. 



The rosebreast preys to some extent upon such beneficial insects as parasitic 

 Hymenoptera, ground beetles, ladybirds, and fireflies. Only a tenth of the animal 

 food is of this character, however, while among the remaining nine-tenths, which 

 consists almost exclusively of injurious insects, is included a large number of for- 

 midable pests. Among these are the cucumber beetles, the hickory borer, plum 

 curculio, Colorado potato beetle, Rocky Mountain locust, spring and fall canker- 

 worms, orchard and forest tent-caterpillars, tussock moth, army worm, gipsy [sic] 

 and brown-tailed moths, and the chinch bug. The bird is known as an active 

 enemy of the cankerworm and the army worm during their extraordinary ingesta- 

 tions, and was among the birds which preyed upon the Rocky Mountain locust 

 and the gipsy moth at the height of their destructiveness. 



Then follow long lists in detail of the various items of the vegetable 

 and animal food. 



H. Lewis Batts, Jr. (1958), specifies leaf beetle larvae, Blepharida 

 rhois, favored as food for the nestlings. 



Mrs. Amelia R. Laskey writes to me that she has seen a rose- 

 breasted grosbeak eating elm seeds, "often hanging head downward 

 Hke a chickadee to pluck the seeds." And Robert H. Hansman 

 tells me that these birds may be "observed opening the long seed 

 pods of the catalpa to obtain the seeds, of which they are very fond." 



B. H. Warren (1890) mentions that all these grosbeaks, taken in 

 May and examined by him, had been feeding on the blossoms of 

 hickory and beech trees. Dr. Charles H. Blake writes that the buds 

 eat buds of the white ash, Fraxinus americana, in spring and the fruit 

 of the European mountain ash, Sorbus aucuparia, in late August. 



