10 BULLETIN 1249, IT. S. DEPARTMENT OF AGRICULTURE. 



and the remaining six months by 41. In view of this unequal 

 seasonal distribution, the winter and summer food habits are con- 

 sidered separately. 



Winter food. — The fondness of the red crossbill for the seeds of 

 conifers, which has been noticed and commented on by almost every 

 ornithologist who has observed its feeding habits, is borne out by 

 stomach examination. Seeds of conifers, almost the entire contents 

 of 195 stomachs, amounted to 96.47 per cent of the winter food. 

 Practically every seed was shelled, even the thin inner seed coat 

 being removed, leaving only the soft white endosperm and embryo. 

 As the contents of the distended esophagus also were examined 

 when available, the seeds were seen before they had been crushed 

 or digested to any appreciable extent. The condition of these seeds 

 furnishes an admirable illustration of the dexterity with which the 

 peculiar mandibles of this species are used, as many stomachs were 

 filled with seeds that were not scratched or broken in any way during 

 the removal of the seed coats. 



The variation in the food of this crossbill seems to be geo- 

 graphical rather than seasonal, and the species of seeds of conifers 

 recognized were from the few that had been swallowed without 

 being hulled. Pines (Pinus spp.) are the ones best represented. 

 Seeds recognized as belonging to this genus comprised 78.29 per cent 

 of the food during the winter. That scrub pine (P. mrginiand) and 

 western yellow pine {P. ponderosa) were the species most commonly 

 found was to be expected, as the majority of the stomachs were 

 collected in localities in which these trees predominated. White 

 pine (P. sfrohus) and red pine (P. resinosa) also were identified. 

 Other conifers recognized were spruce (Picea mariana and Picea 

 sp.) and hemlock (Tsuga canadensis). 



One stomach collected in March was filled with seeds of ragweed 

 (Ambrosia elatior) and two contained chiefly mast, 100 and 80 per 

 cent of the contents, respectively. Other vegetable food included 

 bits of wood, pine needles, and a few small fragments of unidenti- 

 fied seeds. 



Animal matter amounted to only 1.07 per cent of the winter food 

 and was composed of spiders (found in two stomachs to the extent of 

 30 and 20 per cent, respectively), caterpillars (in three stomachs, 

 forming 100, 20, and 10 per cent of the contents), and fly larvae 

 in two stomachs (100 and 50 per cent). Probably all these were 

 picked from conifers ; and this was certainly true of one caterpillar, 

 as it had been feeding on pine needles. 



Summer food. — The material collected during the months from 

 May to October, inclusive, is too scanty to furnish a satisfactory 

 basis; for computing monthly food averages. Tabulation of the 

 contents of the 41 stomachs representing this period shows that the 

 percentage of animal food is 18.02 and vegetable food 81.98, com- 

 pared with 1.07 per cent and 98.93 per cent, respectively, for the 

 winter months. 



Coniferous seeds, constituting 68.34 per cent of the total contents, 

 were found in 31 stomachs. The following species were identified : 

 Western yellow pine {Pinus ponderosa), shortleaf pine (P. echi- 

 nata), Engelmann spruce (Picea engelmanni) , and a larch (Larix). 

 Seeds of a sedge (Scirpus) and of one of the sunflower family 

 (Asteraceae) furnished 1.69 per cent of the food. Unidentified 



