432 ANIMAL LIFE IX THE YOSEMITE 



grow at and above timber line. This is contrary to the testimony of several 

 observers, who, upon seeing the birds hopping about the edges of snow 

 banks where numbers of benumbed insects are often seen stranded on the 

 snow, conclude that the birds are engaged solely in gathering these 'cold- 

 storage bugs.' To most members of our field party who watched them, 

 the birds on or around snow banks appeared to be shucking out the seeds 

 of the previous year's crop, which the melting snow continually exposed. 

 Such a food supply carries over until the new crop is ripe. Some of the 

 seeds are sifted through the snow as it is swept into drifts by the autumn 

 winds; others are buried while still in the head, to be revealed only with 

 the receding of the snowfields as summer advances. One bird watched by 

 the junior author at the head of Lyell Caiion, July 17, was getting seeds 

 out of dry grass-heads at the rate of sixty a minute. 



On the other hand, two of our party reported undoubted instances of 

 animal food being taken. Mr. Camp noted numbers of Leucostictes about 

 the top of Conness Mountain above the 12,000-foot level, July 8, 1915. 

 Here they were, as usual hopping about the snow banks, and one bird 

 was plainly seen to pick up the cold-storage insects "continuously for two 

 minutes at the rate of one insect per second." The insects seen in the 

 snow were mostly small flies. Butterflies, moths, beetles, and squash-bugs 

 were also represented. The birds were in companies of six or less, and 

 would usually allow of an approach to within fifty feet. Again, on Dana 

 Meadows, July 6, 1916, Mr. Dixon watched two adult rosy finches "pulling 

 worms out of the turf." The birds were approached to within a distance 

 of twenty feet and even then they kept at their business with extraordinary 

 indifference. 



The present contention as to the prevalently vegetable character of the 

 food of the Sierra Nevada Rosy Finch is upheld by the contents of the 

 crops of several of the birds taken for specimens in August, 1911, in the 

 Mount Whitney region. These crops, ten in number, were subjected to 

 careful examination and their contents found to consist 91 per cent of 

 small seeds, and 9 per cent only of insects. The dilated gullet of a bob- 

 tailed young one taken August 22, 1915, on Mount Clark contained a gruel- 

 like mixture of shelled seeds (35 per cent) and insects (65 per cent),-* 

 evidently just fed to it by one of the parents. This last bit of evidence 

 is most important ; for in certain seed-eating birds, which adhere closely 

 to a vegetable diet most of the year, the young are fed with a greater or 

 less proportion of insects. The rosy finch seems to belong, along with 

 chipping sparrows and juncos, to this category of fringillids, rather than 

 with the strict vegetarians, like the linnets and goldfinches, to which 

 structurally it is thought to be more nearly related. 



24 Stomach examinations made for us by the United States Biological Survey, through 

 Dr. E. W. Nelson, Chief. 



