430 



ANIMAL LIFE IN THE YOSEMITE 



swings, as are the flight notes of the Willow Goldfinch. While feeding, 

 either on the ground or in the terminal foliage of the lofty trees, the 

 crossbills were silent. 



The usual forage niche of the Sierra Crossbill is in the tops of conifer- 

 ous trees where the bird obtains the seeds from the ripening cones. In 

 extracting these seeds the peculiarly crossed mandibles are believed to 



be especially helpful, for by 

 their use a bird, in turning 

 its head, gets a double lever- 

 age to separate the scales of 

 the cone. (See fig. 51.) 

 Some of the crossbills' sub- 

 sistence is gained on the 

 ground. Like the purple 

 finches, they do not forage in, 

 or frequent, intermediate sit- 

 uations such as brush patches. 

 One of the birds at Tuolumne 

 Meadows, upon being col- 

 lected, was found to have its 

 throat crammed with seeds 

 of the lodgepole pine ; the 

 birds at Hazel Green were 

 getting a variety of seeds and grain from the barnyard litter. 



We found no direct evidence of nesting on the part of the crossbills 

 which we saw or collected, nor were any young in the streaked juvenal 

 plumage observed. The skin of the abdomen of a female collected at Hazel 

 Green on May 14, 1919, was bare and wrinkled, and rather leathery in 

 texture, as if it had been glandular. Its condition was that to be expected 

 in a bird which had been incubating perhaps two months previously. 



Fig. 51. Bill of Sierra Crossbill, from (a) 

 side and (b) above; and (c) cone and (d) seeds 

 of lodgepole pine; all natural size. The twisted 

 mandibles enable the bird easily to spread the 

 scales of the pine cone and to obtain the seeds 

 thus released. 



Sierra Nevada Rosy Finch. Leucosticte tephrocotis dawsoni Grinnell 



Field characters. — Larger than Junco; size of White-crowned Span-ow. Color chiefly 

 deep chestnut brown, with rosy red edges or tipplngs to feathers on rump, tail, and base 

 of wing; forehead black, joined behind by a broad gray patch which extends down to 

 level of eye. Female lighter than male in tones of color; body plumage of young more 

 grayish. (See pi. 1.) Forages in scattered flocks on open ground, usually above timber 

 line. Flight and manner much as in Siskins, though size considerably greater. Voice: 

 Loud, rather hoarse chirps, few together, rarely anything like a chorus. No song of any 

 sort heard by us. 



Occurrence. — Resident in Alpine-Arctic Zone, descending at times into Hudsonian 

 Most often seen in summer on open ground around edges of snow banks above the 10,500- 

 foot contour. "Westernmost stations, Mount Hoffmann and Mount Clark; easternmost, 

 "Warren Mountain. In pairs at nesting time; flocking at other seasons. 



