GOLDFINCHES 435 



over by each individual so that when a number are flying together in open 

 company, as is their custom, each rises and falls rhythmically but inde- 

 pendently of its companions. The relation between the lifting power of 

 the relatively large spread of flight feathers to the total bulk of the body 

 is such that a few rapid strokes of the wings will carry the bird in a 

 buoyant manner quite different from the direct flight of the heavy-bodied, 

 round-winged, brush-inhabiting sparrows. 



The Willow Goldfinch molts twice each year, once in the fall when 

 the entire plumage is replaced and again in late winter and spring when 

 only the body feathers are changed. The brilliant yellow garb of summer 

 is exchanged in August or September for a coat of greenish brown, and 

 the black cap of the male is lost. The prenuptial or spring molt is less 

 definite in time of occurrence. Some birds show new yellow feathers as 

 early as January while others still retain some brown winter feathers as 

 late as May, 



The nesting activities of this goldfinch do not usually begin until 

 summer is w^ell advanced, that is to say, until July. A female bird was 

 seen at Snelling carrying material for a nest on May 29 (1915), but other 

 birds observed on that date gave no indication of nesting. Our field work 

 at the lower altitudes did not cover the summer months when these birds 

 would ordinarily be expected to be nesting in numbers. 



Green-backed Goldfinch. Astragalinus psaltria hesperophilus Oberholser 



Field characters. — Half the size of Junco. Sexes different from one another both 

 summer and winter. Male: Body plumage dark greenish above, yellow below; whole 

 top of head, and wings and tail, black; in flight a patch of pure white appears on 

 middle of each wing and another shows at base of tail (fig. 53b). Female: Dull brown, 

 green-tinged above, and dull yellowish beneath; white patches, showing on wing and 

 tail in flight, small or obscure. Flight course of both sexes undulating. Voice: Male 

 has a pleasing canary -like song; both sexes have plaintive-toned call notes. 



Occurrence. — Common resident at lower altitudes on both sides of Sierra Nevada. 

 Recorded from Snelling and Lagrange eastward to Yosemite Valley; also, east of the 

 Sierras, near "Williams Butte and Mono Lake Post Office. Frequents open situations 

 among scattering trees or bushes; forages mostly in weed patches. Usually in pairs, 

 sometimes in small companies. 



The Green-backed Goldfinch is the most abundant and the most widely 

 distributed in the Yosemite region of the three goldfinches found there. 

 It is the least conspicuously marked of the three, the females in particular 

 being somber-hued. 



The Green-backed Goldfinch is slightly smaller than either the Willow 

 or the Lawrence, and differs from them, for one thing, in having yellow 

 rather than white at the lower base of its tail (the under tail coverts). 

 The white on the inner webs of the outer tail feathers of the Green-backed 



\^} 



LI 



