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 Goldfinch extends to the bases of the feathers, but not to the tips, whereas in the Willow Goldfinch the white extends to the tips of the feathers lint not to their bases. (See fig. 53.) In the Lawrence Goldfinch the white is confined to the middle of the feathers, reaching neither bases nor tips. Sharp observation of the birds is necessary to determine these points, and the marks on the tail are to be seen satisfactorily only when a bird is in flight. There are other characters, however, upon which to depend for identification of the goldfinches.

The Green-backed Goldfinch never shows any yellow on the wing, whereas the Lawrence Goldfinch always shows this color in considerable amount. The male Green-backed Goldfinch is quite dark colored above darker than the males of either of the other two species. It never has the black chin which characterizes the Lawrence Goldfinch. The female Green-backed Goldfinch is merely greenish, with the upper surface brown-tinged; and she lacks prominently contrasted markings of any sort.

Fig. 53. Tails of the (a) Willow, (b) Green-backed, and (c) Lawrence goldfinches, and (d) Pine Siskin; natural size. The distribution of white (clear) is diagnostic in the three Goldfinches; the Siskin has yellow (sparse shading) at base of tail. These differences can often be made out when the birds are in flight.

We found Green-backed Goldfinches common in the lowlands and foothills, for example, at Snelling, Lagrange, and El Portal; and on June 24, 1915, two were noted in Yosemite Valley. By the end of July the same year the species had become common on the floor of the Valley, due no doubt to an up-mountain migration of birds which had nested earlier in the season at the lower levels to the west. On August 19, 1915, fully 15 of the birds were seen on the north side near Yosemite Falls and on September 5 two were noted near the Kenneyville stables. In 1920 individual birds were in the Valley as late as October 24 (C. W. Michael, MS). East of the Sierras the seasonal status of the Green-backed Goldfinch is not definitely known. It was already present in May, and continued there as late as September 20 (1915); but that the birds continue through the winter in that region is doubtful. Eighteen individuals were seen near Williams Butte during an hour's census on the morning of September 18, 1915.

On June 23, 1920, a nest of this goldfinch was under construction 7 feet above the ground on a lower outswaying branch of a lodgepole pine growing on the floor of Yosemite Valley. The female was gathering material and the male was attending her closely; but when they visited the site he did not get into the nest, as she did.

On July 14, 1920, two nests of the Green-backed Goldfinch were found at Dudley, 6 miles east of Coulterville. One was 18 feet above the ground in an upward-shooting 'water-sprout' of a pear tree and the other at an equal height and similarly situated in an apple tree. The eggs numbered 3 and 4, respectively, and were all fresh.

Throughout the year the Green-backed Goldfinch feeds very largely on seeds of herbaceous plants, shelling them out deftly while clinging to the dry flower heads. Plants of the sunflower-thistle order (Asterales) furnish the greater portion of the forage of these, our smallest finches. The dry nature of this food evidently makes it necessary for the birds to drink frequently for they are regularly seen visiting watering places to quench their thirst. About human habitations they are often seen drinking from dripping hydrants. In doing this a bird will perch on the faucet, lean downward, and, maintaining its balance by an occasional flutter of the wings, catch the drops of water as they emerge from the spout.