484 U.S. NATIONAL MUSEUM BULLETUST 2 37 part i 



it a quality characteristic of many finch songs. Other notes com- 

 monly given by the species are the light metallic clanking sounds 

 uttered frequently both perched and in flight. Another common 

 sound is a clear, plaintive, descending note, slightly less than a second 

 long, usually heard when the bird is in fairly dense foliage, often 

 when alone, and less frequently in the usual groups of 7 to 12. M 



Field marks. — Grinnell and Storer (1924) distinguish the green- " 

 backed goldfinch as follows: 



Half the size of Junco. Sexes dififerent 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. * * * 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-hke song; both sexes have plaintive-toned 

 call notes. * * * 



The Green-backed Goldfinch is shghtly smaller than either the Willow or the 

 Lawrence, and differs * * * in having yellow rather than white at the lower base 

 of its tail * * *. 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 * * * Lawrence Goldfinch the white is confined to the middle of 

 the feathers, reaching neither bases nor tips. * * * the marks on the tail are 

 to be seen satisfactorily only when a bird is in flight. * * * 



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. * * * The female Green-backed Goldfinch is 

 merely greenish, with the upper surface brown-tinged; and she lacks prominently 

 contrasted markings of any sort. 



Enemies. — In theu' varied relationships with numerous kinds of 

 birds on the Hastings Reservation, green-backed goldfinches ap- 

 parently recognize the danger in getting too near a Cooper's hawk. 

 In mid-June a male came within three feet of an incubating Cooper's 

 hawk and called repeatedly a series of musical, canarylike chu'ps untU 

 the hawk tried unsuccessfully to catch it. In early August seven 

 goldfinches perched three inches above a juvenal Cooper hawk uttering 

 food cries near the top of a tree. The finches made no attack, but 

 remained above the hawk as if wary of its presence. Later in the 

 month when a Cooper's hawk called, a nesting female goldfinch swung 

 about on her nest, stopped singing abruptly and "froze" for 8 minutes 

 before she again flicked her wings. 



One midday in early October 15 goldfinches dived into a willow 

 when a sharp-shinned hawk flew toward the flock. The hawk 

 singled out and pursued one bird, which twisted in flight to escape, 

 turning sharply each time the hawk was within 6 inches, thereby 

 gaining about two feet. The goldfinch finally dropped to safety into 

 a willow clump and the hawk flew off. During the chase neither 



