The Cooper Hawks 



twenty to fifty feet. Occasionally an old squirrel nest is utilized, though 

 oftener the birds build their own nest, of small sticks neatly lined with 

 smaller twigs, and sometimes of so loose a construction that light appears 

 through any part of it when viewed from below. 



Both birds assist in the duties of incubation, and they are unusually 

 brave in the matter of sticking to the nest under fire. No amount of 

 rapping on the base of the tree will flush the sitting bird, and it will not 

 often leave until the nest is almost reached. When disturbed both birds 

 will make a high-spirited defense; and the female, who is, of course, the 

 larger, will dart at the climber so boldly as occasionally to brush him 

 with her wings. A wrathful yip, yip, yip, yip, yip is likely to accompany 

 this attack; and the notes serve again to remind one of the bird's affinity 

 to the Cooper Hawk. 



Quite apart from any possibility of nest defense — it was in open, 

 hilly country near Cholame — I once heard a Sharp-shin tirade of rather 

 startling proportions. The bird was in full pursuit of a Pacific Horned 

 Owl and it shouted Ricky, ticky, ticky, ticky, ticky, with an animation 

 which was both thrilling and terrifying, — the same note, I should judge, 

 as would have been used by a bird in defense of its young. The hawk 

 dived repeatedly at the owl, as the latter wended her virtuous way to her 

 own nest, and although she took good care not to strike, she upbraided 

 her in language which quivered with passion. Perhaps the owl had been 

 naughty, but what arrant hypocrisy in a Sharp-shin! 



No. 328 



Cooper's Hawk 



A. O. U. No. 333. Accipiter cooperi cooped (Bonaparte). 



Synonym. — Chicken Hawk. 



Description. — Adult: Similar to preceding species, but decidedly larger; the 

 top of head deeper slate, or blackish, in sharper contrast to remaining upperparts, 

 which are lighter than in velox; females average browner, and there is in both sexes a 

 more marked tendency to outcropping of basal white on hind-neck; the tail slightly 

 or considerably rounded; sides of breast often tinged with bluish gray. Immature: 

 Similar to that of preceding species; more extensively tawny on crown and cervix; 

 more outcropping of basal white on hind-neck and scapulars; chest often tinged with 

 cinnamon-rufous; streaking of underparts less abundant, more sharply defined, and of 

 darker shades; belly and sometimes throat immaculate, or tending to become so, 

 Differences between adult and young rather more clearly marked than in A. velox. 

 Very variable in size. Adult male, length: 355.5-431.8 (14.00-17.00); wing 215.9- 

 241.3 (8.50-9.50); 177. 8-215. 9 (7.00-8.50); bill from cere 15. 2-16.5 (-6°-. 65). Adult 



1663 



