The Swainson Hawk 

 No. 334 



Swainson's Hawk 



A. O. U. No. 342. Buteo swainsoni Bonaparte. 



Description. — Adult male in normal plumage: Upperparts dark brown, fairly 

 uniform as compared with other Buteos, but centers of feathers inclining to lustrous 

 blue-black, the edges somewhat varied by lighter, or reddish brown; feathers of back, 

 crown, and nape with darker shafts, and the hind-neck with some outcropping of 

 basal white; upper tail-coverts lighter (area usually conspicuous in flight as whitish 

 patch), mingled gray, ochraceous, and white, with narrow bars of dusky; tail lightening 

 and changing to gray laterally, crossed by 8 or 10 narrow and not very distinct dusky 

 bands, of which the distal member much the largest; flight feathers dark brown to 

 purplish slate (according to age), lightly or scarcely barred on inner webs in de- 

 creasing ratio; point of folded wing formed by 3rd and 4th quills, reaching nearly 

 to end of tail, the 5th primary much shorter, about equal to the 2nd; 1st longer than 

 the 8th; the first three emarginate on inner web, the 2nd and 4th on outer; throat w-hite, 

 nearly immaculate; chest crossed by broad band of bright chestnut, marked by blackish 

 shaft-lines; remaining underparts w r hite, varied more or less by chestnut-rufous; the 

 lining of wings and crissum nearly immaculate. In melanistic phase: Throat pen- 

 cilled with black, and underparts clouded, chiefly in crosswise pattern, with chestnut; 

 upperparts dark sooty brown. (All stages of intergradation between this and normal 

 plumage.) Bill bluish black above and on tip, bright yellow on cere, gape, and base 

 of lower mandible; feet blackish; iris brown. Adult female: Similar to male, but 

 chest-band much darker, dark chestnut to brownish black; and remaining underparts 

 clouded and barred with chestnut or black on white ground; and white-barred poster- 

 iorly. In melanistic phase: Dark sooty brown above. Immature: Above dark 

 brown, varied by tawny edgings of feathers; head, neck, and underparts, including 

 lining of wings, dull tawny or light brown, the throat and middle of breast often nearly 

 immaculate, the head and neck sharply and narrowly streaked, breast, flanks, etc., 

 spotted or blotched variously, with blackish; quills and rectrices somewhat as in adult, 

 but barring usually a little more distinct. Adult male, length 482.6-508 (19.00-20.00); 

 extent 1244.6 (49.00); wing 386.1 (15.20); tail 215.9 (8-5°); tarsus 62.2 (2.45). Adult 

 female, length 520.7-558.8 (20.50-22.00); extent 1270-1422.4 (50.00-56.00); wing 406.4 

 (16.00); tail 241.3 (9.50); tarsus 76 (3.00). 



Recognition Marks. — Crow size; white throat; chestnut pectoral band of male, 

 dark chestnut and blackish of underparts in common melanistic plumage; usually 

 displays whitish rump; tail shorter and all proportions stouter as compared with 

 Marsh Hawk (which also has white rump); less stout and without red tail, as distin- 

 guished from B. borealis calurus. But there is no certain field mark by which a young 

 Swainson may be known from a young Red-tail. 



Nesting. — Nest: A stout platform of sticks, lined with bark-strips and fresh 

 leaves, placed at moderate heights in deciduous trees, tree yuccas, or sahuaros, some- 

 times on cliffs, rarely on the ground. Occasionally an old nest of crow or magpie is 

 refitted. Eggs: 1 to 4, usually 2; pale greenish-, bluish-, or grayish-white, often 

 tinged or obscurely spotted, rarely blotched, with dull reddish brown of various shades 

 or vinaceous gray. Av. size 56.5 x 44 (2.22 x 1.73). 



General Range. — North and South America. In North America only casual 

 east of the Mississippi River. Breeds from Alaska, northwestern Mackenzie, and 



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