The Bonaparte Gull 



No. 280 



Bonaparte's Gull 



A. O. U. No. 60. Chroicocephalus Philadelphia (Ord). 



Synonyms. — Sea Pigeon. Bonaparte's Rosy Gull. 



Description. — Adult in summer: Head including throat blackish slate, mantle 

 pearl-gray; primaries extensively white, the first six with black terminal portions, the 

 third to sixth, in addition, narrowly tipped with white; the first quill with outer web 

 and tip black, the second and third altogether white with black tips, the fourth white 

 on outer web, pearl-gray on inner web, with touch of white at extremity of terminal 

 black, effecting the transition to the nearly uniform basal pearl-gray of inner primaries; 

 remaining plumage pure white, the underparts more or less flushed with pale rosy. 

 Bill jet black; feet and legs rich orange-red, with black nails; feathering of eyelids 

 white posteriorly, the skin carmine. Adult in winter: Without the black hood; a dab 

 of slate behind the ear and another before the eye, with a plumbeous suffusion of occiput 

 instead; rosy tint of underparts wanting; bill lighter basally, and feet pale flesh-color. 

 Immature: Like adult in winter, but plumbeous suffusion of hind-head more extensive 

 and tinged with brownish; the pearl-gray of mantle less distinct and varied by brownish 

 gray; lesser wing-coverts and inner tertials mostly brownish gray; primaries mostly 

 blackish on exposed outer webs, where the adult is white, and white on outer webs of 

 inner primaries, where adult is pearl-gray; the inner primaries narrowly tipped with 

 white as before; tail crossed terminally, or nearly so, with a broad band of blackish 

 or brownish dusky; bill still lighter, but blackish toward tip. First plumage: Much as 

 in immature, but crown, cervix, sides of neck and back, plumbeous dusky varied by 

 brownish gray; feet still lighter. Length of adult: 304.8-355.6 (12.00-14.00); av. of 

 10 Monterey and Alaskan specimens: wing 268 (10.55); ta 'l 101.2 (3.98); bill 28.4 

 (1.12); depth at angle 6.6 (.26); tarsus 35.3 (1.39). 



Recognition Marks. — Little hawk size; with Sabine's, smallest of local gulls; 

 size of Common Tern (Sterna hirundo); head black in breeding plumage; bill black or 

 mostly black; mantle gull-blue; primaries mostly white and gull-blue, tipped with 

 black and very narrowly with white. To be told at a glance from the terns by its 

 shorter, squarish tail, and in breeding plumage by head being black all around. For 

 comparison with Xema sabini see under next species. 



Nesting. — Does not breed in California. Nest: Of sticks, lined with grass, 

 etc. ; placed four to twenty feet high in bushes, trees, or on stumps, or in default of such 

 upon high ground in marsh. Eggs: 3; rarely 4; olive-gray, greenish olive-gray, or 

 brown, with smallish spots or blotches of umber and violet-gray, chiefly about larger 

 end. Av. size 48.3 x 33 (1.90 x 1.30). 



General Range. — North America. Breeds from northern British Columbia, 

 north in Alaska, Yukon, and northern Mackenzie. South in migrations over practi- 

 cally the entire continent to the southern states, Lower California, and northern Mexico. 

 Winters north to South Carolina, and sparingly to Washington. 



Distribution in California. — Abundant during migration along the seacoast, 

 and casually throughout the interior. Winters commonly along the coast north to 

 Monterey and more sparingly northward in suitable harbors. 



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