STERNA. 4} 
b. Wing less than 12.00; occipital feathers short and blended. 
c’, Mantle bluish gray, the tail chiefly white; inner webs of quills largely 
white. (Subgenus Sterna.) 
d’. Top of head without any black at any season. 
Adult in summer: Head, axillars, lining of wing, and tail- 
coverts, white, the first with a dusky stripe along each 
side, entirely surrounding eye, and extending back over 
ear-coverts ; rest of plumage pale pearl-gray, the quills 
inclining to silvery white; bill black in middle portion, the 
base and tip yellowish. Winter plumage : Similar, but lower 
parts white; bill dusky, tipped with yellowish. Length 
15.00-16.00, wing 9.70-10.60, tail 4.60-6.00 (forked for about 
1.60-2.60), culmen 1.50-1.70, tarsus .92-.96. Hab. Atlantic 
coast of South America; casual on Atlantic coast of United 
States (New Jersey and Long Island). 
68. S. trudeaui Aup. Trudeau’s Tern. 
ad. Top of head chiefly or entirely uniform black in summer. 
é'. Top of head entirely black in summer. 
f*. Only one web of outer tail-feather entirely white. 
g’. Inner web of outer tail-feather grayish or dusky 
toward end, the outer web entirely white. Sum- 
mer adult: Above pale pearl-gray, lower parts 
pure white; entire top of head and nape uniform 
deep black ; bill (in life) dull orange, dusky at tip, 
feet fine orange-red. Winter plumage: Similar, 
but whole top of head white, tinged on occiput 
and nape with grayish, the side of the head with 
a dusky stripe surrounding eyes and extending 
across ear-coverts ; tail shorter and less deeply 
forked than in summer, the exterior feathers 
broader and less elongated ; bill duller orange, and 
feet much less intense red; bill dusky or dull 
brownish orange, darker at tip. Young: Similar 
to winter plumage, but top of head, hind-neck, 
back, scapulars, tertials, and wing-coverts over- 
laid by a wash of umber-brown, nearly uniform on 
back and crown; sides of head tinged with same; 
tail-feathers all distinctly dusky terminally, especi- 
ally on inner webs. Downy young: Light brown- 
ish buff, the breast and belly whitish ; upper parts 
coarsely and irregularly marbled with black, the 
sides of the head with a few scattered small mark- 
ings of the same. ° Length about 14.00-15.00, wing 
9.50-10.30, tail 5.00-7.70 (forked for 2.30-5.00), 
culmen 1.50-1.65, tarsus .90-1.00. Mest of dead 
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