42 NORTH AMERICAN BIRDS. 



grasses, etc., in marshes (fresh- or salt-water), often 

 upon " windi'ows" of sea- weed. Eggs 1.78 X 1-23, 

 ovate or short-ovate, vaiying from olive-buff to 

 olive-brown, coarsely spotted or blotched with 

 dark brown or blackish. Hah. Temperate North 

 America, north to Manitoba, south, in winter, 

 to Brazil. 



69. S. forsteri Nutt. Forster's Tern. 

 g*. Inner web of outer tail-feather entirely white, the 

 outer web dusky, in abrupt contrast. 

 /i,^ Summer adult : Lower parts pale lavender-gray, 

 or grajash white ; whole top of head and nape 

 deep black ; rest of upper parts deep pearl- 

 gray, the rump, upper tail-coverts, and greater 

 part of tail pure white ; bill bright vermilion- 

 red, blackish at tip ; feet (in life) rich orange- 

 vermilion. Winter adult: Similar, but fore- 

 head, crown, and anterior part of lores white, 

 mixed with black on crown ; entire lower 

 parts pure white ; bill and feet less intensely 

 red. Young : Orbital region, occiput, and 

 nape, dull black; crown mixed blackish and 

 grayish white ; forehead, lores, entire lower 

 parts, upper tail-coverts, inner webs of rectri- 

 ces, and tips of secondaries, white ; rest of 

 upper parts pale pearl-gray, the scapulars, 

 interscapulars, and tertials, tipped with pale 

 buff, and marked with a subterminal cres- 

 centic spot, or lunule, of dusky brown ; an- 

 terior lesser wing-coverts dusky, forming a 

 distinct bar across wing ; bill brownish dusky, 

 the base of mandible paler and more reddish ; 

 feet pale reddish. Downy young : Above pale 

 fulvous or grayish buff (the precise shade 

 very variable) coarsely and irregularly mar- 

 bled with dusky, except on forehead ; lower 

 parts white, more or less tinged with buff or 

 pale fulvous on sides and flanks, the throat 

 and cheeks distinctly dusky, or grayish. 

 Length 13.00-16.00, wing 9.75-11.75, tail 5.00- 

 7.00 (forked for 3.50, more or less), culmen 

 1.25-1.50, depth of bill at base about .33, tar- 

 sus .66-85. Nest usually a depression in 

 sand or gravel near sea-shore. Eggs 2-4, 1.57 

 X 1.17, averaging a little paler in ground- 



