LAPdD^ — STERNINJE: TERNS, SEA SWALLOWS. 1015 



Islands ; also on opposite side of Bering Sea to Japan ; common June-Sept, about St. Michael's, 

 where it breeds with Arctic Terns, laying on the bare ground; eggs 1-2, 1.70 X 1-12, indis- 

 tinguishable from tliose of several related species. The bird is near S. lunata, an extralimital 

 species, coming between the species of Sterna proper and the sooty Tern group. 



{Subgenus Sternula.) 



S. autilla'rum. (Lat. Antillarum, of the Antilles.) American Least Tern. Antillean 

 Tern. Silver Terxlet. Much smaller than any of the foregoing: Length about 9.00; 

 extent 20.00; wing 6.(50; tail :J. 50, forked 1.75; bill along culmen 1.20; depth at base 0.28; 

 tarsus 0. GO; middle toe and claw 0.75. Young smaller : Length 8.50; wing 6.25; tail 3.00; 

 bill 1.00. Tail moderately forked, the lateral feathers scarcely filamentous, rapidly narrowing to 

 acute tip. Bill about as long as head, rather shorter than whole foot. Adult <J 9 > i^i breed- 

 ing i)lumage : Bill yellow, usually tipped with black for 0.10-0.25. Cap glossy greenish-black, 

 with a narrow white frontal crescent whose horns reach over eyes, the convexity extending to 

 bill, but cut off from white of cheeks by a line of black through eye to end of feathers on bill. 

 Entire upper parts, including tail, pearly-blue, rather dark and of a leaden shade, reaching 

 quite to the black cap, fading on sides of neck and head into the snowy satiny-white of all the 

 under parts. Tail-feathers paler basally, white on their under surfaces and outer web of outer 

 feather. Mantle extending to very tips of secondai'ies, but inner webs of these feathers nearly 

 white toward the base. Shafts of first two primaries black on top, white underneath ; webs 

 black, the inner with a distinct white space, not reaching ends of the feathers; other primaries 

 like back, but darker plumbeous, fading to white on their inner borders. Feet orange-yellow ; 

 claws black. Adult in winter: Bill blackish ; feet dull yellowish. Forehead and lores white; 

 crown white, with black shaft-lines ; occiput and nape blackish, sending forward a band through 

 eye. Mantle darker than in summer, and more restricted, leaving hind-neck white ; a band of 

 grayisli-black along fore-arm, and whole edge of wing <jf this color; most primaries blackish, 

 without silvering. Young of first winter: Similar; forehead not pure white, nor hiud-head 

 quite blackish ; mantle varied with lighter tips of most feathers ; tail with traces of dark spots. 

 Young in August : Bill brownish-black, pale at base below. Forehead mostly white ; crown 

 and hind-head varied with white and brownish-black, the latter color especially forming an 

 auricular patch. Pearl-gray mantle appearing, but interrupted with brown hastate or cres- 

 centic spots, one or more on each feather, mottling tlie whole upper parts. Primaries grayish- 

 black, growing lighter from first to last, margined on inner webs with white, broadly and briefly 

 on outer primaries, more narrowly and lengthily on successive ones; outer web of first, and 

 shafts of all on upper side, black. Tail merely emarginate, pearly-blue, shading toward ends 

 of the feathers to dusky-gray, the tips white. Whole under parts pure white. A pretty little 

 Sea-Swalli)\v, inhabiting temperate North America, esi)i'cially along the Atlantic coast of the 

 U. S., casually to Labrador, and also on hirger inland waters to Minnesota; on the Pacific side 

 to California; S. into the Antilles and Middle America and to northern South America; inti- 

 mately related to the South American superciliaris and P^uropean minitta, but subgenerically 

 <listinct from any North American Tern. In former editions of the Key I combined it with S. 

 superciliaris, but I now revert to the opinion of its specific character which I originally ex- 

 pressed in Proc. Pliila. Acad. 18(52, p. 552, and which has meanwhile acquired the powerful 

 support of the A. 0. U. Eg^s dropped on bare dry sand of beaches, or iu a little shelly dej)res- 

 sion, I, 2, ."}, or 4, 1.20 to 1.30 by O.UO; ground color varying frou) pale clear greenish to dull 

 jiiih- dral), speckled all over with small splashes, irregular spots, and dots of several shades 

 of clear brown, with paler and more lilaceous shell-sjiots ; the markings often evenly distrib- 

 uted, more fn'([ueutly tending to wreathe at or around the larger end, the point often free from 

 marks op with only a few dots. 



