244 BIRDS OF ILLINOIS. 



the year in August: Bill considerably smaller and shorter than in the adult, its tip less 

 acute, and its angles and ridges less sharply denned, mostly reddish yellow, but light yel- 

 lowish at tip. Crown much as in the adults in winter, but the occipital crest scarcely rec- 

 ognizable as such. Upper parts mostly white, but the pearl-gray of the adult appearing in 

 irregular patches, and the whole back marked with small irregularly shaped, but well-de- 

 fined spots of brown. On the tertials the brown occupies nearly the whole of each feather, 

 a narrow edge only remaining white. Lesser wing-coverts dusky plumbeous. Primaries 

 much as in the adults, but the line of demarkation of the black and white wanting sharp- 

 ness of definition. Tail basally white, but soon becoming plumbeous, then decidedly 

 brownish, the extreme tips of the feathers again markedly white. Otherwise as in the 

 adults" (CouES). 



Total length, about 18.00 to 20.00 inches; extent, 42.00 to 44.00; wing, 14.00-15.00; tail. 6.00- 

 8.00; the depth of its fork, about 3.00-4.00 ; culmen, 2.50-2.75 ; depth of bill through base, 70; 

 tarsus, 1.37; middle toe, with claw. 1.40. 



It is very questionable whether the bird with entirely black 

 pileum can be regarded as in full breeding-plumage. In July, 

 1880, I found a colony consisting of several thousands of this 

 species breeding on Cobb's Island, Va. Dozens were shot as 

 they flew from their eggs, and not one could be secured, or even 

 observed, which did not have the forehead and fore part of the 

 crown white. All the eggs were quite fresh; but it is barely 

 possible that the birds may have previously laid in some other 

 place, and their eggs have been taken by fishermen. It seems, 

 therefore, most probable that the wholly black pileum repre- 

 sents the full spring, or perhaps pairing, dress, rather than the 

 livery of the breeding-season. 



This is a truly "royal" bird, for, though somewhat smaller than 

 the Caspian Tern (8. tschegrava) , it is altogether of more elegant 

 form and more striking appearance. It is one of the most gre- 

 garious species of the family, usually nesting in immense colo- 

 nies, some of which number thousands of pairs, their nests occu- 

 pying a comparatively limited area, being often so closely 

 crowded that it is difficult to walk among them without 

 stepping on the . eggs. 



Although accredited to Illinois as an irregular or casual sum- 

 mer visitor, it is possible that individuals of the Caspian Tern 

 have been mistaken for it. 



SUBGENUS STERNA LINN. 



Sterna LINN. 8. N. ed. 10, i, 1758, 137. Type, by elimination, S. hirundo LINN. 



SUBGBN. CHAB. Size medium (wing between 9.00 and 12.00 inches). Tail deeply 

 forked, with lateral feathers much lengthened and narrow towards ends. Feathers of occi- 

 put normal (short and blended, not forming a crest). 



