242 BIRDS OF ILLINOIS. 



SP. CHAK. Largest of the Terns (wing not less than 15.00 inches). Bill very robust, red- 

 dish; tail short and but slightly forked; inner webs of primaries wholly dark slaty. 

 Adult, in summer: Entire pileum, including upper half of lores, deep black, the lower 

 eyelid with a white crescentic spot. Upper parts very pale pearl-gray, fading in- 

 sensibly to white on the upper tail-coverts, the tail bluish white; outer surface of the 

 primaries light hoary ash, their inner webs uniform slate or dark hoary gray. Best of the 

 plumage snow-white. Bill deep coral-red, with a dull suffusion subterminally, the tip 

 orange or yellowish; iris dark brown; legs and feet deep black. Adult, in winter: Simi- 

 lar, but the black of the head streaked with white. Young, first plumage: Similar to the 

 adult, but with the following differences: Pileum (including occiput and upper two thirds 

 of lores) grayish white, thickly streaked with dull black; side of head with a uniform dull 

 black bar, beginning before and beneath the eye and extending back over upper portion of 

 auriculars ; lower portion of lores and auriculars grayish white, mottled with darker gray- 

 ish. Mantle pale pearl-gray, sparsely marked with irregular spots, mostly inclining to 

 crescentic or V-shaped form, of brownish dusky, the wing-coverts, however, nearly im- 

 maculate; the markings largest on longer scapulars and terminal portion of tertials; 

 primaries hoary gray, with white shafts, the shorter ones margined with white; rump and 

 upper tail-coverts immaculate pearly white ; rectrices hoary gray, distinctly spotted with 

 blackish toward tips. Best of plumage plain white. Bill dull orange (in dried skin), dusky 

 subterminally: feet brownish (in skin). (No. 93,033, Warsaw. 111., Sept. 21, 1883; CHARLES K. 

 WORTHEN.) Downy 1'oung: Above, grayish white, the down of the head dusky grayish 

 at the base; back and rump finely and indistinctly mottled with grayish; throat and fore- 

 neck uniform pale grayish; remaining lower parts, including the chin, immajulate white. 

 Bill, legs, and feet dull orange, the former with the tip blackish. 



Total length, about 20.00-22.50 inches; extent, 51.00-55.50; wing, 15.00-17.40 ; tail, 5.30-i : .75, 

 depth of its forking, .75-1.60; culmen, 2.48-3.10; depth of bill through base, .75-.95; tarsus, 1.60- 

 1.95; middle toe, 1.15-1.40. 



The great Caspian Tern is a bird of very irregular distribu- 

 tion, even its breeding grounds being scattered about at dis- 

 tant points, not only in North America but other parts of 

 the world as well. In North America it has been found breed- 

 ing at several localities in the Arctic district, on islands off the 

 coast of Virginia, in Lake Michigan and on the coast of Texas; 

 and the writer found it to be more or less common about 

 Washoe Lake and the Humboldt Marshes, Nevada, and the 

 Great Salt Lake, Utah, where it was no doubt breeding.* 



Unlike most other terns, and conspicuously unlike the almost 

 equally large Royal Tern (S. t>i<i.i:!.ina}, the Caspian Tern ap- 

 pears to breed in isolated pairs instead of large colonies, its 

 nest being usually far removed from that of any other bird, 

 and consisting merely of a shallow depression scooped in the 

 sand, in which its two eggs are laid, with little if any lining, 

 though a few grass, or sedge, blades or other vegetable sub- 

 stance are sometimes added. . It is very bold in defence of its 

 eggs or young, darting impetuously at the intruder, uttering 

 meanwhile hoarse barking or snarling cries. 



* The species was given in the author's "Ornithology of the Fortieth Parallel" as the 

 Boyal Tern, but I am now quite certain that it was this species instead. 



