336 LONG-WINGED SWIMMERS — LONGIPENNES. 



fuliginous-slate, the remiges darker, nearly black terminally. Young, light phase : Head and neck 

 streaked with dusky brown and fulvous-buff, the latter usually predominating ; lower parts more 

 or less distinctly barred, or spotted transversely, with the same. Upper parts brownish dusky, 

 all the feathers bordered terminally with fulvous-buff. Young, dark phase: Prevailing color dark 

 brownish slate, the wings and tail darker. Middle of the neck, all round, indistinctly streaked 

 with grayish white ; lower parts, except jugulum and upper part of breast, barred with grayish 

 white, the bars" broad and sharply defined on the crissum. Scapulars, interscapulars, wing-coverts, 

 upper lail-cn verts, and feathers of the rump narrowly lipped with pale dull buff. " Bill light blue, 

 dusky at the end ; iris brown ; tarsi and basal portion of the toes and webs light blue, the rest 

 black" (Audubon). Downy young: Entirely silky grayish brown, lighter on the under surface. 



^ 



\ 



Adult, light phase. 



Total length, about .18.50 inches; extent, 40.00; wing, 11.80-13.15 (average, 12.67); middle 

 tail-feathers, 7.70-10.25 (8.00), the lateral rectrices, 4.90-0.25 (5.40) ; culnien, 1.15-1.40 (1.27) ; 

 tarsus, 1.50-1.85 (1.70) ; middle toe, 1.20-1.45 (1.34)4 



This species is almost if not <piite as variable in plumage as the S. pomarinus, there being so 

 much individual variation in this respect that we have described only the light and dark extremes 

 of coloration. 



As may be found noted under the head of that species, specimens occur which in every character 

 of plumage, including length of the middle rectrices, are intermediate between the present bird and 

 S. longicavdus. But there are two excellent characters, to which our attention has been directed 

 by Dr. L. Stejneger, which may always be relied on. These consist (1) in the color of the tarsi, 

 which in adult parasiticus are always black, but in longicaudus light bluish (or, in dried skins, 

 mure or less olivaceous) ; and (2) in the different proportions of the bill, parasiticus having the 

 nasal shield much longer, measured along the oilmen, than the distance from the anterior border 

 of the nostril to the tip of the bill, these measurements being equal in hngicaudus. 



The Parasitic Jaeger is a northern species, although not as exclusively boreal as 

 are the pomarinus and the longicaudus. It is common both to Arctic America and. to 

 the more northern portions of Asia and of Europe. Messrs. Evans and Sturge 

 mention meeting with it on Spitzbergen. They saw it tormenting — as is its manner 

 — almost every flock of Kittiwake Gulls and Terns, but they met with neither its 

 nest, nor its eggs or young. Pennant narrates that the Arctic Skua — as he calls 

 this species — was breeding, at his time, on the islands of Islay, Jura, and Eona ; 

 and Mr. A. G. More ("Ibis," 1865) thinks it highly probable that a few pairs still 

 linger in some of the numerous islands of the Hebrides. It is said to be extinct 

 at Jura. 



Thompson, in his "Birds of Ireland," states that a pair was shot in 1837 on 

 the Island of Eona. He further states that they still breed in Sutherland and in 



1 Extreme and average measurements of twenty-two adults. 



