336 



LONG-WINGED SWIMMERS — LONGIPENNES. 



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

 streaked with dusky Ijrown and iulvous-buft", the latter usually predominating ; lower parts more 

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

 all the leathers bordered terminall}- with ful\ous-bufi". Young, dark phase : Prevailing color dark 

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

 \\\{\\ grayish white ; lower parts, except jugulum and upper ])art of breast, barred with grayish 

 while, the bars broad and sharj)ly defined on the crissum. Scapulars, interscapulars, wing-coverts, 

 upper tail-coverts, and featliei's of the rump narnjwly tipped with pale dull buff. " Bill light blue, 

 dusky at the end ; iris brown ; tarsi and basal ])ortion 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; Aviiig, 11.80-13.15 (average, 12.67); middle 

 tail-feathers, 7.70-10.1^5 (S.fUi), the lateral rectrices, 4.90-G.-25 (5 40) ; culmen, 1.15-1.40 (1.27) ; 

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



This species is almost if not quite as -variable in plumage as the S. pomarinns, there being so 

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

 of coloration. 



As may he found noted nnder the head of that specie.s, specimens occur which in every character 

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

 .S. lonyifaudns. But there are two excellent characters, to which our attention has been directeil 

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

 wliich in adnh parasiticus are always black, but in Imujicandus light bluish (ur, in dried skins, 

 more or less olivaceous) ; and (2) in the different ^proportions of the bill, jMrasiticus having the 

 na.sal shield nuich longer, measured along the culmen, than the distance from the anterior border 

 of the nostril to the tip of the bill, these measurements being ec|ual in longicaudus. 



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

 are the jyofnarinus and the lomjkaudus. It is common both to Arctic America and to 

 the more northern portions of Asia and of Euroi)e. Messrs. Evans and Sturge 

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

 — almost every flock of Kitti\vake 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 Rona ; 

 and Mr. A. G. ]\Iore (" Ibis," 1805) thinks it highly probable that a few pairs still 

 linger in some of the nunaerous 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 Bona. He further states that they still breed in Sutherland and in 



^ Extii'iiic :ui(i average mcasurcnieiits of twenty-two adults. 



