976 SYSTEMATIC SYNOPSIS. —LONGIPENNES. 



M. sku'a. (Fferoose name, as given by Hoier about 1604, now spelled sTcuir; Shetland name 

 si-ooi, Icelandic s/;wj»r or sZ;«/r, Norwegian sl-wcf.) Great or Common Skua. Sea-hawk. 

 Sea-hen. Bonxie. Adult $ 9 : Lateronuchal feathers elongated, rigid, with long discon- 

 nected fibrillse. Above, blackish-brown, more or less variegated with chestnut and whitish ; 

 each feather being dark-colored, with a spot of chestnut toward its end, fading into whitish 

 along the shaft. On the lateronuchal region and across throat the chestnut lightens into red- 

 dish-yellow, with a well-defined, narrow, longitudinal white streak on each feather. Crown, . 

 postocular, and mental regions have but little whitish. Inferiorly the plumage is blended 

 fusco-rufous, lighter than back, and with a plumbeous shade. Wings and tail blackish ; their 

 shafts white, except toward tips ; remiges and rectrices white for some distance from base ; 

 this white on tail is concealed by the long coverts, but appears on outer primaries as a con- 

 spicuoiTS spot. Bill and claws blackish ; the cere grayer ; feet black ; iris brown. In another 

 plumage, not known to be regularly characteristic of age or season, the bird is nearly uniformly 

 sooty-blackish, with the white wing-spot very conspicuous. Very old birds may become 

 lighter colored. Length 20.00-22.00; wing 16.00; tail 6.00; tarsus 2.70; middle toe and claw 

 3.10; bill from base to tip 2.10; to end of cere 1.20; gape 3.00; height at base 0.7.5; width a 

 little less; gonys 0.50. Young-of-the-year : Size much less; bill weaker and slenderer; 

 cere illy developed ; striae not apparent, and its ridges and angles all want sharpness of defi- 

 nition. Wings short and rounded, the quills having very diflFerent proportional length from 

 those of adults ; 2d longest, 3d but little shorter, 1st about equal to 4th. The inner or longest 

 secondaries reach, when the wing is folded, to within an inch or so of tip of longest primary. 

 Central rectrices a little shorter than the next. Colors generally as in adult, but duller and 

 more blended, having few or no white spots ; reddish spots dull, numerous, and large, espe- 

 cially along edge of forearm and on least and lesser coverts. On under parts the colors lighter, 

 duller, and more blended than above ; prevailing tint light dull rufous, most marked on abdo- 

 men, but there and elsewhere more or less obscured with ashy or plumbeous. Remiges and 

 rectrices dull brownish-black ; their shafts yellowish-white, darker terminally. At bases of 

 primaries there exists the ordinary large white space, but it is more restricted than in adults, 

 and so much hidden by the bastard quills that it is hardly apparent on outside of wing, though 

 conspicuous underneath. Feet brownish-black, variegated with yellowish. Bill along culmen 

 1.75; along gape 2.75; height at base 0.50; gonys 0.35; tarsus 2.60; middle toe and claw the 

 same; wing 12.25; tail 5.75. Nestlings: Bufify-gray, ruddier above than below. Eggs 2-3, 

 2.75 X 1.95, ovate, pale olivaceous or brownish, spotted and blotched with dark brown. This 

 powerful predatory sea-fowl inhabits the coasts and islands of the N. Atlantic, only casually 

 occurring on inland waters; it is known to breed in Iceland, the Shetland and Fseroe islands, 

 etc. ; S. in winter to the Straits of Gibraltar. On the American side it is rai'e; known to occur 

 from S. Greenland and Hudson's Straits, where possibly it breeds, to Quebec (Auk, Oct. 1890, 

 p. 387), Massachusetts (Bull. Nutt. Club, iii, 1878, p. 188; Auk, i, 1884, p. 395), New York 

 (Niagara, Auk, Oct. 1889, p. 331), Long Island (Auk, iii. 1886, p. 4-32), and casually to North 

 Carolina. Not known to have occurred on the Pacific Coast; the " California" record of our 

 books since 1858 not authenticated. {Stercorarius skua of former editions of Key.) 

 STERCORA'RIUS. Lat. stercorarius, having to do with stercus, dung, ordare, excrement, 

 as a scavenger.) Jaegers. Teasers. Boatswains. Marlingspikes. Dunghunters. 

 Size smaller, and form less robust than in Megalestris; bill weaker, its depth at base less than 

 length of the cere. Tarsus not shorter than middle toe and claw. Central rectrices of adults 

 long-exserted, projecting from 3-4 to 8-10 inches beyond the others. Three species, of wide 

 distribution, all American. (For analysis, see p. 975.) Each of the three is well marked by 

 the characters of the central rectrices of the adults, which in S. pomatorhinus are broad through- 

 out and peculiarly twisted at their ends, so that a vertical spatulate figure results. This species 

 and S. parasiticus are often dichromatic, having a melanotic phase of plumage rarely known 

 to occur in S. longicauda. 



