STERCORARIUS.
Gull-like, but bill more hooked than in "Lams"; claws strong and curved ; middle tail feathers longest ; summer and winter plumages alike; more predatory in habits ; nest of sea weed or grass in depression in moss ; eggs usually 2, pale oliv aceous or olive brown, blotched and spotted with dark brown.
Stercorarius skua skua (Briinnich). GREAT SKUA.
j 9 Above dark brown with rufous streaks ; beneath reddish brown ; tail central feathers slightly longer than others ; primaries white towards base, most marked on 2nd to 5th, and here forming a white patch on wing, best seen when wing extended. Bill black. Legs and feet black. Wing 393-42o (H.). Tarsus 64-71. Bill 44-53. Young : above uniform dark brown, upper wing coverts with white tips ; beneath dark brown, lighter in middle of abdomen.
Preeds.—Iceland, Fames, Shetland, Orkneys (at least recently); possibly also in IIudson Bay. Migratory ; occurs in winter on Atlantic Coasts south to Gibraltar and occasionally Madeira and \V. Mediterranean ; seen chiefly at sea ; on American side, occurs south to New Brunswick and New England States.
Stercorarius pomarinus (Temminck). PomAToRmNE SKUA. Swed. Bredstjerstad Labb.
8 Y Above chocolate brown ; crown and face black, ex tending to below• gape ; nape and sides of neck straw yellow ; beneath white, lower abdomen, under wing and under tail coverts brown ; central tail feathers broad and twisted, 70-38 m.m. longer than others, and tips rounded. Bill greyish black, bluish at base above. Legs and feet black. Wing 345-370. Tarsus 50-56. Bill 34-40. Young : above dark brown with rufous tips, beneath dull white obscurely barred light brown, axillaries and under wing coverts dark brown barred white, tail feathers and primaries dark brown with white bases, and latter with white on inner web, central tail feathers not twisted and only slightly lengthened. Both adults and young have a light and dark phase ; in the latter phase plumage is almost uniform dark brown.
Breeds.—Circumpolar ; Murman Coast, Waigatz, Nova Zembla, Spitzbergen, tundras of N. Asia, Alaska, Greenland. Comes south in autumn and winter but seen chiefly at sea, even mid ocean ; occasionally in Black and Mediterranean Seas, in E. Atlantic south to Madeira and \V. African Coast, in W. Atlantic south to New York and Pennsylvania, and on N. Pacific Coasts both Asiatic and American.
Stercorarius parasiticus parasiticus (L.). RICHARD
SON'S SKUA. Ger. Schmarotzerraubmowe ; Ital. Labbo ; Swed. Vanlig Labb.
? Smaller than "pomarinus " and greyer brown ; black of head not descending below gape, feathers of nape slightly lengthened ; beneath white (throat and chest in some greyish); central tail feathers tapering, projecting 80-190 m.m. beyond others ; 1st four primaries at least have white shafts, and inner webs are white towards root. Bill black, brownish at base above. Legs and feet black. Wing 310-328. Tarsus 40-46. Bill 26-20. A dark phase occurs, in which upper parts are dark brown, and underparts lighter brown. Young : above dark brown with rufous buff tips ; beneath mottled brown and buff, or white mottled and barred with brown, under tail coverts barred brown and white or rufous.
Breeds.—Circumpolar ; N. Scotland, Hebrides, Orkneys, Shetlands, Faroes, Iceland, Norwegian Coasts, Sweden, N. Russia, Waigatz, Nova Zembla, Franz Joseph Land, Jan Mayen, Spitzbergen ; and in N. Siberia, Arctic America and Greenland. Wanders south in autumn and winter ; has been met with in Volga Valley on migration ; not common in Mediterranean ; occurs chiefly down Coasts of W. Europe and W. Africa as far as Cape of Good Hope ; also Coasts of America and India.
Stercorarius 1011gICalld1.18 ViCi I lot. L0N(1- TA 11.ED SKUA. S;a.•d. la IA ? Above much paler brown than in " parasiticus" ; crown glossy deep brown, face and neck straw yellow, throat and chest white, abdomen, under tail coverts, and tail smoky brown ; central tail feathers long and tapering, 210-270 m.m. beyond others ; shafts of rst and 2nd primaries only white. Bill black, olive green at base above. Legs and feet dull blue grey, with black patches on latter. Wing 298-327. Tarsus 40-44. Bill 24-28. Young : above brown, with whitish or buff tips ; beneath brown mottled and barred with white, under tail coverts brown barred white.
Breeds.—N. Scandinavia, Lapland, Finland, N. Russia south to Archangel, Nova Zembla, N. Siberia, Greenland, and probably elsewhere in Arctic regions. Occurs sparingly in autumn and winter in W. Europe, and Mediterranean from Gibraltar to Italy ; also in Asia south to Japan and in America to Florida and Mexico. Irregular on migration on British Coasts.