Order LARIFOBMES 
No. 155. 
Family CATHARACTIDAE. 
COPROTHERES POMARINUS CAMTSCHATICA. 
SIBERIAN POMARINE SKUA. 
(Plate 123.)* 
Catarractes CAMTSCHATICA Pallas, Zoogr. Rosso-Asiat., Vol. II., p. 312, 1826 ; Kamchatka. 
Gatarractes camtschatica Pallas, Zoogr. Rosso-Asiat., Vol. II., p. 312, 1826. 
Lestris pomarina Middendorff, Sibirische Reise, Vol. II., p. 240, pi. xxiv., 1851. 
Stercorarius pomarinus Taczanowski, Mem. I’Acad. Imp. Sci. St. Petersb., ser. vn., 
Vol. XXXIX., p. 1061, 1893. 
Stercorarius pomatorhinus Saunders, Cat. Birds Brit. Mus., Vol. XXV., p. 322, 1896 (pars) ; 
Campbell, Nests and Eggs Austr. Birds, p. 867, 1901 ; Hall, Key Birds Austr., 
p. 91, 1906 ; Mathews, Handl. Birds Austral., p. 22, 1908 ; Bahr, Ibis 1912, p. 286. 
Catharacta pomarina Mathews, Nov. Zool., Vol. XVIII., p. 213, 1912. 
Distribution. Alaska and Siberia (breeding). 
Adult male. General colour of the upper surface sooty-black including the crown of 
head, cheeks, back, wings, and tail ; primary-quills black on the outer webs and 
tips, brown on the inner webs and white at the base, the shafts white, dark brown 
at the tips ; secondaries dark brown, white at the base ; tail dark brown with 
white shafts at the basal portion, the two middle feathers produced beyond the 
rest of the tail and twisted ; hind-neck and sides of neck straw-colour ; a band 
which encircles the fore-neck and lower hind-neck, is composed of white feathers 
barred with brown and fringed with white at the tips. This colour extends on to 
the sides of the body ; throat, breast, and abdomen white ; axillaries and under 
wing-coyerts sooty-black hke the vent and under tail-coverts ; “ Bill horn 
brown ; tarsi and toes reddish black ” {Cat. Birds Brit. Mus.). Total length 
550 mm. ; culmen 38, wing 366, tail 227, tarsus 53. 
Adult female. Similar to the adult male, but not so dark on the head, upper-parts, vent, 
and under tail-coverts. Total length 550 mm. ; culmen 37, wing 348, tail 215, 
tarsus 53. 
Immature. General colour above dark brown, the feathers everywhere margined and 
spotted with ochreous or rufous, more thickly on the rump and upper tail-coverts 
and more sparsely on the head and hind- neck ; the small coverts round the bend 
of the wing white with dark centres ; under-parts more rufous and barred almost 
entirely over the whole surface, each feather being white at the base with two 
brown bars and fringed with rufous, more coarsely on the flanks ; the long under 
tail-coverts have four brown bars ; under wing-coverts brown barred with white ; 
axillaries, some uniform grey with twin spots of rufous at the tips, others are 
greyish-brown barred and irregularly marked with white, fringed also with the 
same colour at the tips ; a dark spot in front of the eye. 
* The Plate is lettered Stercorarius ‘pomatorhinus. 
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