THE POMATORHINE SKUA. 781 



entirely uniform black-brown. Dark form. — No winter birds 

 examined, but judging by examples commencing moult plumage 

 is as summer, but none moulting neck-feathers examined. 



Nestling. — Upper-parts pale brown, under-parts paler grey- 

 brown. Only specimens examined were partially feathered but 

 down is evidently similar to, but paler than, that of Arctic Skua. 



Juvenile. — Pale form. — Upper -parts dark brown, feathers with 

 rufous -buff to pale buff tips varying considerably in width in 

 individuals ; crown and neck usually with very narrow pale fringes 

 but sometimes broad buff fringes ; upper and under tail-coverts 

 broadly barred dark brown and rufous-buff to pale buff and at bases 

 white ; whole under-parts brown barred, usually somewhat ob- 

 scurely, buff, but sometimes more prominently huffish-white ; under 

 wing-coverts and axillaries broadly barred black-brown and white ; 

 tail brown-black usually with inconspicuous pale tips, concealed 

 bases white but extending toward tips and mottled brown on inner 

 webs of outer feathers ; primaries brown-black paler on inner webs, 

 bases white extending further towards tips on inner webs than in 

 Arctic Skua, but not showing beyond coverts on outer webs, tips 

 usually with very narrow pale brown to buff edging ; secondaries as 

 primaries and inner half with very narrow whitish edgings at tips, 

 innermost with buff spot-like edgings ; primary-coverts black- 

 brown faintly tipped paler ; wing-coverts as upper-parts but 

 frequently outer greater and median almost uniform or with only 

 very narrow paler tips. Dark form. — Like pale form but head, 

 neck and throat usually without or with scarcely noticeable pale 

 tips, pale tips on upper-parts and wing-coverts narrower and not so 

 plentiful, under-parts less barred but upper and under tail-coverts, 

 axillaries and under wing-coverts broadly barred as pale form. 



First summer. — Pale form. — Upper-parts much as juvenile but 

 feathers of back of neck with white spots or bars and some with 

 yellow pointed tips ; chin and sides of head white streaked or 

 spotted brown or mostly brown with white spots ; feathers of throat 

 and breast white broadly tipped brown and usually barred buff ; 

 flanks, upper and under tail-coverts broadly barred white or bumsh 

 and dark brown ; rest of breast and belly sometimes white but 

 usually feathers more or less tipped or barred dark brown ; under 

 wing-coverts and axillaries as juvenile broadly barred black-brown 

 and white ; tail and wing-feathers as juvenile but without pale tips ; 

 wing-coverts much as juvenile but upper series of lesser often with 

 conspicuous white tips. Dark form. — Upper- and under-parts and 

 upper wing-coverts uniform brown, under wing-coverts, axillaries, 

 upper and under tail-coverts and feathers of vent narrowly tipped 

 buff, under tail-coverts and under-parts sometimes obscurely barred. 

 The juvenile plumage is completely moulted Dec. to April or May. 



Second winter. — Pale form. — Much as first summer but feathers 

 of upper-mantle with more subterminal bars and those of back of 

 neck barred and not with yellow tips. Second summer. — Body- 

 plumage much same but feathers of upper-mantle tipped white not 



