86 OCEAN BIRDS. 



of 'the iuterveuiug membranes black, and hence called sometimes the 'Black-toed GuU'; 

 but this is only an indication of youth ; as the bird increases in age the yellow colour is 

 lost by degrees. The next stage, which in this species, also, as in the Pomarine 

 Skua, probably occurs in the second year, the plumage is of a uniform greyish umber- 

 brown, the whole of the light brown margins having disappeared, and the bird has 

 now acquired its full size, measuring from the point of the beak to the end of the 

 long feathers of the tail twenty inches, the central pair of tail-feathers being three 

 inches longer than the nest-feather on each side ; the wing, from the anterior bend to 

 the end of the longest quill-feather, thirteen inches and three-quarters ; the middle toe 

 and claw together the same length, or one inch and three-quarters. After this stage 

 a few yellow hair-like streaks appear on the sides of the neck ; next the sides of the 

 neck become lighter in colour ; and, advancing in age, the neck all round becomes 

 white, tinged with yellow, the head remaining of the same colour as the back. Males 

 and females are not distinguishable by their plumage, and as this species, like the smaller 

 Gulls, is capable of breeding when one year old, it is observed that birds, sometimes in 

 similar states, and sometimes in very different states as to plumage, are in pairs at the 

 breeding-stations." 



Mr. Howard Saunders says: — "It is now well known that there are two very distinct 

 plumages to be found in birds of this species, even in the same breeding place, — an entirely 

 sooty form, and one with light under parts, — and that white-breasted birds pair with 

 whole-coloured birds, as well as with those of their respective varieties." He also says : — 

 " Now the particular characteristic by which Richardson's Skua may be distinguished, at 

 any age before that of the nestling, is that the shafts of the other primaries are 

 conspicuously tighter than in those of Buffon's Skua, in which only those of the first and 

 second primaries are white, those of the third and successive primaries being dark. 



Buffon's Skua {Stercorarius parasiticus). — This bird, sometimes called the "Long-tailed 

 Skua," may at once be known by the great length of its two middle tail-feathers, resembling, 

 in fact, the Tropic-birds in this peculiarity. It is also much smaller than the rest of the 

 genus. It is very arctic in habits, but in winter comes down south, and visits the shores 

 of England and America ; so that we might meet it anywhere along our coast. 



In Yarrell's « British Birds ' (vol. iii. p. 496) is the following : — " The egg, as figured 

 by Thienemann, is of a pale green colour, spotted with ash-grey and dark reddish-brown ; 

 the measurements arc two inches in length, by one inch and five lines in breadth. In 

 the adult l)ird the base of the bill, including the cere, is dark greenish-brown, the horny. 



