GREAT BLACK-BACKED GULI.. 
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mottled and barred like the back ; head and hind-neck white, 
streaked with brown, more thickly on the hinder crown and 
nape, and very thinly on the lores, sides of face, and lower 
throat ; chin and upper throat white, unspotted ; remainder of 
under surface of body white, slightly spotted with dusky brown, 
but more distinctly on the sides of the breast and flanks, where 
the dusky bars and arrow-head markings are very distinct; 
under wing-coverls and axillaries white, with dusky bars. 
Concerning the changes in plumage of this species when 
immature, Mr. Howard Saunders writes : — “ Restricting the 
term ‘young’ to a bird of two years, at a later stage black 
feathers appear on the mantle, and the white edges to the 
secondaries are distinct, but the primaries are still without 
‘mirrors.’ Afterwards the primaries have white tips, and the 
fourth, fifth, and sixth e.xhibit what may almost be called sub- 
terminal bars, while the outermost quill shows a sub-apical 
‘ mirror ’ of dull white, and the second quill has an ill-defined 
brownish-white s])ot, the tail being still slightly mottled. I do 
not think that the adult plumage is attained before the bird 
is in its fifth year, and even then the amount of white on the 
two or three outer primaries continues to increase with age.” 
Nestlings. — Ashy-grey above, mottled with blackish-brown 
spots, blacker and more scattered on the head and hind-neck ; 
under parts white, the breast tinged with orange buff. 
Cliaracters. — The large size (wing over 19 inches), slaty- 
black back, and white head distinguish this species when adult, 
as well as the large ivhite tip to the first primary. The size is 
the best guide for the determination of the young birds, added 
to the powerful bill, which far exceeds that of the Lesser Black- 
backed or Herring Gulls. 
Range in Great Britain. — The present species breeds more 
abundantly in Scotland than in England, where only a few 
isolated nesting-places are known on the south-western and 
western coasts. Mr. Usshcr says that in Ireland one or more 
pairs breed on the summits of some stacks and islands off 
Donegal, Dublin, Wexford, Waterford, Cork, Kerry, Galway, 
and Mayo, but there is a considerable colony on the Cov/ Rock, 
off Dursey Head, Cork, and another colony of at least fifty 
pairs on the Bills Rocks, off Achill, Mayo. 
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