436 LARIDAS 
its formidable beak; even weakly lambs may fall victims 
(Saunders). Fish, dead or alive, are consumed in great 
quantities, a Great Black-backed Gull being capable of 
swallowing a mackerel two pounds in weight (Payne- 
Gallwey, ‘Fowler in Ireland’). At the same time this 
species 1s a good scavenger, stranded and foul-smelling 
carcases being speedily demolished. ‘The numbers of dead 
dogs, cats, pigs, &c., washed ashore from time to time at 
the mouths of city rivers always attract party-gatherings. 
I have seen two (which I surmise were the same couple 
each time, one being a mottled first year’s bird, the other 
older, and showing the signs of mature plumage about 
the back and wings) resort daily to a particular spot on 
the beach, just as the receding tide began to lay bare the 
drowned carcase of a large terrier dog moored to the spot 
by a stone -attached to the neck-rope. On my approach 
they walked sedately from their feast, returning when I 
ambushed myself behind a sand-bank. ‘They always moved 
to and from the carcase with the same deliberate gait, 
looking suspiciously on all sides before resuming their 
repast. In less than a week the carcase was reduced to 
hide and skeleton.' The animal had been drowned when 
in good condition, and was fresh when I first discovered 
the Gulls attacking it. 
Nest.—In the breeding-season the Great Black-backed 
Gull becomes more or less gregarious, though its colonies 
are often composed of but very few pairs. It usually selects 
the summit of a lonely stack which is tenanted by a single 
pair, but, on larger islands, several eminences are thus 
occupied ; and in the case of the Bills of Achill, lofty rocks 
that stand seven miles from Achill Head, Mr. Ussher found, 
in 1890, probably the largest British colony known, estimated 
at some fifty pairs. He writes :—‘‘ The young, and the nests 
which they had in many cases quitted, lay around us among 
bosses of gigantic thrift, not on the top of the rocky ridge, but 
on the slope beneath it facing south”’ (‘ Birds of Ireland’). 
In Scotland and in the Lake district, it breeds away from 
the tide on the islets of mountain-lakes. The nest, like 
that of many other Gulls, is composed of grasses, bits of 
' [ kept this carcase under close observation daily for the short time 
that it was visible at ebb-tide, and with the exception of occasional 
visits from a few Herring-Gulls, it was apparently entirely disposed of 
by the two Black-backed Gulls. 
