f) 
GREAT BLACK-BACKED GULL. 
sea-fowl were at times attracted, I could detect no strangers among the swarms collected, and but this single 
specimen of the Black-back was obtained. 
The nest, like that of most sea-birds, is by no means elaborately constructed, differing slightly in its 
composition according to the locality. On the sea-coast it is placed among the rough herbage on the upper 
ledge of a rocky clilf, or at times in some cavity among the bare stones. Coarse grass with strands from any 
adjacent plants are the principal materials, with now and then a small quantity of tine dead sea-weed. A few 
feathers are usually to he seen on the nest or scattered around, but these are probably plucked by the birds 
themselves while cleaning their plumage. On the islands in the freshwater lochs and on the open moors the 
nests are constructed almost entirely of a mixture of tine and coarse grasses, with an occasional blade or two of 
rush or other marsh-plant. In June 1869 I watched a female sitting on her nest on a grassy ledge in the face 
of the cliffs near Duncansby Head in Caithness. The steep and narrow ravine, owing to the shade thrown by 
the lofty rocks, was dark and gloomy in the extreme, the white plumage of the Gull standing out clearly 
defined and making a most striking picture. Though Kitti wakes. Razorbills, and Herring-Gulls were all 
breeding at no great distance, the ledge on which the Black-back had taken up its quarters was otherwise 
untenanted save by a pair of Black Guillemots, whose eggs or young were snugly concealed under a large 
block of stone lying on the grass within a few feet of the nest of the Gull. When the active little divers 
pitched on the ledge, and rapidly made their way to their domicile beneath the slab of rock, I noticed the Gull 
occasionally stretching forward her head, as if warning them against too near an approach. 
The eggs of most of the larger Gulls are much alike in eolouring, and except by means of a large series of 
coloured plates it is impossible to give any description that would be of service. 
