considerable numbers ; the nests are generally placed 

 upon the summits of isolated rocks, or " stacks," as 

 they are locally called, but also by no means uncom- 

 monly upon flat grassy islands in freshwater lakes, and 

 occasionally in open marsh- or moor-land. We found a 

 few nests of this Gull, from which the young had very 

 recently flown, on some isolated rocks of the Scilly 

 group in July. Although the young birds were strong 

 on wing and could take perfectly good care of them- 

 selves, the parents swooped fearlessly at us with fierce 

 barks as we rowed about their nesting-places, and in 

 one or two instances followed our boat closely to a 

 considerable distance. 



The Great Black-back is accused of attacking sickly 

 sheep and lambs, and human beings who may have 

 the misfortune to be found in a drowning condition ; 

 but I can speak from personal knowledge as to its 

 frequent minor delinquencies in the way of destroying 

 the young and eggs of Grouse, Peewits, and other 

 ground-breeding birds. This Gull is by no means 

 common, so far as my experience goes, in the Medi- 

 terranean ; but I have met with it occasionally on the 

 Guadalquivir within a short distance of Seville. 



