1 9 1 8 . ] Birds of the Isle of May. 283 



Larus canus canus. The Common Gull. Visits of this 

 species to the island are recorded in May, September, and 

 October, 



Larus argentatus argentatus. The Herring-Gull. When 

 we first went to the Isle of May in 1907 one pair of 

 Herring-Gulls bred there, but they increased till in 1914 

 about a dozen pairs were nesting. Adults or young birds 

 of this species frequent the May throughout the year. 



Larus marinus. The Greater Black-backed Gull. 

 Chiefly a winter visitor, but a few may be seen throughout 

 the year. 



Larus fuscus affinis. The British Lesser Bl^ck-backed 

 Gull. A bird of double passage, occurring chiefly in April 

 and May and in September and October. 



Larus glaucus glaucus. The Glaucous Gull. There are 

 several records, chiefly of immature birds, in May and 

 October. 



Larus ridibundus. The Black-headed Gull. There 

 are frequent records of small numbers in March, May, 

 September, and October. 



Larus minutus. Thic Little Gull. The only record for 

 the island is of an immature bird seen by us on 17 October 

 1913. 



Rissa tridactyla tridactyla. The Kittiwake. A summer 

 visitor to the island, breeding in numbers on the cliffs, which 

 it first visits in March, leaving them again about mid- 

 August. Flocks of Kittiwakes remain in the adjoining seas, 

 where we used to see them till we left the island in late 

 October. They are usually seen apparently feeding on 

 shoals of fry along with Guillemots and Razorbills ; when 

 these latter come up from a dive the Kittiwakes stoop at 

 them, frequently forcing them to dive again. There is a 



