SULE SKERRY AND ITS BIRD-VISITORS 303 



amid the rough stones ; but Mr Tomison remarks that 

 it is difficult to determine the dates of their arrival and 

 departure. They have, however, been observed in 

 large numbers on ist June, and have been known to 

 visit the lantern in November. 



OcEANODROMA LEUCORRHOA, Fork-tailed Petrel. — Has 

 appeared at the lantern on a number of occasions in 

 May, August, and September. 



FuLMARUS GLACiALis, Fulmar. — This species nests in 

 some numbers at Hoy Head, and hence its occasional 

 appearances off Sule Skerry from February to September 

 are not surprising. On iith February 1909, one was 

 killed at the lantern during clear weather. 



Alle alle, Little Auk. — Mr Tomison tells us that 

 flocks usually appear off the island in January, especially 

 after a northerly gale. On i6th January 1898, two 

 were found dead at the base of the lighthouse, having 

 struck either the lantern or the tower. 



Alca torda, Razorbill. — A considerable number 

 breed on the island. They rarely land before ist May, 

 and leave in August, sometimes as early as the 6th. 



Uria troile. Common Guillemot. — Does not breed, 

 and very few are observed as visitors off the island 

 (Tomison). 



Uria grylle. Black Guillemot. — Mr Tomison 

 records this species as a regular summer visitor, arriving 

 off the island in February and March, but not landing 

 for breeding until the end of April. Single birds are 

 occasionally seen in November and December, but as 

 a rule they do not winter in the vicinity of the island. 



Fratercula arctica, Puffin. — Mr Tomison tells us 

 that enormous numbers make the island their home in 

 summer. The average date of their first appearance is 



