NATATORES. 259 



which is, in fact, the "Common" Gull in Middlesex, 

 nor do they appear so regularly in the spring and 

 autumn. In severe weather, after a strong wind 

 has been blowing from the east or north-east, a few 

 individuals are sometimes seen, but they make no 

 stay. Sir Humphrey Davy says :* — " I believe that 

 the reason of this migration of sea-gulls and other 

 sea-birds to the land, is their security of finding 

 food. They may be observed at this time feeding 

 greedily on the earth-worms and larvffi, driven out 

 of the ground by severe floods, and the fish on which 

 they prey in severe weather in the sea leave the sur- 

 face when storms prevail, and go deeper." On re- 

 ferring to my note-books for different years, under 

 the head of Kittiwake Gull, I find record of one 

 killed at Elstree Keservoir in May, 1850 ; another 

 at the same place in the spring of 1858 ; three at 

 Kingsbury Keservoir in May, 1859 ; one at this 

 sheet of water in August, 1863 ; and another, a fine 

 adult male, now in my collection, shot also at Kings- 

 bury, on the 3rd April, 1865. This last bird was in 

 company with two Blackheaded Gulls, which disap- 

 peared, with loud screams, when their companion 

 fell. 



The Kittiwake may always be known from the 

 Common Gull, which it closely resembles in size 

 and colour when fully adult, by the absence of a 



* ' Salmonia,' p. 193. 



