102 



THE TERNS 



thus from three weeks to a month earlier than they. It is sitting on 

 its eggs when they are still choosing sites for their nests. Like them 

 it arrives in flocks, which are said to be preceded by small advance 

 parties, or even by single pairs. 1 Unlike them, it nests in "packs," 

 the nests being often not more than a foot apart. The packs may 

 vary in size from a few pairs to many thousands. 2 The largest in the 

 British Isles are to be found on the Fames, which is composed, 

 however, of not more than a few hundred pairs. On the same 

 breeding-ground more than one pack may be found. At the Fames 

 in 1909 there was one on the Inner Wideopens and two on the 

 Knoxes. There are usually about half a dozen at Ravenglass, often 

 some hundreds of yards apart. There is reason to believe that 

 these packs or sub-colonies arrive independently of each other and at 

 different dates, for at Ravenglass it was noted by Mr. W. Bickerton 

 that the young in some were hatched out earlier than in others. 

 The following are his records for four groups in 1906. 3 



At Ravenglass the species makes its nest in the marram grass 

 on the sunny slopes of the sandhills, among the blackheaded-gulls, 

 some of the latter actually nesting within the packs. Below, scattered 

 over the flats between the sandhills, are the common-terns. On the 

 Fames the nests were in 1909 on ridges of sand, shingle, and sea- 

 weed (Knoxes), and in the sea-campion well above the beach (Inner 



1 Naumann, Vogel Afitteleuropas, xi. 157. * Ibid., p. 160. 



1 Country Life, Oct. 3, 1908, p. 445. 



