86 THE TERNS 



of this, but others used bents, and a few rabbit bones, both of which 

 they must have carried from the adjoining land. 1 The most common 

 material used by both species are bents, stalks, and a variety of 

 vegetable matter, including occasionally twigs. Pebbles and shells 

 are also used, and at Walney I found some nests of Arctic-terns 

 made both of pebbles and bents, in one case there being a complete 

 outer circle of bents. In the colony of common-terns at Wells, of 

 which mention has been made, Mr. A. H. Patterson found nearly all 

 the nests lined with "sixpenny sized pieces of cockle and oyster- 

 shells." Rabbit bones appear to exercise an attraction on both 

 species, 2 but they are only able to indulge the taste to a limited 

 extent, owing to the natural disinclination of the rabbits to supply 

 the material in large quantities. 



On visiting a colony of Arctic or of common-terns, one does not, 

 as a rule, find them all nesting near together, unless, as at the 

 Fames, the space is confined. Where the breeding-ground is 

 extensive they may be found scattered in groups over a wide area, 

 isolated nests or smaller groups being often met with in between the 

 larger. At Walney or Ravenglass such groups breed in the flats 

 among the sandhills, the latter forming natural boundaries between 

 adjacent settlements. On the shingle stretches of Dungeness, where 

 there are no such boundaries, the common-terns are found dotted in 

 groups that may be a quarter of a mile apart or more. The two 

 species do not mix, and are not, as a rule, found at the same breeding- 

 place. A skerry has been known to be occupied by each species 

 separately in consecutive years. 3 Among places where they can be 

 seen together are Walney Island and the Fames. At both the 

 common are in a minority, or were so in 1905 (Walney) and 1909 

 (Fames). 



The building of the nest has two stages, preparing the saucer- 



1 Zoologist, 1905, 217. 



* H. A. Macpherson, Fauna of Lakeland, p. 414; Zoologist, 1905, 217 (Coward and Oldham). 



3 P. C. R. Jourdain, in litt. 



