COMMON TERN. 235 



able size. The two figured (Plate 104) are from the same 

 colony, on sand dunes, one on sand, the other amongst dwarf 

 willow. The female often lays and adds lining after incubation 

 has begun. The materials vary as much as the site ; I have 

 seen the following used — marram, thick stems of beet, fresh 

 sprigs of ragwort, bits of stick, straw, seaweed, pebbles, broken 

 and perfect shells, and crab-claws. In but few cases were 

 these materials mixed ; each bird seems to select its special 

 decoration. The male feeds the female before and during 

 incubation ; indeed, with all terns, the presentation of a fishy 

 offering is the most important nuptial preliminary. The male 

 depressing his half-spread wings, and elevating head and tail, 

 dangles his gift before the crouching, expectant female, but 

 only delivers it if she accepts his overtures. When the ternery 

 is first approached the birds rise and fly to and fro overhead, 

 many at a great height, filling the air with a maze of white 

 wings and harshly screaming voices, most prominent the long 

 drawn pieerah^ or the sharply repeated kit, kit, of some specially 

 anxious parent ; but the tumult soon subsides and the life of 

 the colony may be watched from close quarters. I have often 

 seen, after they have settled down, the strange simultaneous 

 departure of the birds, a habit shared by Black-headed Gulls 

 and Sand- Martins. A sudden cessation of the normal clamour 

 is followed by an uncanny hush as all wing seaward, but before 

 out of sight a bird calls and the whole body drifts back to 

 resume activities. 



Irate birds will dive savagely at and occasionally strike the 

 head of any one walking amongst the nests. Others than 

 human trespassers are assaulted, even killed. At Ravenglass 

 I have examined the bill-pitted skulls of young rabbits and 

 the juvenile Black-headed Gulls which had foohshly wandered 

 from their own domain. Passing birds, innocent as well as 

 would-be thieves, are driven off or overv/helmed, and even 

 cattle are mobbed. 



