23S THE BIRDS OF THE BRITISH ISLES. 



bare rock, or on the ground without surrounds or lining ; 

 nests as bulky as many of those of the Common Tern are rare. 

 On one small group of stacks on the Welsh coast most eggs 

 are in cracks in jagged rock, some with a few ripped-off strips 

 of lichen around them, but I have seen them in circles of grass 

 and rabbit bones, both of which had certainly been carried 

 from the land. 



Three eggs in a clutch is perhaps normal, but two is common. 

 It is only possible to figure one type (Plate 108), but they vary 

 quite as much as those of the Common Tern, though the 

 average size is smaller. The nestlings are at least dimorphic, 

 there being creamy-white and dusky-brown phases ; the dark 

 markings roughly correspond, but are more distinct on the paler 

 ground. Like the young of the Common Tern they soon leave 

 the nest, and at first stagger, but soon run fairly quickly on their 

 short and thick, light or dark reddish legs, crouching under 

 shelter of rocks or vegetation for protection if alarmed. The 

 parents feed them on fish, usually bringing only one at a time, 

 but in an Irish colony have been seen to supply them with 

 insects, mostly crane-flies. When leaving the colony to fish the 

 old birds fly low over the water, but return at a higher level, and 

 in Scotland are not infrequently robbed of their load by the 

 bullying Skua. The Arctic Skua is one of the few birds which 

 is too much for the terns, for in defence of the young the 

 Arctic Tern is even bolder than the Common ; it will frequently 

 strike the head of a human visitor to the ternery, though I have 

 not personally experienced this, the assaulting bird always 

 sweeping up with a sharp angry cry when within a few inches 

 of my head. The violence with which the bird can strike and 

 then recover itself without breaking its neck is really remark- 

 able ; this power of a sudden reversal of position is shown by 

 its rapid emergence when diving for food. 



The young bird has a whitish forehead and huffish neck and 

 cheeks, whilst its back and wings are mottled with buff ; but 



