40 LLANDDWYN 



fish, but do not breed here. Another snag, nearer in 

 was the resort of Oyster-catchers, which appeared to 

 be feeding upon whatever the flood-tide might throw 

 up on to their stronghold. Although I had satisfied 

 myself that the Oyster-catcher swims readily enough 

 under compulsion, these old birds avoided the water 

 just as carefully as the young one with which I had 

 experimented, running up to the top of the snag 

 whenever the swell flushed its base. 



Westward of Llanddwyn, at a short boat's pull, 

 were two much larger rocks; and the farther one, 

 called Adar Island or Bird Island, is exclusively a 

 breeding station of the Common Tern, which had been 

 the chief object of our visiting Llanddwyn. Already 

 in approaching the latter we had heard from time to 

 time the shrill scream of this bird borne in from the 

 water, for the cry of a Tern will carry from a distance 

 at which it is hard to discern the bird itself with the 

 eye. White in all but its pearl-grey upper parts and 

 its black skull-cap, the Tern is yet modelled upon so 

 delicate a system of shallow curves and vanishing 

 lines that, in watching at no great distance its 

 measured, glancing flight, the bird seems to 

 vanish and reappear as if its cap were indeed some 

 Fortunatus' cap. In his light body, long flickering 

 wings, and extended tail-feathers, he is the very oppo- 

 site of the Guillemot; yet both live upon fish captured 

 beneath the water. Heavy-bodied, short-winged, 

 and with scarcely a tail to speak of, the Guillemot, 

 sitting on the sea, simply ducks down, and using his 

 short, strong wings as fins, propels himself as swiftly 

 beneath the water as he flies above it. He requires 

 no initial impulse, for he carries his generating plant 



