THE NATURAL HISTORY OF AILSA CRAIG. 145 



dead brake-fern are often in the bottom of the holes where the 

 eggs are laid. This is solitary, in size and whiteness somewhat 

 resembling the egg of the common fowl, but it has underlying 

 delicate violet markings. 



The most impressive feature in the ornis of the Craig is the 

 colony of gannets (Su/a bassana). The great size of these birds, 

 their power of flight, the purity of their plumage, their constantly 

 uttered harsh calls, their great numbers and the manner in which 

 they are massed together on the precipices, all contribute to the 

 impression on the spectator. At some points they nest at no 

 great elevation on the cliffs, but from these comparatively low 

 situations they continue upwards in increasing numbers till the 

 summits of the great pillars are reached, and here the visitor can 

 get among them. The majority of the birds are in full plumage, 

 but a fairly large number show slight traces of immaturity. Brown 

 birds are quite rare as far as I have seen. The nest is a large struc- 

 ture, and though this is usually stated to be made of sea-weed, 

 the rank flowering-plants near its nesting site are freely drawn upon. 

 A single egg with a chalky-white exterior is laid. The young, 

 when newly hatched, are black toad-like objects, but they soon 

 become covered with long white down. During the course of 

 the change from this covering to the brown plumage of immaturity, 

 the birds present a remarkable appearance. The neck and head 

 are the last parts to lose the down, and in this state, with the 

 body and wings covered with brown feathers, they appear as if 

 decorated with judges' wigs. A bird of powerful wing and 

 characteristic flight, it can be recognised at a great distance, and 

 forms a splendid adjunct to the bird-life of the estuary. 



There is no recent evidence that I am aware of, of the cormorant 

 or shag nesting on the Craig, and the black guillemot has never 

 occupied a secure place in its avi-fauna. It seems not improbable 

 that it may have nested sparingly in former years, but at present 

 it is either absent or overlooked. 



In autumn the bottom of the cliffs may almost be said to be 

 strewn with dead birds. The sight is a pathetic one and the 

 stench memorable, but a high mortality is such a regular accom- 

 paniment of congested communities as perhaps scarcely to deserve 

 to be remarked upon. 



