OPEN NESTS 149 



This latter species is the Gannet (Sula hassana), which 

 breeds in such abundance at St Kilda, the Bass Rock, 

 Sulisker in the Hebrides, and a few other places. 

 The nest of this bird may best be described as a 

 flattened cone with a cavity at the top for the single 

 egg. This may be built almost anywhere amongst 

 the cliffs, on ledges, in crevices, and amongst the 

 broken rocks at the summit. Numbers of nests are 

 built close together, in some colonies almost every 

 available spot being occupied. The bulk of the nest 

 materials consists of sea weed, turf, straws, tufts of 

 moss, and stalks of marine plants, the whole being 

 matted and caked together almost into a mortar-like 

 mass, and thickly coated with slime, droppings, and 

 remains of flsh. The cavity is shallow, and the whole 

 structure may be a foot or more in height, but 

 some nests are much trodden out of shape by their 

 apparently indifferent owners — a proceeding which 

 often necessitates repairs and additions during the 

 progress of incubation. The noisy stirring panorama 

 of a Gannet's breeding-place during the height of the 

 season forms one of the most remarkable scenes in 

 bird-life. Another species of Gannet {Sula piscator) 

 which breeds on the Fanning group of islands in the 

 North Pacific presents several features of exceptional 

 interest, inasmuch as the birds' habits vary con- 

 siderably according to locality. On Palmyra Island, 

 according to the observations of Dr Streets, the 

 birds build their nests on low trees, constructing 



