Family STERCORARIDiE. 



THE GREAT SKUA. 



Megalestris catarractes (Linnaeus). 

 Plate 75. 



This predatory species, the largest of our "Robber" Gulls, which in Britain 

 until a few years ago only bred on the Islands of Unst and Foula, has now 

 extended its range in the Shetlands, and owing to careful protection appears to 

 be increasing in numbers. During the winter it wanders far from land, but is 

 occasionally seen off various parts of our coasts. 



The breeding stations of the Great Skua in other parts of the world seem to be 

 restricted to Iceland, the Faeroes, and, according to Howard Saunders' Manual of 

 British Birds, " to some islands to the north of Hudson Strait," though its migra- 

 tions extend to the Mediterranean and also to American waters. 



Known in the Shetlands as the " Bonxie," this species breeds high up on the 

 moors among heather, where a slight hollow on the mossy ground, scantily lined 

 with bents, etc., serves as a nest. This contains two eggs, in colour a pale greenish- 

 brown, marked with deeper brown. 



Like other members of this family, the Great Skua obtains a large proportion 

 of its food by chasing the weaker and smaller Gulls and compelling them to 

 disgorge their rightful prey, which is deftly caught by the marauder before reaching 

 the water. This Skua also kills and devours other birds, while food, such as fish 

 stranded on the shore, is not unwelcome. 



When their eggs or young are in danger, the parent birds do not hesitate to 

 attack human beings, and a pair have been seen, according to Macgillivray, to beat 

 off an Eagle from their territory. 



Their cry is loud and sharp, but sometimes rather plaintive. 



IV. 



73 



K 



