GREAT SKUA. 285 



DIAGNOSTIC CHARACTERS : The eggs of this Skua 

 require the most careful identification, as they may 

 easily be confused with those of the Common Gull, 

 which breeds in similar localities. They also resemble 

 very closely certain varieties of those of the Black- 

 headed Gull ; the locality is of the first importance in 

 deciding their authenticity, if not taken from the nest 

 in the presence of the parents. 



Family STERCORARIID/E. Genus STERCORARIUS. 



GREAT SKUA. 



STERCORARIUS CATARRHACTES (Linnteus). 

 Single Brooded. Laying season, May. 



BRITISH BREEDING AREA : The Great Skua is another 

 excessively local species in the British Islands, its only 

 nesting-places being in the Shetlands, small colonies 

 breeding on Unst and Foula, the former the most 

 northerly of the group, and the latter some twenty 

 miles to the westward of Mainland. It is a source of 

 satisfaction to know that the birds are jealously pre- 

 served from extermination ; were it otherwise a few 

 years would suffice to banish this fine bird from the 

 list of our breeding species. 



BREEDING HABITS : The Great Skua is best known 

 on our shores as a coasting migrant on its way to or 

 from more northern breeding-haunts. By the end of 

 April the few pairs that nest within our limits betake 

 themselves to their breeding-places on the high moor- 

 lands. It is not improbable that this species pairs for 

 life, although the sexes do not keep very close company 



