RICHARDSON'S SKUA. 11 9 



confinement. The distinction between the dark and light forms, he avers, is 

 apparent in the earliest stages. Though birds showing white breasts when adult 

 are by far the most numerous, it is easy to trace the two forms in every stage of 

 plumage through which they pass. The order of the autumnal migration of the 

 Pomatorhine Skua appears, from Mr. Booth's observations, to be : first, birds in 

 intermediate plumage, followed by the adults in winter garb, and last of all, the 

 young birds. 



Mr. Pearson remarks that he thinks, from observations made in Novaya 

 Zemlya, that some birds, especially the Skuas, " do not breed in bad seasons. If 

 this idea should prove a fact, it may be a provision of nature to prevent the 

 Skuas becoming too numerous. They are well able to defend their eggs and 

 young from the birds of prey found in the same countries, and equally capable of 

 taking care of themselves ; so the only foes they need fear are old age and 

 deficiency of food." 



Family S TERCORARIIDJE. 



RICHARDSON'S SKUA. 



Stercorarius crepidatus, GMEL. 



RICHARDSON'S Skua, or, as it is often called, The Arctic Skua, is a breeder 

 within our area, and is much commoner than the Great Skua. It does 

 not nest, however, south of the island of Jura, although it occurs along all the 

 coasts of both Great Britain and Ireland during autumn and winter. It was in 

 Jura that it was first found nesting in our islands, by Pennant, in the year 1772. 



Richardson's Skua breeds in the Orkney and Shetland Isles. Of the Orkney 

 Islands where it is known as Scouti-allen Hoy is now the only member in 

 which it builds, and even there "it is limited to the parish of North Walls. 



