284 THE NESTS AND EGGS OF 



whilst it very probably breeds on the Liakoff Islands off 

 the coast of that country in the Arctic Ocean. On the 

 American continent it breeds in Alaska, and probably 

 on the barren grounds across to Greenland, in which 

 latter country it is known to do so in Egedes Land on 

 the east coast in about lat. 67°. 



Breeding habits : The Pomatorhine Skua is a bird 

 of somewhat restricted migration, wintering, as a rule, 

 as far north as it can with safety. It arrives at its 

 Arctic breeding grounds during the first half of June. 

 But little has been recorded of the habits of this bird 

 during the breeding season. Von Middendorff found 

 colonies of this Skua nesting near the Taimyr Lake on 

 the peninsula of that name in Northern Siberia ; and 

 Finsch met with it breeding on the Yalmal peninsula in 

 the same country. It appears to breed in colonies. Of 

 its pairing habits I find nothing recorded. The nest is 

 merely a hollow in the moss- and lichen-covered ground 

 of the tundra. The behaviour of the birds when their 

 breeding grounds are invaded by man is not known 

 to differ from that of allied species. 



Range of egg colouration and measurement: 

 The eggs of the Pomatorhine Skua are two in number, 

 sometimes but one. They vary in ground colour from 

 pale olive to dark oliv^e, with a huffish tinge, spotted and 

 speckled with dull reddish-brown, and with underlying 

 markings similar in character of grayish-brow^n. The 

 spots are not very large, nor very distinctly defined, are 

 irregular in shape, and usually most numerous and 

 largest on the major half of the ^^"g. Average measure- 

 ment, 2*4 inches in length, by 17 inch in breadth. 

 Incubation is apparently performed by the female, but 

 the duration of the period is unknown. 



Diagnostic characters : The eggs of the Poma- 

 torhine Skua are larger than those of Richardson's Skua, 



