GREAT SKUA. 665 



where Mr. Bernard Ross says that he found it. On the 

 east side of North America it was observed in some numbers 

 oif the Grand Banks and in Ipswich Bay, in the autumn of 

 1879 (Bull. Nutt. Orn. Club, 1879, p. 128); but on the 

 west coast it is only known to have occurred once — off 

 Monterey, California — probably owing to insufl&cient ex- 

 ploration. The fact of its being found there at all is 

 interesting, because in South Amei-ica, from Callao, in 

 12" S. lat., down to the Straits of Magellan, and through 

 them, along the east coast as far as Rio de Janeiro, it is 

 represented by its close ally Stercorarius dtilensis, which 

 has a slightly weaker bill, and bright chestnut underparts 

 and axillaries. So far as is known, the latter species does 

 not visit the Falkland Islands, being replaced there by 

 S. antarcticus, which is found on the islands of the 

 Southern Ocean as far as New Zealand, visiting the Cape 

 of Good Hope, and the Indian Ocean up to about 10'^ S. lat. 

 in winter. On comparison with its northern congener, the 

 Antarctic Skua may be distinguished by its stout deep bill, 

 with its well-marked angle at the gonys, larger and coarser 

 feet, and by its nearly uniform sooty-brown plumage, the 

 axillary plumes being invariably smoke-coloured. Some 

 of the examples from the islands between New Zealand 

 and the Cape of Good Hope attain great size, measuring 

 upwards of seventeen inches from the carpal joint to the 

 tip of the primaries ; and although sul)ject to some varia- 

 tions (cf. P. Z. S. 1876, p. 322), this species can always be 

 separated, even from the melanic varieties occasionally found 

 in our northern Skua. 



The Great Skua arrives in the Shetlands about the end 

 of April, and its nest, which consists of a neatly-rounded 

 cavity in the moss and heather of the highest moorlands, 

 is prepared in the latter half of May. According to Major 

 Feilden, the birds appear to prepare several nests before they 

 decide on using one. Two eggs are the full complement, 

 and sometimes there is only one ; their colour is an olive- 

 brown with darker markings, and the average measurements 

 are 2*8 by 2 in. There is no difficulty in finding the nests, 



VOL. Ill, 1 ^) 



