RICHARDSON'S SKUA. 615 



wood brown, mottled and transversely barred with umber- 

 brown ; legs, and the base of the toes yellow, the ends of 

 the toes and the anterior portion of the intervening 

 membranes black, and hence called sometimes the Black- 

 toed Gull ; but this is only an indication of youth : as the 

 bird increases in age the yellow colour is lost by degrees. 



The next stage, which in this species, also, as in the 

 Pomarine Skua, probably occurs in the second year, the 

 plumage is of a uniform greyish umber-brown, the whole of 

 the light brown margins having disappeared, and the bird 

 has now acquired its full size, measuring from the point of 

 the beak to the end of the long feathers of the tail twenty 

 inches, the central pair of tail-feathers being three inches 

 longer than the next feather on each side ; the wing, 

 from the anterior bend to the end of the longest quill- 

 feather, thirteen inches and three-quarters ; the tarsus one 

 inch and three-quarters ; the middle toe and claw together 

 the same length, or one inch and three-quarters. 



After this stage a few yellow hair-like streaks appear on 

 the sides of the neck ; next, the sides of the neck become 

 lighter in colour: and, advancing in age, the neck all 

 round becomes white, tinged with yellow, the head re- 

 maining of the same colour as the back. Males and 

 females are not distinguishable by their plumage, and as 

 this species, like the smaller Gulls, is capable of breeding 

 when one year old, it is observed, that birds, sometimes in 

 similar states, and sometimes in very different states as to 

 plumage, are in pairs at the breeding-stations. 



