Din'ght — A New Race of the Western Gull. 13 



the two races are hardly to be distinguished although occasionally at the first 

 prenuptial moult a few tell-tale gray feathers may appear in the mantle. 

 At the first postnuptial moult, the wholly brownish-black primaries of 

 the first winter are reassumed as well as much of the brown, mottled 

 plumage of the body and wing surfaces, but there are usually more or 

 less gray feathers of the mantle which are diagnostic of the race to which 

 the specimen belongs, and the tail as a rule has more white in it ; the 

 black bill of the first winter has now become partly pale basally and the 

 whole bird is noticeably whiter in the second winter plumage. At the 

 second prenuptial moult much of the white plumage of the head, neck 

 and lower parts is assumed and more gray creeps into the mantle, so that 

 some specimens resemble adults except for the wings and tail. There is 

 no evidence that any birds at the first postnuptial moult acquire the jet 

 black primaries with white tips and a white sub-terminal spot or mirror 

 on the distal primary, but nearly all individuals seem to acquire them at 

 the second postnuptial. Therefore birds in their third winter may be con- 

 sidered as fully adult although some of them may show evidences of im- 

 maturity by primaries with small or imperfect mirrors and by tail- 

 feathers touched with black. The size and shape of the mirror on the distal 

 varies greatly in adults and sometimes a small spot develops on the next. 



