102 THE SCOTTISH NATURALIST 



I. Herring Gulls : I have notes of nine birds examined 

 during the process of moult, viz. : 



3 adults in full moult in late October and beginning of 



November. 

 i assuming adult plumage for the first time, in full moult in 



mid-October, 

 i bird assuming adult plumage for first time, moult nearly 



complete by end of September, 

 i immature bird (final stage), moult completed before 3rd 



November. 

 3 immature birds (second year), with moult nearly complete in 



second half of August. 



II. KlTTIWAKES : 



i immature, in earlier stages of moult on 7th July. 

 1 immature, in late stage of moult, 31st August. 

 Both these were assuming mature plumage. 



The autumn moult of the Herring Gull as a species is 

 thus seen to extend over a considerable part of the year 

 (about four and a half months or more). Judging by the 

 feathers on the beach, the moult began not long before 20th 

 June ; by the beginning of October the numbers of feathers 

 had grown very small, but individual birds were found in 

 process of moult as late as 1st November. Much the same 

 remarks apply to the Great Black-backed Gull and Black- 

 headed Gull. 



Perhaps the most important conclusion that the observa- 

 tions seem to point to is that, in the case of the Herring 

 Gull and Great Black-backed Gull at least, the immature 

 birds begin and complete their moult considerably earlier 

 than the adults. As to the other species, such evidence as 

 there is supports the same view. It seems also that among 

 birds of the same age there is considerable variation in the 

 season of moult. 



It must be mentioned that concurrently with the obser- 

 vations on which the table is founded, notes were made of 

 the proportional numbers of adults and immature birds 

 present on the same stretch of coast. In the case of the 

 Great Black-backed Gull, the adults were as numerous at 



