107 



1922, only with a moderate number of growing feathers on head 

 and upperneck). Others, somewhat later, get their full breedingdress 

 in the second half of March. 



As in the young Guillemot, the moult of the bodyfeathers — 

 also in old Razorbills — varies greatly individually: one bird 

 (cf, March 9th, 1922) shows strong moult all over the body, even 

 on the back (though the belly shows little more than downmoult), 

 other ones chiefly moult the feathers of the flanks, breast, head and 

 neck, again other ones only seem to renew the feathers of the 

 head and those of the neck where the latter will change its colour. 

 In average the Razorbill seems to renew a larger number of body- 

 feathers than the Guillemot. 



It further should be remarked that the moult, not only that of 

 the species as a whole, but also the individual moult, lasts shorter 

 than in the Guillemot. The springmoult of each individual Guillemot 

 may last 5—6 weeks at least, that of the Razorbill 4 weeks and 

 possibly shorter. 



Moulting-period of the old birds: February and March. 



Bird from one to two years old.. — One or two billfurrows 

 as long as the birds are in winterdress; sometimes the second one 

 may be indicated indistinctly ; but it also happens that there are 

 two distinct furrows and that a third one is indicated indistinctly '). 

 The birds in winterplumage with two furrows and even those 

 which have the third furrow indicated indistinctly, don't seem to 

 represent a special year; they always seem to be birds in their 

 second winter which were not yet mature the preceding summer. 

 I suppose that the third furrow arises during the putting on, for 

 the second time, of the breeding plumage -). 



A female of March 3rd and two males of March 28th (1921) are 

 still in winterplumage but the inside of the skin shows moult 

 (I did not note where and how strong this moult was); a male of 

 March 22nd (1920) is in transition, but not far; a male of April 

 24th (1922) is in nearly complete breedingdress, it has two bill- 

 furrows and head and neck are moulting strongly, whereas a small 



1) Observed in 4 specimens : cf 19 Dec. and cT 20 Dec. 1921, 9 21 Dec. 1921, 

 cf 12 January 1922. 



2) I don't think it possible that birds in their second winter ever possess 

 3 furrows in their bill. See Conclusions, Maturity, small letter. 



