104 • 



Observations. 

 I. Moult'). 



Uria troille (L.). — About 450 specimens examined, about 300 

 of which were received during the period ot 

 the springmoult viz. from December 1st onward 

 to May (see also Postscriptum). 



Bird older than two years. — The moult of the so called 

 old birds (birds then about 30 months old and older) was observed 

 to begin in the second half of November with the growth of black 

 contourfeathers in the neck and (often somewhat later) on the head, 

 where the change in breedingdress takes place. Perhaps the growth 

 of these feathers is preceded or accompanied by the growth of a 

 certain number of contourfeathers on the belly and in the flanks; 

 we can 't know this however, as most of the birds, when they begin 

 moulting into breedingdress, still show their autumn-moult in a 

 varying — often rather important — number of growing feathers 

 on the underbreast and the belly and in the flanks. The neck and 

 the head then only show the last traces of their autumn-moult in 

 a varying number of growing downfeathers. The first birds in breeding- 

 plumage (but still with growing feathers) were received on Novem. 

 ber 27th and Deceber 7th (1922); in the first days of January some 

 more birds show the full breedingdress; about the middle of January 

 some have finished moulting, so that one looks in vain for growing 

 feathers. 



Others however moult much later and even in the second half 

 of January there are birds which do not show a trace of moult 

 (9 ad, Jan. 14th, 1922). Late birds like such even at the end of 

 February still show a number of growing downfeathers on the 

 chin, the throat and sometimes the rest of the head (9 ad, February 

 27th 1922, received alive, though apparently in full breeding-plu- 



1) Only the so called springmoult is given here, the autumnmoult will 

 be given when more material will have been examined. 



2) Of about 60 so called old birds, which for the most part I especially 

 examined on this point, I found no specimens wiiich showed strong moult 

 of belly, breast and flanks as I found more than once in the one and two 

 ye.irs old birds. These birds were received in January. 



