272 Prof. R. Collett on the Occurrence 



in their summer (nuptial) plumage, while eight are in the 

 process of change from summer- to the third year's winter- 

 plumage. 



Young of the year. — Of tliese individuals six are young in 

 their first autumn (sliot in November and December), and 

 one is a one-year-old bird^ shot in June. The young of the 

 year ai'e barely full-grown the first autumn. One from the 

 neighbourhood of Tromso (the date is wanting) has still a 

 shortish and undeveloped bill. During the first autumn the 

 winter-plumage is (as in C. glacialis and C. arcticus) recog- 

 nizable by the lights somewhat sharply-defined margins of 

 the feathers of the back. In shape these feathers are rounded 

 or almost pointed. 



The one-year-old bird (South Varanger, 23rd June, 1891) 

 still bears its worn first winter-plumage. The light margins 

 of the upper surface have become bleached, almost whitish, 

 and partly worn, from which the feathers begin to assume 

 the more square-cut edge, which at once distinguishes the 

 bacl\ of the adult bird from those of the younger ones. 



In the autumn and winter of the second year the birds still 

 retain a grey plumage, which is, however, easily distin- 

 guishable from that of the young ones by the colour and 

 shape of the back-feathers. The light marg'ns on the upper 

 parts have been thrown off, and the back, on the whole, 

 has become darker ; most of the feathers have a lighter 

 greyish-brown patch where the large white summer spots will 

 subsequently appear. But these patches are often weakly 

 margined and partly indistinct. 



In shape these feathers are somewhat square-cut, as in all 

 old individuals. The bill has attained its full length and 

 shape, and its colour is about the same as in individuals in 

 their nuptial plumage. The lower neck-bar is luore or less 

 indicated by the dusky terminal rays on the feathers, which 

 are here more dense and darker than on the throat. 



The nuptial plumage is assumed when the individual is at 

 least two years old. It is, however, probable that, as in the 

 case of C. glacialis, these birds are not capable of breeding 

 the first year that they put on the nuptial dress. 



