no 



more tender. The bird in its second winter appears to be fullgrown 

 and its legs mostly seem to have reached the size of the legs ot 

 the old birds; the general colour of the legs however is very olten 

 warm yellowishbrown ; this hue sometimes also occurs . in older 

 birds, but then as an exception whereas in the two years old birds 

 it is the rule. 



The best way to find out whether a bird is fullgrown or not, is 

 to notice its measures and these prove that the apparently fullgrown 

 bird, which is nearly two years old and will come to breeding 

 within a few months, is not fullgrown even then. To this purpose 

 I measured the height of the bill of a good number of Guillemots, 

 a method which is preferable to the measuring of the wings, as it 

 does not matter whether birds are moulting their primaries or not. 

 I measured the bill just there where the feathering of the chin 

 stops between the two halves of the mandible (see page 109). 



Conclusions. 



Moult: From the notes given above, it follows that there is an 

 anticipation of the springmoult when the bird grows older. We 

 further may assume that for a late moult, just the same, whether 

 it is found in older or in younger birds, the parents of the birds 

 in view can be blamed, for we may expect that a late young from 

 a certain year, which for the first time puts on its. breedingdress 

 in May, the next year may be able to anticipate this moult till 

 March, but impossibly till January and the year after that till f. i. 

 January but not till the beginning of December. In consequence of 

 this anticipation of moult early moulting „old" birds may as a rule 

 be older than late moulting „old" ones. 



We may expect however that this does not concern birds which 

 have not been hatched at about the same latitude for more northern 

 breeding birds hatch their young ones later than more southern 

 ones so that these young ones may moult a Httle later. If the 

 communication of Hantzsgh (1905) is exact, the Guillemots of Iceland 

 do not wear their breedingdress before the middle of March, which 

 means a difference of two or three months with our birds. A bird 

 moulting late might be therefore just as well a northern breeding 

 bird as a bird with a retarded moult. 



Old specimens which are really slow in moulting — as they so 

 often occur in other species of sea-birds! — must be very rare 



