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PROFESSOR J. COSSAR EWART AND DOROTHY MACKENZIE ON 
by black feathers, with purple and green reflections on the head and neck, glossy 
black feathers with large, distinct, white spots on the back, and pearly white on the 
under surface — is not finally established in all its splendour until about the end of 
May.* * * § The result is that in the Great Northern Diver moulting is going on during 
the greater part of the year. 
The common duck ( Anas boschas), though doubtless aiming as high, has not yet 
reached the stage gained by the Great Northern Diver, for the female still wears an 
inconspicuous coat all the year round. t In the male duck, as in the Great Northern 
Diver, many months are occupied by the double moult ; in the ptarmigan and grouse 
more or less obvious changes are taking place in the plumage all the year round, 
and, though not so obvious, this is also true of pigeons, kingfishers, parrots, and 
many other birds. In the penguins, on the other hand, the actual moulting period is 
short, and there is no difficulty in ascertaining exactly when it begins and when it ends. 
In the immature Emperor Penguin taken on board the Discovery in Lady Newnes 
Bay the moulting “ took twenty days from start to finish.” In this case “ the feathers 
clinging close to one another came off in spurious sheets or handfuls, first from the 
breast and thighs and then from the face and tail and flippers, but most irregularly, 
until at length there w T as nothing left but a ruffle of old feathers round the neck.”| 
It is conceivable that under natural conditions the duration of the moult in this bird 
would have been under twenty days. 
In the King Penguin which moulted in 1897 in the London Gardens the feathers 
began to fall out about the end of August, but the moult was only completed in the 
third week of September. In 1898 this bird again moulted in August-September, 
and the duration was again about a month. § In the case of the King Penguin 
which moulted twice in six months in the London Gardens, the “process was com- 
pleted on both occasions in just four weeks.” || Though in the King Penguins in the 
London Gardens the duration of the moulting process was decidedly longer than 
in the immature Ejnperor on the Discovery , an immature Humboldt’s Penguin 
(Spheniscus humboldti ) which reached the London Gardens in 1878 moulted in ten 
days. This bird, though out of condition on arrival, rapidly improved. By feeding 
freely and passing much time in the water, it was extremely vigorous when the 
feathers began to fall off on February 26 . Bartlett points out, the process of 
moulting proceeded so rapidly “that by the 7th of March the bird had entirely 
renewed its plumage and appeared in the adult dress.” Though this immature 
Spheniscus, about February 22, appeared dull, was spiteful and ill tempered, and 
* An account of the moulting of the Great Northern Diver, by Smalley, will be found in the Annals of Scot. 
Nat. Hist., 1909, p. 139. 
t Both the duck and the diver, in having an immature down coat, are decidedly less specialised than kingfishers 
and parrots. 
| Wilson, loc. cit., p. 19. 
§ W. E. de Winton, Proc. Zool. Soc., 1898. 
|| Seth-Smith, loc. cit., Proc. Zool. Soc., 1912. 
