370 Correspondence. que 
certain species of ducks the females have a spring moult of the down 
as well as of other parts of the plumage and that not only is the win-: 
ter down renewed but in addition there grows what she terms a ‘“‘nest 
down,” which is longer, coarser and of a different color. 
Yours faithfully, 
H. F. WiTHErRBy. 
326 High Holborn, London, W. C. 
Epitor or ‘THE Aux’: 
In ‘The Auk’ (XXXIV, pp. 206-207) is an interesting note by Mr. 
Bowles, calling attention to the differently coloured down in winter and 
summer in a number of Ducks. Apparently the author has not seen Miss 
Jackson’s article in ‘British Birds’ (IX, p. 35, 1915) where she describes 
the down-moult of certain Ducks. It was first discovered by me in the 
Long-tailed Duck (Clangula hyemalis), where it is very striking, the down 
being whitish in winter and moulting into an almost black one in the spring. 
While studying Ducks I had already noticed that the description of nest- 
down did not agree with what I found on female ducks, but I did not grasp 
the reason, until I noticed the change in the Long-tailed Duck or “Old 
Squaw”. Miss Jackson soon after, while working in the Tring Museum, 
discovered, to use her own words (l. c.) ‘‘that the females of the surface- 
_ feeding Ducks and those of the genus Nyroca also acquired a special down 
just before the breeding season. Female Tadorna tadorna also have a 
down-moult in spring. This down is evidently used for embedding the 
eggs during incubation, and has been designated ‘nest-down’ by Dr. 
Hartert, a term I propose to use in describing it.” I believe that all 
palearctic Ducks, or at least the majority of them, have a down-moult in 
spring, but in some species the colour is the same, though the nest-down 
is often longer and coarser than the ordinary down. Where there is no 
material difference in colour, the down-moult is difficult to observe in skins, 
but of course very easily seen when one skins afresh bird. I may add that 
Miss Jackson’s article contains also valuable details about the spring- 
moult in adult females of several British Ducks, which must also take place 
in American species. 
Ernst Hartert. 
Tring, May 15, 1916. 
Subspecific Designations.! 
Epiror or ‘THE Aux’: 
The exception taken in ‘ Bird-Lore’ to the current practice of subspeci- 
1 Published by permission of the Deputy Minister of Mines, Canada. 
