194 Transactions. — Zoology. 



We know by induction that the ordinary domestic duck is 

 a domesticated form of the European wild duck, the male of 

 which we term a " mallard." The mallard has this special 

 peculiarity : that during winter and spring he is most beauti- 

 fully coloured, the head and neck being of a glossy green ; 

 the breast dark-chestnut ; the back light-grey, as of white 

 feathers plentifully dotted or marked with a dark shade 

 (possibly we might name it slate-colour) ; the tail and tail- 

 coverts blackish, with several dark feathers curling up and 

 backward ; and an approximate colouring to this is seen in 

 some breeds of the domestic drake. But during the seasons 

 of summer and autumn all this bright colouring is lost, the 

 colouring of the male bird then approaching that of the 

 female ; even the white ring around the neck between the 

 green and chestnut colours is absent. How is this change of 

 colour brought about ? The change is gradual, because 

 feathers of the new colour are seen among those of the former 

 plumage. But I do not think the bird moults or sheds the 

 feathers, for the strong flight- or pen-feathers certainly remain 

 in position when the bird takes on the more brilliant plumage. 

 The flight-feathers are annually changed during late summer, 

 when the young birds of the season and many of the older 

 birds are unable to fly owing to these pen-feathers being 

 absent. At this stage they are termed "flappers," and are 

 easily caught. We can see this gradual change of colouring 

 in tame birds having the mallard colours, and it causes us 

 to wonder whether they really change or shed their body- 

 plumage. If we take either the Aylesbury or the white call 

 duck we see no colour-change, and therefore we never have 

 any suspicion that they moult twice during the year. On the 

 other hand, the drake's curled tail-feathers are not visible 

 when the bird is in autumn dress : are they shed, or do they 

 lose the curl and lay flat along the other feathers of the tail? 



Young ducks and other birds in their first plumage are all 

 approximate in colour to that of the female or mother bird, 

 and some do not take on the colours of the male until the 

 ensuing spring, yet they have the inherent faculty or posses- 

 sion, held in abeyance, of the colours of the male ; and, what 

 is a still more singular thing, a female bird may for years be 

 clad m appropriate female costume, but should ovarian disease 

 cause her to be unfertile she is capable of putting on the dress 

 of the male. Here we have birds carrying the unchanged or 

 same cuticle, but capable of producing feathers other than 

 those suitable to their sex. Such are often seen among 

 domestic fowls and pheasants. I have also had two instances 

 among my hybrid ducks, which had lived to a considerable 

 age : these ducks also carried the curled tail-feathers, but one 

 never took on the green head and neck of the male. 



