At Cape Adare the light grey “silvery” coloured chicks mentioned by Dr. Wilson were by no means uncommon; in fact, quite a large proportion of the chicks had very light-coloured down. This is shown in some of the specimens I brought back to the British Museum.
(B) Variations.
Variations occasionally are met with in the plumage and soft parts of Adélies. The least rare of these consist of tufts of white feathers amongst the black plumage of the head. Several specimens so marked were seen at Cape Adare during the summer of 1911–12.
When these white tufts were present the feathers comprising them were usually longer than the black feathers among which they appeared, so that they stuck out in an untidy manner, and were very conspicuous.
In marked distinction to the slight variations above described were the three “Isabelline” varieties that I preserved, and are now to be seen in the British Museum collection. As these variations are very startling, and of the greatest interest, I give below a full description of their plumage and soft parts.
First specimen captured on the Cape Adare rookery on November 4, 1911.
Iris, light brown. Eyelids, white. Bill, light brown. Feet, white. Claws, light brown.
The whole of the area covered by black feathers in the normal bird was covered by those of a very light fawn, somewhat darker on the neck and shoulders than elsewhere. Sex, male.
Second specimen captured on November 14, 1911.
Iris, light brown. Eyelids, white. Bill, light brown; mandible, blackish on dorsum; maxilla, blackish on cutting edges. Feet, white on both surfaces. Claws, light brown.