In place of the black feathers of the normal bird, there was a fawn-coloured plumage, darkest on head and neck; lightest at bottom of back, back of flippers, and on shoulders.
Sex, female.
Third specimen captured on December 23, 1911.
Iris, light brown. Feet, browny white. Claws, brown. Bill, brown; very dark on dorsum of mandible. Eyelids, white with a pink tinge.
In place of the black feathers of the normal bird, this specimen had those of a very light cream colour: in fact very slightly darker than the white area but deepening in shade to light fawn on the head, neck, and shoulders.
Sex, male.
The second specimen had mated with a normal cock. In each case the Isabelline birds were very much more docile than the normal forms. For instance, they did not struggle when picked up, as the others would have done, and the third specimen, when brought into our hut, gazed around with curiosity and apparent contentment, and showed not the least resentment at its captivity. A normal bird would have struggled and fought to the last extremity. Each bird was killed with chloroform.
So carefully did we keep the entire rookery under observation that I do not think it likely there were any more Isabelline forms. Thus we can conclude 3/750000 roughly represents the proportion of Isabelline forms among the species.