The White Chaffinch of Glen Lyon

A recent enquiry in the early summer described a sparrow-sized bird seen nesting in a porch where people passed to and fro. Before any mention of colour, this had to be a spotted flycatcher, and a few questions about its behaviour clinched the diagnosis. There then followed a bizarre description of the bird’s colour which was nothing like that of the delightful Muscicapa striata, which after checking a field guide, my questioner confirmed the bird to be.

Later in the summer a question came through the Comment office: had I ever seen a white chaffinch? I hadn’t, so I drove way up into Glenlyon to have tea with a lady who must spend a small fortune on bird food. I identified her house, which had no visible name, because of the mass of titmice, gold- and green-finches feeding with siskins in the front garden. Before long ‘Snowy’ put in his (or her?) appearance to share my hostess’s largesse.

Partial albinism (such as James Irvine-Robertson’s piebald blackbird reported in an earlier Comment) is not uncommon, but a total albino is rare and this was certainly the first all white chaffinch I had ever seen.

Had I not been warned that the bird had been seen as a fledgling being fed by mother chaffinch, I could easily have mistaken the creature for an escaped, rather washed out, red-eyed, canary.

The bird was feeding happily with several other chaffinches so close to the window that one could see that, in all respects other than colour, it was identical. The other chaffinches appeared to be unconcerned at their peculiar friend.

Inherited Gene

Albinism is inherited as a recessive gene causing failure of the enzyme tyrosinase which forms the black biological pigment melanin. Surprisingly there are only two natural pigments in animals, the black melanin and the red carotene. Mixtures of these two pigments produce the whole range of plumage, skin or hair colour.

The opposite of albinism is melanism caused by an excess of melanin. That is not uncommon in Highland Perthshire where huge numbers of pheasants are reared for sport. The melanistic cock pheasant is not really as black as ‘Snowy’ is white, rather it is a handsome purple sometimes almost navy blue. Where I grew up on a sporting estaste in Hertfordshire pure white albino pheasants were really quite common.

Albinism and melanism also occurs in humans; the latter may confer benefit in tropical countries so leading, in part, to negroid races. Occasionally one sees an albino human, such as the unpleasant Silas in Dan Brown’s novel The Da Vinci Code. A striking feature of such a person is the pink appearance of an eye such as may appear in a flashlit photograph.

So I hope people will continue to report interesting observations or pose problems of identification. I enjoy them but cannot guarantee to be able to help particularly when they fall into the category of a “vulture hovering over the distillery” - though, in that case, I could offer a medical rather than an ornithological diagnosis!

Information that really helps consists of answers to the questions: where was it? when was it? what was it doing? what shape was its bill? how long were its legs? followed by size, habitat, behaviour, song and, last of all, its colour

© Robin Hull