Pied Crow

A pied crow has become a regular visitor to our garden of late. I should explain - there is a bird called a pied crow, common in Africa and also from time to time kept as a pet. It has a white neck and chest, and black head, back, wings and tail, and, although about the same size as our carrion crows, is I think better described as a small raven. The bird that visits us is a native carrion crow, but it has a substantial number of white feathers on each wing. It would look quite handsome, but is in fact a bit on the tatty side - very tatty in fact when we first saw it, with most of his tail feathers missing. He’s beginning to look a little more respectable now, but the very fact that he spends so much time prospecting around our feeders, something our nearby nesting crows never do, would suggest he’s been having a hard time.

The term for his condition, of white feathers instead of black, is leucism, which affects a wide range of common birds. Leucistic blackbirds are quite often seen, ranging from birds with just an occasional white feather to birds with only a few black feathers. No-one knows why blackbirds should display leucism more often than other species, though there is clearly a genetic elements here. Leucistic birds are not albinos, which are completely lacking in pigment - they partly lack the black pigment melanism. Other plumage abnormalities include melanism (extra black pigment, so darker plumage - this is often seen in pheasants), and less often, erythrism which is where  there are additional red pigments, and flavism with extra yellow pigment.

Do these plumage changes cause problems, I wondered, seeing how bedraggled our “pied crow” looked. Yes, is the answer, they can: having plumage that differs from the population 'norm' can give the wrong signals to other individuals, as well as perhaps making the bird more obvious and vulnerable to would-be predators. In addition, research suggests that feathers with reduced pigment may be less robust, wearing more quickly and reducing flight efficiency. They may also be less effective in insulating the bird against cold.

Unusual birds can often be attacked and driven off, and there are many instances of this happening to escaped cage birds, for example. But birds also habitually attack other species that are similar to them but differently plumaged; on these pages I’ve described how robins will attack dunnocks, and blue tits will drive away coal tits (this year, in fact, we have a particularly feisty blue tit using our nest box, and he will fly at almost any other birds that visits our feeders - I mention this because usually blue tits seem to be only one notch up from coal tits at the bottom of the pecking order).

Anyway, I think our visiting crow is most likely to have been attacked by fellow carrion crows spooked by his plumage irregularities. But he’s beginning to get quite feisty himself, the other day seeing off his more regularly pied relative, the magpie, with great promptness and efficiency.