It’s possible that some of you noticed that one of the blue tits in yesterday’s post had an unusually long beak. That’s because, presumably, it is suffering from Avian Keratin Disorder.
This is a condition whereby the bird’s bill grows out the keratin sheath that covers the bone of the bill at an unusually high rate – far higher than the bill is worn down. In many cases, the birds that contract this cannot feed themselves and, ultimately, die.
Amazingly, this bird is in better shape than it was a few weeks ago.
A couple of weeks back I saw it when the upper part of the bill was nearly as long as its body – approaching 10 centimetres. I’d thought it was carrying a length of straw as nesting/roosting material, but after seeing it again a few times knew it was something else. At that point it was really struggling and you could see it trying to break this off, writhing on the floor clawing at its own bill. Very distressing. Somehow, since then, it has managed to do so, survived, and is eating okay.
Quite what causes this, whether an underlying genetic disorder, or some chemical exposure, remains to be seen.