Beak deformities in garden birds

According to the BTO, fewer than 1 in 200 adult birds suffer from a beak deformity. Arriving at a figure like that can't be easy as a large scale survey would need to be undertaken. Fortunately for them, many members, volunteers and enthusiastic nature lovers are all at hand to participate in such a survey (which is ongoing) called the Big Garden Beak Watch.

There are many different types of beak deformities, affecting either or both mandibles, in a manner of different ways. This Great Tit was first spotted here on the 3rd September, with what seemed at first to be just something stuck to his beak. In the time he was around on that day, it couldn't seem to shake it off (though it did seem to try). The (presumably) same bird was back again earlier this week, with the same object stuck, again trying to shake it off. This leads me to think it's not a beak deformity as such, though I'm not certain we'll ever be sure either way.

We have, however, spotted a few confirmed (and recorded) beak deformities here over the years:

Blue Tit with decurved (and slightly crossed) upper mandible

Rook with decurved upper mandible

Blue Tit with elongated mandibles

We have had a few reports and photos brought in to us of beak deformities in Great Spotted Woodpeckers and Blackbirds too, though a total of 36 species have been recorded through the Big Garden Beak Watch. Please do record your sightings to the BTO - this survey, along with many others they undertake, including the Abnormal Plumage Survey, help them to gain a greater insight in to the causes of irregularities in birds.

Goldfinch with leucism

Chaffinch with leucism