At first it looked like the whole bill was crossed but on closer examination it became apparent that the offending article was actually the lower mandible skewing to the left. We debated whether in the interests of the bird's welfare we should try and 'trim' the end to hopefully encourage even wear, but it seems the acquired wisdom is to leave well alone, which we did. The bird had a healthy weight and looked in good shape, so I'm sure it will be OK.
