Recently in Naas I saw a quite large bird which was a beautiful shade of light brown, with wing feathers outlined in brown. It was certainly a large crow with the distinctive beak and the "caw". Later I saw it flying with the other crows. Anne Cowie, Blessington, Co Wicklow It was a rook with a genetic pigment defect. In rooks these can range in colour from white (albinism) to various shades of brown or grey affecting the whole plumage. On the other hand, grey or white patches on a rook's feathers are usually the result of injury or feeding deficiencies.