I recently noticed a lone crow with wings extended walking on the ground nearby. As I got closer, I realised that he was collecting the still lit butts discarded by intending passengers, and was wafting the smoke underneath his wings in some apparent ritual. Was he trying to fumigate mites or other parasites in his plumage, or has he just "taken to the weed"?Terry Lawlor, Ballyduff, Co Waterford. That sounds like a very clever bird! Rooks sit on top of smoking chimney pots for the same purpose - to rid themselves of parasites.