ROGER DOBSON claims that bird "pests" in urban areas are a threat to public health ("Feathered fiends blitz the cities", 22 February). I am not aware of any reliable evidence that this is the case. But I do believe there is ample evidence that the human population and its by- products are harmful to birds, other animals, and humans alike.

I am willing to put up with pigeon droppings on "our beautiful cathedrals" for the pleasure of seeing pigeons with their iridescent feathers fluttering in the concrete jungles of our cities. Nor would I mind if a bird "caused havoc" at a service in one of these cathedrals.

And how can people who eat the flesh of animals which have been raised in crowded and waste- filled conditions, injected with steroids, hormones and antibiotics, say they are afraid of a health threat from urban birds and their droppings on the street?

Bicester, Oxfordshire