How harmful is it to feed swans bread? I feed them bread with grains, etc in it. I see people feeding them mouldy bread, something I would never do, can that make them sick? We have one breeding pair of Mute Swans in the centre of Waterford City, Ireland and this winter and the past have had a visiting Whooper Swan. I have been photographing them and herons and cormorants and more recently filming them with my camcorder. I have observed one swan attacking another and climbing on top of it and like Fiona,wasn't sure if I was watching males fighting or a pair mating. Fiona's photos and description explained this behavior. I can testify to the fact that they are intelligent and remember those who are kind to them,also that they have good eyesight. They will see me at a bridge from a distance and come back to be fed. They will come up a bank to feed out of my hand (or from the water when there is a high tide) and let me feed the cygnets by hand too. They look up at me and almost "beg" for food. I get great enjoyment from them and they have opened a whole new world to me,leading me to discover the heron, Cormorants, mallards and a Red Shank. Sorry to have gone so much!