They swan about but can be aggressive and territorial

Swans tend to be more aggressive towards each other than towards other water birds.

SWANS have a fearsome reputation. They can, it is often said, break a person’s arm with a blow of the wing. 

Having caught and ringed over 1,500 of them, I can confirm that a close encounter of the swan kind is unlikely to lead to more than a few bruises on arms and thighs.