This poor swan was being harassed by a red-winged blackbird. The bird kept trying to land on the swan’s head and back. The swan would dive and flap its wings but the bird was very persistent. The bird finally left and perched on a bush nearby.
Maralee
Through My Lens 
Was it trying to land, or just chasing it away from the nest. Blackbirds nest near water, building a nest on the reeds.
It could be all it was doing is defending its territory. Or, it has a thing for swans.
It was trying to land. It was doing it for a good length of the river.
A very interesting sight.