A group of English swans has seen off a takeover bid by some Australian birds in a battle for territory.
It is thought the black swans may have come out of captivity
About 10 black Australian swans settled on Brayford Pool, in Lincoln, about a month ago.
But about 250 white mute swans were already living on the lake and the birds began fighting for territory.
President of the Swan Preservation Society, Nick May, thought the black swans may have come out of captivity as they allowed people to feed them.