This video is about the fairy tale The Ugly Duckling.
Yesterday, I saw two mute swans swimming in the canal near the river.
They were swimming with a Canada goose (a species which I had never seen there yet).
I heard this same goose had been swimming with those swans a few days earlier as well.
In that tale, a swan’s egg lands in a duck nest, and the young swan grows up in a duck family.
Maybe, a Canada goose egg somehow landed in a swan’s nest. And the swans brought up the gosling as a young swan. And now that it is fully grown, the goose still swims with its foster parents.
In the Netherlands, at least one case is known of an Egyptian goose bringing up a Canada gosling. And also at least one case of the other way round.