Cygnus olor, Mute Swan.
Native to much of Europe and Asia. It is also an introduced species in North America, Australia and southern Africa.
The name "mute" derives from it being less vocal than other swan species.
Safely on mum's back, the other three ones are hiding beneath her wing.
I've been watching this nest for days, it took almost a day for the young ones to hatch.
After that they spent another day underneath mother's wings, and finally after two days the whole family went for a little swim. Afterwards they returned to the nest.