Michelle Warwicker at BBC News: Bewick's swans: Baby boost for threatened birds

The smallest swan in Europe, Bewick’s swans are distinguishable from fellow migrant whooper swans by their size and small yellow blob on their black beaks, rather than the whooper’s yellow wedge.

Experts are still trying to understand what has caused this year’s bumper breeding session.

"[It’s] the golden question that we don’t have the answer to yet," said Ms Newth.

Remember, folks, even when threatened (perhaps especially when threatened), swans should be considered armed and dangerous.