Hi, Thanks for your ideas on this puzzle.

But No- they are a male and female - they have been in the area for over 8 years, with many successful breedings, and there are NO other swans around. I know this is true as I visit them most days with feed, and to check up on them.

What I think has happened is that their original nest was disturbed, either by fox or human and the female has found another site to lay the rest of her eggs - (currently just the one) - today BOTH the male and female are nearer to the latest nest so I am monitoring both nests to see what happens.

I can update you if you would like ?