Curious behaviour

There’s a beautiful pair of Mandarin Ducks on the pond. It’s worrying me though that there seems to be something wrong with the female.

She’s lying as stiff as a board semi-submerged in the water, nostrils barely above the waterline. The male looks attentive and worried. What could be wrong with her?

Is she ill I wonder? I stay watching them for ten minutes or so. I’m convinced she’s likely to die. Then she stretches and simply swims off.

What do you think? Does the male look just a little pleased with himself?