The Diving Mallard?

I've shown this picture before because it's a great picture of our Moscovy duck, but this time I'd like to focus on the brown female mallard in the upper part of the picture.



We have two of these. Mallards are dabbling ducks, which means we spend a lot of time laughing at their little upturned behinds as they reach for food just below the surface. Mallards dabble. They don't dive.

Except for this one. I was out there tonight for quite a while, and she was diving all over the place. It was clearly intentional, and the other female mallard didn't do it once. You can see in the picture below that they're virtually identical.




I did a little online research, and apparently mallards have been seen diving, but it's unusual.

The interesting thing is that we do have a visiting red-headed duck. He's been with us for weeks now, and he's a diving duck.

Could this duck possibly have learned to dive from him?