Eagle Pond: Mallardlings?

More curious a clutch in large ("L").

The middle of these five is more unlike the others than it looks: its "flocking" behaviour is different (the four similar ones typically move together, with the dark one apart), scoots around more quickly, and dives under the water like a tufted duckling. I'm not quite sure what is going on: it seems incredibly improbable that it has been adopted (there are no other tufted ducklings on the pond, and it'd be very coincidental for her to have adopted such a similarly sized duckling, out of nowhere...), yet if they're all hybrids (there is a male tufted duck on the pond) then it seems quite strange that four are such typical mallardlings while the other is so much more like a tufted duckling.
Hmmmm - mallard mysteries.

I was so temped to blip the Goosles today, but had decided that I wouldn't (for variation's sake), so have put them on Flickr (inc. some pictures with which I was very pleased) as well as more pictures of these ducklings, and other pictures of the mallard mother on the boating pond who has 13 tiny ducklings!

Highlights:
More of these mallardlings

Goosles (right from here):
Flapping off the island
Mr. hisses at a gosling / Mrs. hisses at the same gosling
Flapping away from a coot
Mr. is v. handsome [blip alternative]

13 mallardlings: running across the water; overview