Sharp-winged are slightly larger, longer and greyer. Chilean are browner with more spots. At one time there were more Chilean around, then Sharp-winged became available and were more popular because they are slightly prettier. Unfortunately the races have been carelessly hybridised and it may be hard o tell what one is looking at at. Although I have bred Sharp-winged, and worked with Chilean, I may be wrong about the birds in the picture. Sorry to be so vague.
'Lovely weather for (confusing, possibly hybrid, small ornamental) ducks'.
Having disposed of the Anas flavirostris complex, and agreed that the Marbled Teal is OK, let's look at the remaining two ducks at the top of the picture, which at first glance I thought were Chestnut (-breasted) Teal. I still think one of them is, but the duller coloured bird isn't. Any takers?
That's the one. Looks to be male, I'm thinking Wigeon x Chestnut-breasted (but not colourful enough about the head?) or Ferruginous x Chestnut-breasted (but not round enough?).
Yes, FBBird has identified the quote! As for the mystery duck, when seen in the light of day its colours are largely Chestnut-breasted Teal but what the other parent is I am not sure. If I think on I shall ask the Head Keeper on Friday. The other one at the top is indeed a Chestnut-breasted Teal.