Unusual though it seems, for ducks, these ones nest in tree hollows. Doesn't seem to go with webbed feet, does it! Now is the time they will be thinking of establishing a nest.
Thankyou that's interesting to know, I'd never thought they'd nest in trees. It's actually kind of sad as they were in a tree that is about 5 meters away from a 20 hectare block of land due to be cleared next week (just stage 1 clearing right now). So sad how many birds will likely be affected.