It could be that is that the Pink-eared Ducks have
a different feeding regime to other waterfowl ?
They feed by filtering their food from
the surface of the water whereas other
species dabble from below the surface ?
So, if a poison of some sort is floating on the
water they would be a goner !
I am always amused that our
Pink-eared frequently circle around closely behind each other in
twos or threes with their beaks almost up the preceding duck's
Mount Isa, NW