>We noticed a common 'pairing' of individual
> Hardheads and individual Grebes, mostly Hoary-headed but sometimes also
> Australasian. That is to say, an isolated 'pair' would swim together
> within a metre of each other and with nothing else nearby, and would
> dive and surface more or less synchronously, as if the one (the Duck?)
> was disturbing prey for the other (the Grebe?). Has anyone else
> observed this apparently symbiosis?
I have seen this occur between a pair of Hoary-headed Grebes that shadowed a
pair of Hardheads at Banyule Flats Reserve in Melbourne. I noted the
behaviour as odd, but could find no explanation for it other than that which
you came up with -- the Grebes taking advantage of the Duck's food
searching. The Grebes that I saw were very closely shadowing the Hardheads
(without 1-2 feet) and diving a split second after the ducks. Are there any
scientific souls out there that could explain this for me. I'm a
comparatively unseasoned birder, especially with waterbirds, so if this has
come up before somewhere (or the explanation is common knowledge) please
pardon my ignorance.
Caroline Allen
Preston, Victoria.
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