I'd love to know the answer to that. Also with the superficially very similar
Black-shouldered Kite and Letter-winged Kite, why so similar when perched, and
why the different underwing pattern and eye marking?
Peter Shute
Sent from my iPad
On 11/01/2013, at 5:10 PM, "Philip Veerman" <> wrote:
> After contributions from several people to solve the recently Birding-Aus
> posted "Timeless question" of a request to identify some photos as either a
> Collared Sparrowhawk or a Brown Goshawk, it got me wondering has anyone
> investigated or got any ideas why these two species are so similar in the
> colour patterns and remarkably so in both juvenile & adult plumages. The
> first bird book I ever bought was Condon's 1966 Field guide to the hawks of
> Australia when I could afford the 50 cents RRP. It said (snippets) that they
> have "the same pattern, that the Collared Sparrowhawk is a small replica of
> the Brown Goshawk and the female cannot be distinguished from the male Brown
> Goshawk in the field and they can only be picked in museum skins". Well now
> we know better but the point remains that their colour patterns are
> amazingly similar.
>
> As hawk species go, both their colour patterns in juvenile & adult plumages
> are an unremarkable sort of typical for the genus as a whole. But why are
> these two so much more the same than any others. Is it common ancestry that
> these two species are a more recent divergence from each other than to any
> other members of the genus and have changed in size and structure but not in
> colour. It appears to me that in structure their form is divergent along the
> lines of other species of Sparrowhawks and Goshawks. Why should our Brown
> Goshawk look so much more like our Collared Sparrowhawk than say the
> widespread European Northern Goshawk? Could it be colour mimicry of one
> species of another, in which case why? Is it coincidence, and especially
> that they inhabit the same geographic range. Nikolas Haass has mentioned
> that the Cooper's/Sharp-shinned Hawk pair causes in N America very similar
> confusion issues as the Brown G/Collared S pair in Australia. Does the same
> question apply?
>
> Philip
>
>
>
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