[canberrabirds] Why are the C. Sparrowhawk & B.Goshawk so similar?

To: "Jeremy O'Wheel" <>, "Rosemary Royle" <>
Subject: [canberrabirds] Why are the C. Sparrowhawk & B.Goshawk so similar?
From: "Greg and Val Clancy" <>
Date: Sun, 13 Jan 2013 09:27:22 +1100
Whether there is any scientific basis for the ‘cockatoo theory’ or not I am 
sure that the white underparts would assist in camouflage in the sky.

Dr Greg. P. Clancy
Ecologist and Birding-wildlife Guide
PO Box 63 Coutts Crossing NSW 2460
0266493153 0429601960 

From: Jeremy O'Wheel 
Sent: Sunday, January 13, 2013 12:09 AM
To: Rosemary Royle 
Cc: COG line ;  ; Greg ; Denise Goodfellow ; Birding Aus 
Subject: Re: [Birding-Aus] [canberrabirds] Why are the C. Sparrowhawk & 
B.Goshawk so similar?

The problem with the cockatoo theory is that in Tasmania there is good reason 
to think Sulphur-crested Cockatoos are recently introductions, but all the Grey 
Goshawks are white morph. Also Grey Goshawks have a white underside regardless 
of morph, and that's the side prey would normally see. I suspect the underside 
is white for sky camouflage (like the White-breasted Sea-eagle and a number of 
other diurnal birds of prey), while the upper surface possibly represents 
genetic drift, or sexual selection.


On 12/01/2013 11:56 PM, "Rosemary Royle" <> wrote:

  During our latest trip to Australia, up above Gunlom Falls in the NT we 
spotted a dead branch laden with Sulphur-crested Cockatoos plus what appeared 
to be a smaller white cockatoo. It wasn't, it was a white-morph Grey Goshawk, 
and it had obviously chosen to perch with the cockatoos. .

  Only on reading this thread does that sighting make sense.


  Rosemary Royle, Wales, UK


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