birding-aus

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

To: "'Greg and Val Clancy'" <>
Subject: [canberrabirds] Why are the C. Sparrowhawk & B.Goshawk so similar?
From: "Dick Jenkin" <>
Date: Sun, 13 Jan 2013 09:39:32 +1100
Hi Greg and all

Not sure on any scientific basis either but I have seen a white morph Grey 
Goshawk flying with a group of Sulphur-crested Cockatoos around the Dungog 
area. The presumption being they are using the cockatoos as camouflage to 
"sneak" up on unsuspecting prey.  Maybe other people have had similar 
experiences.


Cheers

Dick Jenkin

 Dungog ( 70kms north of Newcastle NSW )


-----Original Message-----
From:  
 On Behalf Of Greg and Val 
Clancy
Sent: Sunday, 13 January 2013 9:27 AM
To: Jeremy O'Wheel; Rosemary Royle
Cc: COG line; Birding Aus; Denise Goodfellow
Subject: Re: [Birding-Aus] [canberrabirds] Why are the C. Sparrowhawk & 
B.Goshawk so similar?

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.

Greg
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.

Jeremy

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

  Rosemary Royle, Wales, UK


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