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 > > > —– Original Message —– From: “Denise Goodfellow” < > goodfellow@bigpond.com.au> > To: “Greg” ; “David Adams” > Cc: “COG line” >; > “Birding Aus” > Sent: Saturday, January 12, 2013 2:00 AM > Subject: Re: [Birding-Aus] [canberrabirds] Why are the C. Sparrowhawk & > B.Goshawk so similar? > > > I have often seen the white morph of Grey Goshawk accompanying flocks of > Little Corellas and Sulphur-crested Cockatoos. I wondered why until some > years ago I saw a bird drop out of such a flock and snatch a pigeon from > the > powerlines. > > > Denise Lawungkurr Goodfellow > 1/7 Songlark Street, > Bakewell, NT 0832 > 043 8650 835 > > PhD candidate, SCU > Vice-chair, Wildlife Tourism Australia > Nominated for the Condé Nast international ecotourism award, 2004 by the > renowned American website, Earthfoot. > Wildlife Adviser, BBC¹s ODeadly 60¹ > > Birds of Australia’s Top End and Quiet Snake Dreaming available on > amazon.com > A second edition of Fauna of Australia¹s Top End used by the University of > NSW as a text for 12 years is now under preparation. > > ‘It gave me huge insight into the lives’ of Aboriginal Australians¹, > Jonathon Franzen, American author, birder, conservationist (August, 2011) > on Quiet Snake Dreaming. > > The best guide in Darwin is Denise Goodfellow. Bo Beolens, the Fat Birder. > > www.denisegoodfellow.com.au > > > > > On 12/1/13 8:31 AM, “Greg and Val Clancy” wrote: > > My understanding is that the white morph of the Grey Goshawk was able to >> survive in a forest situation where it stands out like the proverbial >> because it resembles white coloured cockatoos. I don’t know if there is >> any >> science behind that claim though. >> >> >> Greg >> Dr Greg. P. Clancy >> Ecologist and Birding-wildlife Guide >> PO Box 63 Coutts Crossing NSW 2460 >> 0266493153 0429601960 >> >> —–Original Message—– >> From: David Adams >> Sent: Saturday, January 12, 2013 9:26 AM >> To: David Adams >> Cc: COG line ; Birding-Aus >> Subject: Re: [Birding-Aus] [canberrabirds] Why are the C. Sparrowhawk & >> B.Goshawk so similar? >> >> An all white raptor in the forest? >>> >> >> John Leonard wrote to mention the White Hawk, an unusual New World forest >> raptor: >> >> http://neotropical.birds.**cornell.edu/portal/species/** >> overview?p_p_spp=124796 >> >> Despite often being nearly all white, these birds seem to be doing pretty >> well for themselves over a huge area. The behavior section at the Cornell >> site is interesting. it sounds like these birds follow around parties >> of monkeys (arboreal foragers) and coati (ground foragers – relatives >> of Raccoons) pouncing on whatever prey is flushed. Perhaps their >> coloration >> is not selected for/against as they’re opportunistic feeders? No >> idea…it’s always easy to make up an evolutionary/ecological story…but >> that doesn’t make it true. >> ==============================**= >> >> ==============================**= >> >> To unsubscribe from this mailing list, >> send the message: >> unsubscribe >> (in the body of the message, with no Subject line) >> to: birding-aus-request@vicnet.**net.au >> >> http://birding-aus.org >> ==============================**= >> > > > ==============================**= > > To unsubscribe from this mailing list, > send the message: > unsubscribe > (in the body of the message, with no Subject line) > to: birding-aus-request@vicnet.**net.au > > http://birding-aus.org > ==============================**= > ==============================**= > > To unsubscribe from this mailing list, > send the message: > unsubscribe > (in the body of the message, with no Subject line) > to: birding-aus-request@vicnet.**net.au > > http://birding-aus.org > ==============================**= > ===============================
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