Collared Sparrowhawks anyone?

To: "'Paul T.'" <>, <>
Subject: Collared Sparrowhawks anyone?
From: "Philip Veerman" <>
Date: Sat, 15 Aug 2009 16:11:18 +1000
Hello Paul,
Yes I think that is a very good observation. This on the basis that, pigmentation deficiency, is typically not perfectly symmetrical (as for example in often happens in ducks, chickens, blackbirds, the recent ones in ravens and the one Pied Currawong I found during one of Lindenmayer's surveys at Nanangroe). It certainly appears to be symmetrical this photo, or this case.  That does not mean that a genetic change would not cause a pigmentation deficiency (or any other words we may happen to use) that happens to be symmetrical. I think it would need a really clear close look at the bird and some history to work out this one. Or maybe a look at lots of museum specimens, although looking into the closed wings is not so easy.
Philip Veerman
24 Castley Circuit
Kambah  ACT  2902
02 - 62314041
-----Original Message-----
From: Paul T. [
Sent: Saturday, 15 August 2009 10:31 AM
Subject: RE: [canberrabirds] Collared Sparrowhawks anyone?

At 05:37 PM 14/08/2009, you wrote:
Yes. On the basis of the tail shape is really obvious. It also shows big white spots. Is that a recent thing? I commented several weeks back that these are likely to be pale feather bases made visible during moulting. However this and a few other recent local photos suggest I was wrong in that. Are we getting a plumage pigmentation deficiency?

Philip et al,

If it was a pigmentation deficiency, would the effect be perfectly symmetrical?  If you look at the white feathers (or part feathers) on either wing they match absolutely perfectly (allowing for one white patch which looks like it could be covered by a brown feather on the other wing?).  Unless all these feathers grew at the same time (and coincided with a deficiency or something that can cause feather bleaching) would they be perfectly mirrored like this?  What are the odds of all those feathers being replaced at exactly the same rate?  Is it possibly just a genetic "colour form" unique to this bird?

Fascinating picture, that is for sure.


Paul T.
Higgins, ACT *******************************************************************************************************

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