Dear Ian and John,
Thanks for providing the link to the article. I apologise for the late
reply, but I've been busy preparing for an overseas trip.
If anyone would like more information please feel free to contact me. I
found it quite striking that the differences according to sex and age
were so close a match to the phases/morphs described by previous works
(e.g. HANZAB). I think it has all stemmed more or less from old works
looking at unsexed and museum skins of questionable age (bird not the
specimen). I am confident, at least for the race I monitored at Werribee
in Victoria, that there are no colour morphs or phases of this species,
beyond perhaps the very dark birds (which weren't present in my
population). However, no-one to my knowledge has looked at the age of
these birds elsewhere. It is still possible that these dark,
pseudo-black falcons are all young (<4 years old), even when they are
found breeding. Also, I did find 4-5 adult females which had a distinct
rufous tinge to their ventral plumage (redheads) which didn't fade with
age over the five years of the study. Whether this qualifies as a morph
I am yet to be convinced however, and it certainly doesn't match
descriptions of other birds well in any case.
What is now needed is a thorough description of brownies in other parts
of Australia, such as the interior and northern Aus where these 'phases'
are more prevalent. I would be surprised if the persistence of most
phases currently described stacks up to close scrutiny, the vast most
raptors follow the same pattern of getting lighter as they get older,
and the plumages of brown falcons fit this nicely, with lightening more
pronounced in males.
Another reason to watch brownies more closely in the field!
Happy birding,
Paul
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dr Paul G. McDonald
Visiting Fellow
Department of Zoology
La Trobe University
Bundoora, Victoria
Australia 3083
Ph: 03 9479 1876 (International replace 03 with +613)
Fax: 03 9479 1551
http://zooserv.zoo.latrobe.edu.au/Staff/mfc/PGM/Default.htm
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> -----Original Message-----
> From: [birding-aus-
> On Behalf Of Ian Northcott
> Sent: Monday, 24 April 2006 6:25 PM
> To: Birding-Aus
> Subject: Re: [birding-aus] 'phases' of Brown Falcon
>
> Hi John
>
> Here is a link to the article on the CSIRO Publishing site. It has
the
> abstract and reference.
>
> http://www.publish.csiro.au/paper/MU02028.htm
>
> Cheers
>
> Ian
>
>
> John Leonard <> wrote:
> Alan Morris alluded to an article in the Emu which has proved that
the
> phases of the Brown Falcon are age-related colour changes.
>
> Could someone summarise this article in a few sentences for us? Alan?
>
>
> --
> John Leonard
> Canberra
> Australia
> www.jleonard.net
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