Hi Chris & Chris,
At the risk of splitting feathers, it is a bit more complicated than that:
Tringine and Calidrine waders like godwits and knots do not moult their flight
feathers in the pre-breeding moult. Pre-breeding or pre-alternate moult is
partial. In Black-tailed Godwit, the partial moult to breeding plumage involves
head, neck, mantle, scapulars, underparts and all, some or no tail. However,
they usually retain 10-50% of old mantle and scapulars in males and 20-60% in
females (see Handbook of the Birds of the Western Palearctic Vol 3). So there
is no such thing as 100% breeding plumage. Black colours do not get blacker
or reds redder as the moult progresses. More new feathers with black or bright
red grow in, increasing the percentage of new feathers and the amount of bright
colours. In some cases (knots and stints for instance, but not godwits as far
as I know) have very thin white tips that soon wear off. This makes a slightly
worn plumage appear overall more colourful than a fresh one, but it does not
necessarily
mean that a fresh bird has less breeding plumage than a worn one.
The bird that Chris W photographed has quite a low percentage of new scapulars,
whereas the comparison bird has a high percentage of new scapulars and even a
few new wing coverts.
--- On Wed, 23/3/11, Chris Sanderson <> wrote:
From: Chris Sanderson <>
Subject: Black-tailed Godwit in breeding plumage in Alice Springs
To: "Chris Watson" <>
Cc:
Received: Wednesday, 23 March, 2011, 10:19 AM
Hi Chris,
Yes, birds often leave Australia nearly completely coloured up. I have a
nice shot from Broome of a line of Red Knot in nearly 100% breeding plumage.
More typical though is they reach about 60-80% before departing and
complete the rest either on migration or at the breeding grounds. I believe
how quickly the males colour up is part of how a female decides on a mate -
it is a demonstration of their fitness. After all, on top of replacing
non-essential feathers for breeding plumage they also moult all their flight
feathers, nearly double their weight with fat storage and flight muscle bulk
and complete a host of other physiological changes to be able to make the
arduous trip. If you can do all that, and reach the breeding ground first,
you probably get first pick of females and your offspring will have the best
chance of completing the migration unassisted once you leave.
Another point - I had drilled into me time and time again in Broome by
visitors from the northern hemisphere that what we think of as "full"
breeding isn't. They nearly always complete the moult after they leave.
Your bird is a very good example, but in 100% breeding plumage the reds
would be richer and the blacks blacker. A quick net search shows this:
http://6000k.net/Birds/Black-tailed+Godwit.jpg.php as a fairly good example.
I'd say your bird is in 90-95% colour which is really great to see! More
of the back feathers will change to the buff colouration with the black
spots and more of the face and breast will go deep red, but apart from that
most of the changes have already happened. Probably more coloured up than
any Black-tail I've seen before in Aus.
Thanks for putting the photos out there.
Regards,
Chris Sanderson
On Wed, Mar 23, 2011 at 2:13 AM, Chris Watson <>wrote:
> G'day folks,
> Had a nice flock of 6 Black-tailed Godwits at the sewage
> ponds in Alice on Tuesday including one bird in quite spectacular plumage.
> I've stuck some pictures up on the Birds Central blog if anyone would care
> for a gander.
>
>
> http://comebirdwatching.blogspot.com/2011/03/black-tailed-godwit-in-close-to-full.html
>
> Is this common for migratory birds to be getting close to full breeding
> plumage before departure?
>
> Cheers,
> Chris Watson
> Alice Springs
>
> --
> *BIRDS CENTRAL*
> *Central Australian birding resource*
> *Guiding, writing, and the latest site information*
> *from Alice Springs*
> www.comebirdwatching.blogspot.com
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