Thanks Adrian and David for your corrections to my very general layman's
description of what occurs. As always I am in awe of differences in the
attention to details required between casual field observations and rigorous
scientific ones. It certainly increases my understanding of how the
migration fits together. Adrian I have no idea where the photo was taken,
possibly Holland? It was a random shot from Google Image search to
demonstrate what a bird with worn breeding plumage looks like, roughly.
What it boils down to I guess is for Australian birders we are unlikely to
see waders in their full splendour here, and visiting their breeding grounds
will give a different and more colourful perspective on the overall
migration story.
Regards,
Chris
On Wed, Mar 23, 2011 at 11:44 AM, Adrian Boyle
<>wrote:
> Hi David
>
> Thanks for your posting I was just about to make similar comments.
> Particularly about the colour changes in feathers.
> Breeding plumage is very difficult to score and I often have debates
> between various other researchers on what we score as 100%. There are so
> many variables.
>
> Age of the bird seems to effect amount obtained, there is differences in a
> lot of species between sexes and even individual variation from year to
> year.
> Regarding no such thing as 100% plumage I also agree in most respects. It
> depends on what your scoring system would be. Do you score what 100% would
> look like for an Australian bird before it leaves? Do you score it as what
> 100% would look like say in late may in the Yellow Sea or do you score it on
> the breeding grounds as 100% as if its breeding then thats 100% plumage for
> that individual that year.
>
> Cant say I agree with all the above but they are some of the arguments ive
> been involved in.
> So most researchers have there own personal scoring system when it relates
> to monitoring individuals and recording how much breeding they obtain over
> the course of a season.
> I personally score in percentages of 25% so for example when I say 100%
> breeding for a bird it may not be 100% but is closer to 100% than the score
> of 75%.
> I also record a separate scoring system for the Red Knots that I work on in
> China. I record percenatge on the mantle/back areas as a percentage and
> belly/ flanks and under tail coverts as another.
> Breeding plumage is not easy particularly if you have not seen many
> individuals in breeding plumage or are not familiar with sexes or
> subspecies.
>
>
> Keen to know where the Black-tailed Godwit photo on the post was taken
> because my gut feeling is that its not even our flyways subspecies because
> that plumage colour doesnt suit our birds at all.
> Happy to be proven wrong though.
>
> Cheers Adrian Boyle
>
>
> On 23/03/2011, at 8:46 AM, David James wrote:
>
> > 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: Re: [Birding-Aus] 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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