G'day Simon,
When I say migrates further west I am talking about the thunbergi birds
from the eastern Siberian tundra that are more in line with Australian
longitudes, note that thunbergi is found right across the Asian tundra and
there for is summer distributed both west and east of central Asia. So for
the eastern thunbergi they would have to travel south west( "further west" )
to get to central Asia. Scandinavian thunbergi obviously would have to head
south east to get to the same wintering areas. You have to keep in mind that
vast areas of thunbergi's current range especially in the east would have
been completely unavailable during glaciation. Thunbergi and the eastern
taxa for Yellow Wag would have been separated by vast distances, unlike the
recent/present situation. My comparison with ssp tundrae of Ringed Plover
was made because even though its current breeding distribution extends right
across the Asian Arctic in a similar fashion to thunbergi, they all still
head west to eastern Africa for the winter. That may change in a few
thousand years time and the eastern birds may start to venture directly
south in winter, but for the moment it proves that old pleistocene habits
die hard. There were some pockets available in the far eastern tundra during
glaciation and I would suggest it was probably more likely they were
populated by Semipalmated Plover not Ringed along with tschutschensis, I
like to be controversial.
Cheers Jeff.
From: Simon Mustoe
Sent: Sunday, 21 February 2010 12:38 PM
To: ; ;
; ;
Cc: ; ;
Subject: RE: Western Yellow or Green-headed Wagtails in WA
It is true. The evidence suggests that thunbergi migrates east into Central
Asia, whilst macronyx migrates south along the Pacific rim into southeast
Asia.
Regards,
Simon.
> From:
> To: ; ;
;
> Date: Sat, 20 Feb 2010 15:17:47 +1100
> CC: ; ;
> Subject: [Birding-Aus] RE: Western Yellow or Green-headed Wagtails in WA
>
> Would very much like to see the photos Mike and John.
>
> How have you excluded macronyx in this instance in favour of thunbergi,
did
> the bird show any signs of a nexklace.
> One possibility for us not getting thunbergi is that its expansion into
the
> east is very recent, post glaciation, and like other taxa such as eastern
> populations of Ringed Plover their preference may be to continue migrating
> to regions further west.
>
> Cheers Jeff.
>
>
>
>
> -----Original Message-----
> From: Mike Carter
> Sent: Saturday, 20 February 2010 2:37 PM
> To: BIRDING-AUS; John Darnell; Frank O'Connor
> Cc: Jeff Davies; Sean Dooley; Bill Ramsay; Danny Rogers; Rohan Clarke;
> Adrian Boyle; Tony Palliser
> Subject: Western Yellow or Green-headed Wagtails in WA
>
> John Darnell has sent me some poor photos of some Yellow Wagtails seen at
> Cranbrook in SW WA (north of Albany). Unusually far south for such birds.
If
>
> I read the camera data correctly they were taken on 21 January 2010. It
> seems that several birds were present, some advancing into breeding
plumage.
>
> I'm told that they were initially claimed as Grey Wagtails but this was
> corrected to Yellow Wagtail. They may still be there - are they Frank?.
Now
> the claim is that they are Eastern Yellow Wagtails as one might reasonably
> expect. John agrees that some probably are that species but it is clear
that
>
> some are not. Some have no white supercilium and John suspects that they
are
>
> what today we would call Western Yellow Wagtails of the race thunbergi. He
> uses the name 'plexa' which was the name given to the far eastern forms of
> that taxon now subsumed into thunbergi. Western Yellow Wagtail is not yet
on
>
> the Australian list but perhaps only because of the
difficulty/impossibility
>
> of telling thunbergi apart from macronyx. Although intuitively wrong,
> macronyx is considered a subspecies of Green-headed Wagtail (taivana)
which
> is on the Australian list because adults of the nominate race are annual
but
>
> rare in NW WA and occasional in the NT. Occasionally those areas too get
> birds which look like these. Macronyx has been claimed (with and without
> photographs from both Christmas and Cocos Islands. These are very
colourful
> birds with blue heads. It seems odd to me that we should get the Mongolian
> macronyx and Manchurian taivana rather than the Siberian thunbergi. Our
> usual Eastern Yellow Wagtails tschutschensis breed in the intervening
region
>
> and further east. This situation of the more southerly breeding
populations
> coming further south is contrary to the strategy adopted by other
migrants.
> More northern birds usually leap-frog there southern counterparts.
> Anyway, you Western Australians, get behind John and the WA Museum and not
> call thunbergi/macronyx birds Eastern Yellow Wagtails. They are either
> Western Yellow Wagtails or Green-headed Wagtails even though you may not
> know which!
>
> Mike Carter
> 30 Canadian Bay Road
> Mount Eliza VIC 3930
> Tel (03) 9787 7136
>
> ===============================
> www.birding-aus.org
> birding-aus.blogspot.com
>
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