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
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