Good evening,
Couldn't help getting out my trusty source to Birds of Thailand and Birds of
South-east Asia, both texts by Robson.Checking on the Forest Wagtails that I
saw in northern Thailand over the years I spent there, it would seem that the
birds I observed in the forests around Chiang Mai and further north during the
northern autumn and winter (my records indicate sightings from late September
through to early March), would have been overwintering from SE Siberia, E and
NE China, N Korea and Japan.
The timing of the bird in Alice Springs could therefore indicate a bird that
has worked its way south from its wintering grounds rather than returning
north. Not sure how plausible this is and purposely avoiding any reference to
"reverse migration" from a wintering ground.
There is also evidence from some Thai birders I spoke with on the top of Doi
Lang one winter's day (it actually was cold) that certain populations of Forest
Wagtails are merely short distance and/or altitudinal migrants which, from
memory, supported sightings "out-of-season" through the valleys of Chiang Mai
and along the forests bordering the Mekong - birds that have moved down from
Doi Inthanon, Doi Chiang Dao and Doi Lang where they breed.
Otherwise, as Adrian suggests, the FW could be an overshoot from late
autumn/early winter as it moved to its wintering grounds in South-east Asia,
having been present, but undetected, in Australia for a longer period of time.
With this, I can't see it working its way from northern shores of Australia
through extremely undesirable and non-viable habitat - envisaging more of a
"dropping out of the sky" episode following a severe weather system. How
plausible is this?
My two cents on this fond little bird from one of my old haunts ...
Cheers,
Paul
> Date: Sun, 12 May 2013 09:02:27 +0800
> From:
> To:
> Subject: [Birding-Aus] Reverse Migration in Australia?
>
>
>
>
>
> Hi all
>
>
>
>
> Recent discussions on birding aus about the Forest Wagtail being possibly a
> reverse migrant yet again got me thinking about this.
>
>
>
>
> Do we really get reverse migration in Australia?
>
>
>
>
> I’m not sure to be honest and just putting it out there but there are some
> points that don’t really add up.
>
>
>
>
> I guess reverse migration is often used as a term in Europe where there is a
> lot of evidence to support this. So if they have it there why shouldn’t we?
>
> Europe’s location is the most important thing. Its North of the vagrants
> breeding grounds.
>
>
>
>
> I guess the starting point of a reverse migrant depends on the species in
> question. But to simplify things let’s say it’s a Yellow-browed Warbler. They
> are vagrants in the UK but getting more numerous.
>
>
>
>
> Yellow-browed Warblers breed in various places in Asia but let’s say our
> warbler breeds in Mongolia.
>
> The chick is raised and if it’s got reverse migration then instead of heading
> down to the Malaysian peninsular taking a SE track it takes a NW track and
> ends up in Europe. Some of these birds certainly would die during the harsh
> winter but some clearly survive and in some species it is thought that they
> survive and breed the following season eg back in Mongolia and their
> offspring may even travel back to Europe and hence why some species that were
> super rare 20-30 years ago are now much more common in Europe.
>
>
>
>
> Back to our Yellow-browed Warbler. He/she hangs out in Europe in some nice
> not so cold climate and when the time comes heads back to the breeding
> grounds to breed. Raises young and repeats.
>
>
>
>
> This is reverse migration as its heading in the complete opposite direction
> of where it should have been going eg NW instead of SE.
>
>
>
>
> So how do we explain our Forest Wagtail. If it was raised in say northern
> China and had a problem with reverse migration should it not have headed
> North instead of South after it was born? Maybe our Forest Wagtail did but
> then shouldn’t it now be heading further south back to the breeding grounds?
>
> So that’s the bit I don’t understand if it’s a reverse migrant and its headed
> south to Alice then where did it go after it was born? If it’s a reverse
> migrant then why has it not gone back to the breeding grounds after going
> North?
>
>
>
>
> I hope this makes sense but to me the concept of reverse migration may work
> in Europe it doesn’t seem to work for Australia.
>
> It would make sense if it were a species that bred in Malaysia and in March
> April headed north to take advantage of the Arctic summer but instead headed
> south to Australia.
>
>
>
>
> Why is the Wagtail not just a bird that overshot its wintering grounds in
> Southern Asia in Sept Oct. (lots of birds do this) It could have been in
> Adelaide the whole summer ( maybe in Tony Russel’s garden) and is or was
> heading north and stopped in Alice and ended up in not its ideal habitat and
> has decided to not head north this summer to breed.
>
>
>
>
> Maybe it will head North but it is cutting it a bit fine. The latest personal
> migration I have seen was Red Knots on the 13th of May several years ago out
> of Broome.
>
> Yellow Wagtails tend to leave Broome very late April or early May.
>
>
>
>
> I’m no expert on this. It’s just my thoughts and look forward to someone
> coming up with a possible explanation for me.
>
>
>
>
> Maybe this is what all the OBP’s are doing and instead of heading north to
> the mainland and are instead heading south and dying in Antarctica. (joking)
>
> Cheers Adrian Boyle
>
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