Colin and all,
The GHL was found in 19 Jun. If the bird hadn't been in the country
too long before that, then it's occurrence will have coincided with
it's northerly spring migration, so this would be a reverse migration.
If it had been round for 9 months, then as you rightly point out it
would be an overshoot.
The problem that I see with both these scenarios is not the distance
travelled (there are plenty of vagrancy records which beat the GHL
distance) but the direction travelled.
Going from the distribution of GHL, it appears to do a NE - SW
migration in autumn and visa-versa in spring. So, regardless of
whether it was on its wintering grounds (Nepal-South China) and
undertook a reverse migration (SW instead of NE), or it was an autumn
overshoot (again, it should have been going SW) and it flew the
distance from the wintering grounds to that of Burren Junction, then I
figure it should have turned up in Madagascar!
I'd have to study the distribution maps a bit more carefully, but I
don't see how Australia would end up as part of an over-shoot
'shadow'.
(There's a great piece on vagrancy shadows in Rare Birds in Britain
and Ireland: A Photographic Record by David Cottridge, Keith
Vinicombe).
An interesting record, whatever, and it's on my list!
Cheers,
Graham
On 8/1/06, scouler <> wrote:
Hello birders,
Shane Brady's reference to hearsay from a local at Burren Junction to the
effect that the GHL has been in the area for the last 9 months seems to cast
some doubt on the theory that it got there by "reverse migration".
Hayman et al "Shorebirds indicates that the population which breeds in
Manchuria migrates to its wintering grounds (Nepal-South China) in about
September. So the timing of the bird's reported arrival at BJ would appear
to coincide with that of its normal southward migration. Its presence at BJ
might therefore be the result of an overshoot.
If so, it would be a colossal one, more than double the length of the usual
southbound journey of the species, even given the fact that GHLs has been
known to wander from their normal flight path and turn up as vagrants in the
Andaman Islands, Malaysia, the Philippines and Indonesia.
Colin Scouler.
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Graham Etherington
Indooroopilly,
Queensland, Australia
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