Dave,
With regards to navigating towards/ away from a pole,I would think that the
question is how do the small, <400 angstrom, crystals of magnetite in the
brain react to the magnetic lines of force. As the lines of force are
horizontal and for all practical purposes parallel at the equator I don't
see how crossing the equator would pose a problem in navigation.
I would love some more information on this form of navigation if someone has
recent findings to share.
Regards,
Alan Gillanders
Alan's Wildlife Tours
2 Mather Road
Yungaburra 4884
Phone 07 4095 3784
Mobile 0408 953 786
http://www.alanswildlifetours.com.au/
-----Original Message-----
From: Dave Torr
Sent: Friday, November 29, 2013 11:48 AM
To: Carl Clifford
Cc: Birding-Aus Aus
Subject: What happens to the vagrants
Earlier this year I took a Danish guy out birding - turns out he was a
Professor of Ornithology in Germany. His speciality was migration and - if
I understand correctly - his research shows that birds can basically find
their way towards a pole or away from a pole, and not necessarily north or
south. (This would seem OK for birds that migrate solely within a
hemisphere but seems difficult to apply to our waders for example?). So he
reckoned that once a bird had crossed the equator - and we were talking
about the fairly regular male Northern Shoveller at Werribee - it would
continue its annual migration pattern but be out by 180 degrees - which
would work reasonably well in such cases. But harder to apply to birds
which just make it over the equator I guess
On 29 November 2013 12:32, Carl Clifford <> wrote:
I thought struck me the other day (yes, it was painful). What happens to
the vagrant species that turn up at places such as Ashmore Reef or
Christmas/Cocos Is.? Do they all die? Having arrived at these places due
to
weather conditions or navigational error, many, if not all, would
certainly
have problems re-orienting themselves, so I imagine that the chances of
returning to their normal habitat would be fairly slim. I imagine that
such
places, particularly Ashmore, would be rather like an avian death row.
Carl Clifford
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