Not sure about intelligence involvement in migration.
It has been shown that at least some bird migrations are probably
genetically controlled (1). One example is the European Blackcap where
different populations migrate from central Europe in different
directions. Crosses between individuals give progeny which migrate in an
intermediate direction. Plus there are many shorebirds where juveniles
migrate successfully on their first long distance flight in the absence
of adults. I don't see how this latter would work in the absence of a
large genetically controlled component.
So it wouldnt surprise me if such migration vagrants have some sort of
mutation in the genes of the inbuilt migration navigation system causing
them to migrate incorrectly. In general the migration to a benign
enviroment is likely to be rare but it would be interesting to know if
such vagrants return to the same area in future.
1. Control of Bird Migration by P. Berthold. *Chapman and Hall, 1996.
*
*Cheers
*
*Andrew
*
On 13/05/2013 6:31 AM, Glen Ewers wrote:
Many vagrants to Australia can reasonably be explained as ship- or
storm-'assisted'. Those aside, I've often wondered whether every day there are
birds streaming off land masses in all directions - 99.99% of which drop into
the ocean before reaching landfall, the occasional Hoopoe or Wagtail or Pond
Heron arriving 'safely' (and, even more occasionally, colonising). I have read
about sailors encountering terrestrial birds flying past their ships when miles
out at sea, perhaps resting for a while on the mast or deck, and then
continuing on with no goal apparent.
Birds are, of course, capable of amazing migrations and peregrinations - thanks
to highly evolved and sophisticated brains. We are surely only just beginning
to appreciate how intelligent birds are? We're achieving this, in part, by
removing our own blinkers as to how intelligence might be made manifest. That
said, just as we humans - with our highly evolved and sophisticated brains - do
all sorts of stupid things, why not birds? Some of these birds may have mental
defects, some may just have made a strange (wrong?) decision. We have to be
careful we don't just regard birds as either perfect logicians or else victims
of storms / inadvertent stowaways.
Anyway, after years of voyeurism, that's my virgin sortie into birding-aus.
Cheers, Glen
-
--
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Andrew Hobbs
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