monarchs in New Zealand
Dr. James Adams
jadams at carpet.dalton.peachnet.edu
Thu Apr 16 08:51:50 EDT 1998
Ken Phillip wrote:
> James Adams suggested that if Monarches migrate from the North
> Island to the South Island of New Zealand, that would indicate magnetic
> rather than solar cues are used.
> That is not a _necessary_ conclusion from the data, if what is
> meant is that all Monarchs migrate to the south to hibernate. Remember
> that western US Monarchs migrate towards the coast, which for some
> means going west. Whether solar cues, or magnetic field cues, are being
> used is not ipso facto obvious from the mere fact of migration.
Ken is, of course, correct in part. I was using the fact that the vast
majority of Monarchs have a general north-south direction of
migration. Heck, even here in the SE U.S., when the Monarchs come
through in the fall they are, as you might expect, not flying
directly south but distinctively SW (though it is still not known
whether the ones that come through N. Georgia actually end up in
Mexico). And, the Monarchs in New Zealand, assuming they got there
naturally, would have come from some of the Western U.S. populations,
so Ken's argument is important from this respect as well. All I was
trying to point out was, assuming that the Monarchs actually *do*
move from the North Island to South Island, it that they would have
had to chose a direction to fly *initially*. There would have been
no previous "knowledge" of an *appropriate* overwintering site on the
South Island. I was not trying to say that magnetic cues would be
the only ones in use here, simply that it would have been a mechanism
Monarchs *could have used* in getting from the North to South Island,
similar to a mechanism that *could be used* for the vast majority of
naturally occuring Monarchs in the states. It makes for a nice "easy"
explanation, one that could very easily be wrong!!
More information about the Leps-l