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Re: Avian extinction ref.

On Wed, 6 Oct 2004, MICHAEL HABIB wrote:

> Blackburn et al. looked at oceanic islands on purpose, because he
suspected that island forms should be particularly susceptible to
predator introduction.  He was absolutely correct in this regard, and the
sensitivity of island forms to introduction events has also been shown
(though with less rigor) on previous occasions for several different taxa
(esp. mammals and birds).

Yes.  But until this paper it was not possible to say that it was not man
_per se_ but the predators he brought with him that caused the
extinctions.  Not a general homo blitzkrieg, but a specific targeted
mammal attack!  Not only that, the paper makes the more important claim
that it is the _diversity_ of predators that is critical.

> So, the bottom line is that species with highly restricted ranges,
especially those that are isolated, show a high liklihood of extinction
when faced with waves of introduced predator over a relatively short time
span.  Definitely important, but perhaps not a global kill analog.

I agree with you, of course.  However, it is possible to extrapolate this
as theory to the global ecology.  After all, I'll wager it was more than
mere  timidity that did in the island birds.  And (can you ask) I would
think there was a diversity of susceptibilities, i.e., not just a bunch of
stupid dodos standing around waiting to get clubbed.  What I mean is
inasmuch as these mamals exist on the continents, strategies employed on
the islands would be disallowed on continents--and species who employed
them became extinct when these predatory menageries first appeared.