Re: Barriers to dispersal

[Ronald Orenstein <ornstn@rogers.com>]

At 01:04 AM 20/12/01 -0500, John Bois wrote:
> There is great relatedness among NZ and Australian birds--is this from
> migration or land connections--I think the former.  Quite a distance.  And
> then, over an (arbitrary) 10 million year period, there can be storms,
> rafts, etc., etc.  Islands in the middle of nowhere are populated
> by avian species. Why not massive continents not so far from other massive
> continents?

New Zealand's land birds seem divided, roughly, between ancient taxa that 
probably arrived via Antarctica (I believe I am correct in stating that NZ 
and Australia were never directly joined, but were connected via 
Antarctica) and recent arrivals.  The Silvereye, now a common bird there, 
arrived in the mid 19th century, presumably by natural means, from 
Australia (its Maori name means "stranger").

The American Purple Gallinule is, rather surprisingly, a more or less 
regular wanderer to South Africa, but has never established itself there - 
and of course many American songbirds wind up in Europe every year.


--
Ronald I. Orenstein                           Phone: (905) 820-7886
International Wildlife Coalition              Fax/Modem: (905) 569-0116
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