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From: sandee@sun16.scri.fsu.edu (Daan Sandee)
Newsgroups: rec.birds
Subject: Re: Atitlan Grebe (was:trivia quiz answers)
Message-ID: <687@sun13.scri.fsu.edu>
Date: 14 Sep 90 15:16:06 GMT
References: <1197@cluster.cs.su.oz.au> <675@sun13.scri.fsu.edu> <1201@cluster.cs.su.oz.au>
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In article <1201@cluster.cs.su.oz.au> andrewt@cluster.cs.su.oz (Andrew Taylor) writes:
>In article <675@sun13.scri.fsu.edu> sandee@sun16.scri.fsu.edu (Daan Sandee)
>writes:
>> [useful info about the Atitlan Grebe]
>>It was definitely flightless.
>
>I had a vague memory of being told by someone they had seen one fly but maybe
>my memory is faulty. I checked Seabirds of the World which I think said
>"almost" flightless.

I see I have to back up my statements by citing my authorities.
A. LaBastille, "Ecology & Management of the Atitlan Grebe, Lake Atitlan,
 Guatemala", Wildlife Monographs No. 37, 1974.
[For the purists : there is a diacritical sign on the last a in 'Atitlan',
indicating the stress is on the last syllable.]
LaBastille specifically notes that previous reports have surmised that it
could fly, but refutes this based on
 (a) direct observation, including reports from local inhabitants
 (b) thorough examination of physiology (wing size and pectoral muscles).
>
>> ... the A.O.U. uses interbreeding as the criterium for species determination,
>
>It seems to me this only helps in the easy case. If the ranges of two
>populations overlap but they never interbreed then you call them separate
>species. 
Correct. I wasn't complaining about their criterium - I was merely using it.
LaBastille again : no interbreeding at all was observed between Atitlan Grebe
(Podylimbus gigas) and the sympatric population of Pied-billed Grebe 
(P.podiceps). As with the flightlessness or otherwise, earlier opinions to
the contrary by other scientists are not based on evidence, or based on other
criteria than interbreeding.

>But what does the A.O.U do if the ranges don't overlap (common
>in Australia) and surely it doesn't declare two populations to be
>the same species just because interbreeding has been recorded?
>
>Andrew

David Mark has already answered that question (thanks, David).

Daan Sandee                                           sandee@sun16.scri.fsu.edu
Supercomputer Computations Research Institute
Florida State University, Tallahassee, FL 32306-4052  (904) 644-7045