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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: <689@sun13.scri.fsu.edu>
Date: 14 Sep 90 18:23:23 GMT
References: <1197@cluster.cs.su.oz.au> <675@sun13.scri.fsu.edu> <687@sun13.scri.fsu.edu> <49409@olivea.atc.olivetti.com>
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In article <49409@olivea.atc.olivetti.com> mjm@oliven.olivetti.com (Michael Mammoser) writes:
>In article <687@sun13.scri.fsu.edu>, sandee@sun16.scri.fsu.edu (Daan Sandee) writes:
> > 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).
> 
>	I read that it was a "weak flyer", though this was a general
>literary reference and not a specific study paper. However, I was
>wondering how one goes about verifying flightlessness through direct
>observation. This would seem to be quite tricky. For instance, I have
>directly observed thousands of Pied Billed Grebes, but can't recall 
>ever seeing one fly. What conclusions can I draw from this? :-)
> 
>Mike

You're absolutely right. Direct observation can only provide negative evidence
of flightlessness, which is inconclusive. Hence LaBastille spends several pages
in her monograph on the bird's physiology with respect to its flying potential,
and concludes that it most probably could not fly.
As for Pied-billed Grebe : I can't remember ever having seen one fly, either.
Though people who have seriously studied the bird no doubt have.
There is circumstantial evidence of its flying capacity : it's a partially
migratory bird, and even if there are no banding records, its seasonal 
appearances and disappearances suggest migration ; unless you assume, as 
scientists in centuries past did, that it hibernates in the mud, or gets
turned into a barnacle, or something. And I do suppose it migrates by air -
it doesn't walk, or swim the rivers, or something.
(I'm not being sarcastic. Just making a thorough scientific investigation.:-))

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