This thread focuses on:
> >2) why do Gannets "elongate" their necks before take off from a colony?
>
> Why do I get the feeling it's both to inform cliffmates AND gulp O2?

I wish Dennis was here, because we've disagreed about this question and
it would be interesting to have his two cents (or more likely two bucks
worth) of viewpoint. Birders and other natural history people are always
asking questions like this, and they always bring to mind two other
questions: (1) How would you find out? (2) Why does there have to be
a reason?

Question 1: Seriously, how do you go about telling whether an
explanation is correct or reasonable or a "just so" story? Suppose you
hypothesize that Gannets make this movement to warn cliffmates. Does
that imply any observation or experiment you might make to test the
idea? In this case, maybe it does; maybe you predict that when there is
a real threat, Gannets don't make this movement and everyone takes off.
That would certainly support the hypothesis. What else could you do? I
don't know. Herb Curl's explanation of why it's not likely to be oxygen
gulping seems reasonable, but are there experiments one could do to
substantiate it? Mind you, I'm not picking on this one behavior or one
set of explanations. It just seems to me that in many cases all you can
give are good guesses, with no evidence one way or another.

Question 2: This is where Dennis and I have disagreed. He takes a
strong adaptationist viewpoint; he points out that to produce a certain
structure or engage in a certain behavior takes energy, so there must
always be a reason why that structure or behavior is there. He makes a
good point, and I'm not taking a strong anti-adaptationist stance. But I
have read Gould and Lewontin's paper "The Spandrels of San Marco and the
Panglossian Paradigm," and they make a good case for not assuming that
everything an animal does is an adaptation for some purpose. Krebs and
Davies have made the point by saying that when flamingoes stand against a
pink sunset they're well camouflaged, but we certainly don't think their
pink color is an adaptation for this purpose.

I guess the only take-home lesson I can suggest for now is that we
shouldn't naively look at a bird (or any animal) doing something that
strikes us as odd and assume there's some kind of adaptational reason for
it. Some actions may be inconsequential byproducts with no function at all.

Burt Guttman guttmanb at elwha.evergreen.edu
The Evergreen State College Voice: 360-866-6000, x. 6755
Olympia, WA 98505 FAX: 360-866-6794