Penguins of the North...?

[John Bois <jbois@umd5.umd.edu>]

> I note the fab adaptations of penguins to catch
> fish,
> but, at the same time, their compromised ability to hide nests (i.e., they
> can't fly).  It is reasonable to suggest this is a limitation on their
> distribution (along with the presence of cold current productivity).

There was a suggestion from HP Ron Orenstein that auks are more diverse
than penguins.  Technically this is true.  However, the inference that is
drawn from this--viz., that the penguin niche is just as fruitful
in the north as the south, and it's only because of competition and/or
lack of transport in cold currents that they don't invade the north--does
not follow.  I believe all these
birds fly.  In terms of flightlessness and size, the Great Auk is a
distant
outlier among auks.  For fish-eating Alcids, wing size seems a compromise
between
the needs of flight and swimming; the wings of these birds are as
small as they possibly could be while still allowing flight.  Of what
value is flight such that it needs maintaining at the expense of favorable
aquatic characteristics?  Wings are great for many things--one thing they
do give auks is a greater selection of nesting sites--cliff faces, for
example.  Penguins don't have that luxury.  Finally, while penguins may
indeed be prevented from migrating north by lack of cold currents, flying
auks would seem to have fewer restrictions on their mobility.  Why, then,
did they not invade penguin territory: perhaps because the penguins are
better competitors where they are able to nest!
And it strikes me that this nice story is just like the Balanus and
Chthalamus (sp?) barnacles: penguins are better competitors where they can
tolerate predation.  Where they can't, Alcids can take over.
Thank you, thank you very much.