Re: Bird (Dinosaur?) vision

[Dino Guy Ralph <ralph.miller@alumni.usc.edu>]

From: "Jeff Hecht" <jeff@jeffhecht.com> writes:

> It has also been suggested that the birds may "doze" with eyes open
> to watch for predators, while effectively getting some sleep.

I had read that a group of sleeping birds perched single file along a branch
or power line had lookout birds at each end of the formation.  The birds on
either end kept open those eyes which faced outward, away from the center of
the group.  These open eyes were conscious, and the brain apparently
responded to the usual visual stimuli, but the brain was asleep aside from
those functions that related to viewing and interpreting through the open
eyes.  In this way, birds truly do "sleep with one eye open."

Regarding the alleged inability of birds to see nonmoving items, this seems
absurd to me, especially in light of the fact that of all creatures birds
possess perhaps the best visual acuity on the planet, but I would be happy
to peruse evidence that supports such a claim.
--------
"Dino Guy" Ralph W. Miller III
Docent at the California Academy of Sciences
proud member of the Society of Vertebrate Paleontology