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Bill's abstract is of general interest. It has enough data to estimate
the visual acuity of the Peregrine (a 5cm ? robin at 2 km.?).
It begs some more speculative questions: "if evolutionary design
efficiencies are so darned effective at optimizing a design, why
isn't the direction for maximal acuity situated straight-ahead anyway?"
- for example. The general design layout for the bird has been around
an exceptionally long time - and even a novel construct like the mammal
can fine focus nearly straight ahead, can't it?
This suggests there are competing objectives involved - indeed Bill
mentions head streamlining versus light gathering (where the Owl seems
to have been optimized for rather different visual/flight conditions
as an airborne predator.) I expect that birds in general have the
built in capability of "keeping your head on a swivel!"
- the advice given to novice pilots... by its panoramic view which is
not apparently optimized for binocular fusion and depth perception by
this means.
Recalling the continual tremor without which the human eye rapidly
grays out, it could be that a helical scan offers pattern recognition
virtues too. (I should also finally mention that it is generally conceded
that evolution is not considered a perfect mechanism - but good enough;
that is, until your appendix starts aching interminably, for example.)
Brian
brian whatcott <inet@intellisys.net> Altus OK
Eureka!