Re: Bird (Dinosaur?) vision

[frank bliss <frank@blissnet.com>]

Related to bird vision......I also heard once that if you raised 
kittens in a box with vertical stripes in it, they develop not being 
able to see horizontal surfaces because the rods and cones develop 
acuity only to the highly contrasted vertical surfaces.  The result 
will be that they will never jump up on a table because they never see 
the surface.  Sounds like so much kitty litter because they would 
always see the bottom surface of the box and have that perspective.  
Perhaps it is an urban legend, perhaps it occurs as it has always been 
anecdotal in my mind.  This relates to the bird vision discussion by 
way of the inference that all animals are the sum of the requirements 
that nature throws for their survival and the experience (programming) 
that occurs during ontogeny. Call me a evolutionary purist, (which I am 
in a punctuated sort of way)  but if there was an selective advantage 
to not seeing stationary objects (or at least no serious selective 
forces against survival of the individual as a result of the condition) 
then the trait would be developed over time and adapted by the species. 
 I find it unlikely that in nature, cats developed that can't see 
horizontal surfaces therefore birds that can't see stationary cats are 
bound to meet only when the bird flys straight up.  No survival benefit 
to the cat but a serious benefit to the birds in this scenerio.  Maybe 
this is why birds fly horizontally most of the time......   :-)
Frank Bliss
MS Biostratigraphy
Weston Wyoming.


On Jul 23, 2004, at 3:48 PM, Ronald Orenstein wrote:

> At 05:24 PM 7/22/2004, Ken Carpenter wrote:
> > Is it true that some birds can see only movement -- that they cannot 
> > "see"
> > something that is not moving?  I've recently had this suggested to 
> > me, but
> > I'm not sure I see the sense of it.  Is there such a condition in 
> > nature?
> > If so, what is it called?
>
> I can't imagine that this could be true as stated - how could birds 
> build nests accurately (say) if they literally could not see inanimate 
> objects?  However, an increased acuity to movement could well be 
> present (I have heard it suggested that this is the chief advantage of 
> the compound eye structure of insects), or simply a hightened response 
> to movement as opposed to inanimate objects, with no difference in 
> acuity.  It has been suggested that the pecten, a comb-like structure 
> at the back of the eye, serves to pick up movement, but it may have 
> more to do with nutrient supply and pressure regulation (the pecten is 
> highly vascularized).  There is a good article on "Vision" in "A 
> Dictionary of Birds" (Lack and Campbell, eds, 1985).
>
>
> --
> Ronald I. Orenstein                           Phone: (905) 820-7886
> International Wildlife Coalition              Fax/Modem: (905) 569-0116
> 1825 Shady Creek Court
> Mississauga, Ontario, Canada L5L 3W2          
> mailto:ron.orenstein@rogers.com