Re: Bird (Dinosaur?) vision

[frank bliss <frank@blissnet.com>]

Having owned severals parrots, I will tell you all that there isn't 
much that a bird can't see.  They are inquisitive, intelligent and 
beyond all that, just plain observant.  I have seen them examine 
stationary objects from all angles at a distance and set forth a plan 
of action to obtain it.  I had a blue and gold Macaw that would see a 
stationary pop (soda) can from across the room, plan a method to get 
over to it from it's perch, and proceed to implement the plan to get to 
it (waiting for me to be around the corner).  The goal of course was to 
get to the contents.  After obtaining his goal, he would use his beak 
and dexterous claws to manipulate the pop top open and tip one back 
(about half of it would run down his featherless cheeks and half down 
his gullet).  Nothing worse than a Macaw on a sugar high.  There were 
even times when they had x-ray vision.  This is person observation not 
well studied, controlled fact however.  Something might have gotten by 
him but I suspect that it was by choice not by evolutionary design.  
Smaller(ish) birds may not have the brain power developed by hundreds 
of generations of manipulating the environment with their digits/beaks 
like the Macaws. On the other side of the avian world, I suspect that 
most things may seem to move pretty slow to a hummingbird whose 
metabolism is high enough to make our movement appear in slow motion at 
best.  Their vision is selective no doubt based entirely on food 
gathering or threat assessment. To them, a cat might seem to stand 
still but I bet they would notice them.  Even so, some cats (which use 
the motionless hunting technique) succeed in catching avian prey.  My 
Macaw would have delighted tearing up our cat if he tried.  
(Fortunately for our cat, he was raised around big birds.) The initial 
statement was "some birds".  In the real world where most things do not 
move, visual que's dominate.  Most of them are non-movable ones too.  I 
suspect they can't see objects like I can't see, for instance the table 
leg I stub my toe on occasionally. All motionless objects all move when 
the bird does however.
Frank Bliss
MS Biostratigraphy
Weston, Wyoming


On Jul 23, 2004, at 1:31 AM, K and T Dykes wrote:

> Hi Lawrence,
>
> <<Is it true that some birds can see only movement -- that they cannot 
> "see"
> something that is not moving?>>
>
> They manage to locate our fly-in snack bar in the winter, and that's 
> nailed
> securely to a fence.  Thick tree branches are also prone to long 
> periods of
> motionless meditation.  Birds land on them, rather than fly straight 
> into
> them.  A method of discouraging birds from going near shiny new 
> buildings,
> is to stick silhouettes of vicious birds of prey on the windows.  
> There's
> also a stationary device sometimes used for scaring crows from fields 
> and
> gardens, but I forget the name.
>
> In short, I have my doubts about this.