Re: Birds and perception
Tue, 20 Apr 1999 21:40:24 EDT

In a message dated 4/20/99 6:01:19 PM Mountain Daylight Time, writes:

> Kevin L. O'Brien wrote:
> [...]
> KLOB>These small "creeper" birds hunt by movement and color
> KLOB>contrast, not by pattern recognition.
> Cool. As someone with an interest in animal cognition, this
> statement is very interesting, as I don't recall seeing the
> research that established this. I recall the "What the frog's
> eye tells the frog's brain" classic, but frogs are not birds.
> "Search image" concepts generate some amount of controversy,
> but I did not know that the issue had been settled for birds.
> Could you point to a literature review article or something
> related in the primary literature?

No, actually, I cannot. I read about it back in undergraduate school (an eon
ago) in a reference book about birds, when I was toying with the idea of
becoming an ornithologist specializing in ethology (animal behavior). It
made sense to me, though, because otherwise camouflage would be useless. A
quick bird, darting about in a shaded canopy looking for food, cannot waste
time or energy on fruitless searches, so instead of evolving the ability to
recognize specific patterns it evolved the instinct to attack contrasts and
small moving targets. Even with color vision, camouflage works better in
shade than in broad daylight, and it works better against a color
contrast/movement predator than a pattern recognition predator. Pattern
recognition predators are more often foiled by mimics and "scare tactics"
than camouflage, or at least so my limited reading tells me.

If you find any research confirming or refuting this claim, please post it; I
would like to see it.

Kevin L. O'Brien