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Pet Forum / Birds / Birds / November 2007Birds and their eyes
My last message was cut off, for some reason, but I think I got the "jist" of what I was trying to ask across to the reader. Animals that have eyes that are closer together are usually predators; whereas the opposite is not true; they are not predators. (In fact, one theorist, who studied criminals, once stipulated that "more often than not" the most viscous of all killers in society -- or in the brink -- have an abnormal distance between their eyes: they are usually situation a good deal closer than what one would consider nornal. I raised the previous issue only as an academic question; I was merely curious. Mark > My last message was cut off, for some reason, but I think I got the > "jist" of what I was trying to ask across to the reader. [quoted text clipped - 11 lines] > > Mark It should be obvious it's not the distance between the eyes which differentiates the eyes of predator vs non predator birds, rather it's the angle that they're set on the head. Even on non-predators the eyes aren't at such a great angle they they can't fuse an image and have stereo vision along the central line of their head. I think it's pretty simple, a predator needs stereo vision when it's attacking prey more than it needs nearly full coverage. Even the non predator birds have a blind area to the rear, though that can be filled in with a small turn of the head. Nearly all predators have the ability to turn their heads enough to see directly behind them. Stereo vision is overrated. It's important at very short distances, under a meter or so, which helps an attacker to judge where to bite or drive it's claws, but not so important for a creature trying to escape. Having the wider coverage is more important to both food location and safety for the non-predator. Stereo vision isn't that important for navigation. Sometime try covering one eye and running through a woods. It doesn't make very much difference. > > My last message was cut off, for some reason, but I think I got the > > "jist" of what I was trying to ask across to the reader. [quoted text clipped - 33 lines] > > - Show quoted text - Thanks for the insights. I never thought of it in these terms. Mark |
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