From: Lawrence_Dunn@smbcgroup.com 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'm skeptical about this condition existing in birds, but I have read that it exists in frogs. The sense of it is probably that, if you don't have a lot of brain-power to spare, the really _vital_ things for you to see are almost always going to be the moving ones...especially if you eat insects and not plants.
And it's probably not a case of absolute stillness = invisibility either, just an extreme loss of definition.