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By "perspective" I mean the fact, that a stick twice as far away appears twice as short. Or z-times as far appears z-times shorter. (Providing that no rotation has been invoked.)
Poor bird thus see all the directions parallel. Which is difficult to imagine, but it just must be so.
Then everyone would. What is the difference between a bird flying 2m above the ground, and a 2m tall human? Do all directions seem parallel to you?