Why are owls eyes in the middle while other birds eyes on both sides? This is a question ask by one of my friends when we listen a leture.
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Hunting derived adaptations.. for superior depth of view and hearing, particularly at night thanks to their tube(bell) shaped eyes with a high rod to cone ratio and broad facial discs that position the feathers to collect and direct sound waves. While all birds of prey have binocular vision to some extent owls are particularly in tune. Raptors on the other hand excel during the day using sharp eyesight and speed while soaring and diving where having a sharp yet wider field of view is more beneficial being able to reliably switch to monocular vision. Owls also use monocular vision when bobbing and tilting their heads to gauge position and speed (motion parallax) while other birds of prey might use rapid head movements (saccades) and stare-and-scan methods while surveying an area. All of this contributes to facial structure on some level.
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I think that kanescompendium has answered your question but I will add a bit of trivia. Owls are one of very few vertebrates that are unable to move their eyeballs within the eye socket. To make up for this they are able to swivel their heads more than 180 degrees.
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We have an owl baby at Kirstenbosch. Lots of pictures and video clips on FB. Learning to use his eyes, and his feet.
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So cute! Looking at their facial markings makes me wonder if gesturing/communication has also had any impact on the evolution of Strigiform(Owl) facial structures.. and how this compares to other Aves.
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As a side note: Pupil shapes also affect vision in many ways. For example smaller cats have vertical slits (big cats have round pupils). The improve visibility in shrubs and tall grass by improving the ability to see from small vertical openings and more verticality in the field of view. Many grazers have their pupil horizontally slitted, so when your head is down when eating, it is also vertically to see better through the grass, but gives a wide angle when up straight. The cross-shaped pupils on many cephalopods help filter out the wonky way light travels underwater and bounces from the bottom.
And so on, and so forth. The round pupil is generally superior in most cases, but requires some height from ground to function optimally.
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Are you asking me or… ?
I don’t actually know more, than what I wrote there. I would imagine bird pupils have similar structural variation.
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