Eyes in front, and one good chance
What Makes a Good Hunter?
You can tell a hunter from its skull. Eyes at the front, pointing the same way, at the cost of seeing behind.
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Step 1 of 5
Two forward eyes measure distance.
Each eye sees a slightly different view, and the difference tells the brain how far away something is. That only works where the two views overlap — straight ahead.
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Step 2 of 5
The price is not seeing behind.
A rabbit sees nearly all the way round and judges distance badly. A fox judges distance beautifully and can be crept up on. Neither can have both.
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Step 3 of 5
Most hunts fail.
Hunting is expensive and usually unsuccessful. A lion catches something in a small fraction of its attempts, so everything about a hunt is aimed at not wasting energy.
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Step 4 of 5
So the approach matters more than the chase.
Almost every hunter spends most of its effort getting close unseen. The actual sprint is short, because nothing can sprint for long and a long chase is a lost one.
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Step 5 of 5
Hunters keep the hunted honest.
Removing predators does not simply mean more prey. Grazers spread out, eat everything, and the whole landscape changes — the hunting is part of what shapes it.
Owls hunt by sound, and their ears are set at different heights on the skull so a noise reaches one slightly before the other.
The short version
A hunter trades all-round vision for depth judgement, and spends most of its effort getting close rather than chasing.
Try it yourself
Close one eye and try to touch two fingertips together in front of you. That miss is what side-eyed animals live with.