From World Bird Sanctuary

Owls, such as Uxmal the spectacled owl, have very large eyes to help with their excellent night vision.

Most owl eyes are around 5% of the bird’s body weight. That might not sound like much, but human eyes are only 0.0003% of our body weight.

Owls have additional adaptations in their eyes that help make them the perfect nighttime predator. They can dilate their pupils incredibly wide to bring more light into the eyes, and they can even control how much each eye individually dilates.

Like humans, owls have cones to distinguish color and rods to detect light, however owls have significantly more rods to cones than humans. Behind an owl eye’s rod-packed retina is another layer called the tapetum lucidum, which catches any light that may have passed through the retina and bounces it back to those sensitive rods.

All of these adaptations give these birds the perfect vision for hunting at night.