Owls have such large eyes primarily because their eyes are specially adapted for enhanced night vision. The large size allows their pupils to expand more, letting in more light, which is crucial for seeing in low light or darkness. Their eyes also have more rods—cells that sense light—making their night vision incredibly efficient, estimated to be 35 to 100 times better than humans. The large eyes also provide better depth perception by being forward- facing, allowing owls to accurately judge distances when hunting. Additionally, owls’ eyes are tubular rather than round, maximizing the distance between the lens and retina for sharper focus while keeping their heads lighter for flight. However, these fixed eyes cannot move in their sockets, so owls compensate by having the ability to rotate their heads up to 270 degrees. In summary, owls' large eyes are an evolutionary adaptation to:

• Improve night vision by letting in more light through larger pupils and containing more light-sensitive rods.
• Enhance depth perception with forward-facing eyes for accurate hunting.
• Maintain sharp focus via a tubular eye shape, balancing eye size with head weight.
• Compensate for eye immobility by rotating their heads extensively.

These adaptations make owls powerful nocturnal hunters with exceptional vision in dim light.