Why do owls turn their heads so far?

Unlike humans, owls cannot move their large, tubular eyes within their sockets, so to shift their gaze they must move their entire head. To compensate, they can rotate their heads roughly 270 degrees in either direction. This remarkable flexibility is possible thanks to special adaptations: owls have 14 neck vertebrae (twice as many as humans) and blood vessels with reservoirs and bypass routes that keep blood flowing to the brain even when the neck is severely twisted. Their arteries are also cushioned within wider bony channels, preventing damage during rotation. This design lets an owl scan a wide field of view while sitting perfectly still, an advantage for a silent, ambush predator.