Owl

About 270 degrees in each direction from facing forward, so roughly three quarters of a full circle, not the full 360 degrees of legend. It needs to, because its eyes are locked in place and cannot swivel in the socket the way a human eye does. To make this possible without strangling itself or starving its brain of blood, an owl has extra neck vertebrae, fourteen against a human's seven, and a set of adaptations in the arteries of the neck, including reservoirs that pool blood and pathways that keep flow going even when the main vessels are twisted or pinched during an extreme turn.

Three features of the wing feathers work together. The front edge of the outer flight feathers is broken into a stiff comb of separated barbs that splits the oncoming air into small streams instead of letting it build into a single noisy vortex. The rear edge of the feathers is soft and frayed, which lets air bleed off smoothly rather than snapping free with a hiss. And the whole upper surface of the wing is covered in a fine velvety down that soaks up the higher-frequency sound of feathers brushing air and each other. The result is that a hunting owl produces almost no sound in the frequency range a mouse can hear, so the prey gets no warning. Fishing owls, which do not need stealth over water, have lost most of these adaptations.

Both beliefs exist, in different cultures, and neither has any basis in the bird itself. In ancient Greece the owl was the companion of Athena, goddess of wisdom, and it appeared on Athenian coins, which is the root of the modern Western image of the wise old owl. In many other traditions, across parts of Africa, the Americas, South Asia, and rural Europe, an owl calling near a house has been taken as an omen of death or illness, or associated with witchcraft, largely because owls are nocturnal, near-silent, and have an eerie call and a human-like stare. Owls are simply predatory birds, and these meanings are things people have projected onto them.

An owl swallows small prey whole or in large pieces, and its stomach digests the soft tissue but cannot break down bones, fur, feathers, teeth, and insect shells. Rather than passing this material through the gut, the owl compacts it in a muscular part of the stomach into a firm, dry, oval pellet and regurgitates it, usually several hours after a meal and often from a regular roost, so a favoured perch may have a pile of pellets beneath it. Because the contents are so well preserved, pulling a pellet apart and identifying the tiny skulls and jawbones inside is a standard way for scientists and school classes to work out exactly what an owl has been eating.