Owls have large eyes that help them see well in very low light.

The longer version

Light gathering scales with pupil area, and owls have pushed that to the limit. The eyes are huge relative to the skull, the cornea is large, and the retina is packed with rod cells, the type that works at low light but gives poor colour. A reflective layer behind the retina gives each photon a second pass.

The trade-off is the tubular eye shape, which buys sensitivity at the cost of eye movement and of a narrow field of sharp focus. Owls also hunt by sound. Facial feathers funnel noise toward ears that are often set asymmetrically, letting the bird place a rustle in two dimensions, so people overrate eyesight alone.

Where this entry sits

Here you will find feathered trivia about flight, migration, nests, eggs, and the songs birds sing. Expect short surprising facts on penguins, owls, hummingbirds, and other familiar birds from gardens, forests, wetlands, and distant coastlines. The full list sits on the Birds page, where every entry is listed in order.