Wild File Q&A: Why don’t birds fall off their perches when they’re sleeping or napping?

by CREW Volunteer Naturalist, Dick Brewer

Q:      Why don’t birds fall of their perches when they’re sleeping or napping?

A:      From small wrens and warblers to large herons and egrets, birds have a seemingly uncanny ability to sleep in trees and other vegetation without ever falling off of their perches.  How do they do that?

It’s not magic. The bird’s toes lock around the branch automatically; no conscious action is needed by the bird whether awake or asleep. Tendons pass from the muscle at the back of the bird’s leg, down around the back of its ankle, and to the inside of its toes. When a bird settles its weight on a branch, the legs bend. That tightens the tendons so much that the toes are automatically pulled tight and clamped around the perch. All conscious or controllable actions are bypassed, so even when it’s asleep, the bird cannot possibly move from the perch.          When the bird straightens its legs, the tendons relax and the grip is released. That’s why a bird often seems to ‘spring’ off of its perch — it’s just unlocking its hold. Even if it’s resting on just one leg, the bird is locked onto its perch.

Barred Owl Perched by Dick Brewer
A Barred Owl naps, one leg tucked in and the other firmly locked around the branch. (Photo by Dick Brewer)

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