why does a sleeping bird not fall down sitting on a wire?

Answer 1

"A bird's ability to grasp a branch with its toes is due to the action of tendons in its leg that are pulled tight when a bird crouches on a perch. The tendons are attached to muscles above the bird's heel - the joint that appears to us as a "backward bending knee" in the portion of the leg not covered by feathers. These flexor tendons, as they are called, run down the backs of the legs and to the tips of the toes. When the bird sits, the tendons pull on the toes and close them tightly, like a fist. This automatic grip is strong enough to allow the bird to sleep while perching."

Answer 2

The muscles on the birds legs are set to close in the rest position. Therefore when they fall asleep, and relax, their muscles lock onto the wire or the tree.

I heard this on a nature program, but I couldn't find any sources to prove it. This article: http://en.wikipedia.org/wiki/Bird_anatomy comes close, but not close enough.

Answer 3

Why don't you roll out of bed every night when you sleep...same principal

Answer 4

amazingly enough some do fall down. i think its from inbreeding.

Answer 5

fascinating isn't it. i guess they just have the proper weight balance.

Answer 6

they glue themselves on