Why do birds not fall out of trees when they sleep?

Question

Thanks

Answer 1

They sleep in nests

Answer 2

acording to me, they sleep in nest and it has a shape of a bowl and they do not fall.  

Answer 3

When perching birds sit, a tendon on the backside of the ankle automatically flexes locking their toes around the branch. With feet locked, sleeping birds don't fall. As the bird stands up its feet release. Also, bird do not necessarily sleep in nests..birds do NOT live in nests, they use them to reproduce in..sort of like a nursery, and they are ONLY built in the spring breeding season.  Sure, an adult will sleep in a nest if they are incubating eggs, or have small chicks in the nest..but that is usually only about a month total for the whole year that they will sleep in a nest.  

Answer 4

Birds have good balance and they are use to it. lol

Answer 5

They use one foot to stand on and it locks on. However my parrot is on his perch and quite regularly you her him fall off onto the bottom of the cage lol.

Answer 6

Because there in nests?

Answer 7

When a bird perches, it settles down and the tendons lock the toes in a closed position so it doesn't fall.