"They sit or perch on the branch, and are called perchers. They even sleep like this, and could not fall from their perch if they wished.""How strange," said Norah. "Go on, Will, please." "Teacher showed us the leg and foot of a fowl. He pointed out a flat white cord that runs up the leg from the foot. When he pulled the cord the toes closed up, and when he let go, the toes stretchedthemselves out again.
"He told us that all birds have this same strong cord up the leg. But in these perching birds the cord passes up the leg and over the front of the knee- joint, to the thick part of the thigh. The very act of sitting must of course bend the knee, and this pulls up the cord, and so draws the toes together without any effort of the bird itself.
"The mere weight of the body resting on the legs does it all. The moment the knee bends, the toes draw themselves up to clasp the branch, and they cannot unclasp it until the bird raises itself from its perching position.""Thank you, Will," said Norah. "That is certainly very wonderful."SUMMARY
