Why don’t birds fall off their perches while sleeping?

            Most of the birds that we see around us are perching birds. They have four toes on each foot, three of which point to the front and one point backwards. This enables the birds to perch on leaf stems, telephone wires and even thick branches. The tendons in the feet of perching birds make the toes flexible and allow the birds to bend their toes to grasp the perch tightly. If any movement disturbs the balance of the birds, even while sleeping, their feet automatically tighten their grip on the perch thus preventing the bird from falling off.