Most small songbirds are also called perching birds or passerines.

Their feet are typically small and have no feathers.

Songbird feet have three toes pointed forward and one toe pointed backward. This toe arrangement is known as anisodactyl.

Songbirds have very little feeling in their feet because their feet have few nerves and blood vessels. This adaptation allows songbirds to land on cold perches such as wires when the weather is frosty.

When passerines roost (settle down to rest), their belly feathers cover their feet to keep them warm. If the weather is especially cold, many passerines will squat to cover their feet as they eat.

Maybe you've looked up at passerines on a wire and wondered how they can stay in place when they fall asleep. They're able to keep their grip because perching birds have thin tendons called flexor tendons that extend from the leg muscles down the back of the tarsus bone and attach to the toes.

When a bird lands on a perch, these flexor tendons tighten, causing the toes to lock around the perch. It's an involuntary reflex. The tendons stay tight until the legs straighten.