Have you ever tried sleeping standing on a 2X4 suspended 10 feet in the air? If you have, maybe you’re part bird. Most birds do it every night and never fall to the ground.

It’s not hard to imagine how they hold onto limbs, just look at the shape of their feet and toes. Most of the bones in a bird’s foot have fused together for lighter weight. When we look at their legs, what looks like their knees turned backwards is really their ankles. The long single “foot bone” is known as the tarsus. Relative to our feet, this would be our instep. Birds walk and perch on what we think of as the ball of our foot.

The toes of birds vary in length, shape and form almost as much as their bills. The most common configuration is three toes forward and one toe back. It may seem odd, but the backward facing toe, known as the hallux, is actually the first or big toe. The other common configuration is of toes like a woodpecker in which two toes are forward and two toes face back.

Back to the sleeping question. Yes, the long toes of birds make it easier for them to reach around a small limb and hold on but what about when they fall asleep. Perching birds such as cardinals and juncos have two major flexor tendons that run from their toes to their knee. When a bird perches (squats) those tendons force the hallux and toes to tighten (even lock) around its perch. The bird can relax without fear of falling off.

Birds have so many amazing adaptations it is easy to take them for granted. Whether they are long and slender like a heron or rail, thick and strong like an eagle or webbed like ducks and geese, you can bet that birds always put their best foot forward.

By Mark McKellar

Fall 2008