As I wrote about earlier, the knee joint of a bird is usually hidden under feathers. The backward bending leg joint that you see when birds are walking is the ankle. And when we talk about a birds’ foot we are actually talking about its toes.
Most birds we observe have four toes, but the exact number of toes and their arrangement, as well as their proportions, varies from family to family. The perching birds we see at the feeders in mid-Michigan usually have anisodiactyl feet. That means they have three toes that point forward and one toe that points backward to make it easy to grab a perch. The woodpeckers’ feet are an exception to the birdfeeder crowd. They have zygodactyl feet meaning two toes point forward and two point backward so they can get a good grip on a tree bark.
Birds that use their feet for waiting in trees, climbing, grabbing prey, and carrying it away are equipped with sharp curved and pointed claws like hawks, eagles, and falcons. Feet that run and scratch usually have strong stout toes with blunt claws like turkeys, grouse and others. Feet for swimming may have the first three toes webbed like ducks and gulls or include a webbed back toe as well like the pelicans and cormorants. The grebes and coots just have lobed toes for swimming. And the long toes of the herons spread the bird's weight over a large surface area to facilitate walking on soft surfaces near the water's edge where wading birds like to eat.
The size and shape of the claws and the way the toes are arranged as well as the length of the toes and the degree of webbing are all dependent on what a bird uses its feet for and where it lives. Like a bird's bill its feet reveal a lot about its lifestyle and the next time you have a chance take a close-up look at the fascinating feet of birds.