Anatomy 5 - Feet

Most of the muscle mass of a bird is in close to its core for reasons of aerodynamics, self-protection and warmth. The bulk of its leg is normally invisible to us beneath feathers. The foot emerges into sight at the ankle, a backward-bending joint, like ours, that we could easily mistake for its knee because of its location high up on the leg. From there the toes fan out in many versatile configurations that adapt the bird to its lifestyle.

Ruby-throated Hummingbird

Most birds we encounter away from the shore use their feet for perching and walking. Hummingbirds, on the other hand, spend much of their time and energy hovering. Their physique emphasizes wing muscles over legs. Their feet are notably small.

Brown Creeper

The relatively large feet of another tiny bird suit it for clambering up and down tree trunks in search of insects. Brown Creepers depend on their long, strongly curved rear claws to help with stability and maneuverability. Their legs are much more developed than hummingbirds.

Turkey

At the upper size limit of Halibut Point birds are turkeys that browse on the ground. They have to be wary and able to outrun foxes and coyotes. Turkeys are very fast, but those hefty leg muscles built up from foraging and running make them a prize catch for carnivores, hunters, and domesticated poultry producers. Partly in compensation for this vulnerability turkeys have developed  sharp, bony spurs on their heel that they deploy in aerial attacks against rivals and in self defense.

Downy Woodpecker

The upland birds in our realm almost exclusively have four toes, three pointed forward, one to the rear. Woodpeckers have found an evolutionary advantage in developing a two-forward, two backward combination for anchoring to a tree. Chimney swifts have shifted all four claws to the front to facilitate hanging at rest inside their roost.

Semipalmated Plover

The water's edge offers the greatest variety of foot adaptations. Semipalmated means partially webbed which improves this plover's traction on slippery rocks and quite possibly its 'swimming' movements through shallow water.

Red-necked Grebe

Grebes are able to work their lobed toes as independent paddles for both propulsion and steering in the pursuit of fish. They can twist their foot 90˚ on the forward stroke to minimize drag through the water.

Double-breasted Cormorants

Cormorants are one of the few birds with webbing extending to all four toes. Coupled with their enormous feet they can reach and accelerate quickly in submarine depths.

Mallards

Ducks of all sorts, being dabblers or shallow divers, manage well with webbing limited to the three forward-pointing toes. For an explanation on their ability to stand comfortably on ice, see my previous posting Cold Feet.

Snow Bunting

Another approach to avoiding heat loss through the feet is to bundle up, as this cool-weather visitor to Halibut Point does with tufts of feathers all the way to its toes. Snowy Owls have developed this protection even further.

Peregrine Falcon

The aerial hunters known as raptors all have large feet capable of tremendous crushing force and piercing claws.

Great Blue Heron

Herons have large feet with very little clenching power, to support then on marshy conditions.

Their long toes radiate like spokes on a wheel.

Black-crowned Night Heron

Certainly there is not 'one size fits all' with wading birds. The arrangement‒ and uneven length ‒  of toes on the Black-crowned Night Heron, which often hunts from a perch, gives a compromise solution to its niche at the water's edge.

Oystercatcher

Oystercatchers, with only three toes, occasionally visit our shoreline, showing one of their particular adaptations to foraging on rocky beaches.

Noticing birds' diverse feet is another way to marvel at nature's ongoing adaptations to opportunity.