Wrybill

The wrybill is a small plover that lives only in New Zealand. Gray on top, white underneath — the kind of bird you’d walk past on a beach without noticing. The unusual thing is its beak. It bends sideways, to the right. No other bird in the world has a laterally curved bill.

The bend lets it feed under rounded river stones. The bird sweeps its head in a tight arc around the stone, and the curve of the bill follows the curve of the stone, reaching into places a straight bill couldn’t. They feed mostly on insect larvae in the gravel of braided rivers in the South Island.

Both sexes have it. Chicks start out looking symmetric and develop the bend as they grow. It’s always to the right. No left-billed wrybills exist. The species is right-handed.

Plenty of other birds feed on insects under stones. None of them evolved a curved bill. Why this bird, why right and not left — nobody knows. The wrybill is alone with the asymmetry.