A shorebird that moves to Arctic mountains to breed and spends other seasons on rocky Pacific shores.
In breeding plumage it has dappled black-and-white feathers with rufous wing accents; in winter it is gray-brown.
Outside the breeding season, it searches exposed rocks and beaches for invertebrates when the tide goes out.
It makes a shallow, lichen-lined nest on rocky alpine tundra slopes. Eggs have brownish markings often concentrated at the broad end. Chicks hatch downy and open-eyed and can feed themselves immediately.
Outside breeding it grips mussels, snails and barnacles in its stout bill and uses strong pulls, braced by its legs, to dislodge them, often swallowing the shells whole. On breeding grounds it eats insects such as craneflies, beetles, bees, wasps, butterflies and moths.
The short, stout bill has a yellow base and the legs are greenish yellow. Nonbreeding birds are brownish gray above and white below with some streaking. Juveniles are paler with narrow pale feather edges. The tail is white at its base with a bold black tip.
An extinction-risk assessment has not been added yet.