Rhinoceros auklet are one of the rarer breeding alcids in Oregon. Adults are easily recognized during the breeding season by the vertical "horn" at the base of the upper mandible. Birds in breeding plumage have brownish gray backs, a gray-brown chest, and a dirty white belly. Two distinct plumes are present on the head, one above and one below the eye. The bill is orange. In non-breeding plumage the horn is greatly reduced, the plumes absent or reduced, and the bill duller.
It nests in small numbers in Oregon with Goat and Hunter Islands having the largest concentrations of breeding birds. They offshore in winter months, detected as far out as the seaward side of the continental slope. They are occasionally found in lower estuaries, primarily during summer and fall.