Rhinoceros Auklet

The Rhinoceros Auklet is a relative of the puffins with a more subdued, uniformly dusky plumage rather than the bold black-and-white pattern of its close relatives. Its distinguishing feature, a pale horn-like bill projection present only in breeding adults, is a bare-part feature rather than a feather trait, so plumage alone gives a more understated identification.

• Body feathers are a fairly uniform dark grayish-brown above, with paler, dusky-gray to whitish underparts lacking sharp contrast
• Breeding adults show two thin whitish plume feathers extending back from the face, near the eye and the base of the bill, unique among the puffin relatives
• Flight feathers are broad and rounded, suited to whirring flight and wing-propelled diving
• Tail feathers are short and squared, consistent with the compact auk body form
• Overall feather tones are more muted and monochromatic than the crisp black-and-white auks, aiding identification of body feathers found separately

• Breeding adults show dark grayish-brown upperparts, paler underparts, and two thin whitish facial plumes
• Non-breeding adults lose the facial plumes and the bill projection, appearing plainer overall
• Juveniles are duller and browner, lacking plumes and the bill horn
• Sexes are alike in plumage
• A complete molt after breeding renews body and flight feathers, including a flightless period at sea

Rhinoceros Auklets breed in burrows on forested or grassy islands and coastal slopes around the North Pacific, from California north through British Columbia and Alaska to Japan and Russia. Outside the breeding season they range over open and coastal North Pacific waters, generally remaining within the broader North Pacific basin.

This auklet dives to pursue small schooling fish, carrying multiple prey items crosswise in the bill back to the burrow to provision its chick, often returning to the colony only after dark to avoid predators. It nests in long burrows dug into soil on forested or grassy slopes, sometimes sharing habitat with puffins. Its calls are low, growling or moaning notes given mainly at the nest burrow at night.