The Rhinoceros Auklet (Cerorhinca monocerata) is a seabird considered by some to be a close relative of the puffin. It is the only member of the genus Cerorhinca.
It ranges widely across the North Pacific feeding on small fish and nesting in mixed seabird colonies. Its name is derived from a horn-like extension of the beak. This horn is only present in breeding adults, and like the elaborate sheath on the bill of puffins is shed every year.
The Rhinoceros Auklet (also known as the Rhino Auklet or Rhino), is a medium sized auk with a large, strong, orange/brown bill (with the ‘horn’ protruding from it). The plumage is dark on top, paler below, and the breeding adults possess white plumes above the eyes and behind the bill.
The Rhinoceros Auklet is a North Pacific auk that breeds from California (the Channel Islands) to the Aleutian Islands in Alaska in North America; and Hokkaido and Honshu, Japan, as well as North Korea and Sakhalin Island in Asia. It winters both in offshore and inshore waters, exhibiting slight migration.
The Rhinoceros Auklet nests in burrows dug into the soil or in natural caves and cavities between 1 to 5 m deep. This poor flier prefers nesting sites on slight inclines which aids in take-off. A single egg is incubated by both parents for 45 days. The semiprecocial chick is then fed each night with a bill full of fish (in the manner of puffins) for 50 days. The nocturnal behavior is believed to be a response to predation and kleptoparasitism by gulls.
At sea Rhinoceros Auklets feed on fish, with some krill and squid taken also. They feed inshore during the breeding season in the midwater.