Habitat: This marine species can be found both offshore and along sea coasts and islands. It breeds on maritime and inland grassy slopes, sometimes on predator-free islands, and rarely on steep island or mainland cliffs. It occurs in large aggregations at sea, often forming dense roosting flocks at night in sheltered bays. In winter it is normally pelagic in waters offshore from breeding areas and sometimes in near-shore coastal waters where food is highly concentrated due to oceanographic conditions. Diet: It feeds mostly on fish throughout the year supplemented in winter by small amounts of invertebrates such as squid and krill. Chicks are fed almost exclusively on fish, though invertebrates may also be given to late-hatching young. Breeding: It arrives at colonies in late March and early April, laying from the end of April to mid-June. It is monogamous with high site and mate fidelity. It is highly colonial in small to very large concentrations (sometimes over 100,000 individuals). Laying is often highly asynchronous within a colony. Birds lay in nest chambers at the end of a burrow which are excavated by both sexes (del Hoyo et al. 1996).

The Rhinoceros Auklet is found in the North Pacific and breeds from California, USA, off the coasts of Canada and Alaska to the Aleutian Islands in North America; and on Hokkaido and Honshu, Japan, as well as on the northern tip of North Korea, Sakhalin (Russia) and at two places on the far eastern Siberian coast in Asia (del Hoyo et al. 1996).