Family Auks (Alcidae)

Least Concern

Rhinoceros Auklet (Cerorhinca monocerata)


French: Macareux rhinocéros German: Nashornalk Spanish: Alca unicórnea

Alca monocerata


, 1811,

Cape St Elias, Alaska, USA




SE Russia (Akademii Gulf), S Sakhalin I and S Kuril Is to Japan (Teuri I) and perhaps extreme NE Korea; C Aleutians; S & SE Alaska (W to Barren I, Middleton I, St Lazaria I, Forrester I) S to British Columbia (Triangle I), W Washington (Destruction I) and California (Castle I, Farallon Is, Channel Is). Winters mostly offshore and along coasts, in Asia near breeding areas, and in North America mainly from S British Columbia (casually from SE Alaska) S to Baja California (Santa Margarita I).

Descriptive notes

35–38 cm; c. 533 g; wingspan 56–63 cm. Yellowish-orange bill, with short, vertical whitish knob or “horn” at base of maxilla; darkish brown head with... read more


Generally silent at sea. Near breeding colonies at night utters very low-pitched growling or mooing... read more


Marine offshore and along sea coasts and islands. Breeds on maritime and inland grassy slopes,... read more

Food and feeding

Mostly fish throughout year, supplemented in winter by small amounts of invertebrates (squid, euphausiids and other crustaceans); generally... read more


Arrival at colony normally late Mar and early Apr, slightly later in N; laying from end of Apr to mid Jun, with fledging mostly late... read more


Winters mostly offshore, sometimes near-shore and coastal, usually within breeding range. Southern... read more

Status and conservation

Not globally threatened (Least Concern). Total breeding population estimated at 1,250,000 birds, with c. 347,000 (300,000–400,000) in Asia and c. 903,000 (800,000... read more

Recommended citation

Nettleship, D.N., Garcia, E.F.J. & Boesman, P. (2020). Rhinoceros Auklet (Cerorhinca monocerata). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from on 7 April 2020).