Family Auks (Alcidae)

Near Threatened

Cassin's Auklet (Ptychoramphus aleuticus)


French: Starique de Cassin German: Aleutenalk Spanish: Mérgulo sombrío

Uria Aleutica


, 1811,

north Pacific Ocean


Apparent geographical variation may be clinal. Genetic data show differentiation between individuals breeding north of Point Conception and individuals breeding in southern California and Baja California#R. Two subspecies provisionally recognized.

Subspecies and Distribution
  • P. a. aleuticus (Pallas, 1811) – Aleutian Is to SW & SE Alaska, then S to N Baja California (islands of San Gerónimo, San Martín and Guadalupe).
  • P. a. australis van Rossem, 1939 – W Baja California from San Benito Is S to Asunción I and San Roque I.
  • Winters within breeding range, mostly offshore, from S British Columbia to S Baja California; some N to Alaska.

    Descriptive notes

    23 cm; 150–200 g; wingspan 38 cm. Small, plump alcid; short blackish-grey bill with base of mandible yellowish; white iris; dark greyish-brown head, fading to paler... read more


    Generally silent at sea. At breeding colonies, usually heard from inside nesting burrows. Adults... read more


    Offshore and along sea coasts, mostly over continental shelf to edge, but often beyond into deep... read more

    Food and feeding

    Mostly crustaceans throughout year, supplemented by other invertebrates and small larval fish. Quantitative information largely restricted... read more


    Arrival at colony and start of laying vary greatly with latitude, due largely to differences in oceanographic conditions; nests late Nov to... read more


    Winters mainly offshore within breeding range. S populations relatively sedentary, staying at sea... read more

    Status and conservation

    Not globally threatened. Currently considered Near Threatened. Population sizes and trends relatively well known, though distribution and estimates of Alaskan and Mexican... read more

    Recommended citation

    Nettleship, D.N., Sharpe, C.J. & Boesman, P. (2019). Cassin's Auklet (Ptychoramphus aleuticus). 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 20 September 2019).