Cassins Auklet (Ptychoramphus aleuticus)

Cassins Auklet

[order] CHARADRIIFORMES | [family] Alcidae | [latin] Ptychoramphus aleuticus | [UK] Cassins Auklet | [FR] Starique de Cassin | [DE] Aleutenalk | [ES] Mergulo Sombrio | [NL] Cassins Alk


Genus Species subspecies Breeding Range Breeding Range 2 Non Breeding Range
Aethia aleuticus
Ptychoramphus aleuticus NA nw coasts
Ptychoramphus aleuticus aleuticus Aleutian Is. and s Alaska to n Baja California (Mexico)
Ptychoramphus aleuticus australis s Baja California (Mexico)

Physical charateristics

A small, stubby seabird; all dark except for the white belly; note the pale spot on lower mandible. In winter, all other small alcids in its range show much more white.

Listen to the sound of Cassins Auklet

[audio: Auklet.mp3]

Copyright remark: Most sounds derived from xeno-canto

wingspan min.: 32 cm wingspan max.: 36 cm
size min.: 23 cm size max.: 25 cm
incubation min.: 37 days incubation max.: 40 days
fledging min.: 33 days fledging max.: 37 days
broods: 1   eggs min.: 1  
      eggs max.: 1  


North America : Northwest coasts


Ocean; colonizes sea islands.
May use any kind of island for nesting (barren or forested, steep or level) as long as no predatory mammals are present. Otherwise at sea, often near nesting islands or in upwellings over continental shelf, but also far out over deep water.


Usually first breeds at age 3 years, sometimes earlier. Pairs usually form in late winter. Courtship displays include mutual bowing and head-bobbing, moving head from side to side, touching bills.
Nest: Site is in burrow excavated in soil or in natural crevice, sometimes under debris or driftwood. Both members of pair take part in excavating burrow. Little or no nest material added. Nest reused in following years by same pair.
Eggs: 1. Creamy white, sometimes becoming nest-stained. Incubation by both sexes, usually 38-39 days, sometimes as long as 57 days.
Young: Both parents visit at night to feed young by regurgitation. Young bird nibbles at white spot on parent’s bill to elicit feeding. At 41-
50 days after hatching, young make first flight and go to water, able to swim and dive immediately. Usually 1 brood per year, sometimes 2.

Feeding habits

Mostly small crustaceans. Diet in breeding season includes euphausiid shrimp, amphipods, copepods, some small fish and squid; diet at other seasons not well known.
Behavior: Forages by diving and swimming underwater, using wings for propulsion, feet for steering. May feed by day or night. Can dive to more than 120′ below surface.


This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Cassins Auklet status Least Concern


Pacific coast of North America. Winters to Baj
a California. Migration: Northern birds apparently move south in winter, but details not well known. Southern breeders may remain close to colony site all year.

Distribution map

Cassins Auklet distribution range map

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