Photo: Cathleen Shattuck/Flick Creative Commons

Priority Bird

Cassin's Auklet

Ptychoramphus aleuticus

A small, dark seabird, nesting on islands along the Pacific Coast from Alaska to Mexico. Sociable at all seasons, feeding in flocks at sea and nesting in large colonies. Its small size makes it vulnerable to predators, so it visits its nesting colonies mainly under the protection of darkness. A Cassin's Auklet colony at night may resound with the squealing and peeping of the birds in their burrows.
Conservation status Still abundant in parts of range (especially islands off British Columbia), but has disappeared from many former breeding islands in Alaska and elsewhere because of introduction of foxes or other predators. Vulnerable to disturbance on nesting islands, and to oil spills and other pollution at sea.
Family Auks, Murres, Puffins
Habitat 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.
A small, dark seabird, nesting on islands along the Pacific Coast from Alaska to Mexico. Sociable at all seasons, feeding in flocks at sea and nesting in large colonies. Its small size makes it vulnerable to predators, so it visits its nesting colonies mainly under the protection of darkness. A Cassin's Auklet colony at night may resound with the squealing and peeping of the birds in their burrows.
Photo Gallery
Feeding Behavior

Forages while swimming underwater. May feed by day or night. Can dive to more than 120' below surface.


Eggs

One. Creamy white, sometimes becoming nest-stained. Incubation is 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.


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.

Diet

Mostly small crustaceans. Diet in breeding season includes euphausiid shrimp, amphipods, copepods, some small fish and squid; diet at other seasons not well known.


Nesting

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 re-used in following years by same pair.

Illustration © David Allen Sibley.
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Text © Kenn Kaufman, adapted from
Lives of North American Birds

Migration

Northern birds apparently move south in winter, but details not well known. Southern breeders may remain close to colony site all year.

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Migration

Northern birds apparently move south in winter, but details not well known. Southern breeders may remain close to colony site all year.

  • All Seasons - Common
  • All Seasons - Uncommon
  • Breeding - Common
  • Breeding - Uncommon
  • Winter - Common
  • Winter - Uncommon
  • Migration - Common
  • Migration - Uncommon
Songs and Calls
Weak croaking calls given at night.
Audio © Lang Elliott, Bob McGuire, Kevin Colver, Martyn Stewart and others.
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How Climate Change Will Reshape the Range of the Cassin's Auklet

Audubon’s scientists have used 140 million bird observations and sophisticated climate models to project how climate change will affect this bird’s range in the future.

Zoom in to see how this species’s current range will shift, expand, and contract under increased global temperatures.

Climate threats facing the Cassin's Auklet

Choose a temperature scenario below to see which threats will affect this species as warming increases. The same climate change-driven threats that put birds at risk will affect other wildlife and people, too.

Project Puffin

Project Puffin

Project Puffin improves seabird nesting outcomes, helping those populations to return from the brink

Read more

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