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
  • adult
  • adult
  • adult
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.
Learn more about these drawings.

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.

Download Our Bird Guide App

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.
Learn more about this sound collection.

How climate change could affect this bird's range

In the broadest and most detailed study of its kind, Audubon scientists have used hundreds of thousands of citizen-science observations and sophisticated climate models to predict how birds in the U.S. and Canada will react to climate change.

Learn more

Read more: climate.audubon.org
Auks, Murres, Puffins Upright-perching Water Birds

Cassin's Auklet

The darker the color, the more favorable the climate conditions are for survival. The outlined areas represent approximate current range for each season.

More on reading these maps.

Each map is a visual guide to where a particular bird species may find the climate conditions it needs to survive in the future. We call this the bird’s “climatic range.”

The colors indicate the season in which the bird may find suitable conditions— blue for winter, yellow for summer (breeding), and green for where they overlap (indicating their presence year-round).

The darker the shaded area, the more likely it is the bird species will find suitable climate conditions to survive there.

The outline of the approximate current range for each season remains fixed in each frame, allowing you to compare how the range will expand, contract, or shift in the future.

The first frame of the animation shows where the bird can find a suitable climate today (based on data from 2000). The next three frames predict where this bird’s suitable climate may shift in the future—one frame each for 2020, 2050, and 2080.

You can play or pause the animation with the orange button in the lower left, or select an individual frame to study by clicking on its year.

The darker the color, the more favorable the climate conditions are for survival. The outlined areas represent approximate current range for each season. More on reading these maps.
Winter
Summer

Winter Range
Summer Range
Both Seasons
Zoom InOut
Project Puffin

Project Puffin

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

Read more

Explore Similar Birds