Ptychoramphus aleuticus
The Cassin's Auklet (*Ptychoramphus aleuticus*) is a diminutive, yet robust, pelagic seabird belonging to the Alcid family, closely related to other auklets, puffins, and murres. Measuring around 18-20 cm in length with a wingspan of 35-38 cm and weighing 150-200g, its compact, dark sooty-gray body and short neck give it a distinctive "pushed-in" appearance. Key identification marks include a striking pale blue-gray or white eye, a short, stout black bill, and in breeding plumage, subtle whit...
Cassin's Auklets primarily inhabit pelagic marine environments, spending most of their lives far offshore over deep oceanic waters. They come ashore exclusively to breed on remote, predator-free islands and coastal cliffs, nesting in burrows or rock crevices.
Cassin's Auklets specialize in consuming small marine invertebrates, primarily copepods, euphausiids (krill), amphipods, and occasionally small larval fish. They forage by pursuit diving, actively swimming underwater using their wings.
This highly pelagic species exhibits a fascinating dichotomy in its daily activity: diurnal when foraging at sea, but strictly nocturnal when visiting its breeding colonies ashore, a key adaptation to evade aerial predators like gulls and raptors. Foraging involves pursuit diving, where they use ...
The breeding range of the Cassin's Auklet extends along the Pacific coast of North America, from the western Aleutian Islands and Gulf of Alaska south to Baja California, Mexico. Key breeding colonies are found on offshore islands, including the Farallon Islands and Channel Islands of California,...
Near Threatened
- Cassin's Auklets are known to be one of the deepest-diving auklets, regularly reaching depths of 30-60 meters and occasionally over 100 meters, propelling themselves with their wings. - They are strictly nocturnal at their breeding colonies, arriving and departing under the cover of darkness to...