Cassin's Auklet vs Least Auklet

In short

Cassin's Auklet and Least Auklet are both small seabirds of the Alcidae family, but they can be distinguished by size and plumage. Cassin's Auklet is larger and has a more uniform dark gray plumage, while the Least Auklet is smaller with variable plumage that can range from white to nearly black, often with facial ornaments.

Identification tips

1. Size: Cassin's Auklet is larger. 2. Plumage: Look for the uniform dark gray of Cassin's Auklet versus the variable, often spotted plumage of the Least Auklet. 3. Facial Features: Least Auklet may show white facial plumes and a colorful bill, especially during breeding season.

Size

Cassin's Auklet is noticeably larger than the Least Auklet.

Plumage

Cassin's Auklet has a uniform dark gray plumage, whereas the Least Auklet's plumage varies significantly, from white through spotted intermediates to nearly black on the breast, often with white facial plumes and a colorful bill.

Behaviour

Both species dive for food, but the Least Auklet is known for its high energetic demands, consuming nearly 90% of its body mass per day.

Habitat

Cassin's Auklet is often found along the Pacific coast, while the Least Auklet breeds on remote Aleutian Islands and islands in the Bering Sea, wintering at sea in the North Pacific.