The Four Keys to ID
- Size & Shape
A small but rotund seabird with rounded head, very short neck, short, stubby wings, short but heavy bill, and very short tail.
Relative Size
Larger than a Red Phalarope, smaller than a Rhinoceros Auklet.
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- Both Sexes
- Length: 9.1 in (23 cm)
- Weight: 5.3-7.0 oz (150-200 g)
- Color Pattern
- Behavior
- Habitat
Regional Differences
Two very similar subspecies of Cassin’s Auklet differ mostly in size: the larger aleuticus nests from Alaska to California (and apparently south into Mexico), and the smaller australis nests only in western Mexico, on islands of the Baja California Peninsula.