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.
robin-sizedMeasurements
- Both Sexes
- Length: 9.1 in (23 cm)
- Weight: 5.3-7.0 oz (150-200 g)
© Gary Maschmeyer / Macaulay Library
- Color Pattern
Adult dark gray above, paler gray below, with whitish belly and undertail, pale eye, white arc above eye (like a short eyebrow), and dark bill with pale base. Juvenile similar but paler, with off-white throat and darker eye and bill.
© Yousif Attia / Macaulay Library - Behavior
Catches zooplankton and small fish in the bill, by diving underwater and maneuvering with wings, feet, and tail.
© Carey Bergman / Macaulay Library - Habitat
Marine waters, usually out of sight of land, during most of the year. Breeds in colonies on Pacific islands with many different habits including desert communities, rocky cliffs, grassy slopes, bare soil, or coniferous forests.
© Robin Corcoran / Macaulay Library
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.
