Crested Auklet

Fascinating facts about the Crested Auklet

• When a breeding colony swells to its limit, up to one million crested auklets press together on a rocky slope, with nests sometimes only 0.3 m apart, creating a very dense seabird gathering.
• Each bird wears a forehead crest made of 2 to 23 bristle feathers, most have about 12, that can stretch from 8.1 mm to 58.5 mm, and larger crests attract more mates and speed up pair-bond formation, showing how a tiny feather count can steer reproductive success.
• During courtship the auklet releases a citrus-like scent from tiny wick feathers on its back, and stronger odors draw more partners into the ritual “ruff sniff” where birds insert half-open bills into each other’s plumage, turning smell into a decisive love signal.
• Both sexes share incubation and chick-rearing duties, yet only 10 % of the population engages in extra-pair copulations and just 45.5 % stay with the same partner the following year, illustrating a surprisingly fluid monogamy that balances cooperation with frequent partner changes.
• A juvenile crested auklet reaches full adult size in 33 days, after which it can dive for krill in deep waters and join the flocks that circle 500 m above colonies each day.

At a glance

About the Crested Auklet

The crested auklet (Aethia cristatella) is a compact seabird of the Alcidae family, measuring 18–27 cm in length with a wingspan of 34–50 cm and weighing 195–330 g. Its dark sooty-grey plumage is punctuated by a striking forehead crest of 2–23 forward-curving feathers, averaging twelve, and bright orange-yellow tipped bill. Both sexes sport the same ornamental suite, crest, auricular plumes, and a citrus-like scent that wafts from tiny wick feathers on the back, making them a rare example of monomorphic sexual selection. In the non-breeding months they roam the northern Pacific, especially the Aleutian and Kuril Islands, but return each late spring to the steep slopes, boulder fields, lava flows, and sea cliffs of the Bering Sea and Sea of Okhotsk to breed in colonies that can swell to a million birds, with nests sometimes only 0.3 m apart. During the breeding season, these birds dive from the surface in an underwater "flight" to capture krill, copepods, pteropods, amphipods and larval fish, while their loud trumpet calls and the citrus perfume they release in courtship rituals reinforce pair bonds. A surprising twist is that the scent, besides attracting mates, may also repel ectoparasites, illustrating how a single trait can serve both social and defensive functions in this densely packed, highly social seabird.

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