About Aethia cristatella (Pallas, 1769)
The crested auklet (Aethia cristatella) measures 18–27 cm (7.1–10.6 in) in length, has a 34–50 cm (13–20 in) wingspan, and weighs 195–330 g (6.9–11.6 oz). It has a reddish-orange bill with a yellow tip, yellowish-white irises, and white auricular plumes that extend from its eyes to its ears. Its body, wings, and tail are primarily dark sooty grey; its legs and feet are grey, and its claws are black. Males and females are very similar in appearance, though females have slightly smaller, less curved bills and slightly smaller crests. Crested auklets are best known for their forehead crests, which are made of black, forward-curving feathers. These crests are highly variable, holding between 2 and 23 narrow forward-curving feathers. The average crested auklet has 12 crest feathers, which vary in length from 8.1 to 58.5 millimetres. In addition to auricular plumes, crested auklets have a bright orange bill with curved accessory plates. Like the forehead crests, these features vary widely between individuals in crested auklet populations. Two key characteristics identify crested auklets during the breeding season. The first is the crest itself: a group of bristle feathers located on top of the head above the eyes. The second is a social odor the birds produce during the breeding season, which is described as smelling like tangerines. This odor comes from tiny wick feathers in a small patch of skin between the shoulder blades. In winter plumage, crested auklets have smaller, dull yellow bills, lack accessory plates, and have reduced crests and auricular plumes. Juvenile crested auklets look similar to winter adults, but have no auricular or crest plumes. Their bills are smaller and dull brownish-yellow in color. Juveniles take 33 days to reach adult size. Crested auklets are found across the northern Pacific Ocean and Bering Sea. During the non-breeding winter months, they are particularly common along the Aleutian Islands, Kuril Islands, and the Russian island of Sakhalin. In late spring and summer, they travel to breeding sites on the islands and shorelines of the Sea of Okhotsk and the Bering Sea. Their habitats include slopes, boulder fields, lava flows, and sea cliffs. They are often found alongside other auklet species, such as the least auklet. Each day, crested auklets circle 500 meters above the sea and their breeding colonies. This circling behavior is triggered by disturbances and threatening predators.
