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Least Auklet
Aethia pusilla
Order
CHARADRIIFORMES
– Family
ALCIDAE
Authors: Jones, Ian L.
Revisors: Bond, Alexander L., Ian L. Jones, Sampath Seneviratne, and Sabir Bin Muzaffar

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Introduction

Least Auklets (adult, with subadult on lower right), Sirius Point, Kiska Is., AK, 16 June 2007.

English: Least Auklet

French: Starique minuscule (“tiny auklet”)

German: Zwergalk (“dwarf auk”)

Russian: Конюга-крошка (konyuga kroshka; “little auklet”)

Japanese: コウミスズメ(koumisuzume)

Unangan (Aleut): chuuchii (choochkie)

St. Lawrence Island/Central Siberian Yup’ik: Akmaaliighaq (Ok-ma-lee-a-gok)

This tiny alcid is one of the most abundant seabirds in North America, with a global population of more than 20 million birds that concentrate densely for breeding at a few sites. Least Auklets dive for zooplankton, nest in rock crevice breeding sites, lay just one egg each year, and eat almost 90% of their body mass per day—reflecting the high energetic demands of their flight and foraging. In North America, most birds breed at a few remote Aleutian Islands and islands in the Bering Sea, and winter at sea in the North Pacific.

Like the Dovekie (Alle alle), the Least Auklet’s ecological counterpart in the North Atlantic, calanoid copepods are the preferred prey during summer. During the breeding season, both Least Auklet sexes possess three kinds of facial ornaments: a colorful bill, a horny bill-knob ornament, and white facial plumes. Adult summer plumage varies from white through spotted intermediates to nearly black on the breast, and plumage color correlates with age and social status. This is a socially monogamous species and mate choice is mutual, but there is relatively low mate fidelity between breeding seasons. Sperm competition may be an important aspect of the breeding system—high frequency copulation is a feature of the pre-laying period and males have by far the largest testis size relative to body size of any alcid. Introduced rats threaten some colonies.