Superregnum: Eukaryota
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Cladus: Craniata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Cladus: Reptiliomorpha
Cladus: Amniota
Classis: Reptilia
Cladus: Eureptilia
Cladus: Romeriida
Subclassis: Diapsida
Cladus: Sauria
Infraclassis: Archosauromorpha
Cladus: Crurotarsi
Divisio: Archosauria
Subsectio: Ornithodira
Subtaxon: Dinosauromorpha
Cladus: Dinosauria
Ordo: Saurischia
Cladus: Theropoda
Cladus: Neotheropoda
Infraclassis: Aves
Cladus: Euavialae
Cladus: Avebrevicauda
Cladus: Pygostylia
Cladus: Ornithothoraces
Cladus: Euornithes
Cladus: Ornithuromorpha
Cladus: Ornithurae
Cladus: Carinatae
Parvclassis: Neornithes
Cohors: Neognathae
Ordo: Charadriiformes
Subordo: Alcae
Familia: Alcidae
Genus: Aethia
Species: Aethia pusilla
Name
Aethia pusilla (Pallas, 1811)
Aethia pusilla egg
References
Zoographia Rosso-Asiatica 2 p. 373
Vernacular names
čeština: Alkounek nejmenší
Esperanto: Nana aŭko
suomi: Pikkukiislanen
русский: Конюга-крошка
Türkçe: Cüce dalıcımartı
The least auklet (Aethia pusilla) is a seabird and the smallest species of auk. It is the most abundant seabird in North America, and one of the most abundant in the world, with a population of around nine million birds. They breed on the islands of Alaska and Siberia, and spend the winter close to the edge of the ice sheet[clarification needed]. Their largest colonies are on the Aleutian Islands, St. Lawrence Island and Little Diomede Island.
Diet and feeding
Least auklets feed predominantly on calanoid copepods, particularly those of the genus Neocalanus. They also eat euphausiids, pteropods and other zooplankton species. They hunt for these in stratified waters caused where upwelling and thermoclines cause these prey items to be tightly clumped together. Like all auks they are pursuit divers, using their wings to provide thrust and "fly" under the water. They are voracious predators, consuming 86% of their body weight each day.
Breeding
Least auklets are highly colonial, nesting in rocky crevices in colonies of up to a million birds. These colonies are often mixed, with other species of auklet nesting with, and competing with the least auklets. While this coexistence with other species may bring the benefits of protection from predators, least auklets are vulnerable to being displaced from their nesting sites by the larger crested auklets. A single egg is laid in the crevice and incubated for a month, after which a semi-precocial black downy chick is hatched. Both parents share incubation duties, as well as brooding and feeding duties. Unlike many auks, which are fed fish carried crosswise in the bill, chicks of the least auklet are fed copepods and other zooplankton from a sublingual pouch, as are other small auklets. The chicks receive no further parental care after they fledge, and can dive to hunt as soon as they leave the nest.
Status and conservation
Staffer from the Alaska Maritime National Wildlife Refuge holding a least auklet
Least auklets are vulnerable to oil spills and introduced species. The introduction of Arctic foxes to many of the Aleutian Islands caused the species to be wiped out on many of those islands, and rats are also a problem on many islands. However, at present they are still a very common species, and are not considered threatened by the IUCN.
References
BirdLife International (2020). "Aethia pusilla". IUCN Red List of Threatened Species. 2020: e.T22694921A168850125. doi:10.2305/IUCN.UK.2020-3.RLTS.T22694921A168850125.en. Retrieved 12 November 2021.
Jones, I. L. 1993. Least Auklet (Aethia pusilla). In The Birds of North America, No. 69 (A. Poole and F. Gill, Eds.). Philadelphia: The Academy of Natural Sciences; Washington, D.C.: The American Ornithologists’ Union.
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