The Inca tern (''Larosterna inca'') is a

near-threatened A near-threatened species is a species which has been categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature (IUCN) as that may be vulnerable to endangerment in the near future, but it does not currently qu ...

species of

tern Terns are seabirds in the family Laridae, subfamily Sterninae, that have a worldwide distribution and are normally found near the sea, rivers, or wetlands. Terns are treated in eleven genera in a subgroup of the family Laridae, which also ...

in the subfamily Sterninae of the family

Laridae Laridae is a family of seabirds in the order Charadriiformes that includes the gulls, terns (including white terns), noddies, and skimmers. It includes around 100 species arranged into 22 genera. They are an adaptable group of mostly aerial bird ...

(the

gull Gulls, or colloquially seagulls, are seabirds of the subfamily Larinae. They are most closely related to terns and skimmers, distantly related to auks, and even more distantly related to waders. Until the 21st century, most gulls were placed ...

s, terns, and skimmers). It is found along the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...

coasts of

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

Ecuador Ecuador, officially the Republic of Ecuador, is a country in northwestern South America, bordered by Colombia on the north, Peru on the east and south, and the Pacific Ocean on the west. It also includes the Galápagos Province which contain ...

and

Perú Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

,Remsen, J. V., Jr., J. I. Areta, E. Bonaccorso, S. Claramunt, A. Jaramillo, D. F. Lane, J. F. Pacheco, M. B. Robbins, F. G. Stiles, and K. J. Zimmer. 30 January 2023. Species Lists of Birds for South American Countries and Territories. https://www.museum.lsu.edu/~Remsen/SACCCountryLists.htm retrieved January 30, 2023 and has appeared as a

vagrant Vagrancy is the condition of wandering homelessness without regular employment or income. Vagrants usually live in poverty and support themselves by travelling while engaging in begging, scavenging, or petty theft. In Western countries, ...

Central America Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...

and

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

.R. Terry Chesser, Shawn M. Billerman, Kevin J. Burns, Carla Cicero, Jon L. Dunn, Blanca E. Hernández-Baños, Rosa Alicia Jiménez, Andrew W. Kratter, Nicholas A. Mason, Pamela C. Rasmussen, J. V. Remsen, Jr., Douglas F. Stotz, and Kevin Winker. "Sixty-third supplement to the American Ornithological Society's ''Check-list of North American Birds''". ''American Ornithology'' 2022, vol. 139:1-13 retrieved August 9, 2022

Taxonomy and systematics

The Inca tern is the sole member of its monotypic genus ''Larosterna'', and has no accepted subspecies. Perhaps surprisingly given its highly distinct plumage, the Inca tern is not particularly basal among the terns, being more closely related to typical ''

Sterna ''Sterna'' is a genus of terns in the bird family Laridae. The genus used to encompass most "white" terns indiscriminately, but mtDNA sequence comparisons have determined that this arrangement was paraphyletic. It is now restricted to the typi ...

'' terns than any of the superficially much more similar genera '' Gelochelidon'', '' Hydroprogne'', ''

Onychoprion ''Onychoprion'' is a genus of four species of terns in the family Laridae. The genus name is from Ancient Greek , "claw" or "nail", and , "saw". As a group, they have been variously called "brown-winged terns" or "brown-backed terns", though onl ...

'', '' Phaetusa'', or ''

Sternula ''Sternula'' is a genus of small white terns, with a global distribution along sheltered sandy coasts and large rivers. The seven species are all closely related, with similar plumage and size, all are between 22–28 cm long and 39–63 g weig ...

'' are.

Description

The Inca tern is roughly long and weighs between . Its plumage is uniquely colored among terns; adults have a mostly dark, slate-gray body, with paler underwing

coverts A covert feather or tectrix on a bird is one of a set of feathers, called coverts (or ''tectrices''), which cover other feathers. The coverts help to smooth airflow over the wings and tail. Ear coverts The ear coverts are small feathers behind t ...

, and a slightly paler throat. A white stripe extends back from the base of the bill and fans out like a

Salvador Dalí Salvador Domingo Felipe Jacinto Dalí i Domènech, Marquess of Dalí of Púbol (11 May 190423 January 1989), known as Salvador Dalí ( ; ; ), was a Spanish Surrealism, surrealist artist renowned for his technical skill, precise draftsmanship, ...

esque

mustache A moustache (; mustache, ) is a growth of facial hair grown above the upper lip and under the nose. Moustaches have been worn in various styles throughout history. Etymology The word "moustache" is French, and is derived from the Itali ...

as long, satiny feathers along the side of the neck. The trailing edge of the wing (the tips of the secondaries and the three inner

primaries Primary elections or primaries are elections held to determine which candidates will run in an upcoming general election. In a partisan primary, a political party selects a candidate. Depending on the state and/or party, there may be an "open pri ...

) are white. The tail is black, and moderately forked. The iris is brown, with legs and feet that are dark red. The bill is bright to dark red, with bare yellow skin at the base. The chicks, on hatching, are purplish-brown, progressing through brownish-gray before developing mature plumage. The chicks' bills and legs are dark and horn-colored, and gradually attain the red that adults have.Gochfeld, M. and J. Burger (2020). Inca Tern (''Larosterna inca''), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.incter1.01 retrieved February 17, 2023

Distribution and habitat

The Inca tern is an inhabitant of the

Humboldt Current The Humboldt Current, also called the Peru Current, is a cold, low-salinity ocean current that flows north along the western coast of South America.Montecino, Vivian, and Carina B. Lange. "The Humboldt Current System: Ecosystem components and pro ...

region. It breeds from

Lobos de Tierra Lobos de Tierra is a Peruvian island situated 19 km from the mainland close to the Illescas Peninsula and the boundary between the departments of Piura and Lambayeque regions. Its area is 16 km2, its approximate length is 10 km ...

, in northern Perú, south to the

Aconcagua River The Aconcagua River is a river in Chile that rises from the conflux of two minor tributary rivers at above sea level in the Andes, Juncal River from the east (which rise in the Nevado Juncal) and Blanco River from the south east. The Aconcag ...

, near

Valparaíso Valparaíso () is a major city, Communes of Chile, commune, Port, seaport, and naval base facility in the Valparaíso Region of Chile. Valparaíso was originally named after Valparaíso de Arriba, in Castilla–La Mancha, Castile-La Mancha, Spain ...

, Chile. Some disperse north into Ecuador after breeding, and south to the

Puerto Montt Puerto Montt (Mapuche: Meli Pulli) is a port city and commune in southern Chile, located at the northern end of the Reloncaví Sound in the Llanquihue Province, Los Lagos Region, 1,055 km to the south of the capital, Santiago. The commune ...

area of Chile, where multiple 'research-grade' sightings with photos on the

biodiversity Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distribut ...

database

iNaturalist iNaturalist is an American 501(c)(3) nonprofit social network of naturalists, citizen scientists, and biologists built on the concept of mapping and sharing observations of biodiversity across the globe. iNaturalist may be accessed via its web ...

, including a group of four together. It is a casual visitor to Panamá and

Costa Rica Costa Rica, officially the Republic of Costa Rica, is a country in Central America. It borders Nicaragua to the north, the Caribbean Sea to the northeast, Panama to the southeast, and the Pacific Ocean to the southwest, as well as Maritime bo ...

, and has also been recorded as a

Guatemala Guatemala, officially the Republic of Guatemala, is a country in Central America. It is bordered to the north and west by Mexico, to the northeast by Belize, to the east by Honduras, and to the southeast by El Salvador. It is hydrologically b ...

and Hawaii. The documented Hawaiian birds, in particular, remained from March through November on the

Hawaiian archipelago The Hawaiian Islands () are an archipelago of eight major volcanic islands, several atolls, and numerous smaller islets in the North Pacific Ocean, extending some from the island of Hawaii in the south to northernmost Kure Atoll. Formerly c ...

. The South American Classification Committee of the

American Ornithological Society The American Ornithological Society (AOS) is an ornithological organization based in the United States. The society was formed in October 2016 by the merger of the American Ornithologists' Union (AOU) and the Cooper Ornithological Society. Its ...

treats the Inca tern's presence in

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

as "hypothetical", due to a number of unverified or undocumented sightings. On iNaturalist, one 'research-grade' sighting (with photo) has been documented from the coast of Buenaventura, Colombia's Isla Cascajal, dated July 2023; however, the species' popularity in captivity (see

Captivity Captivity, or being held captive, is a state wherein humans or other animals are confined to a particular space and prevented from leaving or moving freely. An example in humans is imprisonment. Prisoners of war are usually held in captivity by a ...

below) complicates assessment of extralimital records. The Inca tern nests on

sea cliffs A cliffed coast, also called an abrasion coast, is a form of coast where the action of marine waves has formed steep cliffs that may or may not be precipitous. It contrasts with a flat or alluvial coast. Formation In coastal areas in whic ...

and

guano Guano (Spanish from ) is the accumulated excrement of seabirds or bats. Guano is a highly effective fertiliser due to the high content of nitrogen, phosphate, and potassium, all key nutrients essential for plant growth. Guano was also, to a le ...

islands, as well as manmade structures (such as ledges under piers) and abandoned barges. It will gather with other sea and shorebirds on sandy beaches.

Behavior

Movement

The Inca tern is essentially non- migratory, although some disperse northwards after breeding. Some rogue individuals have flown great distances.

Feeding

The Inca tern feeds primarily on small fish, such as anchoveta (''Engraulis ringens''), and also consumes

planktonic Plankton are the diverse collection of organisms that drift in water (or air) but are unable to actively propel themselves against currents (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they pro ...

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s and

offal Offal (), also called variety meats, pluck or organ meats, is the internal organ (anatomy), organs of a butchered animal. Offal may also refer to the by-products of Milling (grinding), milled grains, such as corn or wheat. Some cultures strong ...

carrion Carrion (), also known as a carcass, is the decaying flesh of dead animals. Overview Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures ...

in its diet. Large flocks congregate around fishing boats and will also follow the feeding patterns of

cormorant Phalacrocoracidae is a family of approximately 40 species of aquatic birds commonly known as cormorants and shags. Several different classifications of the family have been proposed, but in 2021 the International Ornithologists' Union (IOU) ado ...

sea lion Sea lions are pinnipeds characterized by external ear flaps, long foreflippers, the ability to walk on all fours, short and thick hair, and a big chest and belly. Together with the fur seals, they make up the family Otariidae, eared seals. ...

s, and

whale Whales are a widely distributed and diverse group of fully Aquatic animal, aquatic placental mammal, placental marine mammals. As an informal and Colloquialism, colloquial grouping, they correspond to large members of the infraorder Cetacea ...

s and

dolphin A dolphin is an aquatic mammal in the cetacean clade Odontoceti (toothed whale). Dolphins belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontopori ...

s. Feeding flocks can number over 5,000 birds. The Inca tern catches its prey mainly by plunge-diving, but also picks items from the surface while flying or floating on the water.

Breeding

Breeding does not appear to be concentrated in any season. Eggs have been found between April and July and between October and December, and other evidence of breeding has been noted in August. It nests in a variety of sites including fissures and caves in rock cliffs, among rocks and boulders on island slopes, in abandoned petrel and penguin burrows, and on and under human structures. The clutch size is usually two eggs though sometimes one. Both sexes incubate the clutch and provision the young. The incubation period is not known; fledging occurs about four weeks after hatch and the young are fully dependent on the adults for at least a month after fledging.

Vocalization

The Inca tern is most vocal at its nesting colonies. Its calls include "raucous cackling notes" and "mewing"; the latter call has been likened to that of a kitten.

Status

The

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

has assessed the Inca tern as Near Threatened. It has a somewhat restricted range; its population size is not known and is believed to be decreasing. "Reproductive success is dramatically reduced during

El Niño EL, El or el may refer to: Arts and entertainment Fictional entities * El, a character from the manga series ''Shugo Chara!'' by Peach-Pit * Eleven (''Stranger Things'') (El), a fictional character in the TV series ''Stranger Things'' * El, fami ...

events". Human harvesting of its primary prey is a probable threat as is climate change. One estimate placed its population at about 150,000 in 2011.

Captivity

Because of its unusual plumage, the species is popular in

zoo A zoo (short for zoological garden; also called an animal park or menagerie) is a facility where animals are kept within enclosures for public exhibition and often bred for conservation purposes. The term ''zoological garden'' refers to zoology, ...

s. Escapes from captivity can occur, which leads to problems determining genuine vagrancy.

References

{{Taxonbar, from=Q839862

Inca tern The Inca tern (''Larosterna inca'') is a Near Threatened, near-threatened species of tern in the subfamily Sterninae of the family Laridae (the gulls, terns, and Rynchops, skimmers). It is found along the Pacific Ocean, Pacific coasts of Chile ...

Birds of Peru Birds of Chile Western South American coastal birds

Taxa named by René Lesson