Ready (inca tern)

The Inca tern (Larosterna inca) is a species of bird in the Sterninae subfamily of the Laridae family, which includes gulls, terns, and skimmers. The bird is categorized as Near Threatened and is found in Chile, Ecuador, and Peru, occasionally venturing to Central America and Hawaii. Importantly, they are the sole member of the Larosterna genus and lack any subspecies...

Inca tern 

( Larosterna inca )

Inca tern image by Dennis Irrgang via Flickr

    

Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Charadriiformes
Family:	Laridae
Genus:	Larosterna Blyth, 1852
Species:	Larosterna inca

The Inca tern (Larosterna inca) is a species of bird in the Sterninae subfamily of the Laridae family, which includes gulls, terns, and skimmers. The bird is categorized as Near Threatened and is found in Chile, Ecuador, and Peru, occasionally venturing to Central America and Hawaii. Importantly, they are the sole member of the Larosterna genus and lack any subspecies.

The Inca tern stands 39 to 42 cm (15 to 17 in) tall and weighs between 180 to 210 g (6.3 to 7.4 oz). Its plumage is distinctive, with adults displaying a predominantly dark slate gray body, complemented by a paler throat and underwing coverts. A white stripe extends rearward from the bill's base and fans out as long satiny feathers along the side of the neck. The distinctive white stripe bears a resemblance to the iconic mustache of Hercule Poirot, a well-known fictional Belgian detective. Because of this resemblance, the bird is often referred to as the 'Poirot bird' on the internet.

The trailing edge of their wing and the peripheries of the four outer primaries are white. Their tail is black and moderately forked. Their iris is brown, their legs and feet are dark red, and their bill is dark red with bare yellow skin at its base. The young ones start as purplish-brown, progressing through brownish-gray to adult plumage. Their bill and legs are dark horn-colored, which gradually attain the red of adults.

Distribition & Habitat

Compiled by Birdlife International and Handbook of the Birds of the World (2016) 2007

Inca terns are native to the Humboldt Current region. They breed from Lobos de Tierra in northern Peru south to the Aconcagua River near Valparaíso, Chile. Some disperse north into Ecuador after breeding. Occasionally, they visit Panama and Costa Rica and have been recorded as vagrants in Guatemala and Hawaii. The last spent March to November wandering among the islands. Undocumented sight records in Colombia lead the South American Classification Committee of the American Ornithological Society to consider them as hypothetical in that country.

Inca terns nest on sea cliffs, guano islands, and artificial structures such as ledges under piers and abandoned barges. They gather with other seabirds on sandy beaches.

 

Feeding Habits

Inca tern at Walsrode Bird Park by Olaf Oliviero Riemer via Wikimedia Commons

They feed primarily on small fish, such as anchoveta ( Engraulis ringens),

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Engraulis ringens

The Peruvian anchoveta (Engraulis ringens) belongs to the anchovy family, Engraulidae, and is found in the Southeast Pacific Ocean. It stands as one of the most commercially significant fish species globally, with annual catches ranging between 3.14 and 8.32 million tonnes from 2010 to 2021.

Initially believed to primarily consume phytoplankton, small zooplankton, and larvae, recent research indicates that anchoveta derive the majority of their energy from larger zooplankton, including macrozooplankton. Krill and substantial copepods play pivotal roles in their diet. Peruvian anchoveta exhibit a lifespan of up to 3 years, attaining a length of 20 cm (8 in).

and also include planktonic crustaceans and offal in their diet. Large flocks attend fishing boats and also follow feeding cormorants, sea lions, and whales and dolphins. Feeding flocks can number 5000 birds. It catches its prey mainly by plunge-diving but also picks items from the surface while flying or on the water.

Behaviour

Inca terns by  Olaf Oliviero Riemer via Wikimedia Commons

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 their nesting colonies. Their calls include "raucous cackling notes" and "mewing"; the latter call has been likened to that of a kitten."

Conservation Status

The IUCN has evaluated the Inca tern as Near Threatened. They possess a somewhat limited range, and their population size is not precisely known, though it is believed to be declining. "Reproductive success undergoes significant reduction during El Niño

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El Niño

The El Niño–Southern Oscillation (ENSO) is a climatic phenomenon characterized by irregular quasi-periodic variations in winds and sea surface temperatures across the tropical Pacific Ocean. It influences the climate in a significant portion of the tropics and subtropics, establishing connections (teleconnections) with higher latitude regions worldwide. The warming stage of sea surface temperatures is referred to as El Niño, while the cooling phase is identified as La Niña. The Southern Oscillation serves as the accompanying atmospheric component, synchronized with changes in sea temperature. El Niño correlates with elevated air sea level pressure over Indonesia, Australia, and spanning the Indian Ocean to the Atlantic.

events." Human harvesting of the tern's primary prey is a potential threat, as is the impact of climate change. One approximation suggested their population was around 150,000 in 2011.

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References

• BirdLife International. 2018. Larosterna inca. The IUCN Red List of Threatened Species 2018: e.T22694834A132576903. http://dx.doi.org/10.2305/IUCN.UK.2018- 2.RLTS.T22694834A132576903.en Retrived on Feb 6, 2024, from
  doi:10.2305/IUCN.UK.2018-2.RLTS.T22694834A132576903.en.
 
• 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. Retrived on Feb 6, 2024, from
https://doi.org/10.2173/bow.incter1.01.

• 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. Retrived on Feb 6, 2024, from
https://www.museum.lsu.edu/~Remsen/SACCCountryLists.htm.

• Gill, F.; Donsker, D.; Rasmussen, P., eds. (January 2023). "Noddies, skimmers, gulls, terns, skuas, auks". IOC World Bird List. v 13.1.
  Retrived on Feb 6, 2023, from
https://www.worldbirdnames.org/new/bow/gulls/.