Larosterna inca 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Charadriiformes Laridae

Scientific Name: Larosterna inca (Lesson, 1827)
Common Name(s):
English Inca Tern
Taxonomic Source(s): SACC. 2005 and updates. A classification of the bird species of South America. Available at: #
Identification information: 41cm. It can be identified by its dark grey body, white moustache on both sides of its head, and red-orange beak and feet. Juveniles lack moustache and have brown plumage and bare parts. Similar species: Adults unmistakeable, juveniles could be mistaken for noddy sps.

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2016
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Engblom, G. & Zavalaga, C.
Facilitator/Compiler(s): Benstead, P., Butchart, S., Frere, E., Lascelles, B., Sharpe, C.J.
This species is listed as Near Threatened because its population has apparently experienced a moderately rapid decline.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Larosterna inca is found along the Pacific coast from northern Peru south to central Chile. Mass dispersal and breeding failures have resulted periodically from El Niño Southern Oscillation (ENSO) events, and both fish-stocks and the populations of seabirds that depend upon them are adapted to these fluctuations. Population declines are usually promptly reversed, suggesting that food shortages trigger rapid dispersal not high mortality in adults and high reproduction rates (up to two successful broods in a year). Although fishing for anchoveta has been banned in Peru, and the guano industry adequately regulated, there are concerns that this species might be badly affected by the El Niño Southern Oscillation event of 1998 (G. Engblom in litt. 2003). Prior to the guano industry (c.1850) there were millions of Inca Terns in Peru (according to accounts from Coker 1919, Hutchison 1950). Current numbers are much lower than two centuries ago, but they are common and breed in some localities. The total population has been estimated at more than 150,000 individuals (Zavalaga et al. unpublished data).

Countries occurrence:
Chile; Colombia; Ecuador; Peru
Additional data:
Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:1650000
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:No
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The total population has been estimated more than 150,000 individuals (Zavaga et al. unpublished data).

Trend Justification:  Survey data suggest that moderately rapid declines have occurred.

Current Population Trend:Decreasing
Additional data:
Continuing decline of mature individuals:Unknown
Extreme fluctuations:NoPopulation severely fragmented:No
Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:It breeds on inshore (and occasionally offshore) islands and rocky coastal cliffs. Nests are placed in suitable fissures, burrows, caves and cavities, sometimes the old nest of a Humboldt Penguin Spheniscus humboldti. It feeds, often in large flocks, on schooling anchoveta Engraulis ringens, mote sculpins Normanychtic crokeri and silversides Odothestes regia regia found in the cold water of the Humboldt Current. Additionally, this species scavenges offal and scraps from sea-lions and fishing boats. One or two eggs are incubated for about four weeks, and the chicks leave the nest after seven weeks. Birds feed by plunge diving for fish.

Systems:Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat:Unknown
Generation Length (years):11
Movement patterns:Full Migrant
Congregatory:Congregatory (and dispersive)

Threats [top]

Major Threat(s): Reduction of nesting habitat as a result of guano harvesting may affect population dynamics. However, Inca Terns are very flexible and successful in using any kind of coverage (natural or artificial) for nesting. They can nest inside abandoned buildings and huts on guano islands, and in any pile of wood and metal slabs. Reduction of anchovy stocks due to commercial fishing may limit population size. The presence of rats and cats on some islands can also prevent nesting or reduce breeding success.

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
Some breeding sites lie within managed guano reserves or protected areas.

Conservation Actions Proposed
Identify those breeding sites where introduced predators are a problem and control/remove them from these sites. Determine effects of interactions with fisheries. Monitor population levels at key sites. Establish key locations as Marine Protected Areas.

Citation: BirdLife International. 2016. Larosterna inca. The IUCN Red List of Threatened Species 2016: e.T22694834A93471847. . Downloaded on 18 July 2018.
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