Sterna hirundinacea


Taxonomy [top]

Kingdom Phylum Class Order Family

Scientific Name: Sterna hirundinacea
Species Authority: Lesson, 1831
Common Name(s):
English South American Tern
Taxonomic Notes: The BirdLife Taxonomic Working Group is aware that phylogenetic analyses have been published which have proposed generic rearrangements which may affect this species, but prefers to wait until work by other taxonomists reveals how these changes affect the entire groups involved.

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Facilitator/Compiler(s): Ekstrom, J., Butchart, S., Malpas, L., Calvert, R.
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size may be moderately small to large, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

Geographic Range [top]

Range Description: This species breeds on the coasts of southern Peru and Espírito Santo, east-central Brazil south to Tierra del Fuego, Argentina and Chile, and the Falkland Islands (Malvinas) (Duffy et al. 1984, Schlatter 1984, Woods 1988, De Tarso Zuquim Antas 1991). In the austral winter, most birds breeding in the extreme south move north to Uruguay (where breeding remains unconfirmed), and the species also winters north to Ecuador and Bahia, Brazil (Antas 1991). There are also large colonies on inshore islands in Guanabara Bay and off the Espírito Santo coast, Brazil (Antas 1991). The population on the Falkland Islands was recently estimated at 6,000-12,000 pairs (Woods and Woods 1997), and a colony exceeding 1,000 pairs was discovered in south Peru in 1995 (del Hoyo et al. 1996), where it is fairly common (Clements and Shany 2001). However, although formerly locally common in Chile, only two breeding sites are now known (Damas Island and Inutil Bay near Porvenir), and extensive searches to locate former colonies between 1994 and 1997 were unsuccessful (Mickstein in litt. 1998).
Argentina; Brazil; Chile; Ecuador; Peru; Uruguay
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: The species is almost exclusively coastal, breeding on rocky or sandy beaches, cliff tops and small islands. Non-breeders frequent coastal waters, beaches, estuaries and harbours. It feeds mainly on small fish and crustaceans and probably also takes insects. Laying occurs in April-June in Brazil, early November in north Argentina and early December in south Argentina. Two to three eggs are laid (del Hoyo et al. 1996).
Systems: Terrestrial; Marine

Threats [top]

Major Threat(s): Tourism may be responsible for the decline of the Chilean population, with a breeding colony at Lake Calafquen apparently deserted due to disturbance from bathing tourists and water bikes (Mickstein in litt. 1998). Tourism has also increased markedly on the Argentinean coast, and this has presumably had a detrimental effect on at least some breeding colonies (del Hoyo et al. 1996). Egg collecting is also a problem at colonies in Espírito Santo, Brazil (Antas 1991), and may have contributed to the decline of the Chilean population (Mickstein in litt. 1998). Commercial fishing and industry are considered potential threats to the Falkland Islands population (Woods and Woods 1997).

Citation: BirdLife International 2012. Sterna hirundinacea. The IUCN Red List of Threatened Species. Version 2014.3. <>. Downloaded on 31 March 2015.
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