Species

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Justification
This species is listed as Endangered because it is estimated to have a very small population which is undergoing continuing declines owing to habitat loss and disturbance on its breeding grounds. It is also restricted to a very small area when breeding and these breeding grounds remain highly threatened.

Taxonomic source(s)
SACC. 2006. A classification of the bird species of South America. Available at: http://www.museum.lsu.edu/~Remsen/SACCBaseline.html.
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.
Stotz, D. F.; Fitzpatrick, J. W.; Parker, T. A.; Moskovits, D. K. 1996. Neotropical birds: ecology and conservation. University of Chicago Press, Chicago.

Taxonomic note
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.

Distribution and population
Sterna lorata is restricted to the Humboldt Current Zone from north Peru to the peninsula of Mejillones in Chile (Enticott and Tipling 1997, Guerra-Correa et al. 2007). Its movements are poorly known, but it has been recorded north to central Ecuador (Enticott and Tipling 1997). There are now only four confirmed breeding sites in Peru, at Pampa Lechuzas, Yanyarina, Paraiso and Pacasmayo (Zavalaga et al. 2008a), and nine in Chile, all of which are located in Mejillones and nearby areas (Guerra-Correa et al. 2007). In Chile all colonies have been found in the desert plains, generally within 1 km of the coast, but in other locations colonies have also been found on sandy beaches associated with wetlands. A well-known former breeding site at Puerto Viejo is now heavily developed and no longer supports breeding birds (Zavalaga et al. 2008a), and population declines have been noted at Pampa Mejillones and La Portada in Chile. One locality was previously reported to have tens of thousands of individuals, but the population is now thought to be significantly reduced, as the numbers at all sites are estimated at 950-1,100 individuals and 150 to 160 pairs (Guerra-Correa et al. 2007). Some reports suggest that the population may have declined by 50% in the last 10 years (Luchsinger 2007). However, there are still unsurveyed sandy beaches away from the Pan-American Highway that could be suitable for nesting, and old colonies that have not been visited since their discovery decades ago, while signs of previously unknown breeding sites have recently been recorded in La Libertad, Peru (Amorós 2011); the total is therefore likely to fall in the range of 1,000-2,500 individuals.

Population justification
Estimates range from 100 pairs (G. Engblom in litt. 2005) to 5,000 pairs (M. Plenge in litt. 1999). Given that there are still unsurveyed sandy beaches away from the Pan-American Highway, the total is perhaps likely to fall in the range of 1,000-2,499 individuals. This equates to 667-1,666 mature individuals, rounded to 600-1,700 individuals here.

Trend justification
Suspected to be declining on the basis of continued destruction, degradation of its breeding habitat, disappearance of breeding colonies in the last 30 years (e.g. Puerto Viejo and Mollendo in Peru) and population decline in some localities (Pampa Mejillones and La Portada in Chile).

Ecology
It breeds either on broad sandy beaches and dunes (100-200 m from the high tide mark) associated with wetlands (Zavalaga et al. 2008a), or in desert plains 1-3 km inland (Vilina 1998, Guerra et al. 2003, Zavalaga et al. 2008a). The shallow waters of wetlands are thought to offer optimal conditions for foraging, both within and outside the breeding season (Zavalaga et al. 2009). Egg-laying is asynchronous both within and between groups, and spread from August to February (Vilina 1998, Guerra et al. 2003), particularly October to late January (Zavalaga et al. 2008b).Clutch size is one or two eggs, but usually only one chick fledges (Vilina 1998, Guerra et al. 2003). To counteract high levels of predation it nests in homogeneous habitat in small groups (3-25 nests), loosely aggregated, with inter-nest distances usually over 100 m (Vilina 1998, Zavalaga et al. 2008b), thus making nests difficult to detect (Zavalaga et al. 2008a). Eggs and chicks are well camouflaged with the bare ground. Inland nesting is believed to be a strategy to reduce risk from terrestrial predation, as predators often patrol closer to the shore. Birds are known to be absent during El Niño events (Zavalaga et al. 2008a) and do not attempt to breed (Zavalaga et al. 2008b). Post-breeding dispersal occurs from April until July, to unknown areas, probably offshore (Mackiernan et al. 2001). During the 1997-1998 El Niño event, hundreds were sighted 25-200 km offshore, suggesting they can disperse widely during oceanographic anomalies (Zavalaga et al. 2008a). It generally forages in inshore areas, but is occasionally seen 10-70 km offshore (Mackiernan et al. 2001). Main prey include anchovies Engraulis ringens, South Pacific sauris Scomberesox saurus scombroides (Guerra et al. 2003), Peruvian silversides Odonthestes regia regia and mote sculpins Normanychtis crockeri. Prey items found in nests measured less than 8 cm, indicating a prey size limit imposed by chick body size (Zavalaga et al. 2008b).

Threats
It undoubtedly suffered from the 1972 collapse of anchoveta Engraulis spp. stocks. which have not subsequently recovered (Schlatter 1984, Gochfeld and Burger 1996). The principle threat to this species is the destruction of breeding habitat, through building of shanty towns, summer homes (as at Puerto Viejo), road constructions and through human activities such as driving 4×4 vehicles on the beaches. Off-road vehicles have also led to increased disturbance in previously inaccessible areas. Other threats include wetland pollution and water use for irrigation (at Paraiso and Mejia), conversion of desert plains into agricultural land (at Punta Literas-Pativilca), management of wetland water levels (at Ite) and oil exploration near tern areas (at San Pedro de Vice). In Chile, risks include the building of port facilities at Mejillones (which would affect at least 200 birds), off-road driving at Rio Loa and the construction of coastal highways throughout the north (Guerra-Corre et al. 2007). Foxes Pseudalopex spp. and aerial raptors are considered the main predators of Peruvian Tern (Vilina 1998, Guerra et al. 2003, Zavalaga et al. 2009).

Conservation actions underway
In Chile, CONAMA (2006) has recognized the species as threatened with extinction, and it has been officially classified as Endangered. In Peru it has been recognized as Vulnerable (Zavalaga et al. 2008a).

Conservation actions proposed
Conduct searches for colonies in previously unsurveyed areas or in areas that need confirmation of breeding (Chavez 2007). Monitor known colonies to assess trends. Restore abandoned colonies using decoys and playbacks. Uplist the conservation status in Peru from Vulnerable to Endangered and include monthly evaluations for the presence of terns in any project for the construction of roads or other facilities in coastal desert plains (up to 5 km inland). Protect known colonies from habitat destruction, disturbance and pollution.

References
Schlatter, R. P. 1984. The status and conservation of seabirds in Chile. In: Croxall, J.P.; Evans, P.G.H.; Schreiber, R.W. (ed.), Status and conservation of the world's seabirds, pp. 261-269. International Council for Bird Preservation, Cambridge, U.K.

Gochfeld, M.; Burger, J. 1996. Sternidae (Terns). In: del Hoyo, J.; Elliott, A.; Sargatal, J. (ed.), Handbook of the birds of the world, pp. 624-667. Lynx Edicions, Barcelona, Spain.

Enticott, J.; Tipling, D. 1997. Photographic handbook of the seabirds of the world. New Holland, London.

Vilina, Y. A. 1998. Breeding observations of the Peruvian Tern in Chile. Colonial Waterbirds 21: 101-103.

Zavalaga, C. B.; Plenge, M. A.; Bertolero, A. 2008. Nesting habitat and numbers of Peruvian Terns at five breeding sites in the central-southern coast of Peru. Ornitologia Neotropical 19(4): 587-594.

Luchsinger F. 2007. Gaviotín en peligro.

Zavalaga, C. B.; Plenge, M. A.; Bertolero, A. 2008. The breeding biology of the Peruvian Tern (Sterna lorata) in Peru. Waterbirds 31(4): 550-560.

Bridge, E.S., Jones, A.W. and Baker, A.J. 2005. A phylogenetic framework for the terns (Sternini) inferred from mtDNA sequences: implications for taxonomy and plumage evolution. Molecular Phylogenetics and Evolution 35(2): 459-469.

Chavez Villavencio, C. 2007. Las aves de Santuario de Conservacion Regional Manglares San Pedro de Vice, Sechura, Peru. Cotinga 27: 32-37.

Guerra, P.A. de C., Rubira, C. and De Lemos, R. 2003. Springer, New York, USA.

Mackiernan, G., Lonsdale, P., Shany, N., Cooper, B. and Ginsburg, P. 2001. Observations of seabirds in Peruvian and Chilean waters during the 1998 El Nino. Cotinga 15: 88-94.

Schulenberg, T. S., Stotz, D. F. Lane, D. F. O'Neill, J. P. Parker, T. A. III. 2007. Birds of Peru.

Tello, A., Engblom, G., Merino, P. and Chalco, J. J. 2005. Sterna lorata, situacion en la costa central del Peru..

Zavalaga, C.B., Hardesty, J., Mori, G.P., Chavez-Villavicencio, C. and Tello, A. 2009. Current status of Peruvian terns Sterna lorata in Peru: threats, conservation and research priorities. Bird Conservation International 19(2): 175-186.

Amorós, S. 2011. Signs of new breeding sites for Peruvian Tern, Sternula lorata (Charadriiformes, Laridae) at La Libertad, Peru, and its implications for conservation. The Biologist (Lima) 9(2): 177-192.

Further web sources of information
View photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Anderson, O., Benstead, P., Calvert, R., Capper, D., Frere, E., Harding, M., Khwaja, N., Lascelles, B., Sharpe, C J, Symes, A.

Contributors
Engblom, G., Guerra, C., Jaramillo, A., Plenge, M., Tello, A., Zavalaga, C.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2013) Species factsheet: Sterna lorata. Downloaded from http://www.birdlife.org on 24/05/2013. Recommended citation for factsheets for more than one species: BirdLife International (2013) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 24/05/2013.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

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Additional resources for this species

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