LC
White-winged Tern Chlidonias leucopterus



Justification

Justification of Red List Category
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). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not 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.

Population justification
The global population is estimated to number c.3,100,000-4,000,000 individuals (Wetlands International 2015). The European population is estimated at 66,600-173,000 pairs, which equates to 133,000-347,000 mature individuals (BirdLife International 2015).

Trend justification
The overall population trend is stable, although some populations have unknown trends (Wetlands International 2015). In Europe the population size is estimated to be fluctuating (BirdLife International 2015).

Distribution and population

Ecology

Behaviour This species is strongly migratory (del Hoyo et al. 1996). It breeds from April to August in small colonies of between 3 and 100 pairs (mostly 20-40 pairs) that may contain other species (del Hoyo et al. 1996). Throughout the year the species feeds in flocks (Snow and Perrins 1998) and migrates and overwinters in large flocks (del Hoyo et al. 1996) of up to tens of thousands of individuals (Snow and Perrins 1998). Habitat Breeding The species breeds inland on freshwater lakes (del Hoyo et al. 1996, Snow and Perrins 1998), swampy standing water, rivers (Snow and Perrins 1998) and shallow naturally flooded grassland (Richards 1990, Snow and Perrins 1998) with areas of open water bordered by stands of reeds, sedge and other aquatic vegetation (Snow and Perrins 1998). It generally avoids fish-ponds, rice-fields and ornamental waters (Richards 1990) but may feed over wet fields, dry farmland and steppe grassland (del Hoyo et al. 1996). Non-breeding On passage and in winter the species frequents a variety of habitats from inland lakes to rocky coasts (del Hoyo et al. 1996), including rivers, flood-plains, lakes (Snow and Perrins 1998), impoundments, lagoons and mangrove swamps, also feeding over wet fields, dry farmland and steppe grassland (del Hoyo et al. 1996). Diet It diet consists predominantly of aquatic insects (especially Diptera, Odonata and Coleoptera) as well as adult and larval terrestrial insects, small fish and tadpoles (del Hoyo et al. 1996). Breeding site The nest is a shallow cup in a mound of aquatic vegetation usually placed over water 30-120 cm deep on floating mats of vegetation, or on dry shores or resting on the bottom in shallow water (del Hoyo et al. 1996). The species nests in single- or mixed-species colonies, neighbouring nests usually widely spaced (i.e. 10-30 m apart) but may be as close as 2.5 m (del Hoyo et al. 1996).

Threats

The main threats to this species within its European range have been identified as habitat destruction and water regulation in wetlands. In the west of its European range the reclamation of wetlands is causing declines and in Russia and the Ukraine dry breeding seasons and an increasing number of drainage schemes pose a threat (Hagemeijer and Blair 1997). In Poland it is threatened by recreational activities causing disturbance (Górski 2004). It is also susceptible to avian influenza so may be threatened by future outbreaks of the virus (Melville and Shortridge 2006).

Conservation actions

Conservation Actions Underway
The following information refers to the species's European range only: Bern Convention Appendix II. There are currently no known conservation measures for this species.

Conservation Actions Proposed
The following information refers to the species's European range only: This species would likely benefit from the protection and conservation of its preferred wetland habitats. Restrictions on access and exclusion zones would help prevent disturbance at key sites.

Acknowledgements

Text account compilers
Butchart, S., Ekstrom, J., Malpas, L., Symes, A., Ashpole, J


Recommended citation
BirdLife International (2019) Species factsheet: Chlidonias leucopterus. Downloaded from http://www.birdlife.org on 20/11/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 20/11/2019.