Data Zone
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 is not known, but it is not thought to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very 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 has been estimated at 310,000-380,000 individuals (Wetlands International 2015). The European population is estimated at 35,900-57,300 pairs, which equates to 71,700-115,000 mature individuals or 107,550-172,500 individuals (BirdLife International 2015). An updated global population estimate using this new information from Europe provides an estimate of 280,000-345,000 individuals. This roughly equates to 180,000-230,000 mature individuals.
Trend justification
The overall population trend is not known. Some populations may be stable or increasing (Wetlands International 2015), whilst the European population is estimated to be decreasing by less than 25% in three generations (BirdLife International 2015).
This species breeds widely at isolated, scattered localities, from Senegal, Mauritania, and the south and east of the Iberian Peninsula, through the Mediterranean, the Black Sea, Asia Minor and the Middle East to east Kazakhstan, Afghanistan, Pakistan and north-west India. It winters in much of the Mediterranean, Black Sea and Caspian Sea including coastlines around the Arabian Peninsula, south to the Horn of Africa (del Hoyo et al. 1996).
Behaviour Populations breeding in central Asia are fully migratory, although other populations are sedentary or only disperse short distances (del Hoyo et al 1996, Snow and Perrins 1998). Migratory populations return to breeding colonies in late-February, most using a route along the west coast of the Black Sea, leaving breeding sites again in July (Olsen and Larsson 2003). Many immatures also remain in winter quarters throughout the breeding season (Olsen and Larsson 2003). The species breeds from late-March to May in dense monospecific or mixed-species colonies (e.g. with terns) in numbers ranging from ten to many thousands of pairs, and is gregarious throughout the year, commonly occurring in flocks of up to 200 individuals, occasionally up to 3,000 individuals (del Hoyo et al 1996, Snow and Perrins 1998).
Habitat Breeding The species breeds on the coasts of land-locked seas, on sand-spits, beaches and islands with mudflats and marshes in shallow tidal waters, and on saline inland seas and steppe lakes (Richards 1990, del Hoyo et al 1996, Snow and Perrins 1998, Olsen and Larsson 2003). It may also frequent meadows and moist grassland by tidal inlets, and brackish or freshwater lagoons or marshes near river deltas during this season (Richards 1990, del Hoyo et al 1996, Snow and Perrins 1998). Non-breeding The species is almost entirely coastal outside of the breeding season, frequenting shallow inshore waters and salt-pans, although it generally avoids harbours (del Hoyo et al 1996).
Diet The diet of the species consists mainly of fish (c.50 % of the diet), as well as insects and marine invertebrates (e.g. crustaceans) (Urban et al. 1986, del Hoyo et al 1996, Snow and Perrins 1998).
Breeding site The species breeds colonially with pairs nesting as close as 20-50 cm; large groups often splitting into subcolonies with group centres 10-50 m apart (Urban et al. 1986). The nest is a deep scrape or shallow depression, preferably positioned on open mud, although some pairs may nest in Salsola or Salicornia (Urban et al. 1986, Richards 1990, del Hoyo et al 1996, Olsen and Larsson 2003).
Management information A conservation scheme for the protection of gull and tern breeding colonies in coastal lagoons and deltas (e.g. Po Delta, Italy) involves protection from human disturbance, prevention of erosion of islet complexes, habitat maintenance and the creation of new islets for nest sites (Fasola and Canova 1996). The scheme particularly specifies that bare islets with 30-100 % cover of low vegetation (sward heights less than 20 cm) should be maintained or created as nesting sites (Fasola and Canova 1996).
Contamination in the Caspian Sea is an issue that may reduce reproductive success (Burger et al. 2018).
Conservation Actions Underway
The following information refers to the species's European range only: Listed on Appendix II of the Convention on Migratory Species and listed under the African Eurasian Waterbird Agreement. It is listed on Appendix II of the Bern Convention. Listed on Annex I of the EU Birds Directive. It is listed within 45 marine Important Bird Areas within Europe. In the EU it is listed in 131 Special Protection Areas.
Conservation Actions Proposed
The following information refers to the species's European range only: Identify Important Bird Areas and designate them as protected areas. Increase management in key breeding areas to prevent disturbance from tourism and recreational activities.
Text account compilers
Malpas, L., Elliott, N., Ashpole, J, Martin, R., Stuart, A., Taylor, J., Calvert, R., Butchart, S., Ekstrom, J., Everest, J.
Contributors
Nisbet, I.
Recommended citation
BirdLife International (2024) Species factsheet: Slender-billed Gull Larus genei. Downloaded from
https://datazone.birdlife.org/species/factsheet/slender-billed-gull-larus-genei on 26/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 26/12/2024.