• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.
SACC. 2005 and updates. A classification of the bird species of South America. Available at: https://www.museum.lsu.edu/~Remsen/SACCBaseline.htm.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	-

Red List history

Year	Category	Criteria
2018	Least Concern
2016	Least Concern
2012	Least Concern
2009	Least Concern
2008	Least Concern
2004	Least Concern
2000	Lower Risk/Least Concern
1994	Lower Risk/Least Concern
1988	Lower Risk/Least Concern

Migratory status	full migrant	Forest dependency	does not normally occur in forest
Land-mass type		Average mass	344 g

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	106,000 km2	medium
Extent of Occurrence (non-breeding)	3,150,000 km2	medium
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	unknown	poor	estimated	2006
Population trend	decreasing	-	suspected	-
Generation length	11.5 years	-	-	-

Population justification: Delany and Scott (2006) estimate the population at 25,000 individuals.

Trend justification: The population is suspected to be in decline owing to ongoing threats.

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Chile	extant	native		yes
Colombia	extant	native
Costa Rica	extant	native			yes
Ecuador	extant	native			yes
Falkland Islands (Malvinas)	extant	native
Panama	extant	vagrant
Peru	extant	native			yes
South Georgia & the South Sandwich Islands	extant	uncertain

Country/Territory	IBA Name
Chile	Bahía de Mejillones
Chile	Costa sur de Arica
Chile	Desembocadura del Río Lluta
Chile	Desembocadura del Río Loa
Chile	Desembocadura del Río Maipo
Chile	Desembocadura Río Mataquito
Chile	Estero Mantagua y Desembocadura del Río Aconcagua
Chile	Parque Nacional Pan de Azúcar
Chile	Playa las Machas
Chile	Reserva Nacional Pingüino de Humboldt - Isla Choros, Damas y Punta de Choros
Chile	Santuario de la Naturaleza Humedal Laguna Reloca
Peru	Laguna de Ite
Peru	Reserva Nacional de Paracas
Peru	Río Tambo y Lagunas de Mejía

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Marine Intertidal	Sandy Shoreline and/or Beaches, Sand Bars, Spits, Etc	major	non-breeding
Marine Neritic	Macroalgal/Kelp	major	non-breeding
Marine Neritic	Macroalgal/Kelp	major	breeding
Marine Neritic	Pelagic	suitable	non-breeding
Marine Neritic	Pelagic	suitable	breeding
Marine Neritic	Seagrass (Submerged)	major	non-breeding
Marine Neritic	Seagrass (Submerged)	major	breeding
Marine Neritic	Subtidal Loose Rock/pebble/gravel	major	non-breeding
Marine Neritic	Subtidal Loose Rock/pebble/gravel	major	breeding
Marine Neritic	Subtidal Rock and Rocky Reefs	major	non-breeding
Marine Neritic	Subtidal Rock and Rocky Reefs	major	breeding
Marine Neritic	Subtidal Sandy	major	non-breeding
Marine Neritic	Subtidal Sandy	major	breeding
Marine Neritic	Subtidal Sandy-Mud	major	non-breeding
Marine Neritic	Subtidal Sandy-Mud	major	breeding
Altitude		Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Biological resource use	Hunting & trapping terrestrial animals - Intentional use (species is the target)	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Causing/Could cause fluctuations		Low Impact: 5
		Stresses Reduced reproductive success
Climate change & severe weather	Temperature extremes	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Causing/Could cause fluctuations		Medium Impact: 6
		Stresses Indirect ecosystem effects, Reduced reproductive success
Energy production & mining	Mining & quarrying	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Causing/Could cause fluctuations		Low Impact: 5
		Stresses Species disturbance, Reduced reproductive success
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Canis familiaris	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Causing/Could cause fluctuations		Low Impact: 5
		Stresses Species disturbance, Reduced reproductive success

Purpose	Scale
Food - human	subsistence, national
Pets/display animals, horticulture	international

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Recommended citation
BirdLife International (2024) Species factsheet: Grey Gull Larus modestus. Downloaded from https://datazone.birdlife.org/species/factsheet/grey-gull-larus-modestus on 23/11/2024.
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 23/11/2024.