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

Taxonomic source(s)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: http://www.aerc.eu/DOCS/Bird_taxa_of_the_WP15.xls.
Cramp, S. and Simmons, K.E.L. (eds). 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.
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.
Turbott, E.G. 1990. Checklist of the Birds of New Zealand. Ornithological Society of New Zealand, Wellington.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	-

Red List history

Year	Category	Criteria
2024	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	-

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	950,000 km2
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	3500000 mature individuals	good	estimated	2023
Population trend	decreasing	-	suspected	-
Generation length	4.57 years	-	-	-

Population justification: The species has a large estimated population size (3,500,000 mature individuals; Partners in Flight 2023).

Trend justification: Considering its population trend over three generations (c. 14 years), data from the Christmas Bird Count (Meehan et al. 2022) indicate that it has remained broadly stable, albeit with interannual fluctuations. Over the same period, the Breeding Bird Survey (Ziolkowski et al. 2022) reported a decline, but with huge confidence intervals. In the non-breeding season, non-significant declines were recorded by both the Migratory Shorebird Project (unpublished data) and eBird (Fink et al. 2023). Although the population may be declining, it does not currently appear to be declining at a rate approaching Criterion A thresholds.

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Anguilla (to UK)	extant	native			yes	yes
Antigua and Barbuda	extant	native			yes	yes
Aruba (to Netherlands)	extant	native				yes
Bahamas	extant	native			yes	yes
Barbados	extant	native			yes	yes
Belize	extant	native			yes	yes
Bonaire, Sint Eustatius and Saba (to Netherlands)	extant	native			yes	yes
Canada	extant	native			yes	yes
Cayman Islands (to UK)	extant	native			yes	yes
Colombia	extant	native			yes	yes
Costa Rica	extant	native			yes	yes
Cuba	extant	native			yes	yes
Curaçao (to Netherlands)	extant	native			yes	yes
Dominica	extant	native			yes	yes
Dominican Republic	extant	native			yes	yes
Ecuador	extant	native			yes	yes
El Salvador	extant	native			yes	yes
France	extant	vagrant
French Guiana	extant	native			yes	yes
Grenada	extant	native			yes	yes
Guadeloupe (to France)	extant	native			yes	yes
Guatemala	extant	native			yes	yes
Guyana	extant	native			yes	yes
Haiti	extant	native			yes	yes
Honduras	extant	native			yes	yes
Ireland	extant	vagrant
Jamaica	extant	native			yes	yes
Japan	extant	vagrant
Martinique (to France)	extant	native			yes	yes
Mexico	extant	native			yes	yes
Montserrat (to UK)	extant	native			yes	yes
New Zealand	extant	vagrant
Nicaragua	extant	native			yes	yes
Panama	extant	native			yes	yes
Peru	extant	native			yes	yes
Portugal	extant	vagrant
Puerto Rico (to USA)	extant	native			yes	yes
Russia	extant	native		yes		yes
Russia (Asian)	extant	native		yes		yes
Sint Maarten (to Netherlands)	extant	native			yes	yes
Spain	extant	vagrant
St Barthelemy (to France)	extant	native			yes	yes
St Kitts and Nevis	extant	native			yes	yes
St Lucia	extant	native			yes	yes
St Martin (to France)	extant	native			yes	yes
St Pierre and Miquelon (to France)	extant	vagrant				yes
St Vincent and the Grenadines	extant	native			yes	yes
Suriname	extant	native			yes	yes
Sweden	extant	vagrant
Taiwan, China	extant	vagrant
Trinidad and Tobago	extant	native			yes	yes
Turks and Caicos Islands (to UK)	extant	native			yes	yes
United Kingdom	extant	vagrant
USA	extant	native		yes	yes	yes
Venezuela	extant	native			yes	yes
Virgin Islands (to UK)	extant	native			yes	yes
Virgin Islands (to USA)	extant	native			yes	yes

Country/Territory	IBA Name
Canada	Boundary Bay - Roberts Bank - Sturgeon Bank (Fraser River Estuary)
Canada	Tofino Mudflats
Costa Rica	Nicoya Gulf mangroves and coastal areas
Mexico	Bahía Santa María
Mexico	Complejo Lagunar Ojo de Liebre
Mexico	Delta del Río Colorado
Mexico	Ensenada de Pabellones
Mexico	Istmo de Tehuantepec - Mar Muerto
Mexico	Marismas Nacionales
Mexico	Sistema Tóbari
Mexico	Zonas Húmedas de Yávaros
Panama	Chimán Wetlands
Panama	Chorrera Bay
Panama	Parita Bay
Panama	Upper Bay of Panamá
USA	Bear River Bay UT02
USA	Copper River Delta
USA	Fox River Flats
USA	Redoubt Bay
USA	Salton Sea
USA	Stikine River Delta
USA	Trading Bay
Venezuela	Humedales Boca del Río Unare

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Grassland	Tundra	major	breeding
Marine Coastal/Supratidal	Coastal Brackish/Saline Lagoons/Marine Lakes	suitable	non-breeding
Marine Coastal/Supratidal	Coastal Freshwater Lakes	suitable	non-breeding
Marine Intertidal	Mud Flats and Salt Flats	major	non-breeding
Marine Intertidal	Sandy Shoreline and/or Beaches, Sand Bars, Spits, Etc	major	non-breeding
Marine Neritic	Estuaries	major	non-breeding
Altitude		Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Agriculture & aquaculture	Marine & freshwater aquaculture - Industrial aquaculture	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation
Climate change & severe weather	Habitat shifting & alteration	Timing		Scope		Severity		Impact
		Future		Whole (>90%)		Unknown		Unknown
		Stresses Indirect ecosystem effects, Ecosystem degradation
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Spartina alterniflora	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Natural system modifications	Dams & water management/use - Abstraction of surface water (agricultural use)	Timing		Scope		Severity		Impact
		Ongoing		Unknown		Slow, Significant Declines		Unknown
		Stresses Ecosystem degradation, Ecosystem conversion
Pollution	Industrial & military effluents - Oil spills	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Ecosystem degradation, Species mortality
Residential & commercial development	Commercial & industrial areas	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Residential & commercial development	Housing & urban areas	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Residential & commercial development	Tourism & recreation areas	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Species disturbance

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Recommended citation
BirdLife International (2024) Species factsheet: Western Sandpiper Calidris mauri. Downloaded from https://datazone.birdlife.org/species/factsheet/western-sandpiper-calidris-mauri 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.