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

Taxonomic note
Circus spilonotus and C. spilothorax (del Hoyo and Collar 2014) were previously lumped as C. spilonotus following Sibley and Monroe (1990, 1993).

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.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	-

Red List history

Year	Category	Criteria
2021	Least Concern
2016	Least Concern
2014	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 (km2)	7,180,000
Extent of Occurrence non-breeding (km2)	14,400,000
Number of locations		-
Severely Fragmented		-

	Value	Data quality	Derivation	Year of estimate
No. of mature individuals	40000-60000	poor	suspected	2001
Population trend	stable		suspected	-
Decline (3 years/1 generation past)		-	-	-
Decline (5 years/1 generation past)		-	-	-
Decline (10 years/1 generation past)		-	-	-
Decline (10 years/3 generation future)		-	-	-
Decline (10 years/3 generation past and future)		-	-	-
Number of subpopulations		-	-	-
Percentage in largest subpopulation		-	-	-
Generation length (yrs)	6.73	-	-	-

Population justification: Ferguson-Lees and Christie (2001) estimate the population at 20,000-30,000 pairs which equates to 40,000 to 60,000 mature individuals. The species is described as generally rare in Russia and uncommon in northern Japan (del Hoyo et al. 1992).

Trend justification: The population is suspected to be stable in the absence of evidence for any declines or substantial threats. Monitoring surveys of wintering birds at roosting sites in central Japan during 1994-2009 found that numbers fluctuated from year to year, but that the overall trend was fairly stable (Hirano et al. 2010).

Country/Territory	Presence	Origin	Resident	Breeding	Non-breeding	Passage
Bangladesh	extant	vagrant			yes
Brunei	extant	native			yes
Cambodia	extant	native			yes
China (mainland)	extant	native		yes	yes
Cocos (Keeling) Islands (to Australia)	extant	native			yes
Hong Kong (China)	extant	native			yes
India	extant	vagrant			yes
Indonesia	extant	native			yes
Iran, Islamic Republic of	extant	vagrant			yes
Japan	extant	native		yes	yes
Laos	extant	native			yes
Malaysia	extant	native			yes
Mongolia	extant	native		yes
Myanmar	extant	native			yes
Northern Mariana Islands (to USA)	extant	vagrant
Philippines	extant	native			yes
Russia	extant	native		yes
Russia (Asian)	extant	native		yes
Singapore	extant	native			yes
South Korea	extant	native			yes
Taiwan, China	extant	native			yes
Thailand	extant	native			yes
Vietnam	extant	native			yes

Country/Territory	IBA Name

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Artificial/Aquatic & Marine	Artificial/Aquatic - Irrigated Land (includes irrigation channels)	suitable	resident
Artificial/Aquatic & Marine	Artificial/Aquatic - Water Storage Areas (over 8ha)	suitable	resident
Artificial/Terrestrial	Arable Land	suitable	resident
Grassland	Subtropical/Tropical Seasonally Wet/Flooded	suitable	resident
Marine Intertidal	Salt Marshes (Emergent Grasses)	suitable	resident
Wetlands (inland)	Bogs, Marshes, Swamps, Fens, Peatlands	major	resident
Wetlands (inland)	Permanent Freshwater Lakes (over 8ha)	suitable	resident
Wetlands (inland)	Permanent Freshwater Marshes/Pools (under 8ha)	major	resident
Wetlands (inland)	Permanent Inland Deltas	suitable	resident
Wetlands (inland)	Seasonal/Intermittent/Irregular Rivers/Streams/Creeks	suitable	resident
Altitude	0 - 2000 m	Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Agriculture & aquaculture	Annual & perennial non-timber crops - Small-holder farming	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Negligible declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Biological resource use	Hunting & trapping terrestrial animals - Unintentional effects (species is not the target)	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Unknown		Unknown
		Stresses Species mortality
Biological resource use	Logging & wood harvesting - Unintentional effects: (subsistence/small scale) [harvest]	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Negligible declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Energy production & mining	Mining & quarrying	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Ecosystem degradation
Energy production & mining	Oil & gas drilling	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Ecosystem degradation
Natural system modifications	Dams & water management/use - Abstraction of surface water (unknown use)	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Negligible declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Pollution	Agricultural & forestry effluents - Type Unknown/Unrecorded	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Negligible declines		Low Impact: 5
		Stresses Ecosystem degradation
Residential & commercial development	Housing & urban areas	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Negligible declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion

Purpose	Primary form used	Life stage used	Source	Scale	Level	Timing
Pets/display animals, horticulture	-	-			non-trivial	recent
Sport hunting/specimen collecting	-	-			non-trivial	recent

---

Recommended citation
BirdLife International (2023) Species factsheet: Circus spilonotus. Downloaded from http://datazone.birdlife.org/species/factsheet/eastern-marsh-harrier-circus-spilonotus on 03/06/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://datazone.birdlife.org on 03/06/2023.