• 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., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	A2bc+4bc	A2bc+4bc

Red List history

Year	Category	Criteria
2020	Endangered	A2bc+4bc
2018	Endangered	A2bc+3bc+4bc
2016	Endangered	A2bc+3bc+4bc
2012	Endangered	A2bc+3bc+4bc
2008	Endangered	A2b,c; A3b,c; A4b,c
2006	Endangered
2004	Least Concern
2000	Lower Risk/Least Concern
1994	Lower Risk/Least Concern
1988	Lower Risk/Least Concern

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

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	758,000 km2	medium
Extent of Occurrence (non-breeding)	192,000 km2	medium
Number of locations	11-100	-
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	unknown	medium	estimated	2017
Population trend	decreasing	unknown	estimated	2012-2024
Rate of change over the past 10 years/3 generations (longer of the two periods)	50-79%	-	-	-
Rate of change over the past & future 10 years/3 generations (longer of the two periods)	50-79%	-	-	-
Generation length	3.98 years	-	-	-
Number of subpopulations	2-100	-	-	-

Population justification: The global population size has been estimated at 175,000 individuals (Meese 2017), up slightly from the estimate of 145,000 individuals in 2014 (Meese 2014), indicating that the global population is considerably below 200,000 individuals.

Trend justification: Agelaius tricolor has undergone extremely rapid population declines in the past. Declines were thought to reach a maximum between 2008-2014 where statewide surveys in California (which comprises over 95% of the global population) revealed a 63% decline, equivalent to an ~86% decline across three generation lengths (12 years) (Meese 2015). However, tentative population increases have been suggested in the years since, particularly between 2014-2017 (Meese 2017, R. Meese in litt. 2020, Meehan et al. 2018) and as such, it is thought that such rapid declines may be historic. A new statewide population survey scheduled for early 2020 was postponed and as such, the population trend is retained here within the band 50-79% to reflect the recent, rapid declines but also possible recovery in the past few years.

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Mexico	extant	native	yes
USA	extant	native	yes

Country/Territory	IBA Name
Mexico	Sierra Juárez
USA	Antelope Valley (Lancaster)
USA	Byron Area
USA	Edwards Air Force Base
USA	Grasslands Ecological Area
USA	La Grange - Waterford Grasslands
USA	Panoche Valley
USA	San Antonio Valley
USA	San Jacinto Valley
USA	San Joaquin Hills
USA	San Pasqual Valley - Lake Hodges
USA	Sand Ridge - Tulare Lake Bed (incl. Pixley and Kern NWRs, Creighton Ranch)
USA	Santa Ana River Valley
USA	Santa Clara River Valley
USA	South Fork Kern River Valley
USA	Yolo Bypass Area

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Artificial/Terrestrial	Arable Land	major	resident
Wetlands (inland)	Bogs, Marshes, Swamps, Fens, Peatlands	major	resident
Altitude	0 - 1300 m	Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Agriculture & aquaculture	Annual & perennial non-timber crops - Agro-industry farming	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Rapid Declines		Medium Impact: 7
		Stresses Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture	Livestock farming & ranching - Agro-industry grazing, ranching or farming	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Rapid Declines		Medium Impact: 7
		Stresses Ecosystem degradation, Ecosystem conversion
Biological resource use	Hunting & trapping terrestrial animals - Persecution/control	Timing		Scope		Severity		Impact
		Past, Unlikely to Return		Majority (50-90%)		Slow, Significant Declines		Past Impact
		Stresses Species mortality
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Bubulcus ibis	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Species mortality
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Unspecified species	Timing		Scope		Severity		Impact
		Future		Majority (50-90%)		Slow, Significant Declines		Low Impact: 4
		Stresses Species mortality
Pollution	Agricultural & forestry effluents - Type Unknown/Unrecorded	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation

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Recommended citation
BirdLife International (2024) Species factsheet: Tricolored Blackbird Agelaius tricolor. Downloaded from https://datazone.birdlife.org/species/factsheet/tricolored-blackbird-agelaius-tricolor on 25/12/2024.
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 25/12/2024.