• 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
B1ab(ii,iii)	B1ab(ii,iii); D	B1ab(ii,iii); D1+2

Red List history

Year	Category	Criteria
2020	Critically Endangered	B1ab(ii,iii)
2018	Critically Endangered	B1ab(ii,iii)
2016	Critically Endangered	B1ab(ii,iii)
2013	Critically Endangered	B1ab(ii,iii)
2012	Critically Endangered	B1ab(ii,iii)
2009	Critically Endangered	B1a+b(ii,iii)
2008	Critically Endangered
2007	Critically Endangered
2006	Critically Endangered
2004	Critically Endangered
2000	Critically Endangered
1996	Endangered
1994	Endangered
1988	Threatened

Migratory status	not a migrant	Forest dependency	medium
Land-mass type		Average mass	-

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	50 km2	medium
Number of locations	1	-
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	190-280 mature individuals	good	estimated	2006
Population trend	stable	good	estimated	1999-2009
Generation length	3.87 years	-	-	-
Number of subpopulations	1	-	-	-
Percentage of mature individuals in largest subpopulation	100%	-	-	-

Population justification: Martínez-Gómez and Curry (1996) calculated a total population of 353 (287-419) individuals based upon comprehensive ringing data. Visits to the same sites during 2006-2007 reported a similar population. The estimate is best applied to the area of the island where ringing took place. This implies that the total population of the island may be larger (J. E. Martinez-Gomez in litt. 2007). This roughly equates to 190-280 mature individuals.

Trend justification: Largely owing to ongoing control of sheep on the island, the population appears to have stabilised; however, productivity may be more severely impacted by locust swarms in some years. The species has yet to expand its range following sheep eradication and ongoing feral cat eradication efforts (J. E. Martínez-Gómez in litt. 2016). Juveniles have moved into disturbed areas in the south-east of Socorro Island, but failed to successfully establish breeding territories. Adult males have occasionally established in these areas, but without adult females (J. E. Martínez-Gómez in litt. 2016).

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

Country/Territory	IBA Name
Mexico	Islas Revillagigedo

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Forest	Subtropical/Tropical Dry	major	resident
Altitude	300 - 950 m	Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Felis catus	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Indirect ecosystem effects, Ecosystem degradation
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Ovis aries	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		No decline		Low Impact: 4
		Stresses Ecosystem degradation
Invasive and other problematic species, genes & diseases	Problematic native species/diseases - Schistocerca piceifrons	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses Ecosystem degradation, Ecosystem conversion
Residential & commercial development	Commercial & industrial areas	Timing		Scope		Severity		Impact
		Future		Minority (<50%)		Slow, Significant Declines		Low Impact: 3
		Stresses Species disturbance, Ecosystem conversion
Residential & commercial development	Housing & urban areas	Timing		Scope		Severity		Impact
		Future		Minority (<50%)		Slow, Significant Declines		Low Impact: 3
		Stresses Species disturbance, Ecosystem conversion

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Recommended citation
BirdLife International (2024) Species factsheet: Socorro Mockingbird Mimus graysoni. Downloaded from https://datazone.birdlife.org/species/factsheet/socorro-mockingbird-mimus-graysoni 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.