CR
Socorro Mockingbird Mimus graysoni



Taxonomy

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.

IUCN Red list criteria met and history
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
Species attributes

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

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 50 medium
Number of locations 1 -
Severely Fragmented -
Population and trend
Value Data quality Derivation Year of estimate
No. of mature individuals 190-280 good estimated 2006
Population trend Stable good estimated -
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 1 - - -
Percentage in largest subpopulation 100 - - -
Generation length (yrs) 3.87 - - -

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 distribution
Country/Territory Occurrence status Presence Resident Breeding Non-breeding Passage
Mexico N Extant Yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Mexico Islas Revillagigedo
Mexico Isla Socorro

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

Threats & impact
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

Recommended citation
BirdLife International (2023) Species factsheet: Mimus graysoni. Downloaded from http://www.birdlife.org on 05/02/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 05/02/2023.