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Worthen's Sparrow Spizella wortheni

IUCN Red List Criteria

Critically Endangered  
Endangered B1ab(i,ii,iii,v); C2a(i); D 
Vulnerable B1ab(i,ii,iii,v); C2a(i); D1+2 

IUCN Red List history

Year Category
2013 Endangered
2012 Endangered
2008 Endangered
2004 Endangered
2000 Endangered
1996 Endangered
1994 Endangered
1988 Lower Risk/Least Concern

Species attributes

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

Distribution

  Estimate Data quality
Extent of Occurrence breeding/resident (km2) 25 medium
Number of locations 2 -
Fragmentation -

Population & trend

  Estimate Data quality Derivation Year of estimate
No. of mature individuals 100 good Estimated 2006
Population trend Decreasing poor -
Number of subpopulations 2 - - -
Largest subpopulation 51-71 - - -
Generation length (yrs) 3.8 - - -
Population justification: Wintering flocks of 100 and 60 individuals were observed in February 2006 (Canales del Castillo et al. 2010). Precautionarily assuming that these comprise the majority or even all of the remaining population, the global population could therefore number as few as c.100 mature individuals.
Trend justification: There are no new data on population trends; however, the species is suspected to be declining at a slow rate owing to inappropriate grazing regimes.

Country/Territory distribution

Country/Territory Occurrence status Presence Breeding Non-breeding Passage
Mexico Native Extant      
USA Native Extinct Yes    

Habitats & altitude

Habitat (level 1) Habitat (level 2) Importance Occurrence
Grassland Subtropical/Tropical High Altitude major resident
Shrubland Subtropical/Tropical Dry major resident
Altitude 1200 - 2450 m Occasional altitudinal limits  

Threats & impact

Threat (level 1) Threat (level 2) Impact and Stresses
Agriculture & aquaculture Annual & perennial non-timber crops / Scale Unknown/Unrecorded Timing Scope Severity Impact
Ongoing Whole (>90%) Slow, Significant Decline Medium Impact:
Stresses
Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture Annual & perennial non-timber crops / Small-holder farming Timing Scope Severity Impact
Ongoing Majority (50-90%) Slow, Significant Decline Medium Impact:
Stresses
Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture Livestock farming & ranching / Agro-industry grazing, ranching or farming Timing Scope Severity Impact
Ongoing Whole (>90%) Slow, Significant Decline Medium Impact:
Stresses
Ecosystem degradation, Ecosystem conversion
Invasive and other problematic species, genes & diseases Problematic native species/diseases Timing Scope Severity Impact
Ongoing Majority (50-90%) Unknown Unknown
Stresses
Reduced reproductive success

Recommended citation
BirdLife International (2014) Species factsheet: Spizella wortheni. Downloaded from http://www.birdlife.org on 23/07/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 23/07/2014.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Key facts
Current IUCN Red List category Endangered
Family Emberizidae (Buntings, American sparrows and allies)
Species name author Ridgway, 1884
Population size 100 mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 25 km2
Country endemic? Yes
Links to further information
- Summary information on this species