EN
Yellow-shouldered Blackbird Agelaius xanthomus



Taxonomy

Taxonomic note

Taxonomic source(s)
AOU. 1998. Check-list of North American birds. American Ornithologists' Union, Washington, D.C.
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.
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.
Stotz, D. F.; Fitzpatrick, J. W.; Parker, T. A.; Moskovits, D. K. 1996. Neotropical birds: ecology and conservation. University of Chicago Press, Chicago.

IUCN Red list criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
- B2ab(iii,v); C2a(ii) B1ab(iii,v)+2ab(iii,v); C1+2a(i,ii); D1

Red List history
Year Category Criteria
2016 Endangered B2ab(iii,v)
2012 Endangered B1ab(i,ii,iii,v)
2008 Endangered B1a+b(i,ii,iii)
2004 Endangered
2000 Endangered
1996 Endangered
1994 Endangered
1988 Threatened
Species attributes

Migratory status not a migrant Forest dependency Low
Land mass type Average mass 38.40000153 g
Extent of occurrence (EOO)

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 9,000 medium
Extent of Occurrence breeding/resident (km2) 260
Number of locations 2-5 -
Fragmentation -
Population and trend
Estimate Data quality Derivation Year of estimate
No. of mature individuals 250-999 poor estimated 1998
Population trend Decreasing poor inferred -
Decline (3 years/1 generation past) - - -
Decline (5 years/1 generation past) - - -
Decline (10 years/1 generation past) - - -
Decline (10 years/3 generation future) 20 - - -
Decline (10 years/3 generation past and future) 1-19 - - -
Number of subpopulations 2-100 - - -
Largest subpopulations 1-89 - - -
Generation length (yrs) 6 - - -

Population justification: In early 1998, the total population was estimated at 1,250 individuals (Jaramillo and Burke 1999), which equates to 833 mature individuals, placed here in the band 250-999 mature individuals to reflect uncertainty and the fluctuations seen in subsequent surveys of subpopulations.

Trend justification: The population in southwestern Puerto Rico was considered improving in 2011 (USFWS 2011). However, the population then declined by more than 50%, leaving fewer than 400 individuals by August 2012 (Miller et al., 2016). Subsequently, the population was estimated through the post-breeding survey in 2012 at more than 650 individuals (Miller et. al., 2016). The status of the eastern and southern populations is unknown, but overall the population is considered to be stable  (R. Miranda-Medina in litt. 2012). In Salinas (southeastern Puerto Rico), 113 individuals were observed during the post-breeding census of 2005, a slight increase from 2004 (97 individuals) (USFWS 2011). Overall, there is no clear reduction over the past three generations (18 years). In 2012, a population and habitat viability analysis (PHVA) modelled the outcomes of different management strategies and found that, even with incumbent management practices, the yellow-shouldered blackbird is currently experiencing a negative growth rate with a 31 % chance of extinction in the next 50 years (Medina-Miranda et al. 2013).


Country/territory distribution
Country/Territory Occurrence status Presence Resident Breeding Non-breeding Passage
Puerto Rico (to USA) N Extant Yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Puerto Rico (to USA) Bosque Estatal de Boquerón inlcuyendo Punta Melones y Pitahaya
Puerto Rico (to USA) Guaniquilla and Boquerón
Puerto Rico (to USA) Jobos Bay
Puerto Rico (to USA) Mona and Monito
Puerto Rico (to USA) Sierra Bermeja and Laguna Cartagena
Puerto Rico (to USA) Suroeste

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Artificial/Terrestrial Arable Land suitable non-breeding
Artificial/Terrestrial Pastureland suitable non-breeding
Forest Subtropical/Tropical Mangrove Vegetation Above High Tide Level suitable breeding
Shrubland Subtropical/Tropical Dry suitable breeding
Altitude   Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Agriculture & aquaculture Annual & perennial non-timber crops Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation, Ecosystem conversion
Human intrusions & disturbance Recreational activities Timing Scope Severity Impact
Ongoing Unknown Unknown Unknown
Stresses
Species disturbance
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases Timing Scope Severity Impact
Ongoing Majority (50-90%) Rapid Declines Medium Impact: 7
Stresses
Reduced reproductive success
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases Timing Scope Severity Impact
Ongoing Minority (<50%) Unknown Unknown
Stresses
Reduced reproductive success
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases Timing Scope Severity Impact
Ongoing Majority (50-90%) Rapid Declines Medium Impact: 7
Stresses
Reduced reproductive success
Invasive and other problematic species, genes & diseases Problematic native species/diseases Timing Scope Severity Impact
Ongoing Majority (50-90%) Negligible declines Low Impact: 5
Stresses
Species disturbance, Reduced reproductive success
Invasive and other problematic species, genes & diseases Problematic native species/diseases Timing Scope Severity Impact
Ongoing Majority (50-90%) Negligible declines Low Impact: 5
Stresses
Species disturbance, Reduced reproductive success
Invasive and other problematic species, genes & diseases Problematic native species/diseases Timing Scope Severity Impact
Ongoing Unknown Unknown Unknown
Stresses
Reduced reproductive success
Other options Other threat Timing Scope Severity Impact
Ongoing Whole (>90%) Unknown Unknown
Stresses
Inbreeding, Other
Residential & commercial development Housing & urban areas Timing Scope Severity Impact
Ongoing Unknown Unknown Unknown
Stresses
Ecosystem conversion
Residential & commercial development Tourism & recreation areas Timing Scope Severity Impact
Ongoing Unknown Unknown Unknown
Stresses
Ecosystem conversion

Utilisation
Purpose Primary form used Life stage used Source Scale Level Timing
Pets Whole Adults and juveniles Wild International Non-trivial Recent

Recommended citation
BirdLife International (2017) Species factsheet: Agelaius xanthomus. Downloaded from http://www.birdlife.org on 25/11/2017. Recommended citation for factsheets for more than one species: BirdLife International (2017) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 25/11/2017.