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Yellow-shouldered Blackbird Agelaius xanthomus
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This species has a very small, fragmented and declining range. An ongoing conservation programme has substantially improved its status but, until habitat loss is halted, the species will continue to qualify as Endangered.

Taxonomic source(s)
AOU. 1998. Check-list of North American birds. American Ornithologists' Union, Washington, D.C.
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.

Taxonomic note

20-23 cm. Glossy black icterid with distinctive yellow shoulder patch. Immature is duller and brownish. Similar spp. Black-cowled Oriole Icterus dominicensis has finer bill and yellow rump and undertail. Greater Antillean Grackle Quiscalus niger is larger and all black. Voice Various, including whistles, squawks, squeaks and rasping notes. Hints Large numbers fly to and from roost-sites in late afternoon and early morning.

Distribution and population
Agelaius xanthomus was formerly widespread on Puerto Rico (to USA), where it occurs in two forms. The race monensis is found throughout the offshore islands of Mona and Monito. The nominate race occurs on the mainland, but is now mostly restricted to south-west coastal areas. There is also a population in eastern coastal areas, but this has almost vanished, with no breeding records since 1986 (USFWS 1996c,d). The south-west population declined by c.80% in 1975-1981 to a low of 300 individuals in 1982, but pre-reproductive season roost counts in 1985-1995 showed an average annual increase of 14% (USFWS 1996c,d); by 2011 there were 850 individuals, with an additional 60 at Salinas (R. Miranda-Medina in litt. 2012). In early 1998, the total population was estimated at 1,250 individuals (Jaramillo and Burke 1999).

Population justification
Jaramillo and Burke (1999).

Trend justification
The population is stable  (R. Miranda-Medina in litt. 2012).

It formerly occurred in mangroves, pastures, coconut and palm-stands, cactus scrub, coastal cliffs, and rarely woodland, and has always been commonest near the coast (Jaramillo and Burke 1999). Many birds now breed on offshore cays (Skutch 1996). It forages both terrestrially and in trees (Skutch 1996), feeding on insects (especially moths and crickets), seeds and nectar (Raffaele et al. 1998). Birds gather at communal feeding-sites, with large flocks forming during the non-breeding season (Jaramillo and Burke 1999). Nests are often built low in mangrove trees, or in large deciduous trees in pastures near to mangroves (Skutch 1996), with several nests being built in close proximity (Jaramillo and Burke 1999). On Mona Island, nests are placed in crevices or on ledges on high, vertical sea-cliffs (Skutch 1996). Three clutches are usually laid per year (Skutch 1996), and the breeding season is May-September.

Brood-parasitism by Shiny Cowbird Molothrus bonariensis has greatly reduced numbers and resulted in most birds breeding on offshore cays. Additional threats are the competition for nesting areas by Caribbean Martin Progne dominicensis, habitat loss clearance for agriculture, nest-predation by the Pearly-eyed Thrasher Margarops fuscatus and elevated mortality by introduced carnivores such as Indian Mongoose (Herpestes auropunctatus).

Conservation Actions Underway
A programme installing artificial nests, monitoring reproduction and controlling populations of Molothrus bonariensis, rats and nest-mites has operated since 1982 (USFWS 1996c,d). The Boquerón Commonwealth Forest is a stronghold for the species on the mainland (Jaramillo and Burke 1999). Conservation Actions Proposed
Continue to protect and manage the species and its habitat, including the provision of artificial nests and control of Shiny Cowbirds (USFWS 1996c,d). Monitor the success of artificial nests (USFWS 1996c,d). Integrate the conservation of this species with existing education schemes (USFWS 1996c,d).

Collar, N. J.; Gonzaga, L. P.; Krabbe, N.; Madroño Nieto, A.; Naranjo, L. G.; Parker, T. A.; Wege, D. C. 1992. Threatened birds of the Americas: the ICBP/IUCN Red Data Book. International Council for Bird Preservation, Cambridge, U.K.

Jaramillo, A.; Burke, P. 1999. New World blackbirds: the icterids. Christopher Helm, London.

Raffaele, H.; Wiley, J.; Garrido, O.; Keith, A.; Raffaele, J. 1998. Birds of the West Indies. Christopher Helm, London.

Skutch, A. F. 1996. Orioles, blackbirds and their kin: a natural history. University of Arizona Press, Tucson.

U. S. Fish and Wildlife Service. 1996. Yellow-shouldered Blackbird (Agelaius xanthomus): revised recovery plan.

Further web sources of information
Detailed species account from the Threatened birds of the Americas: the BirdLife International Red Data Book (BirdLife International 1992). Please note taxonomic treatment and IUCN Red List category may have changed since publication.

Detailed species account from the Threatened birds of the Americas: the BirdLife International Red Data Book (BirdLife International 1992). Please note, taxonomic treatment and IUCN Red List category may have changed since publication.

Explore HBW Alive for further information on this species

Recuento detallado de la especie tomado del libro Aves Amenazadas de las Americas, Libro Rojo de BirdLife International (BirdLife International 1992). Nota: la taxonomoía y la categoría de la Lista Roja de la UICN pudo haber cambiado desde esta publicación.

U.S. Fish and Wildlife Service - Recovery Plan

View photos and videos and hear sounds of this species from the Internet Bird Collection

Text account compilers
Isherwood, I., Mahood, S., Pople, R., Sharpe, C J, Wege, D.

Miranda-Medina, R.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2016) Species factsheet: Agelaius xanthomus. Downloaded from on 26/10/2016. Recommended citation for factsheets for more than one species: BirdLife International (2016) IUCN Red List for birds. Downloaded from on 26/10/2016.

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.

Additional resources for this species

ARKive species - Yellow-shouldered blackbird (Agelaius xanthomus) 0

Key facts
Current IUCN Red List category Endangered
Family Icteridae (New World blackbirds)
Species name author (Sclater, 1862)
Population size mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 210 km2
Country endemic? Yes
Links to further information
- Additional Information on this species