Yellow-Shouldered Blackbird Agelaius xanthomus Distribution August. The nest’s structure is cup-shaped, formed out of dry grass or algae, and lined with soft vegetable matter. These nests are built in trees, often in aggregation, to protect from predators. The incubation and nesting is done solely by the females. However, both parents work together to feed the hatchlings. Habitat The YSBL primarily nests in black mangroves (Avicennia germinans) and coconut palms (Cocos nucifera). It also nests in: West Indian locust (Hymenaea courbaril), red mangroves (Rhizophora mangle), Puerto Rico royal palm (Roystonea Familia: Icteridae borinquena), and oxhorn bucida (Bucida buceras), Orden: Passeriformes among others. The subspecies of Mona and Monito Islands make their nests in exposed cavities along the Description limestone cliffs. Before and after breeding and nesting season, the YSBL is frequently observed in mangroves The yellow-shouldered blackbird (YSBL), also known and coastal scrub vegetation harboring American as the mariquita de Puerto Rico or capitán, is a glossy carob (Prosopis pallida), oxhorn bucida (Bucida black bird with bright yellow spots on the shoulder of buceras) and guaiacwood (Guaiacum officinale). each wing. Adults reach approximately 8 inches (20 centimeters) in length. Females are slightly smaller Diet than males. The hatchlings are similar to the adults, The YSBL is omnivorous, feeding on both animal and with a duller black color. vegetable matter alike. It may also be classified as an Biological Information arboreal insectivore. This species is one of the nine species included in the Distribution Agelaius genus. There are two subspecies: Agelaius xanthomus xanthomus, known only on Puerto Rico’s The YSBL is an endemic species; that is to say, it main island and on Vieques, and Agelaius xanthomus only exists in Puerto Rico. In the past, this species monensis, found only on the Mona and Monito was abundant throughout the Island, and has been Islands. documented in Adjunstas, Aguadilla, Arecibo, Añasco, Barranquitas, Cabo Rojo, Caguas, Carolina, Cataño, Reproduction Cayey, Ceiba, Ciales, Cidra, Coamo, Fajardo, Florida, The YSBL breeding season lasts from April through Guánica, Guayama, Guayanilla, Hormigueros, Juncos, ENDANGERED Lajas, Lares, Loíza, Mayagüez, Mona, Monito, Conservation Measures Naguabo, Salinas, San Germán, San Juan, Utuado, Vieques, Peñuelas, Ponce, Rincón, Río Grande, San The yellow-shouldered blackbird was included in the Sebastián, Santa Isabel and Yauco. Endangered Species list in 1976. Critical habitat for this species was designated in southwestern Puerto However, in the 1970’s there was a very sharp decline Rico, the municipality of San Germán, the former in populations, with approximately 2,400 individuals RRNS in the municipality of Ceiba, and Mona Island. left in the wild throughout the entire island. This amount was concentrated in three main populations: The U.S. Fish and Wildlife Service wrote the first the yellow-shouldered blackbirds in southwest Recovery Plan for the YSBL in 1983, with an updated Puerto Rico (Boquerón Commonwealth Forest and version in 1996. La Parguera in Lajas), the group in southeast Puerto Rico (Former Roosevelt Roads Naval Station, RRNS), Within the current range of the YSBL there are at least and the population in Mona and Monito islands. At four areas protected in perpetuity: La Parguera Natural present, the Boquerón Commonwealth Forest, the Reserve, Boquerón Commonwealth Forest, Cabo Rojo southern region of Puerto Rico (Salinas and Guayama) National Wildlife Refuge, and Boquerón Wildlife and Mona and Monito islands host the largest YSBL Refuge, and the wetland forest in the former RRNS. populations. The YSBL Recovery Project was established in 1984. Threats Since its inception, the project has installed numerous The major threats to the YSBL are: artificial nesting structures for the species. These • Destruction or modification of coastal forests for structures have the purpose of reducing nest predation agricultural, residential, and tourism development. and improving monitoring activities. During the 1985 breeding season, the project only had two nests in • Predators: artificial structures. To date, that number has reached • Pearly-eyed thrasher (Margarops fuscatus) 255. Nearly 30 years after initiating this project, these • American kestrel (Falco sparverius) nests have produced approximately 7,326 fledglings • Merlin (Falco columbarius) • Red-tailed hawk (Buteo jamaicensis) (young birds that have left the nest). • Small Indian mongoose (Herpestes auropunctatus) The Endangered Species Act of1973, as amended, • Green iguana (Iguana iguana) prohibits the killing, harassing, trapping, purchasing • Rats (Rattus rattus) or selling any species, as well as parts and products • Feral cat (Felis catus) derived from the species. • Brood parasitism: References • Shiny cowbird (Molothrus bonariensis) – This species performs brood parasitism; that is to say, Departamento de Recursos Naturales y Ambientales de Puerto it lays its eggs in the YSBL’s nest, affecting the Rico. http://www.drna.gobierno.pr/oficinas/arn/recursosvivientes/ success rate of the blackbirds. negociado-de-pesca-y-vida-silvestre/division-de-recursos- • Parasites that feed on chicks and adults, sometimes terrestres-1/proyecto_mariquita/mariquita cause nest abandonment by the adults, increasing Lewis, A. R., J. A. Cruz-Burgos, and F. J. Vilella. 1999. chick mortality: Movements, activity patterns and habitat use of the endangered • Mites (Ornithonyssus bursa and Androlaelaps Yellow-shouldered Blackbird (Agelaius xanthomus xanthomus casalis) [Sclater]). Final report submitted to the U.S. Fish and • Lice (Philopterus agelaii, Machaerilaemus sp., Wildlife Service, Caribbean Field Office. 106 pp. and Myrsidea sp.) López-Ortiz, R., E. A. Ventosa-Febles, L. R. Reitsma, D. • Diseases: Hengstenberg, and W. Deluca.2002. Increasing nest success in the yellow-shouldered blackbird (Agelaius xanthomus) in southwest • Avian pox – This virus causes lesions that affect Puerto Rico. Biological Conservation 108: 259-263. the vision, breathing and feeding processes of affected birds. ENDANGERED López-Ortiz, R., E. A. Ventosa-Febles, K. R. Ramos-Álvarez, Puerto Rico Department of Natural and Environmental R. Medina-Miranda, andA. Cruz. 2006. Reduction in host use Resources. 2009. Designación de hábitat crítico natural para la suggests host specificity in individual shiny cowbirds Molothrus( mariquita de Puerto Rico (Agelaius xanthomus).198 pp. bonariensis). Ornitología Neotropical 17: 259-269. U.S. Fish and Wildlife Service. 1996. Yellow-shouldered López-Ortiz, R., E. A. Ventosa-Febles, K. R. Ramos-Álvarez, Blackbird (Agelaius xanthomus) Revised Recovery Plan. Atlanta, R. Medina-Miranda, andA. Dragoni. 2008. Nesting macro- Georgia. 77 pp. habitat preferences of the Yellow-shouldered blackbird, Agelaius xanthomus. Department of Natural and Environmental Resources, U.S. Fish and Wildlife Service. 1996. Yellow-shouldered unpublished report. 19 pp. Blackbird (Agelaius xanthomus) Revised Recovery Plan. Atlanta, Georgia. 77 pp. Medina-Miranda R., K. R. Ramos-Álvarez, and R. López-Ortiz. 2006. Annual Progress report. Puerto Rico Endangered Species U.S. Fish and Wildlife Service. 2011. Yellow-shouldered Program ES 1-14, Study II. Yellow-shouldered Blackbird Blackbird (Agelaius xanthomus) 5-Yr Review and Summary. Recovery Actions. Report submitted to the U.S. Fish and Wildlife Atlanta, Georgia. 34 pp. Service, Caribbean Field Office. 5 pp. 25 Vincenty, M. 2006. Yellow Warbler (Dendroica petechia) Medina-Miranda R., K. R. Ramos-Álvarez, and R. López-Ortiz. breeding biology and parasitism by the shiny cowbird (Molothrus 2007. Annual Progress report. Puerto Rico Endangered Species bonariensis) in Boquerón, Puerto Rico. MS Thesis. Program ES 1-14, Study II. Yellow-shouldered Blackbird Recovery Actions. Report submitted to the U.S. Fish and Wildlife Additional Information Service, Caribbean Field Office. 6 pp. Caribbean Ecological Services Field Office Medina-Miranda, R. 2008. Estrategias anti-parásitos en la Address: PO Box 491, Boquerón, PR 00622 mariquita de Puerto Rico (Agelaius xanthomus) y el canario de Telephone: 787-851-7297 mangle (Dendroica petechia): dentro y fuera del área de manejo Fax: 787-851-7440 del tordo lustroso (Molothrus bonariensis). MS Thesis, Internet: www.fws.gov/caribbean Department of Biology, University of Puerto Rico, Mayagüez Campus. 41 pp. Porrata-Doria, T. 2006. Genetic diversity of the Shiny Cowbird (Molothrus bonariensis): A mtDNA study on the variability within original and expanded range. MS Thesis, Department of Biology, University of Puerto Rico, Mayagüez Campus. 87 pp. ENDANGERED.