Endangered
Yellow-shouldered Blackbird
Agelaius xanthomus
The yellow-shouldered blackbird, known in Puerto Rican Spanish as mariquita de Puerto Rico or capitán, is a blackbird endemic to Puerto Rico.
Appearance
The yellow-shouldered blackbird, as its name implies, is a glossy black bird with a small yellow humeral patch around its "shoulders" outlined by a white margin. Immature individuals possess a duller coloration and a brown abdomen. Although plumage coloration is indistinguishable between the sexes, sexual dimorphism is present in this species with males being larger than females.
Adult individuals measure from 20–23 cm (7.9–9.1 in). On average, males weigh 41 g (1.4 oz) and females weigh 35 g (1.2 oz).
Range and habitat
The yellow-shouldered blackbird, known in Puerto Rican Spanish as mariquita de Puerto Rico or capitán, is a blackbird endemic to Puerto Rico.
As a result, the species is now limited to three areas: the islands of Mona and Monito, where a subspecies developed (A. G. Xmonensis). The Roosevelt Roads Naval Station area in eastern Puerto Rico, and the southern Puerto Rican dry forests and mangroves. Studies performed in the island of Monito, located 5 km (3.1 mi) northwest of Mona, revealed an average of 25 individuals with breeding being observed.
Pins are Wikidata “endemic to” fields. Orange dots, when present, are GBIF occurrence tiles — survey bias included.
Diet and breeding
Yellow-shouldered blackbirds are omnivorous, but are considered to be arboreal insectivores since the majority of their diet consists of insects. During the nesting season their diet is composed of 90% arthropod material.
The yellow-shouldered blackbird breeding season commonly spans from April to August but breeding activity has been observed from February to November. The breeding season's start coincides with the start of the rainy season, thus explaining the fluctuation in the start and end of the breeding season. As with other Agelaius species, it usually builds open, cup-shaped nests in trees, but nest locations and shapes may vary depending on location and availability of building materials.
In crisis
The destruction of habitat and brood parasitism by the shiny cowbird (Molothrus bonariensis) led to a drastic population decline from the mid-1970s to early 1980s. In 1976, the population of the nominate form was estimated at 2000 individuals, but in 1982, the population estimate dropped to 300 individuals. Conservation efforts have increased the population to 1250 pairs.
In 1976 Post and Wiley estimated the Mona subspecies population at 200 individuals. Subsequent roost counts and studies from 1981 to 1995 estimated the population at anywhere between 220 and 400 individuals.
Yellow-shouldered Blackbird is Endangered on this catalog because that is the IUCN category stored on Wikidata. Confirm the official criteria and any later count on iucnredlist.org.
Sources
Written for this catalog from the English Wikipedia article on Yellow-shouldered Blackbird, Wikidata item Q602134. Family and order context is original field-guide writing about the group, not a copied assessment of this one species. Wikipedia text is CC BY-SA. Not an IUCN assessment. Counts, when quoted, can change — confirm them on the recovery programme and on iucnredlist.org.
