The yellow-shouldered blackbird (Agelaius xanthomus), also known as la Mariquita de Puerto Rico or capitán, is a diurnal blackbird endemic to the archipelago of Puerto Rico and one of the species belonging to the genus Agelaius of the family Icteridae. It has black plumage with a prominent yellow shoulder on its wing. Adult males and females are of similar appearance. The species is predominantly insectivorous. (source)