Yellow-shouldered Blackbird - Taxonomy

Taxonomy

The nominate form of the Yellow-shouldered Blackbird (A. x. xanthomus) was first described from Puerto Rico and Vieques in 1862 by Philip Sclater as Icterus xanthomus. The species is closely related to, and possibly derived from, the Red-winged Blackbird (Agelaius pheoniceus). The Tawny-shouldered Blackbird (Agelaius humeralis), a species from Cuba and Haiti, is morphologically intermediate between A. xanthomus and A. humeralis. Until recently, some authors considered A. xanthomus as a subspecies of A. humeralis. The 1983 American Ornithologists' Union edition considered A. xanthomus, together with A. humeralis, a superspecies. The main physical difference between A. xanthomus and A. humeralis resides in their bills, with A. humerali's being broader toward the base. The recognized subspecies A. x. monensis, or Mona Yellow-shouldered Blackbird, was described by Barnes in 1945 from the islands of Mona and Monito.