Yellow-crowned Amazon - Taxonomy

Taxonomy

The Amazona ochrocephala complex, which has been described as "a taxonomic headache", is considered a single species by some authorities and split into three species, A. ochrocephala (Yellow-crowned Amazon), A. auropalliata (Yellow-naped Amazon) and A. oratrix (Yellow-headed Amazon), by others. The split is mainly based on the amount of yellow in the plumage, the colour of the legs and bill, the close proximity of the oratrix group and auropalliata group in Oaxaca, Mexico, without apparent interbreeding, and the presence of members of both the nominate group and the auropalliata group in northern Honduras. This evaluation has, however, been confused by misunderstandings regarding the plumage variations in the populations in northern Honduras, where birds vary greatly in amount of yellow on the head, crown and nape, but have pale bills and a juvenile plumage matching the oratrix group, but neither the nominate nor the auropalliata group. The taxon caribaea from the Bay Islands is a member of the auropalliata group, and occurs in relatively close proximity to the members of the oratrix group. As caribaea may have a relatively pale lower mandible, this could indicating a level of gene flow between this and the nearby taxa of the oratrix group. If confirmed, this could suggest that the two are better considered conspecific. Alternatively, it has been suggested that caribaea and parvipes, both typically placed in the auropalliata group, may be closer to the oratrix than they are to the auropalliata sensu stricto. Both are relatively small and have red to the shoulder as in the members of the oratrix group, but unlike auropalliata sensu stricto.

The members of this complex are known to hybridize in captivity, and recent phylogenetic analysis of DNA did not support the split into the three "traditional" biological species, but did reveal three clades, which potentially could be split into three phylogenetic species: A Mexican and Central American species (incl. panamensis, which extends slightly into South America), a species of northern South America (northern nominate), and a species from the southern Amazon Basin (nattereri, xantholaema and southern nominate). The Central American clade can potentially be split further, with panamensis and tresmariae recognized as two monotypic species. The members of the clade from the southern Amazon Basin should arguably be included as subspecies of the Blue-fronted Amazon, as they are closer to each other than to the northern clades. Disregarding these problems, the following taxa are part of the Amazona ochrocephala complex as traditionally delimited:

• nominate group ("true" Yellow-crowned Amazon):
  • Amazona o. ochrocephala: East-central and south-eastern Colombia, Venezuela, Trinidad, Guyana, Suriname, French Guiana and the northern and eastern Amazon Basin in Brazil.
  • Amazona o. xantholaema: Marajó Island, in the Amazon River delta of north-eastern Brazil.
  • Amazona o. nattereri: Far south-eastern Colombia, eastern Ecuador, eastern Peru, northern Bolivia and south-western Amazon Basin of Brazil (east to around Mato Grosso). Often included in A. o. ochrocephala.
  • Amazona o. panamensis: Western Panama to north-western Colombia; sometimes called the Panama Amazon

• auropalliata group (Yellow-naped Amazon):
  • Amazona a./o. auropalliata: Southern Mexico to north-western Costa Rica.
  • Amazona a./o. parvipes: Mosquito Coast in eastern Honduras and north-eastern Nicaragua.
  • Amazona a./o. caribaea: Bay Islands, Honduras.

• oratrix group (Yellow-headed Amazon):
  • Amazona o./o. oratrix: Pacific and Gulf slopes of Mexico. Also a population in Stuttgart exists.
  • Amazona o./o. tresmariae: Tres Marías Islands, off west-central Mexico.
  • Amazona o./o. belizensis: Belize.
  • Amazona o./o. hondurensis: Sula Valley, Honduras.

Of these, hondurensis was only recently described, while the population in north-western Honduras and adjacent eastern Guatemala (near Puerto Barrios) resembles belizensis and commonly is included in that subspecies, but may actually represent an undescribed subspecies. It has sometimes been referred to as guatemalensis, but until officially described, the name remains provisional. An additional subspecies, magna, has sometimes been recognized for the population on the Gulf slope of Mexico, but today most authorities consider it invalid, instead including this population in oratrix.