three phylogenetic species: a Mexican and Central American species (including panamensis, which extends slightly into South America), a species of northern South America, and a species from the southern Amazon Basin. The Central American clade can potentially be split further, with panamensis (the Panama amazon) and tresmariae (the Tres Marías amazon) recognized as two monotypic species. According to the traditional split, A. oratrix includes the taxa tresmariae (from the Tres Marías Islands), belizensis (from Belize) and hondurensis (from the Sula Valley in northern Honduras) as subspecies. 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, which also occurs on the Pacific slope of Mexico. In contrast, the population in northwestern Honduras and adjacent eastern Guatemala (near Puerto Barrios), which resembles A. oratrix belizensis and commonly is included in that subspecies, may represent an undescribed subspecies. It has sometimes been referred to as guatemalensis, but until this population is officially described, the name remains provisional. The origin of the common epithet "double yellow-headed" is that this species is differentiated from the others in the yellow-headed amazon complex by possessing both the yellow nape and yellow crown of its two close relatives, hence a "double-yellow" head. Description The yellow-headed amazon averages long. The shape is typical of amazons, with a robust build, rounded wings, and a square tail. The body is bright green, with yellow on the head, dark scallops on the neck, red at the bend of the wing, and yellow thighs. The flight feathers are blackish to bluish violet with a red patch on the outer secondaries. The base of the tail also has a red patch, which is usually hidden. The outer tail feathers have yellowish tips. The bill is horn-colored (gray), darker in immatures of the Belizean subspecies. The eye ring is whitish in Mexican birds and grayish in others. The most conspicuous geographical difference is the amount of yellow. In adults, the head and upper chest are yellow in the subspecies of the Tres Marías Islands (tresmariae); just the head in the widespread subspecies of Mexico (oratrix); just the crown in Belize (belizensis); and the crown and nape in the Sula Valley of Honduras (hondurensis, which thus resembles the yellow-naped parrot). Immatures have less yellow than adults; they attain adult plumage in 2 to 4 years.