Two populations (sometimes recognized as different subspecies; see Geographic Variation) with partly allopatric distributions on Pacific and Caribbean slopes of Central America. Absent from volcanic mountains in central Guatemala, Honduras, and Nicaragua. T. m. melanocephalus: eastern slope of Mexico and Central America, from the Gulf Coast of southern Veracruz south through the Yucatan (including islands off Quintana Roo), including the Gulf Coastal Plain, Tabasco Plain, and Yucatan Platform; bordered on the south by the Chiapas Highlands; through Belize, the Petén lowlands of northeastern Guatemala, the Atlantic coast of Honduras, and the Atlantic lowlands of Nicaragua extending into northern Costa Rica (bordered on the west by the Amerrisque mountains). T. m. illaetabilis: Pacific coast of Central America, from El Salvador south through western Nicaragua and northwestern Costa Rica, including the Nicoya Peninsula and Valle de Tempisque south to Jacó (approximately); rare stray south to Golfo Dulce; distribution limited on the east and south by the Cordillera de Guanacaste and Cordillera de Tilaran. Populations overlap in Nicaraguan lowlands east of Lake Nicaragua.
Observational records of Black-headed Trogons have been reported from eBird well south of the breeding range. Records from southern Costa Rica (concentrated in the Osa Peninsula on the southern Pacific coast) remain unsubstantiated and require further documentation. Photos and detailed plumage descriptions that distinguish this species from the similar Gartered Trogon (Trogon caligatus) will be valuable in determining the southern limits of the Black-headed Trogon's distribution.
Distribution outside the Americas
Endemic to the Americas.
Open lowland forests including forest edges, banana plantations, cacao plantations, mangroves, secondary forest, gallery forest, moist forest, tropical wet forest, pinelands, and dry (deciduous) forest (Skutch 1948, Greenberg et al. 2000, Johnsgard 2000). Also found in suburban areas, gardens, and degraded forests (Skutch 1948). In Guatemala and Honduras, Skutch (1948) found this species in "pastures with scattered trees, light second-growth woodland, along the edges of banana plantations, and among the fringes of trees bordering rivers". In the Area de Conservación Guanacaste, Costa Rica, nested in lowland deciduous forest, abandoned pasture, and upland oak forest, but not humid evergreen forest (Riehl 2005). Typically avoids dense, humid forest interior (Russell 1964). Recorded as high as 1,000 m (3300 feet) in elevation, but usually found below 600 m (2,000 feet; Johnsgard 2000). Unlike the Elegant Trogon (Trogonelegans), which also inhabits tropical dry forest, the Black-headed Trogon does not move seasonally in response to dry environmental conditions (Barrantes and Sánchez 2004).
No information available.
No fossils of T. melanocephalus are known. Most early trogon fossils are from Europe, where no representatives of the family currently exist. The majority of these have been found in France and Germany, dating from the Oligocene and Eocene (Mayr 1998). The earliest known specimens are from the lower Eocene in Denmark (54 million years ago) and from the middle Eocene in Germany (49 mya). The earliest trogon fossil with a heterodactyl foot (a derived trait uniting all extant trogoniformes) is Primotrogonwintersteini, described from one French specimen dating to the Oligocene (33 mya). This specimen is thought to represent the sister clade of extant Trogoniformes (Mayr 2009). This fossil is very similar to extant trogons in skeletal morphology (though the eye is smaller and the bill narrower). The oldest known New World trogon fossils are much more recent, dating from Pleistocene deposits of less than 2.6 mya. These are thought to represent the extant speciesPriotelus roseigaster (Hispaniolan Trogon), from the Dominican Republic, and Trogon surrucura (Surucua Trogon), from Brazil (Brodkorb 1971). Although more species of trogons currently exist in the New World tropics than in the Old World, this fossil record supports molecular evidence for an Old World origin of the family with subsequent dispersal and radiation in the New World (Espinosa de los Monteros 1998, DaCosta and Klicka 2008).