The Scarlet Macaw is widely distributed across the Neotropical countries, from Mexico to Brazil. It is a species restricted to tropical evergreen forests in Mexico, Guatemala, Belize, Honduras, El Salvador, Nicaragua, Costa Rica, Panama, Colombia, Venezuela, Guyana, Suriname, French Guiana, Brazil, Ecuador, Peru, Bolivia, and Trinidad and Tobago (Loetscher 1941, Haverschmidt and Mees 1994, Forshaw 2006, Juniper and Parr 1998). However, the species has always had a patchy and restricted area of distribution, limited to tropical riparian and flooded forests (Freidman et al. 1950, Slud 1964, Snyder 1966, Monroe 1968, Forshaw 1977, Meyer de Schauensee and Phelps 1978, Ridgely 1981, Parker et al. 1982, Hilty and Brown 1986, Remsen and Traylor 1989, Ridgely and Gwynne1989, Stiles et al. 1989, Ffrench 1991, Martinez-Sanchez 1991, Tostain et al. 1992, Sick 1993, Haverschmidt and Mees 1994, Renton 1994, Howell and Webb 1995, Iñigo-Elias 1996, Ridgely and Greenfield 2001, Schulenberg et al. 2007).
In Mexico the wild populations of the states of Tabasco, Veracruz, Campeche, San Luis Potosí and Tamaulipas are already extirpated (Loetscher 1941, Friedmann, Griscom and Moore 1950). There are only two remain extant small and isolated populations; one in the state of Oaxaca (approximately 50 individuals) in the region of the upper Uxpanapa river and the other in the state of Chiapas in the basin of the Usumacinta river (approximately 400 individuals) in the region known as Selva Lacandona (Binford 1989; Iñigo-Elias 1996, Iñigo-Elias et al. 2001; Macias et al. 2000, Marco Lazcano personal comm., Eglantina Canales personal comm and Javier Castañeda personal comm.).
In Guatemala the species is restricted to the Laguna del Tigre National Park, Sierra del Lacandón, La Danta Biological Corridor and western forestry areas within the Mayan Biosphere Reserve. (M. C. Paiz pers. comm., Pérez-Pérez 1998, Iñigo-Elias et al. 2001, Iñigo-Elias 2008 pers. obs.). It is estimated that between 100 birds still exist in the whole country of Guatemala (Carreón et al. 2001).
Currently in Belize there is a very small population of 40 or less birds located in the southwest of the country in the valleys of the Maya Centrales mountains, in the area known as Upper Macal and Raspaculo River, Chiquibul and Red Bank in the Mountain Pine Ridge Forest Reserves (Kainer 1991, Manzanero 1991, Renton 2000, Iñigo-Elias et al. 2001, Barcott 2008, Matola, S. pers. comm., 2009).
In Honduras at the present time, only a small and isolated population remains in the north-west region of the country, in the provinces of Olancho and Gracias a Dios; along the brooks of the Rió Plátano Biosphere Reserve. Occasionally it moves into the El Paraíso district (Thorn 1991, Renton 2000).
In El Salvador the species became extinct in this country between the seventies and the eighties. It was already considered rare between 1968 and 1970 (Thurber et al. 1987). There are not recent report of the species in the country.
In Nicaragua the population is very small and isolated, not exceeding a hundred specimens. It is found towards the Atlantic ridge in the Cosiguina region, in the Bosawas Reserve and more towards the south in the Prinzapolka and Río Grande de Matagalpa rivers (Martínez-Sánchez 1991, Renton 2000).
In Costa Rica there is a population towards the Pacific coastal plain, located in the Osa Peninsula in the Corcovado National Park (approximately 50-100 individuals), Carara Biosphere Reserve (approximately 219 individuals) and in the Province of Guanacaste in the Palo Verde National Wildlife Reserve (approximately 6 to 8 individuals) (Vaughan et al. 1991, Marineros and Vaughan 1995, Renton 2000). In Panama the Scarlet Macaw are today a rare species. It is being currently limited to two small populations, one on the island of Coiba and the other in the Azuero peninsula in the south-west of the Los Santos region. It survives on the island of Coiba because this is a high-security prison, heavily guarded and with few visitors (ANCONA 2001).
In Colombia this species it is found in the regions of the country known as Orinoquia and Amazónica (MMARCO 2001c). There are no population estimates, but it is believed to be common.
In Venezuela the species is also becoming rare and with patchy distribution in the states of Bolívar and Monagas, in the Caura forest reserve and on land alongside the Caura river (Desenne and Strahl 1991, Morales et al. 1994).
In Trinidad and Tobago the species has been reported for flooded forest of Nariva, Waller Field and more recently near Granville (Ffrench 1991).
In Suriname this macaw is found along tropical riparian evergreen forests such as in Cottica, Morico, Wayambo, Kuruni, Kabalebo and Marowijne rivers in Wetern Suriname and near Tafelberg in central Suriname (Haverschmidt and Mees 1994).
French Guiana, In French Guiana see Thiollay work.
In Brazil the species occurs in large numbers throughout the Amazon region (Roth 1984, Sick 1993); however there is not published information on recent population estimates or current distribution.
Ecuador, In Ecuador the species occur only in the Amazon region, towards the Yuturi lagoon along the Napo river.
Peru, In Peru this species is uncommon and declining acros its range from North East to South Est Peru. Ths species is within the repairan ecosystems of the country towards the Amazon region east of the Andes range in the basin of the Manu and Tambopata rivers, above the Manu National Park, Tambopata-Candamo Reserve Zone (Munn 1988, Munn et al 1991, Schulenberg et al. 2007).
In Bolivia (ASK BENETT???). In Trinidad and Tobago.