This EBA traverses the length of western Colombia and Ecuador, although the majority of the ranges of its restricted-range species terminate north of Guayaquil at c.2°S. The area comprises the Pacific slope of the Colombian West Andes, the Pacific slope of the Andes in Nariño department (southernmost Colombia), and south into Ecuador where it incorporates the westernmost volcanic peaks and Pacific slope of the Andes south to Cañar province. A few species occur in the Cordillera de Chilla. Some geographical overlap with the North Central Andes (EBA 042) may occur in parts of northern Ecuador, although the species endemic to that EBA all inhabit higher altitudes (primarily above 2,500 m). In the lowlands, the EBA extends throughout the Chocó from the southern end of the Serranía de Baudó (where it abuts the Darién lowlands, EBA 023), south along the Andean foothills and through the Pacific coast lowlands into northern Esmeraldas province, and from there along the base of the Andes in Pichincha, Los Ríos, and northern Guayas provinces of Ecuador.

The EBA is characterized by wet forest, and indeed, with up to 16,000 mm of rain per year in some places, this is probably the wettest place on earth. The major vegetation zones of the Pacific slope vary considerably according to local climatic and altitudinal conditions. Lowland tropical wet forest is found in the Pacific lowlands and lower foothills (0-1,000 m) in areas with high rainfall (4,000-8,000 mm/year). Super-wet (pluvial) forest occurs in a limited zone (with an excess of 8,000 mm/year rainfall) between the dominant wet lowland and foothill forests. Subtropical forest replaces the tropical forest between 1,000 and 2,300 m in a zone of lower rainfall (2,000-6,000 mm/year) but with very high humidity. From 2,000 m towards the treeline at c.3,200 m, temperate Andean humid forest persists, trees becoming increasingly stunted with altitude and eventually giving way to wet grassland or páramo, which is characterized by stands of tall composites like Espeletia and Puya, and isolated, small dense patches of Polylepis-dominated woodland in sheltered areas (Salaman 1994).

The Chocó has one of the world's richest lowland biotas, with exceptional richness and endemism in a wide range of taxa including plants, reptiles, amphibians and butterflies (Dinerstein et al. 1995). In the case of plants, over 10% (8,000-9,000) of species recorded from the Neotropics have been found from the narrow band of pluvial forest that runs through the Chocó; it has been suggested that 25% of these species are endemic to the area (Salaman 1994).

The Chocó EBA supports the largest number of restricted-range birds of any EBA in the Americas, over 50 species being endemic to the area. A large number of birds are confined to the tropical lowland and lower subtropical foothill forests, with the remainder primarily found in the subtropical zone; only a few species occur in the high-altitude temperate areas. This bias is primarily due to the West Andes of Colombia having an average ridge height of c.2,000 m, with relatively few mountain peaks above this (Hilty and Brown 1986). The birds restricted to the subtropical zone and above are almost invariably found on the disjunct peaks of the Colombian West Andes (e.g. Paramillo, Páramo Frontino, Cerro Tatamá, Cerro Munchique), and further south in southern Colombia and northern Ecuador (e.g. Nevado Cumbal, Volcán Chiles, Cotacachi, Pichincha).

With relatively little known about the precise distributions, altitudinal movements and ecological requirements of the restricted-range birds, it is not currently possible to further divide this EBA. It does, however, seem likely that the ranges of tropical foothill and lowland species are associated with the band of pluvial forest that runs through the centre of the Chocó region (Hilty and Brown 1986); also, (in Colombia) forest composition changes strikingly from lowland to montane at 1,000-1,500 m (L. G. Olarte in litt. 1993), and this may form the natural boundary between distinct groups of tropical lowland and higher Pacific slope birds.

Five species Otus colombianus, Aglaiocercus coelestis, Semnornis ramphastinus, Habia cristata and Iridosornis porphyrocephala - although regarded as confined to the EBA, occur locally on the eastern slope of the West Andes (in the Cauca valley), primarily near low wet passes (Hilty and Brown 1986), much as Cauca Guan Penelope perspicax does from the opposite direction (see EBA 040, where local distributions of species are discussed). A similar situation exists with Greyish Piculet Picumnus granadensis and Apical Flycatcher Myiarchus apicalis, which occur in the dry Dagua and Calima valleys on the Pacific slope. Both of these species are primarily dry forest, woodland or scrub birds, and are thus considered endemic to the inter-Andean valleys (EBA 039), rather than being shared with the more humid forest species of the Chocó. Bangsia melanochlamys is known from a disjunct population on the northern and western slopes of the North Central Andes (EBA 042) in Antioquia department, where, however, it has been recorded from very few localities, and not since 1948 (Collar et al. 1992). In northern Ecuador (e.g. in the Bilsa area), Haplophaedia lugens and Cephalopterus penduliger (and possibly other species) have been recorded at the same localities as species characteristic of the Tumbesian region (EBA 045), namely Grey-backed Hawk Leucopternis occidentalis, Rufous-headed Chachalaca Ortalis erythroptera and Slaty Becard Pachyramphus spodiurus (Wege and Long 1995). The extent to which these species (and thus the two EBAs) overlap is unknown.

Unplanned colonization following the completion of roads and massive logging concessions are major threats to the Chocó forests. Since 1960, over 40% of the forest area has been cleared or heavily degraded, and deforestation rates are accelerating (Salaman 1994). Currently, intensive logging, human settlement, cattle-grazing, mining, wildlife exploitation, and coca and palm cultivation all threaten the region, with forest destruction most severe in the coastal plain and foothills below c.2,000 m. Over the next 5-10 years the region faces threats from national development projects including dams, roads, sea ports, pipelines and military installations (Dinerstein et al. 1995, Wege and Long 1995).

A total of 16 of the restricted-range species are presently thought to be threatened (with a further 14 Near Threatened), primarily due to the widespread destruction of forest throughout the region. A number of species are extremely poorly known or localized: Eriocnemis godini, for example, is known from just one locality in Pichincha province of Ecuador, where it is possibly extinct; Neomorphus radiolosus is genuinely localized, being recorded from very few localities; Eriocnemis mirabilis is known only from within the boundary of Munchique National Park in Colombia; Micrastur plumbeus has recently (since c.1960) been recorded from fewer than five localities; Vireo masteri is currently known from just two localities; and the two Dacnis species are patchily distributed, occur at low densities and, though poorly known, appear to be genuinely rare (Collar et al. 1994, Salaman and Stiles 1996). Compounding the effects of habitat destruction is hunting pressure which appears to be having a significant negative impact on Penelope ortoni and Cephalopterus penduliger (the latter species is also captured for the pet trade). Additional, more widespread threatened species that occur within the EBA include Yellow-eared Parrot Ognorhynchus icterotis (classified as Critical) and Brown Wood-rail Aramides wolfi

Seventeen Key Areas were recently identified for the EBA's threatened species (10 in Colombia and seven in Ecuador), with at least 10 currently having some form of protected status (Wege and Long 1995). In Colombia, the most important protected areas include Paramillo, Las Orquideas, Tatamá, Los Farallones and Munchique National Parks, Tambito Nature Reserve, Río Ñambi Community Nature Reserve and La Planada Nature Reserve. In Ecuador, protected areas include the Awa Forest Reserve Zone, Jatun Sacha Bilsa Biological Reserve, Mindo Nambillo Protection Forest and the Río Palenque Scientific Centre. Total coverage remains, however, relatively small, with very little lowland and foothill forest (below c.1,000 m) represented in these primarily montane protected areas, leaving perhaps the most important portion of this EBA insufficiently protected and exposed to yet further degradation.

Stattersfield, A. J., Crosby, M. J., Long, A. J. and Wege, D. C. (1998) Endemic Bird Areas of the World. Priorities for biodiversity conservation. BirdLife Conservation Series 7. Cambridge, UK: BirdLife International.

Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: Chocó. Downloaded from https://datazone.birdlife.org/eba/factsheet/42 on 21/12/2024.