This EBA embraces the Pacific slope lowlands and foothills from northern Costa Rica on the slopes of the Cordillera de Guanacaste, south along the coast including the Osa and Burica peninsulas, and east along the coast of Panama including and to just east of the Azuero peninsula; also the Panamanian islands of Coiba and Cebaco. The boundary of the EBA overlaps altitudinally with that of the Costa Rica and Panama highlands (EBA 020), and the poorly known altitudinal migrations of the restricted-range species tend to confuse this separation.

The primary vegetation types are seasonal dry to moist forests in the north-west, which merge with the wetter forest around the Golfo Dulce and Osa peninsula; there is a pronounced dry season on the Pacific slope of Panama, again resulting in dry to moist forest. Areas of mangrove swamp are found in all suitable coastal situations.

The majority of the species on the Pacific slope are found in lowland and foothill evergreen forest, although some clearly show a preference for more open areas of secondary growth. Most of the restricted-range species are relatively widespread within the EBA, although the centre of abundance is the area of wetter forest around the Golfo Dulce and Osa peninsula (known to support over 50% of this EBA's restricted-range species). The exceptions to this are the two (threatened) birds (Amazilia boucardi and Carpodectes antoniae, essentially confined to areas of mangrove), Cranioleuca dissita (occurs only on Coiba island, also a stronghold for Leptotila battyi: Ridgely and Gwynne 1989), and Habia atrimaxillaris (see below). The other threatened and Near Threatened birds also tend to have more limited distributions within the EBA (see below; Ridgely and Gwynne 1989, Stiles and Skutch 1989). Geotrygon lawrencii is primarily confined to the foothills of the Central American Caribbean slope (EBA 019) and the Darién lowlands (EBA 023) of eastern Panama, although it has been recorded from the Pacific slope in Veraguas province (Ridgely and Gwynne 1989).

A subspecies of Painted Parakeet, Pyrrhura picta eisenmanni (discovered in 1979), is endemic to the Azuero peninsula (Delgado 1985). The Garden Emerald Chlorostilbon assimilis occurs in open areas throughout this EBA, but is also found locally on the Caribbean slope and as far east as Darién province (Ridgely and Gwynne 1989), and is not therefore considered a restricted-range species.

Widespread and extensive destruction of forest (including major stands of mangroves) throughout this Pacific region has caused a serious decline in the extent of available habitat, leading to those species with the most specific habitat needs or the most restricted ranges being considered threatened; increasing threat is also posed to a number of the other endemics present. Amazilia boucardi and Carpodectes antoniae are both essentially confined to the now much depleted and seriously threatened areas of mangrove, although C. antoniae has the additional seasonal requirement for nearby areas of humid forest. Habia atrimaxillaris is restricted to the lowlands in a small area of southern Costa Rica around the Golfo Dulce and Osa peninsula where, due to forest loss, it may well become confined to the Corcovado National Park (Collar et al. 1994). Cotinga ridgwayi inhabits the dwindling lowland and foothill forests in central and southern Costa Rica, and westernmost Panama.

Eleven Key Areas for threatened birds have been identified in this EBA (only one of which is in Panama), including five that are formally protected: Carara Biological Reserve, Golfo Dulce Forest Reserve, Corcovado National Park, Río Tivives Protection Zone and Golfito Faunal Refuge (Wege and Long 1995). Other protected areas in the EBA include Palo Verde National Park (Costa Rica) and Coiba National Park, Sarigua National Park and Montuoso Forest Reserve (Panama) (IUCN 1992a)-but this EBA, and in particular its threatened species, remain inadequately covered by protected areas.

Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: South Central American Pacific slope. Downloaded from https://datazone.birdlife.org/eba/factsheet/17 on 23/11/2024.