This EBA runs from extreme south-east Peru north and east of the Inambari river and south-eastwards along the eastern Andean slope of west-central Bolivia in the departments of La Paz and Cochabamba and extreme western Santa Cruz. The southern part of the EBA ends on the northern slope of the Cordillera Central of Bolivia, which branches out westwards from the main Andean range. The EBA is primarily in the upper tropical and middle montane zone of the East Andean slope from 450 to 2,000 m (and occasionally as high as 2,600 m). The topography of the East Andes in this EBA is complex, there being numerous outlying ridges from the main Andean chain.

The EBA overlaps at its upper altitudinal limit with the Upper yungas of Bolivia and Peru (EBA 055). There is also overlap with the Peruvian East Andean foothills (EBA 053) in south-east Peru, and dry inter-montane Andean valleys (EBA 056 in part) lie close in west-central Bolivia. The South-east Peruvian lowlands (EBA 068) are found to the north.

The habitat of the lower yungas is mainly wet lowland evergreen forest and montane evergreen forest. Much of the terrain comprises rugged ridges and valleys which promote high plant diversity, especially along the wet ridges; at Cerros del Távara (Peru), for example, the forest is very mixed with considerable differences in species composition from hectare to hectare (Foster et al. 1994).

All the restricted-range birds are found in lowland and/or montane evergreen forest. Many are present in montane forests which mark the lower limits of species confined to the upper montane zone of the eastern Andes yungas in Bolivia and south-east Peru (EBA 055).

Although the Inambari valley forms a geographical barrier between this EBA and the Peruvian East Andean foothills (EBA 053), seven species are shared between them, though, of these seven, most of the ranges of Pauxi unicornis (but see below), Chiroxiphia boliviana and Tangara argyrofenges fall within this EBA, whereas Phlogophilus harterti and 127> Tinamus osgoodi are each known from only a single record within it.

Pauxi unicornis appears to have a particularly restricted range; it is believed to be confined to ridges which form outliers from the main Andean chain (Foster et al. 1994). For a long time it was only known from the Bolivian part of the EBA but a disjunct population assigned to a new subspecies, koepckeae, was discovered at Cerros del Sira (in EBA 053) in 1969. A further sighting at Cerros del Távara (in the northern end of the present EBA) in 1992 suggests that the bird may be more continuously distributed between the known central Peruvian and Bolivian populations (Collar et al. 1992, Foster et al. 1994).

The forests which occur on moderate slopes with rich soils are well-suited to subsistence agriculture, as well as to the cultivation of cash crops such as coca and coffee and are both more accessible and easier to burn than true montane forest. For these reasons these forests are a favoured target for colonists from the altiplano, and large areas especially in La Paz and Cochabamba (Bolivia) have already been deforested (Collar . 1992).

There are several enormous, and recently established, protected areas in both Peru and Bolivia that hold some of this EBA's habitat. The most important of these are, in Peru, the Tambopata-Candamo Reserved Zone (14,800 km²) and, in Bolivia, Madidi National Park and Integrated Management Area (19,000 km²), Amboró National Park (1,800 km<+>2), Isiboro Sécure National Park (11,000 km²), Bellavista Protection Forest Reserve (900 km<+>2) and Carrasco National Park (13,000 km²). The newly established Madidi reserve has created a continuous network of reserved land from Tambopata-Candamo in Peru to Ulla-Ulla and Pilon Lajas Biosphere Reserves in Bolivia.

Four of the restricted-range species are considered threatened, all known from just a handful of localities. There are single records of Pauxi unicornis and Terenura sharpei from the Tambopata-Candamo Reserved Zone, and Pauxi unicornis, Simoxenops striatus and Myrmotherula grisea are found in Amboró National Park. It is thought likely that most of the threatened species will eventually be found in Carrasco National Park, adjacent to Amboró, and within Madidi National Park (Collar et al. 1992, Remsen and Parker 1995).

Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: Bolivian and Peruvian lower yungas. Downloaded from https://datazone.birdlife.org/eba/factsheet/58 on 22/11/2024.