The upper Amazon-Napo lowlands cover a vast area of eastern Ecuador (Napo and Pastaza states), northern Peru (Amazonas, Loreto and San Martín departments), westernmost Amazonas state of Brazil and the southern border area of Colombia. The area is centred on the lowland and foothill forests of the upper Putumayo river, the middle and upper Napo, the Marañón (including the Pastaza and Huallaga rivers), the Ucayali (and possibly the Javarí), and the Amazonas drainages, generally west of the confluence of the Putumayo and Amazonas, and primarily from the lowlands up to 600 m. The area is characterized by high rainfall (which is relatively constant year-round), complex topography and soils, and vast meandering river systems that create habitat mosaics. This ecosystem is extraordinarily diverse and comprises primary humid forest, some of which is seasonally inundated (várzea) forest, with other areas more characteristic of nutrient-poor white-sand forest.

All the EBA's restricted-range species occur in the humid lowland forest (either terra firme or várzea), or within more open areas of secondary vegetation and woodland. Within the EBA there are a number of interesting distributional patterns. Only two species are found on the Amazonas and Ucayali rivers: Myrmoborus melanurus occurs only on these two rivers, and Leucippus chlorocercus is present also on the Napo and Marañón, but both are found exclusively along the river systems or on river islands, either in riverine or várzea forest. Thamnophilus praecox is apparently confined to seasonally flooded (blackwater) várzea forest (R. S. Ridgely in litt. 1991), and it has been suggested that Heterocercus aurantiivertex is restricted to areas of riverine white-sand forest (T. A. Parker in litt. 1991).

The species in this area are the most restricted of a larger suite of birds that are variously distributed throughout the river islands and riverine forest of the Amazon basin rivers. Many of the endemics appear to be confined to riverine situations (Meyer de Schauensee 1982, Hilty and Brown 1986, Ridgely and Tudor 1989), although bird distributions in this part of the Amazon basin are very poorly known. This is perhaps best demonstrated by Pithys castanea, which is still known only from the type-specimen collected in 1937 along the upper Pastaza (Collar et al. 1992); by Thamnophilus praecox, which until 1991 (when it was found to be quite common) was only known from the type-specimen taken in 1926 on the Napo in Ecuador (R. S. Ridgely in litt. 1991); and by Myrmoborus melanurus, which is known from just a few localities south of the Amazonas and east of the Ucayali (Ridgely and Tudor 1994). To help better define the EBA, further work is needed to determine the true distributions and ecology of the endemics in this area.

White-lored Antpitta Hylopezus fulviventris has recently been considered as distinct from H. dives by Ridgely and Tudor (1994), and is endemic to the northern portion of the EBA.

The forest in this region is reasonably intact (Forero 1989, Gentry 1989), although deforestation has been quite extensive in western Ecuador and parts of south-east Colombia, and the region is also under threat from oil exploration and extraction (L. M. Renjifo in litt. 1993), while associated road-building has caused degradation and fragmentation, and has accelerated these processes by facilitating further human colonization; virtually all of the Ecuadorian portion of the Napo is open for oil leasing. Border controversies between Ecuador and Peru have spurred further colonization in attempts to claim disputed territory (Dinerstein et al. 1995).

Due to the relatively good state of the forest in this region, none of the endemics is presently considered threatened solely from habitat destruction. Myrmoborus melanurus is threatened by virtue of its apparent rarity and small range within which it is poorly known, and it is particularly susceptible to any future habitat loss. Pithys castanea is considered Data Deficient due to an almost total lack of information (see above). Widespread threatened species in this region include the Wattled Curassow Crax globulosa (Vulnerable), which is suffering from the loss of its riverine habitat and from hunting pressure (Collar et al. 1992, 1994).

In Ecuador, typical lowland forest habitat is protected by the Yasuní National Park, Limoncocha Biological Reserve and Cuyabeno Faunal Production Reserve (IUCN 1992a), with the private Zancudo Multiple-use Reserve also providing protection (R. S. Ridgely in litt. 1992). In Colombia, the only sizeable protected areas are Amacayacu and La Paya National Parks, with the Pacaya-Samiria National Reserve protecting a large area of forest between the Marañón and Ucayali rivers in Peru (IUCN 1992a).

Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: Upper Amazon-Napo lowlands. Downloaded from https://datazone.birdlife.org/eba/factsheet/46 on 22/11/2024.