This EBA lies in west Ecuador and north-west Peru, an area often called the Tumbesian centre (after Tumbes department of Peru). It primarily is centred on El Oro and Azuay provinces in south-west Ecuador, and Tumbes and Piura departments in north-west Peru, but it extends in patches northwards along the coast of Ecuador in Guayas, Los Ríos, Manabí and even Esmeraldas provinces, and runs southwards in Peru along the narrow coastal strip to northernmost Lima department (at c.11°S), where it adjoins the Peru-Chile Pacific slope (EBA 052). The Tumbesian region lies adjacent to a number of Andean EBAs, and the Tumbesian restricted-range species overlap with the Andean birds at some sites where the habitat is humid enough to support the latter; of the Andean EBAs, only the Peru-Chile Pacific slope (EBA 052) and the arid Marañón valley (EBA 048) are considered to share restricted-range species with the Tumbesian region.

The EBA covers a large area, embracing altitudes from sea-level to 3,000 m (but primarily below 2,000 m). The vegetation in this region is extremely diverse, with a large number of distinct habitat types (at least 18: Best and Kessler 1995) in an area which has remained climatically stable for long periods due to the influence of the adjacent ocean currents (J. Fjeldså in litt. 1993). Thus habitats range from arid scrub and desert, through deciduous tropical thorn-forest and deciduous Ceiba trichistandra forest, then, depending on altitude and humidity, semi-evergreen Ceiba pentandra forest, semi-evergreen lowland and premontane tall forest, moist lowland forest, humid pre-montane and lower montane cloud forest, deciduous to semi-evergreen inter-montane scrub, etc. (Best and Kessler 1995).

The forests of the Tumbesian region represent one of the richest and most threatened biotic sites on earth. A number of endemic floras and faunas converge in this region, and the forests thus feature large concentrations of species and high levels of endemism in many groups of organisms (Best and Kessler 1995).

The result of such a diversity of vegetation types is a specialized and distinctive endemic avifauna, which can broadly be split into five groups depending on their preferred habitat types. The EBA is characterized by species dependent on deciduous forest (including Acacia thorn-forest and Ceiba trichistandra-dominated forest, up to 1,400 m) for at least part of the year. Many other species also occur in semi-evergreen Ceiba pentandra forest, the higher elevations usually resulting from birds ranging into humid montane evergreen forest, although similar evergreen forest does occur at lower altitudes (Best and Kessler 1995). The precise ecological requirements of many of the restricted-range species have not been determined, and it is probable that there will be some future reclassification of species between habitats. For example, some species move seasonally into the dry deciduous forest zone, although the birds may actually be confined to the more humid elements (e.g. along watercourses) within this forest type. Similarly, the altitudinal distribution of species is poorly understood, with some birds apparently undertaking seasonal migrations between habitat types (Parker et al. 1995).

The main distributional trends of the restricted-range species are, unsurprisingly, determined by their habitat preferences. The species found in northern Ecuador (Esmeraldas province) are primarily those reliant on evergreen forest, and those that reach La Libertad department or further south in Peru (to northern Lima department, or are shared with the Peru-Chile Pacific slope, EBA 052) are all deciduous forest/arid scrub/desert species. A number of species are confined to the arid scrub and desert habitats of coastal Peru and south-west Ecuador, but although they are characteristic of this arid vegetation and possibly constitute a discrete area of endemism, most of them are found overlapping ecologically and geographically with deciduous forest/arid scrub birds. Similarly, some of the dry deciduous forest species also occupy the arid scrub found in southern Guayas province and Isla Puna, south-west Ecuador, and on the coastal plain of Tumbes and Piura departments in north-west Peru. Of the species shared with the Peru-Chile Pacific slope EBA, Geositta peruviana and Cinclodes taczanowskii are essentially coastal species that have radiated from southern Patagonia (J. Fjeldså in litt. 1993); C. taczanowskii, confined to the littoral zone, is described as the most maritime of all passerine birds (Ridgely and Tudor 1994). The threatened Ochraceous Attila Attila torridus is not a restricted-range species, but is essentially confined to the humid and semi-humid forests of the Tumbesian region (its range extends into south-west Colombia) (Collar et al. 1992, 1994).

The Tumbesian region is one of the most important and threatened of all EBAs. Less than 5% of the area remains forested: the landscape is a patchwork of cropland, only occasionally punctuated by small forest patches which are often confined to steep slopes that cannot be cultivated. Most forest types have suffered catastrophic losses since the 1950s. At only a handful of sites does the forest stretch unbroken for more than a few kilometres, but even then the forest, especially the understorey, is often degraded. The more arid vegetation, although affected by grazing and agriculture in valley bottoms, remains in a reasonable state within the region as a whole.

The Tumbesian avifauna is affected by five primary threats: most important is deforestation and understorey degradation, but also of significance is hunting, trade and tiny range sizes. The most severely endangered species are those which suffer a combination of these threats such as Penelope albipennis which is imperilled by both habitat destruction and hunting, compounded by its tiny range and population (Collar et al. 1992, Best and Kessler 1995). Due primarily to the widespread destruction and degradation of the characteristic forests, 15 of the restricted-range birds are considered threatened. Only one of these species, Phytotoma raimondii, is confined to the desert zone, where it is under threat from the loss (through irrigated agriculture) of its riverine thicket habitat (Collar et al. 1992). Atlapetes pallidiceps (classified as Critical) has not been seen since 1969 and may already be extinct (Collar et al. 1994).

Various initiatives have prioritized the remnant forest blocks in this EBA in terms of their conservation importance: Best and Kessler (1995) documented 15 priority sites for habitat conservation and 30 sites for bird conservation, while Wege and Long (1995) detailed 43 Key Areas for the threatened birds in the region. These assessments are complementary, and they present clear recommendations for conservation action that is urgently needed if a number of species are to survive in the long term, given the continued loss of habitat and the current inadequacy of forest protection. Protected-area coverage in this EBA, while prolonging the survival of a number of forest patches, does not presently ensure the survival of all the threatened birds, many of which require large, relatively undisturbed tracts incorporating a number of forest types (Collar et al. 1992). However, Machalilla National Park (Ecuador) and the North-west Peru Biosphere Reserve support the largest remaining forest fragments within the EBA, and consequently stand out as being critically important for many threatened species (see also Parker et al. 1995). Smaller, but extremely important reserves currently include Jatun Sacha Bilsa Biological Reserve, Río Palenque Scientific Centre, Jauneche Biological Research Station, Cerro Blanco Protected Forest, Manglares-Churute Ecological Reserve and Arenillas Military Reserve, all of which are in Ecuador (Wege and Long 1995).

Recommended citation
BirdLife International (2023) Endemic Bird Areas factsheet: Tumbesian region. Downloaded from http://datazone.birdlife.org/eba/search on 10/06/2023.