The rich geographical complexities of Ecuador can be oversimplified as follows: the Andes follow a north-south axis, dividing the country roughly in half, while the Andes themselves are actually two parallel mountain ranges containing a high-altitude valley between their walls. Following the convention of Birds of Ecuador: Status, Distribution, and Taxonomy, I'm dividing the country similarly, but into four distinctive regions, each compromised of a variety of natural habitats, all of which will be discussed below in their primary state. In fact, this discussion of habitats won't be much more than a paraphrase of the chapter entitled Geography, Climate, and Vegetation, although the pictures and links should help you develop a clearer sense of the geography of Ecuador and provide some guidance for planning trips. As Ridgely and Greenfield point out, these habitats exist on a continuous spectrum are distinguished from each other only for purposes of organization.
WESTERN LOWLAND REGION
With annual precipitation from 3-4m, this evergreen forest of the northwestern lowlands grows to 30-40m in height. While much has been cleared, some forest still exists in Esmeraldas Province, although it is increasingly coming under further duress thanks to the illegal logging industry.
Important sites include Bosque Protector Humedal del Yalare, Playa de Oro, Rio Canandé Reserve, and Bilsa Biological Station.
Similar to wet forest but with annual precipitation of only 1.5-3m, this predominantly evergreen forest once covered much of the western lowlands particularly in the provinces of Manabí and Los Ríos, which are now covered in banana and African Palm plantations (growing in relatively flat areas has made this habitat particularly vulnerable to conversion to agricultural land). While there are still patches of humid and semihumid forest remaining, what is left is only a very small fraction of its original extent.
Listed from north to south, important sites include Rio Silanche Bird Sanctuary, Rio Palenque Scientific Station, Rio Ayampe, and Manglares-Churute Reserve.
Growing in southwestern Ecuador, deciduous forest reaches heights of 20-25m in strongly seasonal climate paterns of 0.5-1.5m of precipitation per year. In the dry season, most trees lose their leaves, creating a barren and desicated appearance in which colorful birds like the Pacific Parrotlet and White-Edged Oriole stand out dramatically. Most of this habitat, which makes up part of the Tumbes endemic region, is disturbed as domestic animals are often free to graze, destroying much of the critical understory. The number of endemic bird species in this habitat is quite high making it a crucial visit for birders in Ecuador.
Important sites include Machalilla National Park, Agua Blanca Archaeological Site, Isla de la Plata, Rio Ayampe, Cerro Blanco, Manglares-Churute Reserve, and Jorupe Reserve.
Desert Woodland and Arid Scrub
Growing in areas with less than 0.5m of precipitation, this open and shrubby habitat has scattered trees and relatively low bird diversity. Almost desert-like conditions are created when rainfall has been scarce, making these areas in western Guayas, southern coastal El Oro, and southwestern Loja Provinces of comparatively little interest.
Important sites include Ecuasal and the Guayaquil-Salinas Road.
Geographic, oceanic, and climatic conditions combine to create this unique habitat in the coastal mountain ranges of southwestern Ecuador. Ranging in elevations from 700-1100m, moisture from the ocean is trapped against these modest mountains creating nearly continuously damp conditions. Little of this habitat remains in Guayas and Manabí Provinces, and what does is rarely visited by birders. This habitat also occurs in southern Azuay and El Oro Provinces, where the same affect is produced along the foothills of the Andes.
Important sites include Machalilla National Park, Cerro San Sebastian, Cerro La Torre, and Salanguilla, and Buenaventura Reserve.
Not nearly as diverse as other bird habitats, mangrove forests are made up of a few tree species that have adapted to growing in brackish water. Found along the coastline as well as in estuaries and lagoons, mangroves are home to a few specialized bird species, including the Mangrove Warbler, and provide critical habitat to a large variety of wading birds and shorebirds. Much of this habitat has been destroyed in the last two decades to make room for the shrimp-farming industry, although some remains, particularly in Esmeraldas Province.
Listed from north to south, important sites include Manglares-Cayapas Reserve, Muisne, Puerto Hondo, Manglares-Churute Reserve.
On either side of the Andes, the foothills are considered to begin at around 500m and rise to approximately 1250m in altitude. The weather is generally warm and wet, with 3m of annual rainfall in most places, and as a result the 20-25m tall forest is covered in rich epiphytic growth. Bird diversity is exceptionally high in these areas, which abound in specialties as well as a mixture of lowland and montane species.
Listed from north to south, important sites in the west include El Placer, Milpe Bird Sanctuary, Tinalandia, and Buenaventura Reserve. In the east, the lower slopes of Volcán Sumaco, Wild Sumaco Wildlife Sanctuary, the Rio Bombuscaro entrance of Podocarpus National Park, and Cabañas Ecologica Copalinga.
Subtropical Montane Forest
Forest in this habitat, which rises up both the western and eastern slopes of the Andes until approximately 2400m, is 15-20m tall with an annual precipitation of 2-2.5m. Popularly referred to as Cloud Forest, this habitat contains evidence of much speciation as similar but distinct bird species replace each other on either slope.
Listed from north to south, important sites in the west include Maquipucuna Reserve, Tandayapa Valley, Bellavista Cloud Forest Reserve, Mindo, Chiriboga Road, and Buenaventura Reserve. In the east, Cabañas San Isidro, Guacamayos Ridge Trail, the old Loja-Zamora road, and Quebrada Honda.
Temperate Montane Forest
Occurring in zones up to about 3200m, both on the outer slopes of the Andes and in some places on the inner slopes of the central interandean valley, this habitat is shorter and cooler than the subtropical montane forest. Large stands of Chusquea bamboo are frequent in this varied and choppy appearing habitat. There is less speciation in this habitat than the previous because of its original extent in the central valley.
Listed from north to south, important sites in the west include Yanacocha Reserve, the Chiriboga Road, and Utuana Reserve. In the central valley, Cerro Mongus, Pasachoa, and Ancanama. In the east, Guango Lodge, the Gualaceo-Limon road, the old Loja-Zamora road, the Cajanuma Entrance of Podocarpus National Park, and Tapichalaca Reserve.
This transitory habitat occurs around treeline on both slopes and in places in the central valley, where from 3100-3400m, depending on rainfall, montane forest transitions into paramo. Conditions are notably cooler than in temperate montane forest, with regular frosts, but the habitat supports a surprising number of bird specialties, especially on the eastern slope.
Listed from north to south, important sites in the west include Yanacocha Reserve and Utuana Reserve. In the central valley, Cerro Mongus, Pasachoa, and Ancanama. In the east, Papallacta Pass, the upper slopes of Volcán Sumaco, the Gualaceo-Limon road, the old Loja-Zamora road, the Cajanuma Entrance of Podocarpus National Park, and Tapichalaca Reserve.
Patchy, monospecific forest that is found at high elevations, Polylepis is a unique genus of low, twisted trees characterized by their red, flaky bark. It occurs in sheltered slopes and ravines in paramo habitat above treeline at 3500-4200m and contains several specialized bird species, including the Giant Conebill and Tit-Like Dacnis.
Listed from north to south, important sites in the west include Yanacocha Reserve, Iliniza Reserve, El Cajas National Park. In the east, Papallacta Pass, Antisana Reserve, and Podocarpus National Park.
High-altitude grassy areas found above treeline, this low but dense habitat often contains a variety of flowering shrubs depending on the level of rainfall in the area. Frosts and even snow occur regularly, and the abundant precipitation collects in variety of bogs, ponds, and lakes. From 4000 to 5000m, the grass thins to bare rock as even higher peaks are covered throughout the year in snow.
Listed from north to south, important sites in the west include Yanacocha Reserve, Iliniza Reserve, El Cajas National Park. In the east, Papallacta Pass, Antisana Reserve, Cotopaxi National Park, and Podocarpus National Park.
EASTERN LOWLAND REGION
Terra Firme Forest
Located upland and significantly back from rivers and lakes, this massive forest can reach 30-40m in height and is extremely biodiverse, although many bird species occur at considerably low densities. This is by far the most common habitat in Ecuadorian Amazonia, and while there are some subdivisions in this habitat, from an avian perspective they're not terribly importatn. Except for treefall areas, the understory is fairly open, which suprises most visitors on first sight.
Imporant sites include Sacha Lodge, La Selva Lodge, Sani Lodge, Napo Wildlife Center, and Tiputini Biodiversity Center.
Occurring in areas that are seasonally flooded, this forest can be significantly lower in stature than terra firme forest, only reaching 15-20m in some places. While difficult to access except by dugout canoe, this habitat is of great importance to a surprisingly wide variety of bird species and is a real treat to bird in as its generally done from a seated position.
Important sites include Cuyabeno Wildlife Reserve, Sacha Lodge, La Selva Lodge, and Sani Lodge.
River Island Scrub
This habitat occurs on recently created or exposed river islands. Although not impressive or significant looking at first glance, this habitat supports several bird species found nowhere else. Access can be difficult, though, as these islands are generally found in the middle of large, swiftly flowing rivers such as the Napo.
Important sites include a variety of islands on the Rio Napo.
Eventually developing on river islands and in floodplain areas along rivers, this forest is at first dominated by a few genus of tree species and gradually becomes more diverse over time. With respect to birds, a wide variety of edge species are found here including several specialists.
Important sites include a variety of islands on the Rio Napo and many floodplain areas.
This habitat is formed in the lowlands as rivers flood and change course, leaving their old channels, which often become separated from the river itself and form lakes of unusually curved shape. A wide variety of bird species thrive in the marshy and swampy habitats around the lakes, which eventually fill in with sediment over centuries.
Important sites include Cuyabeno Wildlife Reserve, Sacha Lodge, Sani Lodge.
Moriche Palm Swamps
Permanent stands of water where one species of tall palm predominates, these swamps are most often found near oxbow lakes or in other areas where drainage is poor. Several bird species are specialists in this habitat.
Important sites include Cuyabeno Wildlife Reserve.
RIO MARAÑON DRAINAGE
Geographically isolated from the eastern lowlands by the Cordillera del Condor and other mountain ridges, the area in far southeastern Zamora-Chinchipe Province falls within the drainage of the Rio Marañon. A handful of bird species that were originally thought to only occur in northwestern Peru around the upper Marañon can also be found in this remote and difficult-to-access region in Ecuador. Starting around Valladolid just south of Tapichalaca Reserve, this region continues south through Zumba to the border with Peru. Much of the deciduous or semihumid forest along the road is disturbed, although patches remain particularly south of Zumba in which the Marañon Spinetail, Marañon Crescentchest, and Marañon Slaty Antshrike can be found. At higher elevations in the region, these habitats merge into subtropical montane forest, becoming less unique in terms of bird species.
Imporant sites include the Tapichalaca-Valladolid Road, the Valladolid-Zumba Road, and the patches of forest south of Zumba.