TOPOGRAPHY OF PERU – AMAZON BIRDS
The topography of Peru – Amazon Birds, is very complex, resulting in a delightful variety of habitats and bird species (fig. 4). A dominant feature of Peru is the Andean cordillera, which runs north/south down the length of country. The Andes interrupt the westward flow of air across the Amazon Basin of South America. As a result the east-facing slopes of the Andes, and Amazonian lowlands to the east, are very humid. Typically the Amazon Basin and the humid forests of the east slopes of the Andes are covered in humid evergreen forest, rich in species. Local soil differences, perhaps coupled with a history of fire, can produce less diverse forests or even scrub and savanna – birds of peru.
Most of Amazonian Peru is flat and low. Much of eastern Peru is little more than 300 m above sea level, despite being some 2500 km from the Atlantic Ocean. The large floodplains of the Amazon and its major tributaries (including the Napo, Marañón, Huallaga, Ucayali, Yavarí, and Madre de Dios) are wide and flat. Within these floodplains the rivers are constantly scouring out new channels, periodically leaving behind detached old bends (oxbow lakes) and forming or consuming islands. The action of the rivers contributes a variety of additional habitats that are important for birds, such as different types of river-edge forest and scrub, marshes at the edges of oxbow lakes, and the secondary vegetation that develops as older oxbow lakes slowly fill in with sediment and are reclaimed. The largest Amazonian rivers often are important barriers to bird species distribution; frequently the edge of a species’ range will coincide with one bank of a river, and there is no sign of that birds species on the opposite bank only a short distance away – birds of peru.
Portions of the Amazon Basin, although still quite low in elevation, have somewhat greater relief, with series of very low hills or ridges, even far from the Andes (such as along the upper Río Purús). Areas with substantial relief are quite rare in eastern Amazonian Peru, the most notable exception being the Sierra del Divisor on the Brazilian border in central Peru, but ridges become more frequent, and increasingly higher, near the base of the Andes. The tops of these outlying ridges often harbor bird species that are not found in adjacent lower elevations, and that are scarce or absent at comparable elevations farther west on main slopes of the Andes – Birds of Peru amazon.
The eastern slope of the Andes is especially humid and often exceedingly steep. Landslides are frequent. In contrast to the relatively lazy, looping courses of rivers and streams in the Amazon, Andean streams and rivers typically flow very fast. These east-facing slopes typically are forested up to 3000+ m, eventually giving way to shrub zones and grasslands, the most humid of which are termed “paramo” or “jalca.” Treeline varies across Peru from about 3200 m to 3600 m. Above treeline isolated groves of Polylepis trees can be found, growing up to about 4500 m. Amazon Birds of Peru.
Intermontane valleys of the Andes are drier than the eastern slopes, due to rainshadow effects. The upper portions of these valleys, although less humid than east-facing slopes, still may be wet enough to support evergreen forest. Often the lower elevations in these valleys are much more arid and can be covered in deciduous forest, dry scrub, and columnar cacti. The larger dry intermontane valleys, such as the broad valley of the Río Marañón, often are barriers to the distributions of birds in humid forest. The majority of the human population of the Andes lives in intermontane valleys, however, and now much of the original vegetation in these regions is degraded or lost completely. Amazon Birds of Peru.
The highest parts of the Andes – Peru amazon, the puna, are above treeline and are covered in dry grassland up to about 5000 m, variably laced with wet meadows, bogs, lakes, and streams. Above 5000 m, most land is unvegetated rock and snow – Amazon Bird.
The western (Pacific) coast of Peru is very dry. Most of the coast of central and southern Peru is bare desert, with little or no vegetation other than on lomas and in river valleys. Lomas are hills near the coast that are high enough to intercept the low clouds coming in off the cold ocean and to capture, seasonally, sufficient humidity to support more vegetation than the lower, surrounding desert. Originally rivers crossing the coast would have supported riparian forest. The coastal valleys now are heavily populated, however, and are dominated by agriculture and by cities and towns. The north coast of Peru is more humid than are the central and southern sectors – bird of amazon.
Remnant deciduous forest is found at lower elevations along the coast and in the Andean foothills, south to Lambayeque; at higher elevations humid montane forest, similar to that found on the east slopes of the Andes, occurs patchily south to Cajamarca. These forested areas on the western slope always were patchy distributed, but habitat destruction has reduced their extent dramatically, and little intact forest remains – bird of amazon.
East of the Andes there is a pronounced dry season (variable, but typically May–October) in central and southern Peru. Seasonality is much reduced in the northern portion of the Peruvian Amazon. On the coast, the winter months (May–October) are cool, and skies often are overcast; however, typically there is little or no rain in central and southern Peru, although fog may “mist” the ground (especially on lomas). Rainfall is more frequent in the northwest and tends to occur December–March – birds of peru amazon.
HABITATS OF PERU – AMAZON BIRDS:
More detailed descriptions of bird habitats can be found elsewhere. Many of our habitat descriptions are based on Stotz et al. (1996); habitat names presented here in italics correspond to terms used by that source birds of peru amazon.
FOREST As used here, “forest” refers to humid lowland forests, including both tropical lowland evergreen forests and flooded tropical evergreen forests. Most of the Amazon Basin is covered by these two tropical evergreen forests – birds amazon.
These forests amazon typically are tall (25–40 m, with scattered emergents that can reach 50–60 m). Forests amazon may be found on upland terraces that never flood (terra firme) or occupy low-lying areas that are flooded for at least a portion of the year. These seasonally flooded forests amazon include varzea, transitional forests, and swamp forests amazon, depending upon the duration of flooding. In the species accounts we refer to these habitats as “forest,” with the understanding that, in the context of a species with an Amazonian distribution, the habitat will include the full spectrum of tropical evergreen forests amazon. We use terms such as “terra firme” or “varzea” for species that are restricted to, or particularly associated with, these types of forest – amazon of birds.
Tropical lowland evergreen forests of much lower stature are found locally in extreme northwestern Peru, in Tumbes and perhaps in northernmost Piura – bird of peru.
RIVER-EDGE FOREST.- Amazonian rivers are bordered by a variety of lower-stature, successional vegetation, which may include grasses and other herbs or a mix of herbs and tall shrubs, such as cane (Gynerium), willow (Salix), and Tessaria, and low-stature forests (10–25 m tall) that form a narrow band between the river and taller forest in the interior. These forests often grow in even-aged stands and are dominated by genera such as Cecropia and Ochroma. The understory of these river-edge forests often is quite dense. Similar habitats are found on islands in the larger Amazonian rivers, especially in northern and central Amazonian Peru birds.
MONTANE FOREST – AMAZON BIRD.- We use montane evergreen forest, or humid montane forest amazon, for the forests amazon that cover the eastern slopes of the Andes and outlying ridges from about 500 m up to treeline. It is lower in stature than tropical evergreen forests amazon, rarely exceeding 30 m in height; forest stature also tends to decrease with increasing elevation or steepness of terrain. The canopy often is broken, and branches and trunks of many trees are covered in moss, bromeliads, orchids, ferns, and other epiphytes. Tree species composition of montane evergreen forests usually changes significantly above 1500–1800 m, above which point epiphytes, including bryophytes, and lichens also become more prevalent. Below this elevation the montane forest contains significant elements of the lowland flora and is transitional between lowland terra firme forest and true montane forest – Peru amazon birds.
ELFIN FOREST – AMAZON BIRD.- At the highest elevations (and locally much lower, depending upon soil and wind conditions), forests are particularly low and dense. These forests, which usually are on ridgetops or at treeline, sometimes are referred to as elfin forests – Peru amazon bird.