Lowland Evergreen Forest: Lowland humid forests in the Neotropics have the highest single-site bird diversity in the world. Thorough inventories at a single site in central Amazonia reveal nearly 400 species, and this number climbs to 500 or more in western Amazonia, the region where we will be birding.

Several distinctive forest types cloak the humid lowland rainforest each with distinct avifauna. Terra firme forests are by far the most dominant type, both in the land area covered and in the number of species they contain. Other forest types occur as strands along rivers or as patches within the matrix of Terra Firme forest. Terra firme forests are found in areas high enough to escape seasonal inundations. They are typically rich in buttressed trees, a canopy forest that reach 25-40 m with emergents of 50-60 m. The undergrowth is relatively thin and includes palms, woody vines and vascular epiphytes such as ferns, bromeliads, and orchids.

Seasonally flooded forest or varzea forests constitute a small but important forest type in the areas visited. This forest type forms a narrow zone (rarely more than 100 m) between the riverbank and the terra firme forest. These are overall less diverse than the terra firme forest in species of birds and plants but equally tall, with numerous heavily buttressed trees and abundant ferns, bromeliads and orchids. This forest type often includes a dense undergrowth.

Another important habitat is bamboo. Dense thickets and tangled branches of bamboo mainly Guadua (Graminea) occur in discrete patches. With dense foliage and a height of up to 20 m, bamboo thickets provide numerous foraging substrates for insectivorous birds, some of which are entirely restricted to this habitat type in southeastern Peru. Overall, most bird species are associated with terra firme forest but will bird the most significant forest types during our stay in western Amazonia.

Subtropical-Montane Forest: Montane forest is the altitudinal continuation of the lowland forest toward the Andes. The exact point of transition varies from 600 m to 1500 m and it is highly dependent on the point where the clouds from the lowland Amazonia forest hit the Andean mountain chain. Montane forests above 1500 m of altitude have a forest canopy of 25-30 m tall, having short, stout unbuttressed trunks with rough bark. The tree crowns are relatively small, compact and round. The transition from lowland to montane forest is often abrupt. As one hikes from foothill forest of Amazonia into Andean forest at 900-1200 m the sudden appearance of moss-covered trees, as well as tree ferns, bromeliads, orchids and montane bamboo is striking. The bird fauna in montane forest is well segregated in altitudinal bands with subsets of species being replaced by others along the altitudinal gradient. There is more overlap in the range of species between both extremes of the vast Amazon basin than among the bird communnities of contiguous altitudinal gradients of some montane forests. Birding at Machu-Picchu area will allow sampling the bird community of the montane forest found at approximately 6500'.

Arid Montane Scrub: The arid montane habitat expands from middle Central America to Chile and Argentina. This habitat is characterized by shrubby vegetation, often mixed with cacti, terrestrial bromeliads and grasses. In spite of its similarity in plant composition, bird communities differ considerably mostly due to local and regional geographic characteristics that have led to the speciation of unique species. Species such as Chestnut-breasted Mountain Finch, Rusty-fronted Canastero and Bearded Mountaineer are restricted to a few valleys in southern Peru and can be seen in Lake Huacarpay area. The lake itself supports some of classic high Andean and widespread species.

Polylepis forest. Polylepis forest is a high altitude woodland of the Andes that varies in its composition from dense humid vegetation (i.e. lichens and mistletoes of a rich soil) to scattered shrub of barren desert soil. The tree that gives the forest its name comes from the rose family (Rosaceae) and has 20 known species, all of which occur at altitudes above tree line ranging from 4000-5000 meters (13,000-16,000 feet). In fact, Polylepis shares the altitudinal record for trees with Himalayan pines. Living in such a harsh environment requires adaptations to intense radiation, drought, wind, and severe frost. To combat such conditions, the tree has several layers of reddish, paper like bark that serves as an insulation barrier.

Once thought to have covered land that is now largely dominated by low, open grasses and shrubs, Polylepis forest has become restricted to small pockets, typically fringing streams and forming patches in gorges and on rocky slopes and cliff ledges. Patches usually are of only a few hectares in size, sometimes occurring close to tree line where they may mix with elfin forest (cloud forest of high elevation and stunted vegetation). Its isolation is considered to have resulted from years of human influence.

Contained within these isolated patches is a wealth of unique flora and fauna. Up to 25 bird species, many of which are threatened endemics, occur exclusively in Polylepis woodlands. Examples include the Andean Conebill (Oreomanes fraserii), White-browed Tit-Spinetail (Lepostenura xenothorax) , the Ash-breasted Tit-Tyrant (Anairetes alpinus) and the Royal Cinclodes (Cinclodes aricomae). We will be birding Polylepis at Abra Malaga.

The puna grasslands. The Andean highlands above 3800 meters (12,500 feet), known as the puna grasslands, bear no resemblance to the idealized conception of the tropics. This frigid, moonscape habitat of thin air is characterized by the absence of forests, the abundance of gramineous herbs, and by its vicinity to snow-capped peaks. Precipitation and temperature, are highly dependent on altitude. Rainfall averages from 600 to 1000 mm (24 to 40 in) a year, increasing with elevation, whereas average temperatures decrease with altitude. Frosts are common and wildlife is well adapted to it, as well as to the low oxygen concentration and high solar radiation.

The vegetation of the puna grasslands is composed principally of clumps of yellowish herbs from the genera Festuca, Calamagrostis, and Stipa (locally known as ichu). At elevations above 4400 meters (14,000 feet) a bizarre plant association resembling the Arctic tundra occurs. Green, pillow like plants known as yaretas (Azorella yareta) stand out among the rocks, their slow metabolism adapted to withstand temperatures of -25C (-13F) and snow.