The eastern slopes of Peru’s Andes, as they descend to the Amazon Basin, are biologically one of the richest areas of the world … as well as one of the most scenic.
Many of Peru’s best-loved sites, including Kuelap and Machu Picchu are to be found in the region known in Peruvian Spanish, rather wonderfully, as ceja de selva (eyebrow of the rainforest). In English, this is known as cloud forest, although there are numerous sub-categories within these terms that reflect the endless ecological diversity therein.
Contained within this biological zone are some of Peru's most spectacular - and yet little-visited - conservation areas. These include the remote Rio Abiseo National Park, one of Peru’s 12 World Heritage sites; and the Yanachaga-Chemillen National Park, which is home to endemic species and indigenous groups.
These areas are shaped by the waterways that have formed as rain falling on the Andean mountains makes its way downhill to the Amazon River; and some of the world’s tallest waterfalls - such as Gocta and Yumbilla - are to be found here.
While the Low Amazon, at an altitude below 400m (1,300 ft), such as to be found around Iquitos, may have the the greater number of species overall, the slopes of the Andes have greater eco-system diversity and species density. In a 200 km (124 mile) corridor between the western edges of the flood plains of Amazonia to the peaks of the Andes mountains, one can find 1,000 species of bird, equivalent to the number of species to be found in 5 million square km (2 million square miles) of low Amazon.
The most important variable, impacting on the diversity of flora and fauna as one ascends the Andes, is temperature, which drops 0.6ºC (1.8ºF) every 100 m (328 ft). As moist air from the Low Amazon rises, it cools to form clouds, which cover the region most of the time. And even though the period from May to September is relatively dry, the cloud forest interior stays fresh and humid.
By contrast, less cloudy areas, above 4,000 m (13,100 ft) are subject to extreme variations, from intense heat during the day to freezing temperatures at night.
As one ascends, the structure of the forest visibly changes. In the low zone, the tree trunks are usually straight and smooth, a characteristic typical of pioneer trees, such as Cecropia, that grow fast and upwards in search of sunlight. Whereas, cloud forest is short and often impenetrably dense. The trees are twisted and covered in epiphytes such as mosses, ferns and large bromeliads.
This is the realm of Peru’s national bird, the cock-of-the-rock, and where colourful tanagers, almost always in mixed species groups, are abundant. The many species of birds that live in the understory and bamboo thickets can only be identified by their calls.
Cloud forest at high elevation is known as dwarf forest, elfin forest, or pygmy forest. Always wrapped in lichens, the tree leaves are small and leathery. The foliage effectively condenses the humidity, that occurs in the form of mist, into small droplets, that run to the base of the plant. In this way, the forests serve an important role as a source of water for mountain streams during the dry season.
Above 3,800 m (12,500 ft), the forest is dominated by one tree, the queñua (Polylepis rugulosa). Sadly, many of the areas of this altitude have lost their trees as a result of frequent fires, over-grazing and a lack of reforestation.
Above 4,000 m (13,100 ft), vegetation becomes increasingly scarce, principally consisting of creeping plants, in rosette or cushion form, that are adapted to stand the ice, snow and intense radiation of the sun.
Paramo is the ecosystem of those Andean regions above the tree line and below the permanent snowline. Where there is moisture, the vegetation is spongy, consisting of mosses, high grasses and low shrubs.
The drier areas at these elevations, such as around Lake Titicaca, is a scrubland known as puna.
How to visit Northern Peru’s cloud forest:
And given the abundance of bird species found in cloud forest, many of PeruNorth’s birding itineraries will spend at least some time birding there:
You can also visit cloud forest in Ecuador’s Andean region, as part of our Southern Ecuador itinerary.