The New Neotropical Companion

and transitional zones. In some places the corridor is

only 4– 6 km (2.5– 3.7 mi) wide, rather narrow to assure

sufficient usage by migrant species. Areas outside the

corridor are heavily used by humans and therefore do

not represent suitable habitats for elevational migrants

and most other tropical forest species.

Scaling the Andes: High- Elevation

Ecology

You can’t miss them, especially as you gaze out from

a comfortable cruising altitude of perhaps 10,000 m

(33,000 ft) aboard a jetliner flying north from Lima,

Peru, to Quito, Ecuador. The Andes are the dominant

topographic feature throughout all of western South

America. The ancient Incan city of Machu Picchu, at

an elevation of 2,430 m (7,972 ft), is a World Heritage

Site near the city of Cuzco, Peru, visited annually by

thousands of tourists (plate 13- 21). Approaching Quito,

which itself is at an elevation of 2,858 m (9,375 ft), you

hope the clouds will lift sufficiently that you can see

Cotopaxi, the currently quiescent volcano that looms

above the city at an elevation of 5,897 m (19,344 ft), one of

many potentially turbulent mountains along the Andes

chain. The youthful mountain range stretches from

Cape Horn, the southernmost tip of South America, all

the way north to the Caribbean Sea, finally terminating

in the gentle, densely forested Northern Range on the

island of Trinidad. The Andes are the longest continental

mountain chain in the world, stretching about 7,000

km (4,300 mi) from end to end. The width ranges from

about 200 to 700 km (120 to 430 mi).

The Andes Mountains began forming after dinosaurs

became extinct and are still growing and changing.

Some of the snow- covered peaks are geologically

recent. The Andes form an immense chain of granite

stretching below your plane as far as you can see in

either direction. To the east, over the high peaks, lies

the vastness of the Amazon Basin, while to the west is

a narrow belt of coastline, much of it Atacama Desert,

one of the most arid regions in the world. In between,

within the complex peaks and valleys of the mountains,

are the high puna, the páramo, and the flat altiplano

of the high Andes. The puffy cumulus clouds that

sometimes obscure the view of the mountains below

owe their existence to the presence of the mountains,

which force moisture- laden air over the peaks, causing

condensation into clouds (plate 13- 22).

Plate 13- 20. Spectacled Bear, relaxing. Photo by Andrew

Whittaker.

Plate 13- 21. Machu Picchu, near Cuzco, Peru, is one of the

archaeological wonders of the world, a major city during the

Incan Empire. Photo by David Clapp.

Plate 13- 22. The Andes Mountains are extensive, complex,

and active. The chain has numerous snow- capped peaks,

including those here, partly enshrouded in clouds. Photo by

John Kricher.

chapter 13 scaling the andes 243