A Bolivian 'Cloud Forest' Reveals a Bonanza of New Species

An expedition into a steep, remote mountain area unveils discoveries of strange frogs, snakes, and plants—and the return of species thought to be extinct.
cloud forest
Photograph: Trond Larsen/Conservation International

There are some special places on Earth that scientists are pretty sure will yield new species when they manage to get there. The deepest parts of the ocean, for example, or remote islands that haven’t been trampled by tourists. But a high-altitude Bolivian cloud forest has staked its claim as a global biodiversity hotspot as biologists announced today that they discovered an amazing 20 species new to science, including a poisonous viper, a super tiny frog, and four species each of orchids and butterflies.

This Shangri-La of biodiversity is known as the Zongo Valley, located about 30 miles from the city of La Paz, Bolivia. It has been protected from human intrusion because of the steepness of the mountain slopes, which range from 2,000 to 17,000 feet in elevation. These slopes are home to a “cloud forest” that forms as rising moist air condenses and produces a constant high-altitude rainfall that supports a wide variety of animals, from the rare Andean bear to tiny dung beetles and unusual plants that resemble insects. Andean cloud forests like the Zongo also produce most of the water that drains into the Amazon River basin. The Zongo’s rugged terrain and steep hillsides have also isolated animals and plants from each other, thereby producing new species over generations.

The Zongo Valley is difficult to access for both scientists and loggers, according to Trond Larsen, director of the rapid assessment program for Conservation International, and coordinator of the Bolivian expedition. “It’s a reason why we find a lot of unique species,” Larsen says. “When you find a lot of steep valleys, it blocks the movement of animals, and so it has pockets of high endemism. The same features that lead this area to have natural protection also contribute to unique things that we find.”

Among the trove of biological finds announced today: The lilliputian frog (Noblella sp. nov.), which measures approximately 10 millimeters in length, or about half the width of a dime, which makes it among the smallest amphibians in the world. It lives in tunnels beneath moss and was only found by patiently tracking its low-pitched call. The expedition team also found the mountain fer-de-lance (Bothrops monsignifer), a new species of venomous pit viper, which uses heat-sensing pits on its head to detect prey, and the Bolivian flag snake (Eutrachelophis sp. nov.), which is distinguished by red, yellow, and green colors similar to the Bolivian flag. It was discovered in the thick undergrowth along the crest of the mountain at the highest elevation surveyed.

Photograph: Trond Larsen/Conservation International

The team also isolated four new butterfly species, including two species that feed on flower nectar in open areas and forest clearings, and two that were only caught with a long-handled net while flying high in the forest canopy. They also cataloged four new kinds of orchids, including a species with flower parts that appear to mimic an insect to fool unwitting pollinators.

Photograph: Fernando Guerra/Conservation International

Larsen led a group of 17 scientists and staff from Conservation International, the Wildlife Conservation Society, and several Bolivian natural history museums during the two-week census of biodiversity that occurred in March 2017—it's taken this long to accurately research the discoveries. The results of the expedition are being released today in conjunction with an effort by Bolivian conservation groups to seek protection for the Zonga region, which also is an important upstream source of drinking water for the 2.7 million residents of the city of La Paz.

The purpose of the expedition and the rapid biological assessment was to give information to local authorities in the surrounding state of La Paz who are working to protect the valley. Growers of coca, the plant that is refined into cocaine, have begun planting crops in the high-altitude region surrounding the Zongo. Coca growers use pesticides and fertilizers that are poisoning local waterways, according to Steffen Reichle, a Bolivian ecologist and leader of the herpetology team on the expedition. “It’s an important crop because of the high price, and you can harvest three times a year,” Reichle says.

Reichle says that for him the biggest moment was re-discovering a “devil-eyed” frog that he first discovered back in 1997. He thought the species had been wiped out by the construction of a nearby hydropower plant, and because subsequent visits by other biologists to the area had turned up empty-handed. “Any species you describe feels like having an offspring,” Reichle said from his ranch in Santiago de Chiquitos, Bolivia. “You put a lot of work into it and, frankly, it feels better to find them again because I know there has been so much decline of amphibians worldwide. To me, it was more exciting to find an old species than the new ones.”

Photograph: Trond Larsen/Conservation International

Other team members rediscovered a species of satyr butterfly last seen in 1919, which they captured in a cylindrical mesh trap where it was attracted to a bait of rotten fruit and dung. They also found a small arrowroot plant, documented 125 years ago, that moves its leaves vertically to close them at night, similar to hands in prayer.

Conservation International’s Larsen says that the Zongo Valley cloud forest just isn’t a neat place for biologists like himself and Reichle, it also provides benefits to indigenous communities who live there around the forest. “It’s important to conserve biodiversity at the same time as protecting the benefits that the ecosystem is providing to the people,” Larsen says. “Keeping the forest intact provides the drinking water, the building materials, and medicines and food that people are getting as well.”

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