By Mary Kate McCoy
December 20, 2024
‘I almost couldn’t believe it’: Amazon expedition stuns researchers
7 min
In the Andean foothills of the Peruvian Amazon, Trond Larsen carefully scanned the forest floor.
Out of the corner of his eye, a dark brown frog with a long snout hopped across the leaves, briefly exposing a bright pink underbelly. Larsen immediately knew what it was.
Once a common sight, this harlequin frog (Atelopus seminiferus) is now extremely rare. By all accounts, it shouldn’t have been there at all, said Larsen, a biologist at Conservation International.
“I almost couldn’t believe it,” he said. “Not only is this frog endangered, but this species has never been found this low on the mountainside. It was our first important discovery — and it was a harbinger of more to come.”
Researchers were surprised to find a number of harlequin frogs (Atelopus seminiferus) during the expedition.
For an expedition like this — designed, as the program’s name suggests, to find as many species as possible in a short amount of time — the setting was unusual. Rather than a “pristine” forest far from human activity where one would expect to find an abundance of wildlife, this area, known as the Alto Mayo, has an abundance of human settlements and deforestation remains persistently commonplace. Just moments before discovering the frog, Larsen had crossed a muddy logging track, where a donkey pulled a cart of fresh-cut timber through the forest.
“We know very little about the planet’s biodiversity, and these ecosystems hold so many mysteries,” said Wily Palomino, a Conservation International biologist who was part of the expedition. “It would take 10 lifetimes to truly understand them. Expeditions like this are just the beginning.”
A member of the Indigenous Awajún community captures fish to assist with the research.
A trove of discoveries
Over the course of 38 days, the researchers trudged through swamps, lagoons and rivers, climbed mountains to cloud forests, and crossed farm fields. All the while, the team of 20, including Indigenous guides and scientists from Global Earth, collected samples, set up camera traps and nets, and kept a keen eye out for movements and signs of animals.
The Alto Mayo is known to be home to extraordinary biodiversity. Still, the findings stunned the researchers.
The team recorded more than 2,000 species of plants and animals, including 27 that are new to science and 49 that are threatened with extinction. Notably, four of the new discoveries were mammal species.
“Mammals are the best-known animal group in the world — so discovering four new mammals in any expedition is surprising,” Larsen said. “Finding them in a region with significant human populations is extraordinary.”
Among the new discoveries: an amphibious mouse. The semi-aquatic species lives in an ecosystem known as aguajales — swampy areas dominated by aguaje palm trees. Spotted in an area designated as an ecosystem recovery zone, deforestation for rice farming threatens the mouse’s unique habitat. This species, which likely only lives in the Alto Mayo, belongs to a group of semi-aquatic rodents for which most of the known species are extremely rare, Larsen said. Documenting even one individual is a huge accomplishment.
The newly discovered amphibious mouse belongs to a group of semi-aquatic rodents that are among the rarest in the world.
Mammals weren’t the only discoveries that made the researchers question what they thought they knew about the forest, Palomino said.
Take a humble dung beetle.
Typically found only in forests that haven't been damaged by human activity, certain dung beetle species are indicators of a healthy habitat, he said. Yet there they were, in the middle of a forest with clear scars where humans had felled trees, as well as in coffee plantations.
“This discovery made us rethink what might be happening in these habitats,” Palomino said. “Why are primary forest species showing up in secondary forests? It’s an area that needs further investigation.”
Many researchers hypothesize that in fragmented forested areas, there is little biodiversity, he said. That’s why areas like the Alto Mayo have largely been ignored by researchers.
This expedition challenges those views.
“The discovery of so many new and threatened species was so surprising, in part, because it was a nearly blank slate — no one has ever really looked,” Palomino said. “Now, we’re proving the unexpected: Small patches of healthy forests can support a wealth of species.”
A rare hummingbird (Lophornis delattrei). The expedition documented 536 bird species, 26 of which are threatened with extinction.
A vision for the future
Roughly 280,000 people reside in the Alto Mayo landscape, including the Indigenous Awajún people. In the late 1990s and early 2000s, many in their community had to rent their lands to migrant farmers to make ends meet.
This practice led to an alarming rise in deforestation, said Diego Dourojeanni, who leads Conservation International’s work with the Indigenous peoples of the Alto Mayo.
“Communities didn’t deforest their land because they wanted to — it was out of necessity,” he said. “While it helped in the short term, it became clear that this practice came at a steep cost to resources, food security and the ecosystem services like clean water that the forests provide.”
An area within the Alto Mayo that has been logged for agriculture. Deforestation remains a persistent threat in the region.
The recent expedition was borne out of these efforts, the start of an ambitious strategy to connect remaining patches of high biodiversity within the Alto Mayo and create a protected conservation corridor that is essential for the long-term survival of the region’s wildlife.
“To effectively protect nature, you first need to know what’s there,” Dourojeanni said. “By understanding where wildlife lives, we can make better land management decisions and target areas that are best suited for conservation and sustainable activities like ecotourism, selective logging and sustainable agriculture.”
Yet a better understanding of what resides in the forest isn’t only important for economic reasons, he said.
Compared with a decade ago, Dourojeanni said there are signs of progress. Communities are renting their land out less, and he sees a greater understanding of the importance of protecting their forests.
“It’s not too late yet,” he said. “If we do the right thing, people and nature can co-exist on this landscape.”
Sunrise over the Alto Mayo, which stretches from the Andes to the Amazon.
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