Above: Vicuña, wild relatives of llamas and alpacas. Image Credit: TrexExperience

At over 17,700 ft. in elevation, the High Andean slopes are expected to be frigid. Home to over 99% of tropical glaciers on Earth, this tropical andean landscape is coated with massive glaciers. However, global warming is causing these glaciers to melt at unprecedented rates. In some areas, glaciers have lost over 40% of their surface area^[¹^]. As glaciers recede, the high altitude land they once covered is left behind, creating a dense, unusable rocky terrain which life struggles to survive in. Normally, the process of creating usable soil in such an area would take over a century. However, a wild relative of llamas may be single-handedly speeding this up by over 100 years. The vicuña consume seeds and grass at lower elevations before climbing to higher elevations and defecating. Because a herd will all defecate in the same area, huge mounds of feces are built up. These natural latrines quickly sprout into life, and the vicuña graze on the new vegetation, transforming once barren ground into green landscapes. This greenery attracts animals, insects, and even apex predators to high elevations, creating diverse ecosystems – all sprouted from the vicuña’s feces. However, even though the vicuña can speed up this growth, this process still takes decades– and at the rate the glaciers are receding, this process is struggling to keep pace with the environmental crisis that is rapidly transforming the region’s geography.

Tropical Andean Glaciers are some of the fastest melting glaciers in the world^[²^,³^]. Located in the northern and central regions of South America, they run directly along the equator and tropics. Because these glaciers are present in a warm climate, they are only present at extreme, high-altitude peaks typically above 5,000 meters (16,400 ft.). As these glaciers melt, they recede higher and higher into the mountains, leaving behind a bare, rocky landscape known as the “proglacial zone”.

Above: Zones in proportion to glaciers. As glaciers recede, they leave behind bare, unusable land in the proglacial zone. Below the proglacial zone lies the distal zone, where vicuña graze before migrating to the proglacial zone. Image Credit: ResearchGate

Proglacial zones are generally nutrient-deficient, and present at high altitudes^[⁴^,⁵^]. Because they have been coated with raw ice for thousands of years, the soil is brittle and dense. Necessary components for life in these areas, such as nitrogen, phosphorus, and stable organic matter, are all effectively nonexistent^[²^,⁶^]. In order to transform such landscapes into ecosystems suitable for life, these areas undergo a process known as “primary succession”. Primary succession is the process by which a new ecosystem is created from absolutely nothing. Because there is no existing soil, seeds cannot take root, and beneficial soil bacteria do not exist. Because organisms must build a soil layer line by line, primary succession is a slow process, generally taking 100 to 150 years simply to establish stable plant life^[⁷^,⁸^]. In the High Tropical Andes, primary succession is slowed even further by the high-altitude environment. In the mountains, there are extreme daily temperature swings, ranging from below freezing at night to severe heat and intense solar radiation during the day (e.g. -10°C at night to over 30°C in the day)^[²^,⁹^]. This makes it difficult for plants and animals to survive, regardless of the lack of usable soil or nutrients. In addition, the glacial till has a very low moisture retaining capacity, causing any available water needed for seeds to germinate to quickly drain away^[²^,⁵^].

The University of Colorado (CU) and James Madison University (JMU) led an international team of researchers in late 2024 and early 2025 to map how wild vicuñas altered proglacial zones. Using a mixture of field monitoring, drone imagery, soil chemistry tests, and environmental DNA (eDNA) sequencing, the researchers discovered how vicuña were rewiring high alpine ecosystems^[¹⁰^]. As vicuñas forage, they migrate from lower, vegetated valleys to barren, high altitude terrains^[³^,⁶^]. In this way, they transfer seeds and organic matter to higher altitude regions like the newly exposed proglacial zones. The species exhibit a unique social behavior when herds use the same area to defecate, creating massive communal dung piles^[⁸^,⁹^]. This creates localized abundances of nutrients. The mounds blend into the ground, dropping the soil’s bulk density by shifting edaphic properties and giving roots room to grow. Simultaneously, they spike electrical conductivity and introduce mycorrhizae, helping plants to absorb difficult-to-reach minerals^[²^,⁷^]. As these dung gardens take root, hardy bunchgrasses such as Stipa Ichu quickly sprout^[²^,⁶^]. As the vicuña repeatedly graze these new-found sources of food and continue to fertilize these areas, these small mini-ecosystems are transformed into dense, green mats of plants dominated by plants like Calamagrostis Vicunarum^[²^,⁹^]. Motion-activated field cameras deployed by scientists revealed that these local islands of greenery quickly attracted insects, small rodents, mountain birds, and even apex predators like pumas ascending to unprecedented elevations^[¹⁰^,³^].

Simply by grazing and defecating, vicuña are unknowingly speeding up primary succession by over a hundred years. A process once taking over a century now takes just a few decades. However, as glacier receding rates continue to accelerate, vicuña are struggling to keep up as more and more landscapes once covered in glacial ice become barren, unusable ground. Although vicuñas are speeding up natural processes, the process still takes decades – and glaciers are melting much faster. While the vicuñas are vital to ecosystem recovery, they are simply no match for the unprecedented glacial retreats currently occurring all over the world.