Gold-mining with deforestation | by George Olah on 01 September 2020

Biogeographically Peru can be divided into three major units: the deserts along the Pacific coast, the Andean mountain range that forms the backbone of the country, and the Amazon to the east. Most of the waters of the Amazon Basin originate in the Peruvian Andes. These mountains provided the stage for many important South American civilizations, such as the Chavín culture (900–200 BC), the Huari Empire (600–1000 BC), the co-existing Tiwanaku civilization, and finally the Inca empire (1438–1572 AD). The capital of the Inca Empire – or Tawantinsuyu in their own Quechua language – was Cuzco, located in southeastern Peru, not far from Machu Picchu. The Incas were not short of non-ferrous and precious metals, which they revered as their gods. They could not have guessed that gold would bring great trouble to their heads, just as the Indian tribes living in the rainforest did not think that their great rivers were rich in gold, the extraction of which would lead to an environmental catastrophe.

Civilizations like the Andeans did not develop in the Amazon, nor did the Incas occupy these tropical regions. One of their tropical cities was Vilcabamba, surrounded by cloud forests. From 1539, this city also became the capital of the Incas fleeing the Spaniards, until 1572. Vilcabamba is also referred to as the lost city of the Incas, as it was only discovered by Hiram Bingham in 1911, although its significance was not realized until its rediscovery in 1964, which was documented by the Hungarian filmmaker Géza Rosner. According to an Inca legend, there was another lost city rich in gold, in the tropical rainforest. Countless explorers and adventurers have tried to find the legendary city of Paititi, so far to no avail. Thus, for the time being, we can only admire this mysterious city in the world of adventure movies and video games.

As a doctoral student in the Peruvian Amazon

In late 2009, as a PhD scholar of the Australian National University, I returned to Tambopata. It was very exciting to start my own research in this area, mainly based in the Tambopata Research Center. A variety of nest boxes have been set up for macaws since the start of the Tambopata Macaw Project, which differed in material, size, height, interior design and many other features. Although wild macaws were happy to occupy these artificial nests, scientists had not yet analyzed the breeding preference of macaws and which nests were the most successful. For collecting such data, we often had to climb up to the realm of macaws – at a height of 30–40 m (100–130 ft) in the canopy – by industrial mountaineering methods on a rope. From the long-term data mostly collected by the Brightsmith research group, it became clear that the macaws remembered which nests were the most successful in the previous breeding season, and they fought vigorously for them. Since publishing these results (Journal for Nature Conservation 2014 | PDF), nest box designs tested in Tambopata have been used in Bolivia, Mexico, and Guatemala to help endangered populations of macaws there.

The other part of my research examined the population genetics of large macaws. I developed species-specific genetic markers for the Scarlet Macaw (Ara macao) and other closely related macaw species (Conservation Genetics Resources 2015 | PDF). With these microsatellite markers, we were able to individually identify the samples, while also getting an accurate picture of the genetic diversity of the populations. We also calibrated these genetic methods for non-invasive samples (Conservation Genetics Resources 2016 | PDF), and thus it was sufficient to collect only feather samples without capturing the birds. DNA was extracted from the feathers in the laboratories of the Cayetano Heredia University in Lima and then shipped to Australia after obtaining the appropriate permits. Our colleagues at the Texas A&M University sequenced the entire genome of a Scarlet Macaw, which was of great help in developing the species-specific markers in Australia. Still, collecting feathers in the rainforest turned out to be the biggest challenge. In order to get a comprehensive picture of the populations of macaws in the area, it was necessary to search for feathers over a very large area. In the absence of roads, I first had to buy a 12 m (40 ft) long motorized longboat, which proved to be an indispensable means of transportation in the river highways.

The diversity of habitats

The wildlife of Tambopata is not much different from other regions of the Southwestern Amazon Basin. What makes it special is the diversity of the habitats and the overall richness of the species. Most of the area belongs to the Southwest Amazon moist forests ecoregion. Within this we find habitats of terra firme – rainforests never reached by the floodwater of rivers –, as opposed to periodically flooded rainforests. Furthermore, we can also find palm swamps with very low nutrient soils, and areas at different stages of succession, which are mostly formed by the landscaping work of the rivers. This is also how oxbow lakes are created, which maintain their own ecosystems. In the region of the Heath River, which forms a natural border between Peru and Bolivia, there are special extrazonal savannas belonging to the Beni savanna ecoregion. Within the rainforests around Heath, we can find patches of natural clearings that become more and more connected towards Bolivia and eventually replace the rainforest. Both sides of the river are protected areas, with the Bahuaja-Sonene National Park on the Peruvian side and the Madidi National Park on the Bolivian side.

The region of Tambopata provides habitat for more than 100 species of mammals, close to 700 species of birds, about 100 species of amphibians, and 100 species of reptiles. There are more than 20,000 species of plants throughout Peru, most of which are found in the rainforest and many can be used for medicinal purposes. The Native Community of Infierno has a famous botanical garden, where generations of shamans have collected their most important herbs from the surrounding forests. The garden is called Centro Ñape, and the shaman was the uncle of my research assistant, Braulio from the Ese’eja tribe, so we often visited his uncle if we had any medical issues during the fieldwork. Don Honorato always found the right herb that really helped. I was even able to join the local ayahuasca ceremony after each field season, which was a special honor as an outsider.

Birds of a feather flock together

Collecting bird feathers in the dense rainforest does not seem like a very sensible undertaking. However, clay licks where the birds come to eat soil are found in large numbers along the rivers in this area and they “collected” the feathers for us. The feathers we found were given a unique identifier, recording the exact location, time of collection, and the presumed owner of the feather, at the species level. Ecologists often use a method called capture-mark-recapture (CMR) to estimate the number of individuals in a population. This is based on the principle that if we regularly capture and mark/tag individuals of the studied species in a given area, we are likely to recapture previously marked individuals. Examining the ratio of tagged vs. untagged individuals, we can estimate the size of the population using statistical methods.

Birds are most often caught with mist nets and marked by a unique band. However, capturing macaws in a tropical rainforest is not an easy task. We did that before with my supervisor Dr. Brightsmith and his team to equip individuals with a satellite tracker. This required a great deal of time and energy, and would not have been sufficient to estimate the population size. Therefore, we chose a method often used in forensic genetics. We collected feathers from larger clay licks on a monthly basis. Later, thanks to genetic markers developed in the lab, we analyzed each DNA sample to reveal its unique genetic “fingerprint” or genotype. When a match was found in the database, it indicated that the samples tested were from the same individual. Hence, the feathers provided the basis for a genetic capture-mark-recapture or genetic tagging. For example, if we had always recovered feathers on a clay lick from the same individuals, it would have indicated a very small population size visiting the clay lick.

Shed feather samples collected on a single day from various parrot species at the Chuncho clay lick in Tambopata. © George Olah

In reality, we rarely found a match between feathers from different clay licks, indicating that parrots from a nearby area prefer to use a single clay lick. The clientele of the largest clay licks comprised about a thousand macaws based on our genetic analysis and usually consisted of close relatives. The most interesting genetic trace showed a match between a feather sample found on a clay lick and a blood sample taken from a chick a few years earlier (Conservation Genetics 2017 | PDF). This data, like the annual movement of macaws tracked by satellite telemetry, seems to demonstrate that macaws are keen to return to the areas where they hatched. The home-range they use over their long lives proved to be much larger than we thought. This is an important information and confirms the need for large protected areas in Peru and nearby countries to fully protect these species.

Gold rush

People visiting Tambopata these days can observe large open areas (or pampas) from their flight as they approach Puerto Maldonado. But these are not the natural pampas of the Heath River but reflect destructive human activities: scars from our modern gold rush! Today’s gold miners wash the sediment of riverbanks through increasingly finer filters by using a generator-operated water pumps. The fine particles obtained are then mixed with mercury in a large barrel. Unaware of the dangers, the miners often use their feet to mix the mercury with the fine particles. Because mercury dissolves gold, this technique has long been used to extract this precious metal. The mixture of gold dissolved in the mercury is finally separated from the water and then the mercury is evaporated by burning, which leaves pure gold behind. During these operations, not only does mercury enter the atmosphere, but it also leaches into the rivers and accumulates in the food chain. Mercury, this highly toxic element, poses the greatest danger to the fetus and children, but mercury poisoning also causes serious neurological diseases in adults. In South America, gold miners use tons of mercury each year. In Puerto Maldonado, the amount of mercury measured at fish markets has now exceeded critical value, so the sale of fish has been banned in several places.

Gold miners working illegally in the Tambopata River in 2018. © Balázs Tisza

Gold-mining is an illegal activity in Peru without a permit. Yet, around Tambopata, this is practiced by many as a “family business” or by more organized, mafia-type illegal groups. In many areas, small, temporary gold miner villages have been assembled. At these places, other illegal activities have spread as well. Prostitution is one of them, which is especially worrisome as it is often carried out on minors that have been abducted from nearby local villages. Transport to these places was very slow in the past, until the completion of the Interoceanic highway in 2013, which integrated these areas into the international trade network. This has also opened access to Tambopata not only for local but also outsiders, including criminals attracted by the many illegal activities in the region. Due to this tragic situation, even Pope Francis visited Puerto Maldonado in 2018. Unfortunately, over the years, the country’s leadership did not make much effort to remedy this situation. By 2019, the crime rate has extremely elevated in Puerto Maldonado and around, and even several tourists were robbed by gunmen. Finally, the government ordered a local emergency and sent soldiers to the area. A few gold miner villages were broken up, after which only the bare, lunar landscapes remained. This is the direct consequence of gold-mining, when not only the trees but also the soil is removed as they move forward in the forest. In tropical rainforest, there is a very fast decomposition of organic materials quickly absorbed by the trees, so these forests inherently have very thin soil. Hence, after the removal of this thin layer, the regeneration of the forest is very slow, if at all happens. But this process might be stopped in time, if the story of Tambopata is learned worldwide. (Coming up next: Films for conservation)

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