The Cerrado, the World’s Most Biodiverse Tropical Savannah, Is in Peril

The Serra dos Pireneus mountain range juts out from the Brazil savanna like ancient, rusty saw teeth, all sharp edges and craggy rocks. The red dirt road that winds through Pireneus State Park to the foot of its highest peak, Pico dos Pireneus, is pocked by potholes that threaten to destroy the underside of my rental car. On either side stand wizened trees, their waxy, rigid leaves evidence of a complex evolutionary entanglement with the parched environment.

As we park at the Pico dos Pireneus trailhead, my passenger, Estevão Santos, points to a pair of large grassland birds that immediately call to mind dinosaurs. Red-legged Seriemas prey on venomous snakes, he explains, by scooping them up in their bills and beating them on the ground until they’re dead or stunned enough to be eaten. Santos relays this natural history with a casual confidence that belies the expert birder’s young age. At 18 he is tall and slender, and with his long black hair pulled into a ponytail, white linen shirt, leather satchel, and binoculars with a frayed strap, he appears more modern-day Alexander von Humboldt than a high schooler.

Santos started documenting birds when he was seven. He’d scribble observations in a notebook and sketch the birds in his backyard in the state of Goiás in central Brazil. What his parents thought was a passing interest has become his passion. He’s logged more species on eBird than anyone else in Goiás: 512 species to be exact. Since 2016 he’s been working on a book about the birds of central Brazil that contains years of his observations and field studies, which have yielded new information about bird ecology, behavior, and biogeography. “Birds have revealed the landscape to me,” Santos says.

That landscape is no simple swath of habitat. The Cerrado, South America’s second-largest biome after the Amazon and Earth’s most biodiverse tropical savanna, is made up of at least 19 different kinds of ecosystems. It’s hard to find a researcher who studies this ancient biome and has not become enthralled with it.

Marcelo Kuhlmann is a botanist who works as a consultant for Embrapa, the state-owned agricultural research corporation. He’s published several books on native fruits, flora, and fauna of the Cerrado. “Every time I go on an expedition, I find something new,” he says. “You could spend your life studying the Cerrado and still find things to learn.”

Kuhlmann met Santos about six years ago. “He was fanatical for birds,” Kuhlmann tells me. “He knew everything about birds, common names, scientific names, bird calls.” The two frequently go on expeditions together in the Cerrado, documenting plants and animals. In 2020, they found a Blue-necked Tanager subspecies that hadn’t been recorded in almost 100 years.

Santos and Kuhlmann are among a small, passionate group of scientists whose fascination with the understudied landscape borders on obsession—and whose concern about the Cerrado’s future has them racing to document its life and advocating for its conservation. Over the past half century the biome has become the country’s breadbasket, the long roots of this ancient savanna torn up and transformed into fields of soy, corn, sugarcane, and eucalyptus. Santos travels to government meetings and research roundtables to call attention to the rapid habitat loss and build support for stemming it.

On our trek today, Santos will introduce me to a slice of this remarkable biome. He has been coming to Pico dos Pireneus to look for one specific bird: the Velvety Black-Tyrant. The large, obsidian flycatcher is more commonly found several hundred miles away, in Brazil’s coastal rainforest, which has lost almost 90 percent of its original vegetation. But populations exist in slivers of highlands in the Cerrado, Santos tells me, which serve as a refuge for the tyrant and countless other species—at least for now.

As we begin hiking, Santos points out a large shrub in the nightshade family called lobeira, or “wolf plant.” Its leaves are thick, covered with an almost invisible fluff that provides protection from extended droughts and seasonal fires. Between the leaves hide green, softball-size globes that are the primary food for the maned wolf, one of the Cerrado’s most elusive mammals. The largest canine in South America, it looks like a long-legged, mystical fox and is the only member of its genus, Santos says.

As we wind our way up the trail, Santos scans the rocky outcrops above us. Velvety Black-Tyrants are partial to trees growing out of the rock, which are easier to swoop from to catch insects. We don’t see any tyrants, but Santos delightedly points to an unremarkable-looking plant clinging to the rocks. The small, brownish bromeliad is endemic to this very peak, according to Santos’s botanist friend and colleague Orlando Graeff, who first sought out the bromeliad in 2001 after seeing it described in botany journals. As is the case with many of Santos’s friends, Graeff is his senior by decades and shares his affinity for this underdog landscape. Like the Cerrado biome, at first glance the bromeliad seems unimpressive. Yet once you understand how it got here, you can’t help but be amazed at what’s before you, Santos says.

At least 65 million years ago in what is now central Brazil, the earth started pushing upward, forming high plateaus. Over millions of years, shifting climates eroded the soils, stripping them of nutrients and leaving them with high concentrations of iron and aluminum—metals toxic to most plants. Vegetation adapted to the soils and later to the long dry seasons and frequent fires that came to define the biome. Plants developed flame-resistant bark and deep root systems to store water and access nutrients. So much of the savanna’s biomass is underground—70 percent by some estimates—that ecologists call it “the upside-down forest.”

This unique history, combined with the location of the Cerrado in the center of Brazil’s other major biomes, means that it has an extraordinarily high level of biodiversity. Almost one-third of all species found in Brazil and around 5 percent of global plant species grow here. The Cerrado is home to more than 12,000 plants, one-third of which are endemic. Scientists have noted up to nearly 1,000 vascular plant species per acre in parts of the Cerrado, a density few tropical forests can compete with.

Despite the savanna’s botanical riches, most of the 1.2 million square miles were long considered a wasteland. Grass growing in the infertile soil was so nutrient-poor and toxic that it would break the bones of cows that grazed on it, making both ranching and large-scale agriculture impracticable. The area was left to Indigenous peoples, escaped enslaved people called Quilombola, and traditional communities who knew how to subsist in the extreme environment.

Then, in the mid-20th century, Brazil moved its capital from Rio de Janeiro to the central Cerrado. Construction of the new capital, Brasilia, built to be a beacon of modernity, transformed thousands of square miles of native grasslands and savanna. Amid the new focus on the country’s interior, scientists found they could coax the soils into production by using lime, fertilizers, and drought-resistant tropical crop cultivars.

The results were astounding: From 1955 to 2005, the amount of arable land exploded from about half a million acres to almost 100 million, widely considered to be the single largest increase in farmland since the settlement of the United States’ Midwest prairie in the 1850s. Brazil went from a net food importer to a key global food exporter. Soybeans, grown mostly in the Cerrado, are the country’s most lucrative export, surpassing petroleum, beef, sugarcane, and iron ore by billions of dollars.

Agriculture has destroyed more than half of the Cerrado’s native vegetation. What’s more, only 12.6 percent of the biome has some form of protection, compared with 44 percent of the Amazon. “If we compare rates of deforestation to the Amazon, the velocity of what is happening in the Cerrado is much higher,” says Ane Alencar, science director at the Instituto de Pesquisa Ambiental da Amazônia (Amazon Environmental Research Institute). “Current environmental protections are not enough.”

Most of the Cerrado is now privately owned, and laws about how much native vegetation a farmer can clear are lax. That makes establishing new protected areas or expanding existing ones like Pireneus State Park difficult and expensive.

Meanwhile, development is ramping up. Last year deforestation grew by 25 percent, with most of the activity in the Cerrado’s northern reaches, where land is cheaper, and often more intact. Even in Santos’s home state of Goiás in the southern Cerrado, where much of the native vegetation has already been cleared, the hunger for soybeans is pushing agriculture into increasingly vulnerable areas and destroying an evolutionary history that scientists are only beginning to understand.

For the past eight years, Santos has been trekking up and down the Serra dos Pireneus’s steep, rocky paths, noting the birds and their interactions with the myriad ecosystems that make up the savanna. Today we stop and rest a mile in, halfway to the peak, and Santos orients me to the landscape that spreads out like an intricate tapestry below. Where the mountain slope starts to flatten out is cerrado stricto sensu, dominated by tall grasses, hardy shrubs, and crooked trees. In the distance, a line of buriti palms reveals the presence of a vereda, or wetland, where water bubbles up through the surface, creating crystalline pools surrounded by thick mats of black soil. To our left, in a valley dense with trees, he points out the Juçara palm, native to the coastal forest and harvested almost to extinction for its sweet palm heart.

The ledge we’re standing on, Santos tells me, is in one of the most-threatened, least-known ecosystems, called cerrado rupestre. While savanna on rocky outcrops covers less than 1 percent of the region, the cracks, fissures, exposed rocks, and altitude of this micro-ecosystem boast an extraordinarily high degree of endemism. Santos scans the surrounding shrubby vegetation for the birds whose calls liven the air around us, like Rufous-collared Sparrows and Stripe-tailed Yellow-Finches. Suddenly he cocks his head, his body alert. “Oh wow. I think that this is a Checkered Woodpecker,” he says. Native to the Cerrado and South America’s dry Chaco forest, the bird is difficult to see unless it’s making a high-pitched trill, as it is now. Santos trains his binoculars on the drab female, which, lacking the red-tipped crown feathers of a male, is nearly invisible against a tree with gray and brown bark.

A Plain-crested Elaenia swoops out from a tree on the rocky outcrop above us in elegant loops. We watch the gray bird with a yellow belly and conspicuous crest fly back to its perch. It’s a flycatcher, he tells me, like the tyrant that we are looking for.

The Velvety Black-Tyrant is a present-day marker of a deep history that fascinates Santos. It’s one of some three dozen Atlantic bird species that Santos alone has recorded in the central Cerrado, many of which may be limited to the Serra dos Pireneus. Similarly, several birds otherwise found only in the Amazon live in small pockets of forest in the Cerrado. “The Cerrado is called the father of all vegetation in Brazil because it was here before everything else,” Santos says. “Birds are a way to understand something much wider.”

Looking at specimens preserved in botanical gardens and museums all over Brazil and diaries of naturalists who recorded their travels in this region centuries before, Santos has been piecing together what the natural environment used to look like, based in large part on the birds that occupied this area. His results have painted a sobering picture. “What I’ve been seeing is that lots of species that once existed here no longer exist,” Santos says.

That knowledge is hard to come by in Brazil, says Sérgio Posso, a Federal University of Mato Grosso do Sul ornithologist who has been studying birds in the Cerrado and beyond for three decades. Because the savanna has long been considered less ecologically intriguing than the Amazon, only a couple of articles have been published about avian diversity in the Serra dos Pireneus, he says. “The Cerrado in Brazil in general is considered not a forest, not an important place to preserve, because it’s predominantly shrubs and grasslands,” he says. “This lack of interest in the Cerrado also applies to its birds.”

As part of an initiative of the Brazilian Ornithological Records Committee—unrelated to Santos’s work—Posso is updating a comprehensive list of birds found in the Cerrado. Last compiled in 1995, it named 837 birds, around half of those found in Brazil, of which 32 were endemic. Posso’s updated list, only a few months in the making, has as many as 1,000 birds, of which up to 40 could be endemic.

The final tally will likely still be an underestimate, says Posso. While birding has slowly become more popular and the number of bird lists is increasing alongside funding for research, few Brazilians publish their findings in scientific journals, which limits knowledge of avian distribution. At the same time, rapid habitat loss means that Posso’s calculus will be a moving target. “In some areas, we have endemic birds that will probably disappear in 10 to 30 years,” he says. That warning echoes one of the most comprehensive English-language books about the Cerrado, published in 2002. The editors note that, left unchecked, large-scale habitat change in the Cerrado “will undoubtedly limit the breeding ranges of most of these species, while reducing or completely eliminating endemic bird populations.”

Documenting these birds now could help direct efforts to protect them in the future. Because they interact with so many different environments and are so sensitive to disturbances, birds are a valuable bioindicator. In the past few years, researchers have begun using birds to determine what areas of the Cerrado could serve as wildlife strongholds amid future land-use alterations and climate change. The Brazilian Ornithological Records Committee is actively encouraging more people to publish their avian observations, Posso says, which help to bolster science-based arguments for protecting critical habitat before it disappears.

When we reach the top of Pico dos Pireneus, the view is nothing like what French botanist Augustin de Saint-Hilaire, one of the first to survey the region, saw in 1819. He described a vast landscape with no visible settlements except one small town, “an oasis in the middle of a desert.” More than 200 years later we can just make out Brasilia’s skyline 75 miles away, and a ring of bright green squares of soybean and pasture abuts the boundary of the park. “When I started visiting Pirenópolis, like, 12 years ago, there wasn’t soy here,” says Santos. “Now it’s reaching farther and faster than we thought.”

Santos points to an open-pit mine amid a swath of brown grass. Mining occupies a fraction of the land agriculture does in the Cerrado, with more than 50,000 acres mined here in 2020. But the localized effects are often severe, and restoration impossible. The industry is one of the biggest threats for grassland birds, Santos says. A few years ago, where the mine sits now, he observed a flock of Black-masked Finches, a species found only in tropical savanna grasslands and extremely vulnerable to extinction. “I’m not sure how impactful this pit will be for them…,” he says, trailing off. He can only imagine it doesn’t bode well for their future.

Working to conserve the Cerrado has been an uphill battle, says Isabel Figueiredo, coordinator of the Cerrado and Caatinga Program at the Institute for Society, Population, and Nature, a group that works on developing sustainable livelihoods. Key priorities, she says, include guaranteeing recognition of local and Indigenous communities, creating new protected areas, and better enforcing environmental laws.

At the COP27 climate summit last year in Egypt, Brazil’s new president, Luiz Inácio Lula da Silva, pledged “zero deforestation and degradation of our biomes by 2030” and has reportedly explored working with farmers and traders to stop deforestation caused by the soybean industry.

But powerful pressures are fighting against conservation, most notably the agribusiness sector, which accounted for 8 percent of the country’s GDP in 2021. What’s more, Brazil is still dealing with political unrest amid a tempestuous presidential election last year. It remains to be seen if Lula will risk political capital to take on the agricultural lobby, which so far has pushed back strongly on any measure to restrict deforestation.

Creating new protected areas in the savanna is not only politically difficult but also a costly endeavor. In the Amazon much of the land is either public or cheap, and political buy-in is large, whereas most of the land in the Cerrado is private and expensive. Politicians face pushback in trying to protect a biome whose value is largely unknown to Brazilians and that many see as best suited for agricultural production. Organizations like The Nature Conservancy, which buys up large tracts of land, have successfully created parks in the Cerrado. Internationally, however, conservationists struggle to attract interest and funding for safeguarding this critical biome.

Aside from establishing new parks, one of the most lasting ways to protect Cerrado habitat entails protecting the land rights of the Indigenous, Quilombola, and traditional communities who live in the biome. They sustainably manage large amounts of native Cerrado vegetation surrounding their communities, but many of those communities lack land titles and risk falling victim to the rampant land-grabbing that accompanies the expansion of the agricultural frontier. “They are protecting the Cerrado with their own bodies,” Figueiredo says. Together with the Cerrado Institute, and the Amazon Environmental Research Institute, her organization has mapped 20,000 families so far using a cellphone app that helps communities start the process of gaining official land titles. And in April of this year, Lula signed six new Indigenous territories into existence, one of which was the 77,000-acre Ava-Canoeiro territory in northern Goiás.

On the peak, a raincloud converges, splattering small, hard raindrops on the pale, naked rock. A distant flash of lightning spurs us down the mountain.

The sparse vegetation offers little cover as we descend, Santos as sure-footed in flip-flops as I am in hiking boots. Near the trailhead, he steps over a flat rock with a brown protrusion. It moves slightly and I stop to look at a young pit viper, inches from where Santos just tread. “Oh cool,” he says, doubling back. “These are rarely this visible.” He takes several videos; then, almost as an afterthought, he brushes his hands briefly over his naked ankles to make sure he wasn’t bitten, his face registering delayed shock.

The rain briefly subsides as we reach the car, and Santos scans the landscape one last time for the Velvety Black-Tyrant, with no success. His disappointment is evident as he slides into the car. Still, he says as we inch our way down the slick dirt road, he’s glad we spotted the Checkered Woodpecker. It’s a common enough sight and he has no doubt he’ll see it again. As for many of the other birds in this ancient biome, still unknown to so many, he’s not as sure.

This story originally ran in the Summer 2023 issue. To receive our print magazine, become a member by making a donation today.