The Kingdom of Rarities (26 page)

After lunch and a short drive, we arrived at a soy plantation that bordered the park. We stepped out of the car and into a completely different environment. Walking among the neat rows of soy, I asked Carly how many planters grew soybeans on farms adjacent to Emas. Gauging by my experience with rice cultivation in Nepal, I expected the answer to be in the hundreds. I was off by two orders of magnitude. Carly held up one finger. “This 40,000-hectare ranch is owned by one person. There probably aren't more than a few landowning entities in this entire area.”

Big soy. It was my first encounter with such a vast expanse of agriculture. The lucrative plants covered the entire landscape. Corn grows here also, and in some parts of the Cerrado cotton is added to the rotation. The soybean is a recent addition to the farming economy of the region.
Glycine max
, as it is known to science, might have been more aptly named
Glycine “min”
until a few years ago, when crop and soil scientists figured out that the addition of lime to reduce soil acidity enabled the conversion of pasture and cattle ranching to soybean cultivation. As a consequence, the nitrogen-fixing legume began to prosper in areas where it could not grow before.

Brazilian farming practices changed almost overnight. Brazil has become the second-largest exporter of soy, after the United States. Much of it is exported as soybean oil, the most widely used cooking oil, or soybean meal, which has many uses but largely is fed to cattle. Producing high yields requires extensive use of fungicides, which are applied every few days. The corn grown in the next pasture was subjected to heavy doses of Roundup to control weeds. Pesticide use was rampant. White-tailed hawks and some kestrels flew by, but raptors and other birds were few. The agrotoxins may have already thinned their numbers. Perhaps a rumored decline in the bird fauna here, however anecdotal, is an early warning signal as to what lies ahead for surviving Cerrado wildlife.

That night at dinner with Leandro Silveira, Anah, and their team of researchers, the conversation focused on big mammals, beginning with rhinos and elephants in Asia and Africa. “Our biggest
herbivore in Brazil is now the tapir,” Leandro noted, “small by megaherbivore standards.” A tapir is about the size of a large pony, with a pig-shaped body. Leandro was pointing out one of the great anomalies of nature. Even though there are more mammal species in South America than anywhere else, large mammals are even rarer here than in other parts of the world. In truth, most South American mammals can fit inside a shoe box. Of course, there are important exceptions that are considerably bigger—the larger primates, peccaries, capybaras and other large rodents, deer, and larger predators—all of which are well documented as having a major impact on their surroundings.

It was not always so. Paleontologists tell us that we are simply several million years too late to witness the South American Serengeti. Back in the Pliocene epoch, about 5.3 to 2.6 million years before the present, a rich megafauna filled South American forests, savannas, and pampas. Giant ground sloths rose up on their hind legs like giraffes to browse tree branches. Swamp mammals the size of hippos and rhinos crashed through the canebrakes. Across the grasslands galloped camel-like creatures. Around the waterholes lurked long-fanged marsupials that shared a common ancestor with opossums but bore a remarkable resemblance to saber-toothed cats.

The large mammals were basically done for before humans arrived, likely as a result of climate change. During most of the Age of Mammals—when the class Mammalia first evolved about 60 million years ago, after the ebb of the dinosaurs—South America was a continental island, and its unusual mammalian fauna evolved in isolation from the fauna of other continents. The first and probably greatest wave of extinctions occurred during the Great American Interchange about 4 million years ago, when the Isthmus of Panama rose above sea level, and resulted in a massively biased colonization. North American mammals flooded into South America and are now major components of the fauna (the maned wolf among them). Many fewer South American mammals became established in North America, and today only three species
—the Virginia opossum, the porcupine, and the nine-banded armadillo—still survive there. Interestingly, two of the three species of our focus in this chapter—anteater and armadillo—are remnants of that native South American fauna.

When the renowned paleontologist George Gaylord Simpson came out with his 1980 classic
Splendid Isolation: The Curious History of South American Mammals
, he highlighted the divergent route South American mammals took in evolution because of physical barriers posed by the oceans and the flooded isthmus, as well as by the Andes, high deserts, and rain forests. These virtual fences prevented the mixing of the fauna. Thirty years after the publication of his work, intensive human activities including agricultural expansion, settlement, and transportation infrastructure, rather than mountain ranges or large rivers, have become the great isolators. The results, too, threaten millions of years of evolution. The IUCN Red List now includes many formerly common species that cannot persist in human-dominated landscapes, such as many antelope species and other large, hoofed mammals that used to migrate across large grasslands.

I asked Leandro and Carly to assess which of the mammals they were studying would survive in the face of expanding agriculture. I wondered if it was an ecological stretch for the grassland-loving mammals to occupy soybean fields, should landowners happen to allow it. Alternatively, I wondered whether some might be preadapted to colonize and persist in another open habitat, albeit one with a monoculture of soy, or on cattle ranches where the grass was cropped to the ground.

Carly's scat data showed that the answer varied, depending on the species. Maned wolves preferred Emas's grasslands and avoided closed-canopy forests inside and outside the park. Surprisingly, maned wolf scats were quite common out in the soy, however. She attributed the presence of the species there to the abundance of rodents, its dietary staple. Soy acted like natural vegetation and gave the rodents shelter. As long as they could go a-ratting, the wolves
seemed to do fine in the croplands. Carly noted, “In spite of its shy nature, the maned wolf is adapting to expansion of agriculture.” Maned wolves are common in Brazil's agriculture-dominated landscapes, at least those of soy, it seems, because they are not persecuted as is the gray wolf in northern climes. Maned wolves tend to avoid cattle ranchlands, though, as those lands are too bare even for rats.

In contrast, the giant armadillo had no use for soy plantations. Giant anteaters also avoided the agricultural fields, but they visited the cattle pastures because these appeared to have greater populations of ants and termites. Ranchers often left the termite mounds and ant nests intact, and the long-snouted opportunists showed no hesitance in excavating their dinner in man-made habitat. Giant anteaters were also more common where ranchlands abutted riparian forests. The shaggy creatures entered these forests and bathed in the water to cool down. Jaguars tended to stay inside the park but occasionally wandered into nearby fields. Pumas spent more time outside the park in areas with heavily forested groves lining rivers and streams. Tapirs liked to be near springs close to the remaining forest fragments outside the park.

Overall, the landscape matrix in this region was friendlier to rarity than most pessimistic biologists would have predicted. Some of the large mammals survived massive land-use change in the Cerrado because enough bits of natural habitat remained in the matrix to meet their needs for food and cover. How long these vital pieces would remain before becoming soy or sugarcane fields was an open question. Leandro was lobbying in favor of forever. He is one of the few muddy-boots biologists who has learned to rub elbows with lawmakers, and he spends as much time working with them as he does tracking jaguars. Leandro practices what the best conservation biologists preach, that conservation is 10 percent science and 90 percent negotiation. He had fought hard to enact the current federal law requiring landowners to keep a minimum of 20 to 30 percent of their property in natural vegetation, as well as to keep their
hands off development of river- and streamside forests. Depending on topography and drainage systems, this measure potentially protects more than 35 percent of the Cerrado outside the reserves.

The Round Table on Responsible Soy Association, an effort to bring together all the big soy producers, conservation groups, and the Brazilian government, is trying to make cultivation more harmonious with nature conservation. Leandro's first step was to convince the group that the best-practices goal of leaving 20 to 30 percent of land as natural habitat would help the maned wolf persist in the Cerrado. It would be ideal if the protected areas were in contiguous blocks connecting ranchlands in one area to those in another. Carly worried that all of the set-asides would be in forests because including grassland in the 20 to 30 percent mix of intact land would bite into the profits of the ranchers. Under the current system, the big producers would benefit most by converting to agriculture as much grassland habitat as allowed. And that is what is happening. Even with a law that sounds good on paper, legislation that is not based on strong science will have uneven results. The current law could conserve good jaguar and tapir habitat outside reserves but do little for the grassland-dependent maned wolf.

The next morning, we were out early again with Mason. We stopped at a huge hole in the ground. Here were the signature diggings of a giant armadillo, one dedicated earthmover. “There must be an ant nest or termite mound nearby,” Carly said. Giant armadillos often excavate burrows to reach under the nests of their favorite prey. Few people have ever seen a giant armadillo aboveground or in a zoo, so it's hard to picture one. A good start would be to multiply the size of the common nine-banded armadillo by ten. The nine-banded armadillo, the unofficial state mammal of Texas, is among the most common roadkill along highways in the state. If striking a poor nine-banded would feel like rolling over a speed bump, hitting a giant armadillo, which can weigh up to 60 kilograms, would be like smashing into a retaining wall. Fortunately, giant armadillos tend to stay clear of roads in the Cerrado, though some
are run over by passing vehicles anyway. Unlike the nine-banded, which ranges across much of the southern and southeastern United States all the way to Argentina and parts of the Caribbean, the giant armadillo is limited to South America. There it ranges widely into the Amazon basin, where very little is known about its habits and needs. Most likely, though, giant armadillos, which are both rare and considered by the IUCN to be threatened, thrive in the drier portions of the range, in Venezuela, the Cerrado, and the Chaco region, which extends into Paraguay.

Carly and Mason found nearly sixty scats of this subterranean mammal. Together with the data from Leandro's team, which was the first to radio-track the species, giant armadillo ecology moved beyond the anecdotal phase. Even though tracked individuals proved to be largely nocturnal, this armadillo turned out to be the most sensitive of the large mammals to human disturbance. Not surprisingly, it shuns life in the soy fields. Leandro and his coworkers found that the home ranges of five individuals were about 10 square kilometers and put the density of armadillos in Emas proper at about 3.4 animals per 100 square kilometers, more akin to the densities of a top predator such as a jaguar than of a species that eats more abundant ants and termites. “Just like the anteaters, giant armadillos also have low birthrates,” Carly mentioned. In the scientific literature, low reproductive rate is not itself viewed as an initial cause of rarity, but as we saw with the greater one-horned rhino, serious depletion of a population hampers rapid recovery and can leave the species more vulnerable to extinction.

At lunch, Carly and I discussed the peculiar habitats of the guild of ant- and termite-loving mammals. Mammals that subsist on the social insects are few in number and restricted to the tropics and subtropics, but their taxonomic spread is remarkable. Biologists call different groups that feed in a similar way an example of “convergence”; the various species that fill the termite-eating niche (or any analogous niche) are said to be “ecological equivalents.” In South America, anteaters and armadillos, of the orders Pilosa and
Cingulata, respectively, are examples. Africa is home to the aardvark, the sole living member of the order Tubulidentata; the aardwolf, a hyena relative; and pangolins, or scaly anteaters, also in their own order, Pholidota. Asia also harbors pangolins and has the sloth bear, a true carnivore and a termite connoisseur. Australia and New Guinea have the spiny anteaters or echidnas, which represent the monotremes, and Australia's bandicoots represent the marsupials (though the most prevalent and species-rich termite-eating animals in Australia are not mammals but lizards).

Little is known about the ecology of pangolins, aardvarks, aardwolves, and sloth bears, but evidence indicates that where there are termites, the density of termite eaters can be impressive, even if their mostly nocturnal behavior makes them hard to see. Some, such as pangolins and sloth bears, are hunted for body parts used in folk medicine, and pangolins and armadillos are hunted for meat. Some of these species, including the sloth bear and some pangolins, are considered threatened by the IUCN. Without human pressures, then, the ant- and termite-eating contingent of the mammalian fauna might be even more common.

Back at the guesthouse, I had left my sneakers near where Mason was resting on the porch with his besotted curassow. “Be careful not to leave your shoes out at night,” Carly warned. “The maned wolves steal them and chew them up for the salt.”

I needed my shoes for the drive Carly was organizing for one of my last nights on the Cerrado, a trip to spotlight tapirs, crab-eating foxes, and the most important target, the maned wolf. Carly often searched along secondary roads, a mode of travel used by maned wolves that frequented the croplands. Giant armadillos, giant anteaters, tapirs, and pumas, however, avoided roads as much as possible.