The Kingdom of Rarities (27 page)

The drive through the park grasslands turned up very few animals, but once we crossed over into searching the soy, sightings increased dramatically. Crab-eating foxes were everywhere and quite approachable. Nightjars, a kind of nighthawk also known as
goatsuckers, sat on the roads that had been baked by the day's sun to stay warm in the chilly night. Carly said she had often spotlighted tapirs out in the Ag, but we saw none. More crab-eating foxes. These canids were certainly attractive, but we wanted the red fox on stilts, the maned wolf.

On the secondary road bordering the edge of Emas, Carly swung her spotlight in a wide arc. The driver slammed on the brakes, and all of us standing in the back of the open-air pickup lurched forward. A maned wolf stopped and then resumed sauntering along the road. For the next twenty minutes we motored along a road inside Emas, the wolf just outside on a parallel road bordering the soy. We were all surprised at how effortlessly the wolf kept up with the vehicle; we were moving at nearly 16 kilometers an hour, and the wolf seemed to maintain its graceful rapid walk. Finally, it slipped back into the soy. On the drive back to camp, the image of the dashing wolf stayed in my head, and it remains in my memory as vivid as ever.

Ten months later, in May 2010, I had a chance to stop in Seattle and again see Carly, who was in the last stages of completing her dissertation, and Mason, now officially retired (at the age of six) from his scat-searching expeditions. Carly had just answered one of her research questions with some final lab work on maned wolf hormones: Were the maned wolves that lived in the soy fields less healthy than those that stayed within the boundaries of Emas National Park? Carly bubbled with excitement over her findings. “The thyroid hormones from wolves in croplands are actually higher than from those in the park.” High thyroid hormone levels were a good thing, and thyroid levels are useful indicators of nutritional status. The story emerging from Carly's work was that the maned wolves were selecting croplands for hunting rodents, partly because the hunting was easy and efficient. But there was more. Carly had discovered that the cropland wolves had higher levels of cortisol,
indicating that the Ag land was also more stressful for that species to live in. So the soy fields may be an ecological trade-off for this elegant animal. Abundant food awaits in the soy, but so does the stress of leaving its natural habitat and venturing into the human landscape, where perhaps it feels more exposed and vulnerable.

We compared notes about how natural landscapes were being transformed in the places we had been working. I mentioned the vast plantations of oil palm and acacia (cultivated for pulp) I had just seen on Borneo and Sumatra. “Remember the soy plantation we walked through looking for wolf scat?” Carly interjected. “In one year, it changed over to sugarcane.”

Does it matter to rare grassland mammals if the agricultural expansion involves sugarcane, soy, tapioca, or cacao? To the Cerrado trio, the answer is yes. The conversion of low-growing soy to sugarcane will shake things up ecologically, Carly explained. With the soy, there is a relatively welcoming landscape matrix for the wild animals in the region. “But when converted to sugarcane, it becomes inhospitable to an open vegetation–adapted species like my wolves.” Compared with soy, sugarcane is a longer-growing crop between harvest periods, and it forms tall, dark stands, which entails loss of the open-landscape qualities mimicked by soy fields that are conducive to species such as the maned wolf. Sugarcane also requires more manual cultivation, and factories may be built to handle the cane on-site, so it could become a magnet to draw in workers. Carly didn't sound hopeful. “I see conflict as animals try to avoid humans, and as poachers seek out the wildlife that wanders into the Ag.”

In Sumatra, I had spoken to David McLaughlin, an agricultural expert for the World Wildlife Fund who had worked in tropical agriculture all over the world. I asked him how agribusiness can maintain, year after year, the commodities we use without tropical nature evolving innovative pathogens and leaf pests to attack the widespread cultivated plants. Every crop plant has legions of pests, some minor, some fatal if not controlled, he replied. “For your oil
palm, it's lethal spear rot, found in South America in the 1980s but not yet present in Southeast Asia. Cacao trees have all sorts of things that can hit them. And tropical soy needs constant vigilance against fungi and herbivores.”

“So,” I continued, “you mean if some careless biologist introduced a pathogen into a soy or oil palm plantation, it could wipe out the whole place and native vegetation would return?” David eyed me suspiciously. What Carly had observed around Emas foreshadowed his answer. “Remember, commodity production can turn on a dime. Even if a crop pest attacked soy, farmers could shift immediately to growing sugarcane for biofuels. And if the sugarcane succumbed, they might go back to cattle ranching or corn.” The point is that land once converted to agriculture will likely never go back to native vegetation but rather will be converted to the next big monoculture. The same holds true in the vast oil palm developments in Southeast Asia. Those that fall to some new pathogen will probably be replaced by acacia trees for pulpwood or return to rubber. The commodities are never stable, but the pressure applied by the growing human footprint is mounting. In the meantime, programs designed to enhance wildlife-friendly certification of major cash crops—whereby consumers know that production of the crop has avoided the conversion of natural habitat to produce it—is still years away.

The Cerrado story helps us put countryside biogeography, or matrix conservation—or whatever term we create to describe the landscape approach to conservation that considers species both in parks and in the human-dominated areas outside of formal protection—into a larger context. Many species that do fine in wild habitats can persist in adjacent farmland dotted with pockets of natural vegetation. This is especially the case where riparian zones are protected from development. But for how long? Perhaps our assumption that various species will persist in agricultural lands is an ecological mirage: it may be that they will merely hang on for another decade or two and then start to decline as a result of pesticide
residues, stress, or other sources of mortality. Furthermore, species that survive in human-dominated landscapes tend to be generalists, not the specialists or the rarities that this book portrays. Carly believes that upholding the Forest Code of Brazil is key, that it is these scattered remnant habitats that enable species to use the landscape as a whole. The future challenge of agroecology is to identify the opportunities for mutual accommodation and its limits—in the Cerrado and elsewhere as well.

The scale at which the face of Earth is being converted from natural habitats to cultivation and the pace of it are truly staggering. Global projections are that with 9 billion people on board Earth, world food demand will double by 2050, and the Cerrado will play a key role. Yet most people are unaware of the enormity of agriculturalization and other habitat encroachment. Various small-scale local accommodations, even if increased in number, may not be enough to protect wild nature. A hidden aspect of this problem is the scale of buy-ups of land in the tropics and elsewhere by corporations and nations as they position themselves for the future of their food supplies.

So the problem grows larger: wholesale conversion of land not only threatens to make no small number of common species rare through human activity; it also threatens the very existence of what is now rare. One has to hope that the rare species of the Cerrado and other areas of intensive cultivation are more adaptable than we think and that efforts to enable coexistence on working lands, by habitat protection and then by best practices on and near agricultural lands, will enable persistence. It would be a shame for others to lose the chance to observe the remarkable silhouette of a giant anteater or the outline of a graceful maned wolf on a moonlit night in the Cerrado.

A
BOUT A CENTURY AGO, SUGARCANE PLANTERS
in Hawaii faced major crop losses from a teeming rat population. Their solution seemed practical at the time: import the South Asian common mongoose—by way of Jamaica—to eradicate the vermin. The planters unfortunately selected the wrong control agent, with disastrous consequences. The diurnal mongooses were exposed as abysmal predators of the nocturnal rats (which at an earlier time had also been introduced into Hawaii) but avid consumers of the eggs and nestlings of native birds, many of them rare and found nowhere else in the world. It was too late to correct the mistake; the mongooses had been set free on all the main islands except Kauai. En route to that island, a wise official is said to have dumped the mongooses overboard. Stuart Pimm, an expert on Hawaiian extinctions, corrects the account in this way: “The mongooses
intended for Kauai bit the fingers of the boatman and he drowned them. That's why they never made it there.”

Hawaii's imported rats and mongooses are part of a group that ecologists term invasive exotic species. These interlopers have the ability to outcompete native flora or fauna when they are introduced into an ecosystem where they do not occur naturally. Every continent has them; in North America, some of the worst invasives are plants such as purple loosestrife from Europe and kudzu from China. In Nepal, the explosion of mile-a-minute vine from South America threatens to drape over much of the greater one-horned rhinoceros's prime feeding areas. Rabbits and red foxes are invasive exotic mammal species in Australia. Some species come to or are brought to a land and have no effect on the local flora and fauna, but others crowd out or kill off native species, not infrequently rare ones, and those obviously are the ones of great concern. Introductions of mammals onto islands—giant ones such as Australia or small archipelagoes such as Hawaii—have nearly always been disastrous because mammals, as we saw in Peru and Nepal (chapters 3 and 5), are the prime ecosystem engineers everywhere.

Fortunately, most mainland mammals—be they mongooses or monkeys—and many reptiles and amphibians and even ants rarely occupied distant islands before human navigation. The exceptions are continental islands that were once connected to a large landmass, such as those islands that were part of the Sunda Shelf, once connecting Southeast Asia that sits west of Wallace's Line, and another once linking Australia to New Guinea by a land bridge (see chapter 2). There are good reasons why this is so: most terrestrial creatures simply can't swim far enough or survive the passage from the mainland by clinging to a raft of floating vegetation, although snakes and lizards are much better at it than mammals. Terrestrial mammals (with the exception of bats) and amphibians are especially poor dispersers over marine barriers for another vital reason: like humans, if they drink seawater they lose more water in trying to excrete the excess salt ingested. Here, two lines from Samuel Taylor
Coleridge's
Rime of the Ancient Mariner
are as apt as basic physiology to explain the conundrum: “Water, water, everywhere, / Nor any drop to drink.” In the absence of most terrestrial mammals, different ecological worlds evolve. For example, there are places without large cats as top predators, such as on the islands of Komodo and New Caledonia. Komodo has a dinosaur ecosystem where a large monitor lizard has become the apex predator, even hunting mammals. In New Caledonia, in the absence of mammalian predators, the geckos of the island have undergone a divergence of species, the largest of which has become the “tiger” of the island, eating smaller vertebrates.

Even the most remote archipelagoes that, like Hawaii, have never been connected to a mainland, however, experience waves of potential invasions by various species. Some come as stowaways on human-powered vessels, like Polynesian rats, or, like the mongoose, are deliberately introduced. But dispersal is a natural process that happens without human assistance. Some colonists do survive on floating mats of vegetation, carried by the ocean's currents to their new destinations. The vast majority of natural colonizations fail, however. Most species drown en route or die of dehydration, as already noted, or starve to death soon after arrival, or fail to find a mate or to leave enough offspring to carry on. This chapter focuses on the devastating effects of successful invasive species and the ecological disruption they cause to island life, especially the rarities endemic to the islands.

Invasive species can disrupt local ecologies anywhere, but for several evolutionary reasons they often hit remote oceanic islands especially hard. Being a great disperser allows a species to colonize a remote island such as Hawaii. But once there, in the absence of significant predators, natural selection strongly favors against dispersing offspring because they end up drowning if they head out to find new places to live and breed. One outcome is that on oceanic islands flightless birds and insects have repeatedly evolved. A paradox of nature: once arrived on such an island, it is better to become
sedentary, but as a result, those species that do are more vulnerable to predators that are later introduced.