The Kingdom of Rarities (25 page)

The purpose of Carly's study was to determine how wide-ranging, low-density species such as maned wolves, jaguars, and pumas navigate the countryside and to learn how they circulate among the highly altered and fragmented habitats outside reserves. She also wanted to learn whether these wild species can shift from living in natural grasslands and adapt to feeding in soy fields and cattle ranches. Finally, using maned wolves as a test case, she wanted to learn if animals that live in the Ag are more stressed, less healthy, or less reproductively active than individuals that live inside the park. New techniques that Sam and Carly were developing back at the lab allowed them to measure health from hormones extracted from the dung. If Carly and Mason could find enough scats of this grassland wolf, this charismatic species might be the most revealing one to study.

Biologists use the terms “source” and “sink” to define the dynamic at work here in the Cerrado. Source sites are places where recruitment, or population increase, exceeds mortality. The expectation is that maned wolves have greater breeding success inside Emas than in Ag land, but because the park is too small to hold all the individuals born in the reserve, breeding individuals must spill out into the surrounding landscape. Sinks present the opposite situation, in which maned wolves (or members of another species) emigrate from the source to a location where they die in higher numbers than are recruited into the local population. With not enough large, preferably linked sources, and too many sinks, the species eventually will die off.

Some biologists avoid following their species into farmland or altered habitats. But in order to answer her questions, Carly randomly selected sampling routes that wound through the park as well as an additional 4,000 square kilometers of soybean fields, cattle ranches, and forest fragments on adjacent private lands. Curious about this woman and her dog, the local ranchers agreed to allow her to roam freely.

Within weeks after arriving in Emas, Mason had made the Cerrado his home, adapting well from a stint in the bitter cold of the
Canadian Rockies, where he had worked on wolf, caribou, and moose scats. Now he was in the dry oven of the Cerrado and was mastering Cerrado mammal spoor: puma, jaguar, giant anteater, giant armadillo, and maned wolf. To train Mason on tropical mammals, Carly had obtained sample scats from zoos in the United States and from Leandro Silveira, the dean of Brazilian carnivore biologists, and his biologist spouse, Anah Tereza de Almeida Jácomo, whose home base was Emas.

When Carly told her friends about her project, they all expressed admiration for the maned wolf. The maned wolf, though, it should be said, is not actually a wolf at all, bearing no relation to the gray wolf. The vivid red fur, trimmed in black and white, and the lovely mane of this Cerrado carnivore make it one of the most striking of mammals. The showstopper is to watch a maned wolf 's aristocratic gait—a smooth trot on its strikingly long legs that matches the elegance of its coat. Nothing else on nature's runway compares to this handsome wild canid.

If the maned wolf is not a wolf, and the giant anteater an evolutionary oddity, no mammal is as strange as a giant armadillo. Its armorlike plating and bullet-train shape make it the perfect inspiration for a futuristic subterranean vehicle. Its huge claws, designed for digging its way through the underworld, are also impressive. Few biologists had ever studied this species before, and those who did mostly focused on its burrowing behavior and diet. Few had even found one alive, with or without the help of scent dogs. George Powell, our jaguar tracker from Peru (chapter 3), told me that once his research staff had heard loud snoring sounds coming from a burrow. They crawled in and pulled out a sleeping giant armadillo. Leandro Silveira also had an anecdotal encounter. But that was the extent of giant armadillo natural history—a few paragraphs.

These three rare mammals can all be described as unusual looking. So one might wonder if odd body plan, at least to human observers, is a predictor or correlate of rarity. I asked Carly about the link between countenance and ecology of giant armadillos, giant
anteaters, and maned wolves and what it might tell us about rarity. Her answers had as much to do with the energetic balance of these mammals as with their appearance.

Maned wolf (
Chrysocyon brachyurus
) being followed by an aplomado falcon (
Falco femoralis
)

“Even though these creatures eat different things, they specialize on food items that just don't support high densities of big mammals,” she responded. This, not appearance, is key. Giant anteaters and giant armadillos are equipped to feed on ants and termites. While their food resource is ubiquitous, it is also of low nutritional quality (with some exceptions, such as fat-filled winged termites). The physiological and behavioral adaptations of these animals to their food resources may account for both their looks and their rarity in nature.

Giant anteaters have low metabolic rates relative to their body size. One consequence of their slo-mo lifestyle is that they produce only a single offspring at a time and only every other year. They occur at their highest-known densities in grasslands where their food resources are concentrated. But even here, anteater populations are
severely constrained by the wildfires that regularly burn through. So even where their favorite foods—ants and termites—are highly concentrated, giant anteater populations are often knocked back by killer fires racing across the pampas.

Maned wolves, which are restricted to the grasslands of central South America, also occur at naturally low densities, half of our two-part condition of rarity. The maned wolf is the largest canid that does not hunt prey larger than itself. Its body mass may well be the limit at which a canid is able to survive on small prey—primarily rodents, birds, and armadillos, heavily supplemented with fruit. To meet their dietary demands, maned wolves traditionally forage across large home ranges of about 70 square kilometers, thus contributing to their natural rarity.

These unique adaptations—the elongated, toothless skull of the giant anteater that accommodates its extra-long ant-lapping tongue; the large claws of the burrowing giant armadillo, used for ripping open termite mounds; the fox-on-stilts appearance of the maned wolf—can be viewed in a new light. These striking features are all the evolutionary products of highly specialized feeding behaviors. Might they be unfavorable attributes in a changing world? An intense specialization on a highly patchy food source, such as termite mounds, works only if the species in question—in this case an anteater—can move effectively between patches. Thus, if the species is to thrive here in the Cerrado, surrounding ranchers would need to keep the termite mounds in their cattle pastures and anteaters would need corridors to reach these patches of rich termite concentrations. The long legs of the maned wolf might allow it to travel long distances easily and pounce effectively on its abundant prey. Being a medium-sized predator but basically subsisting on abundant small mammals such as rats means that you could find your principal food source in any open habitat. Natural selection may have no foresight, but it seems to have left the maned wolf a better chance of survival than the other members of the Cerrado trio.

Before heading out in the morning, Carly checked her data sheets and GPS unit and strapped on her snake guards. She counted
the bottles of drinking water on hand for us and Mason, and we set out. When we reached her starting point on the transect, Carly released Mason with the command “Let's go to work!” Nose and tail in the air—the posture of a skilled scent dog—Mason trotted off into the grass.

The scent dog weaved back and forth across the route, off leash but always within sight of Carly. Within minutes, he came running back to fetch us. Then he raced back into a grassy area under some trees and sat down with his nose pointing a few inches away from a pile of maned wolf dung. Despite being an excellent fieldworker, Carly admitted she would have walked right past this scat had she been on her own. She immediately praised the dog and set about collecting the scat and noting its location on her GPS unit. The Cerrado project marked only the second time scent dogs had been called to duty outside the United States and Canada and the first under the tropical sun. By the end of a six-week pilot study here in 2004, three dog-handler teams had collected more than 650 scat samples from pumas, jaguars, and maned wolves. Their initial success made them believe that this novel technique could work well in the hot Cerrado.

We stopped for a break so Carly could give Mason a drink of water. The bells on his collar jingled as he lapped up the water from his bowl. The bells were a holdover from his grizzly work, a safety precaution designed to warn grizzlies that the team and Mason were near. Here in the Cerrado, Mason had wakened sleeping giant anteaters, and the nearsighted creatures merely ignored him and moved on as Mason retreated. He had also roused tapirs dozing in the grasslands, and Mason gave them a wide berth. Once he came face-to-face with a coiled rattlesnake, but Carly gently called him back to her side and the curious dog left the snake alone.

Here, the main reason for the bells was to warn off herds of peccaries. Only two months earlier, Mason had had a potentially fatal encounter. He was plowing through the grass and ran into a large gang of fierce peccaries. One turned and attacked, slashing Mason across his rump. Fortunately, Carly was close by and rushed Mason
to the vet. After a few weeks of rest, Mason was ready to return to action, more wary of peccaries than ever before.

When we returned to camp, Carly took out Mason's bowl and fed him his ration. Rather than put him back in his holding crate for his afternoon siesta, she left him on the porch, tethered to a post by a long chain. Out of the nearby forest came a female black-and-white curassow. This heavy-bodied, sharp-clawed ground dweller was a favorite of local hunters but not a bird to mess with. She made her way over to where Mason was resting, but rather than claw at him as a possible predator, she snuggled close. According to Carly, this had become a daily routine. The male black-and-white curassow is all black, like Mason, and she may have seen him as a larger version of a possible mate. A female curassow in love, but one with a mean streak. This same female had run down one of Leandro's roosters and killed it.

The next morning we left Mason and his curassow flame snuggling on the porch while we toured Emas by car. We drove a long way to the northern border of the park but saw no anteaters or rheas. Their absence surprised me because we came upon huge numbers of termite mounds sticking up in odd funnel-like shapes. The mystery of the missing anteaters had a gruesome explanation. A catastrophic grassland fire had swept across Emas in 2005. The long fur of the anteaters had turned them into panicked torches, and five years later the population had yet to recover, in part because of their slow breeding pattern.

A central tenet of park design is to create reserves large enough to allow wildlife populations and natural processes, such as fire, to fluctuate naturally, with little or no human intervention. In this case, Emas would need to be several times larger than the area burned by the worst grassland fire of the century. An alternative design scenario would require that Emas be well connected by habitat corridors to other anteater reserves, to maintain a resupply route if a population inside a reserve is decimated by fire, poaching, or disease.

Somewhat discouraged by the lack of wildlife, we headed for lunch at a canteen attached to a run-down pool hall on the park's
outskirts. Over a meal of rice,
plátanos
, and beefsteak, I mentioned that my Serra da Canastra birding trip, with its added sightings of maned wolves and giant anteaters, had sparked the collective curiosity of the van passengers. Together with Wes Sechrest, then head of the Global Mammal Assessment project of the International Union for Conservation of Nature and Natural Resources, John Morrison, David Wilcove, and I wondered: How many places on Earth still support the same roster of large mammals that were present there 500 years ago? Is Emas one of them? The question has an important relationship to rarity because 39 percent of large mammals with body mass greater than 20 kilograms (a maned wolf weighs in at around 23 kilograms) are considered threatened with extinction, as compared with 25 percent of mammals overall. Theory and lots of empirical data tell us that bigger mammals tend to be more wide-ranging than smaller mammals, and as George Powell had shown in Peru, most parks are too small to support them. With hunting of large mammals common almost everywhere today, the answer to our question, we speculated, could well be zero or at best very few places left on Earth with intact large-mammal faunas.

But the results of our research on the topic were more optimistic than we expected. The article we published in the
Journal of Mammalogy
in 2007 reported that 130 places on Earth serve as large-mammal refuges and that they support the full roster of big mammals that lived there 500 years ago. These refuges fell into two categories. One category included the most inhospitable places on Earth, places that were too cold, too damp, too dry, too humid, or too remote for humans to develop. This group featured vast regions of Siberia, northern Canada, Alaska, and the Amazon and Congo basins. The other group included a much smaller set of places, including Emas—remnants still afloat in human-dominated landscapes. We made no claims about whether the species survived at carrying capacity in these places—often they were present at much lower numbers or densities than in the past. It was clear, though, that places such as Emas would need intensive management to maintain the rich large-mammal fauna still present.