The Secret Wolf
by Louise Emmons
with Sharon L. Deem, Melissa Rodden, and Jesús
Maldonado
On a black humid night in the Bolivian pampa, I know from the blasting of the radio signal in my earphones that Beatriz, the radiocollared maned wolf that I am following on foot, is but a few yards away. I twist down the control knob on the receiver until I hear no sound, but I watch the frenzied jumping of the needle on the meter, and point the antenna toward where she must be standing, perhaps listening to me. I have been following her since late afternoon, before she stirred from her cool daytime den; and now it is two in the morning, and neither she nor I have rested since sundown. She is just returning from a water hole where I know she has gone to drink. I hope our automatic camera there caught her in the act, because she outpaced me when she headed for it two hours ago from four kilometers (about 2.5 miles) away, and I lost time climbing trees to capture her vanishing signal.
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| Scientists set up camera traps on the Bolivian pampas to capture maned wolves on film. (Louise Emmons/NMNH) |
Now she is on her way back. I hear nothing but chirping insects. Briefly pointing my headlight toward her, I see nothing at all. I turn off my light and stand immobile for minutes, not wanting to interfere with her behavior. Then I notice from the radio signal that she is resting (its sensor changes the signal when she moves), so I carefully sit down, drink some water, take out a tiny penlight and a book, and read for 90 minutes, thankful for rest, while she stays motionless, apparently relaxing in the bushes only a few yards away. When she starts to move again, she does so with such extreme slowness that it is a while before I am sure that she has budged. She must be hunting. She detours slowly around me, her radio signal so loud that I feel I could touch her; but I see nothing, not a glint of eyeshine nor a flash from the reflective tape on her collar, and I hear not the slightest rustle in the grass. From dusk to dawn I may not see her. If I do, she is totally casual and unafraid, walking calmly away after giving me the once-over as if saying to herself: "Oh, it’s you again—have you nothing better to do than wave that antenna around?"
Maned wolf: Does the name ring a bell? How about aguará guazú, lobo de crin, borochi, or lobo-guará, as these animals are called in various parts of their wild range, or Chrysocyon brachyurus, as scientists dub them? If not, you join most people, even in the countries where this species lives. It seems amazing that a wolf could live among us so little noticed, especially one so striking as a maned wolf. Standing a yard at the shoulder, as tall as an Irish wolfhound, this wolf of the South American savannas is the tallest of all wild canids. Bright rusty red, with pitch-black legs, white-tipped tail, snow-white throat, and enormous, white-lined ears, a 55-pound maned wolf looks like a cross between a red fox on steroids and a big-eared kit fox, morphed upward, but not in length, and narrow as a rail. A mane of long black-tipped hair on the neck and shoulders can bristle to make the wolf look even taller. How does such a creature go unnoticed?
"Wolf" evokes images of size and power multiplied by grouping in packs to bring down large game. However, maned wolves are wolflike in size, but foxlike in nature. They are shy and nocturnal, hunting alone for mice, guinea pigs, other small animals, and fruit. A favorite food is a tomato-like fruit called lobeira (wolf fruit). Maned wolves move with catlike stealth, at first surprising for so large an animal; but less so when you realize that they hunt small game by pouncing on it, so they must walk softly on their giant, padded feet to catch their prey unaware. When hunting, maned wolves walk slowly, head stretched low and forward with their great ears cocked and muzzle near the ground, listening and smelling.
Despite their reclusive ways, mild manners (maned wolves don’t compete with people for prey and don’t kill livestock except for the odd chicken), and lack of value as tasty food or for fine fur, the species is threatened. Maned wolves' only habitat is a narrow band of South American savannas, called Cerrado or pampa, sandwiched between the southern fringe of the Amazon rainforests and the more southerly flooded landscape called Pantanal and the parched Chaco landscapes of the tropical edge. Most remaining maned wolves live in Bolivia and Brazil, with a handful persisting in Argentina and Paraguay. Peru has room for but a single pair, in the tiny remnant grassland of the Pampas del Heath, while they may be extinct in Uruguay except for an occasional wandering transient. Why are they now threatened? Our answer to this, based on more than 30 years of research, frames a conservation portrait whose model could be interchanged with other threatened species, for the same dangers are common to many animals.
Science Behind the Scenes
As they do in the wild, maned wolves have lurked behind
the scenes, hidden from sight, in several Smithsonian
endeavors for more than 30 years. In the late 1970s,
Jim Dietz made the first, now classic, study of wild
maned wolves for his doctoral thesis from Michigan State
University. Dietz, now an associate professor at the
University of Maryland, was the first to follow maned
wolves in the wild by radiotracking. He supplemented
his work on wild wolves in Brazil by watching the behavior
of captive maned wolves in the tranquil Virginia countryside
of the Smithsonian National Zoo’s Conservation
and Research Center (CRC) near Front Royal. He began
this work as a postdoctoral fellow under the auspices
of behavioral scientist Devra Kleiman, then a Zoo staff
scientist.
Since then, students at CRC have spied on the secret lives of maned wolves from an observation tower high above a huge, isolated enclosure where maned wolves rear their pups among tall pampas grasses in a naturalistic environment. Their findings contribute to the maned wolf breeding program that began so many years ago.
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| A maned wolf at the Zoo's Conservation and Research Center. (Jessie Cohen/NZP) |
Veterinarians and scientists at CRC collaborate with their counterparts at other institutions to study maned wolf behavior, health, nutrition, and reproductive physiology. To understand why these canids do not breed consistently in zoos, CRC gamete biologist Nucharin Songsasen is leading a study funded by the Morris Animal Foundation (MAF) to determine if chronic stress affects maned wolf reproduction in North and South American zoos. Songsasen is also working with scientists of the Associação Pró-Carnívoros in Brazil to determine how tourism and farming affect maned wolves living in the Brazilian Cerrado, in a study funded by MAF and the National Brazilian Environmental Agency.
Over the years, National Zoo veterinarians and scientists have learned how to keep these delicate creatures healthy, breeding, and rearing their own pups. Their expertise helps zoos around the world keep healthy populations of maned wolves. Melissa Rodden of CRC coordinates the American Zoo Association's Species Survival Plan (SSP) for maned wolves, a program to cooperatively manage captive breeding efforts by a consortium of zoos, and she recently co-edited the maned wolf account for the World Conservation Union's Canid Action Plan.
In a lab at the Zoo, the team of researchers in the Smithsonian’s National Museum of Natural History Genetics Program is also hidden from public view like a rare species. The evolutionary biologists there are on the forefront of endangered species conservation research, with projects on elephants, black-footed ferrets, Indian wolves, kit foxes, Hawaiian birds, and avian malaria, to mention just a few. Senior scientist Jesús E. Maldonado is an expert on canid genetics, with a library of genetic information that can be used to quickly reference and examine DNA from almost all the wild dog species of the Americas. Rosário Franco, a master’s degree student from Uruguay, came to the Zoo to work under Jesús on a study of the genetic diversity of maned wolves, and their project quickly joined up with mine.
My own maned wolf studies began in 1998, when I went to Bolivia to study the mammal community in remote Noël Kempff National Park (NKNP) on the southern boundary of the Amazon rainforest, just where the habitat switches from humid forest to dry forest and savanna. After a career working deep in equatorial forests, I wanted to find out what mammal communities are like at their environmental limits, where two major biomes come together, and where a small change in climate can transform the entire ecosystem from rainforest to savanna or vice versa. There in the savanna, I became entranced by maned wolves and could not resist adding them to my project, a study of the biodiversity of the park, which is in collaboration with the Museo Noël Kempff Mercado of the Universidad Agraria "Gabriel René Moreno" of Santa Cruz. Students from the Museo help conduct field surveys and radiotracking of wolves as an essential part of the project.
Maned wolves are the largest living carnivores endemic to the southern pampas, and after the spectacled bears of the Andes mountains, they are also the largest living carnivores endemic to South America. They are the odd man out among members of the dog family, for according to recent theory, they are way too big for the lifestyle they live. Canids of this size are supposed to be meat-eaters that hunt big game, yet they do not. To me this suggests that the theory, not the animal, is at odds with nature, and leaves a question to be solved about how this eccentric fox-wolf manages to live on its diet of small animals and fruit. Answering this question is one major focus of my research. But the globally threatened status of the maned wolf brought conservation to the fore, and eventually created an urgent need for a multidisciplinary approach to maned wolf conservation. This is what brought so many Smithsonian scientists together.
Bad Luck Wolves
The tale of why maned wolves are in trouble is a mini-lesson
in conservation biology. The first bad roll of the dice
is maned wolves' restricted distribution in a small
number of grassland habitat types; and the dice are
loaded against them, because another species finds the
same habitats perfect for its own uses—Homo
sapiens.
Worldwide, the natural savannas that border temperate
or equatorial forests have been the areas first and
most profitably exploited for cattle grazing. The temperate
grasslands of Argentina and Uruguay were the first parts
of South America to be almost totally converted to cattle
ranching, and more recently, to industrial grain production.
The natural savannas of Brazil and Bolivia have grazed
cattle for more than two centuries, but in only the
past decade, millions of acres of both Cerrado and dry
forests were irreversibly swept by bulldozers, burned,
ploughed, and converted to chemical-intensive soybean,
cotton, wheat, maize, and oilseed monocultures. Well-managed
cattle ranching on natural grasslands is not incompatible
with maned wolf survival—most maned wolves now
share their habitat with cattle, as do many other native
species of mammals and birds. But a monoculture field
of soybeans or cotton is worse than a desert: Nothing
of the native community of fauna or flora survives there.
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| Maned wolves' habitat in the grasslands of Brazil and Bolivia is shrinking, due to cattle grazing, agriculture, and other human activities. (Louise Emmons/NMNH) |
The second bad toss for the wolves is the combination of their XXL size and their social behavior. Large size itself is not a handicap to species survival. Just the opposite can be true, as large species usually have large geographic ranges; pumas, which range through large parts of the Americas, are a good example. But for maned wolves, large size is directly linked with being naturally, without any other problem, very rare. Maned wolves may walk alone, but they are not solitary. Each breeding wolf lives monogamously with its lifelong mate, and the pair shares a mutual territory. Some overlap can occur with neighbors, but for the most part, each pair and its young occupy by themselves an area of 25 to 100 square kilometers (roughly 10 to 40 square miles). Their large body size thus translates into a need for large living space. The area of NKNP is 1.5 million hectares (about 5,800 square miles). About a third of the park’s area is suitable for maned wolves, but all of that space is estimated to hold only about 120 breeding pairs. Yet a conservation biology rule of thumb is that a population of 500 individuals is needed for long-term sustainability.
In the Genes
Most of us know that inbreeding is a bad idea, and conversely,
that hybrid vigor can produce exceptionally resistant
individuals because they are often more robust in physiology
and other areas. The wide array of genes in living organisms
acts like a heritable baggage of contingency plans.
If a disease epidemic devastates a population, there
are usually at least some survivors, because some individuals
happen to possess genes that make them less susceptible
to the disease. A different disease will pass over those
with a different set of genes. Similarly, if famine
strikes, only those with genetically low metabolic rates
may survive, while in good times, skinny folks may have
an advantage. If members of a population are all genetically
identical as a result of excessive inbreeding, all could
be swept away by a single surprise event. Nature is
intrinsically unpredictable and often inhospitable,
and exerts a mindless triage on every organism. The
best insurance for a species' long-term survival in
the face of an unpredictable Nature is to have a big
population of individuals that carry a big population
of different variants of genes; in other words, a population
with high genetic diversity. This makes a species more
likely not only to resist disease or deleterious genetic
mutations, but also to be able to adapt to changes in
habitat or climate. The more individuals there are,
the more probable it is that some will escape a natural
disaster.
Knowing something about a species' genetic diversity is thus a key to predicting its long-term prospects. I have been working with Jesús Maldonado and Rosário Franco to measure the genetic diversity of maned wolves at the Los Fierros study area in NKNP. We collect some DNA from blood samples taken from captured individuals, but most is gleaned from small samples cut from feces encountered on the pampa, where location of the feces is mapped by GPS. Feces include some cells (and their DNA) from the intestines of the depositor, and modern technology can isolate these from everything else that the animal ate. Our results are valuable standing alone, but Jesús and Rosario have put them into a global context by comparing the genetics of my study animals with that of maned wolves from Brazil in the CRC breeding colony, as well as of animals from Argentina. Based on these samples, we learned that maned wolves have low genetic diversity as a species, and perhaps suffered a genetic bottleneck in their past.
But the good news for the conservation of maned wolves in NKNP is that, within the small geographic area we have sampled thus far, the wolves exhibit a good amount of the variability that exists in the species. Further, Los Fierros is bordered on one side by cattle estancias, the nearest of them owned by a conservationist who prohibits hunting. Maned wolves on these estancias interbreed with the park population and thus can be included in conservation plans. As well as measuring genetic diversity for conservation predictions, we are using the DNA samples to evaluate kinship between the individuals we sample. This will help us to better understand the social structure of the population and try to answer such questions as whether neighbors are closely related and how far youngsters of each sex disperse when they leave their parents' territories.
Disease Alert
At the start of my study I was leery of anesthetizing
maned wolves to capture them for radiocollaring without
expert advice, so I enlisted the support of the Field
Veterinary Program of the Wildlife Conservation Society,
which sent wildlife veterinarian Sharon Deem to join
me in Bolivia. Sharon, now part of the Zoo’s Department
of Animal Health, helped capture and collect health
data on the first maned wolves we radiocollared. Since
then, Sharon and other National Zoo vets have become
important participants in the project.
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| The author, Louise Emmons, stands in front of a box trap used to capture maned wolves for a study. (Suzan Murray/NZP) |
Maned wolves suffer from a serious and possibly hereditary metabolic flaw, which may result in a syndrome called cystinuria, a failure of the renal system to absorb the amino acid cystine. Cystine is excreted in the wolves' urine, and may cause crystals to form in their kidneys and bladder, which can cause death from kidney failure or blockages in the urinary tract. Most of what is known about cystinuria in maned wolves comes from the work of Mitchell Bush, a veterinarian at CRC and a leader of the Zoo's maned wolf research, in collaboration with veterinarian Kenneth Bovee from the University of Pennsylvania. In addition, many wild wolves are infected by the giant kidney worm (Dioctophyme renale), a parasite introduced from the Northern Hemisphere that completely destroys the right kidney. These problems have been known for many decades, so that when the analyses of Sharon’s samples from the first two animals came in, we were not surprised to find both kidney diseases in the Bolivian wolves.
We were much concerned to find that the wolves also had antibodies showing that they had been exposed to many infectious diseases common in domestic dogs, and likely introduced to South America. These included canine heartworm, distemper, parvovirus, adenovirus, and toxoplasmosis, among other, less well-known diseases—not to mention a number of intestinal parasites. A wolf caught on one of our later trips also had antibodies to rabies virus and coronavirus. This alerted us to a hidden disease threat to the survival of wild maned wolves.
To determine whether a species is threatened, and, if it is, whether we can improve its future prospects, we need to know what individuals die of, and whether the population is stable or decreasing. Discovering what maned wolves die from is not easy—they live out of sight in a climate where dead bodies are skeletonized by scavengers, and the bones are dispersed within a few days. In Brazil’s Emas National Park, where Leandro Silveira is leading a long-term study of maned wolves, 475 kilometers (nearly 300 miles) of roads crisscross the park, and road kill by vehicles is a major cause of mortality in maned wolves. In contrast, NKNP is nearly roadless, so vehicles are no threat. We are usually able to identify sources of mortality only indirectly, largely by recording the presence and subsequent disappearance of individual animals in photos taken by camera trapping. But we did learn that one collared maned wolf at a different site in the park died at the same time as we noted a drastic drop in numbers of foxes, suggesting that a canine disease epidemic may have hit the area. Another maned wolf died of old age. In the future, we plan to extend our veterinary studies to include wild foxes in the park and domestic dogs in bordering communities, to see whether we can help secure the future of wild carnivores by improving the health of dogs in the surrounding areas. Historical studies of maned wolves' response to canine diseases in captivity at CRC and elsewhere will help us understand what diseases threaten wild wolves, and how best to manage parks to help ensure a long future for wild carnivores.
As parks become isolated islands of natural habitat in seas of human-dominated landscapes, it becomes more and more necessary to actively and proactively manage them to optimize ecosystem or species survival. Management can take many forms: monitoring of populations to make sure they are healthy; burning of grasslands or naturally fire-adapted forests to maintain the habitat; preventing fire in non-fire-adapted forests; augmenting water sources or maintaining wetlands; controlling pollution; removing introduced species; and trying to prevent the introduction of exotic diseases. And all such management activities involve education and participation of people in local communities. With Fundación Amigos de la Naturaleza, the Bolivian non-governmental organization that supports scientific studies in the park, I am helping to design the management plan for maned wolves. This plan will be the result not only of our field studies, but equally of the critical knowledge provided by the other Smithsonian scientists.
People living near the Zoo, along Rock Creek Park, and in Cleveland Park and Adams Morgan may sometimes hear strange, deep, resonant barks in the nighttime since maned wolves went on exhibit at the Zoo in August. We hope that, like giant pandas have done for the conservation of wilderness areas in China, these skinny giants' appeal to the public will lead to better conservation of the southern pampas, maned wolves, and all pampas wildlife. And while maned wolves are reclusive near-ghosts in the wild, as I learned when I radiotracked them on foot, the maned wolves at the Zoo are there for people to see.
These days, thanks to our generous project supporters at the National Geographic Society and the Wildlife Conservation Society, we have upgraded to the latest technology and now equip the maned wolves we catch with GPS collars that automatically track their movements and store the data in a memory card. We still do some tracking on foot, to make sure that we know their home areas, and to check that they are well, but the GPS collars do a much better job of following than we can. But I confess that I often miss the long nights alone with the wolves in the pampa, listening for a distant bark or glimpsing a pair of green-white eyes moving through the long grass.
—Louise Emmons is a research associate at the National Museum of Natural History; Sharon L. Deem is a veterinarian at the National Zoo; Melissa Rodden is a computer specialist at the Zoo’s Conservation and Research Center; and Jesús E. Maldonado is a research geneticist with the National Museum of Natural History’s Genetics Program.
ZooGoer 33(6) 2004. Copyright
2004 Friends of the National Zoo.
All rights reserved.
