By Ron Arias
November 14, 1988 12:00 PM

In 1973, while sightseeing in Brazil, Heidi Mosbacher was browsing in a marketplace when she heard the terrified cries of a small, sad-eyed animal she had never seen before. The snub-nosed creature, which turned out to be an infant three-toed sloth, was tied up alongside a few monkeys and offered for sale as a pet. “It was crying like a baby,” Mosbacher recalls. “My only thought was to save it. I didn’t think twice. I paid almost nothing for a little life. What I didn’t know then was that it would completely change my life.”

Mosbacher, 46, now lives alone in a ramshackle house on stilts far up the Cuieiras River in the Amazon jungle, about 120 miles from Manaus, studying a group of sloths she has gathered and nurtured for the past 11 years. “It began with Susi, my first sloth,” says the tall blond from Munich, West Germany, who abandoned a career as a chemist to follow her passion for a creature more caricatured than understood. “People make jokes about these animals,” she says, “but what Jane Good-all did for chimpanzees in Africa, I want to do for sloths in the Amazon.”

Sloths, Mosbacher explains, are not lazy. That impression may have come from the fact that they cannot walk, let alone run. They can, however, move relatively quickly if they need to, sliding hand over hand through the treetops to escape their natural enemies, which include jaguars. Though sloths, which can grow to 26 inches long and weigh up to 10 lbs., are not an endangered species, their numbers are shrinking rapidly as lumber companies and a growing number of farmers and miners move farther into the rain forest. “Man is now the sloth’s worst enemy,” she says. “But I think this is because people don’t understand that sloths are really harmless and even affectionate when they feel secure around people. They hurt no one.”

In the same way that Dian Fossey antagonized the poachers of Rwanda who preyed on her gorillas, Mosbacher has made her own enemies among the people she thinks are wiping out the sloths.

It’s just after sunrise, and Mosbacher, wearing pants and a long-sleeved shirt, deftly hacks her way into the jungle with a machete. Occasionally she glances upward to search for the shiny leaves of the cecropia tree, a staple for her 14 sloths. Every morning she harvests a bagful of young leaves, severing them in bunches with a hook attached to a long pole. The effort takes two hours, in part because Mosbacher must keep an eye out for wasps, scorpions, snakes, wild pigs—and the silent, stalking jaguar, whose presence usually is announced to his victims only by a sudden fatal pounce. “Once I was out here without my machete, and I saw some fresh jaguar prints,” she says. “I felt that one was watching me. I was terrified. I turned around very slowly and quietly started back. I thought I’d never make it to the house.”

On this particular morning, Mosbacher has to contend only with a wasp sting and the chore of brushing ants from the leaves. Though sloths are distantly related to anteaters, she explains, they won’t eat leaves with ants on them. “And these ants are harmless,” she says, trudging back to her riverbank home. “The really bad ones are the big army ants. They’ll come marching right through the house. They’ll eat anything.”

Entering the clearing behind her house, Mosbacher points to the termite-infested remains of her first experiment in sloth housing. Once a spacious wire enclosure, 15 feet high and filled with living trees and plants, it soon rotted and collapsed under heavy rains. “They didn’t like it out here anyway—always getting wet and never enough room for each one to be alone,” she says. Since the sloth’s preference for tree-top living makes it all but impossible to study in its natural habitat, Mosbacher brought the creatures into the house and put them in separate cages attached to an improvised veranda. In each cage she placed tree limbs so that the sloths could hang or curl up in the forks of branches. “Now they’re much happier,” she says—and she is able to observe closely their grooming and eating habits, as well as mating, births and the raising of the young. Next year she plans to return to West Germany to complete a book for schoolchildren based on her life with the sloths.

By midmorning, Mosbacher—now in shorts and a T-shirt dotted with holes from the clinging claws of her charges—has finished placing leaves in the half-dozen cages and several hanging baskets in her bedroom, where she keeps six infants. She has collected most of the sloths in yearly downriver trips by hired boat to areas where they face destruction at the hands of hunters and slash-and-burn farmers. At times she has kept up to 25 sloths—giving them names like Mona Lisa and Good Day; she keeps a permanent core group and eventually releases the rest in safer, wild areas.

In addition to her sloth-collecting trips, Mosbacher makes an annual round-trip journey to Manaus by boat to buy house-repair supplies and such staples as rice, beans and flour. She still has a few friends in the city, but aside from picking up her mail at the West German consulate, she no longer maintains close personal ties to West Germany. Living on only about $500 annually—mostly from savings and a small inheritance—Mosbacher supplements her regular diet of rice, beans, oats and corn porridge with fish, chicken eggs and vegetables from her garden. “There used to be a family nearby, and they’d give me fruit and meat,” she says. “But they’ve left, and now I’m pretty much left alone, except for the tourists who get this far up the river. Lonely? Yes, but I’m usually too busy to notice for very long.”

Disappointed that she hasn’t completed a lengthy report for the Munich-based Max Planck Institute, which initially funded her project in 1979 with a small grant, Heidi explains that she has little time to write and read. Her favorite books include Charles Darwin’s Origin of Species and Jane Goodall’s In the Shadow of Man. “I always wanted to have a mentor like Goodall had in Dr. [Louis B.] Leakey,” she says. “I started this on my own and in a way trained myself to study animal behavior.”

When she’s not caring for her sloths, Mosbacher fights a daily one-woman battle to keep the jungle forces from demolishing her one-room house and makeshift outdoor kitchen. She collects her drinking water from the river every day and usually spends an hour or so fishing. By evening, she says, “It’s all I can do to light my candle and write down a few of my thoughts.”

Although she admits she has no academic credentials in the study of animal behavior, she believes her observations will someday provide scientists with valuable information on the three-toed sloth’s breeding habits and diet. Next year, if Brazilian authorities agree, she plans to take six young sloths back to West Germany to try to raise them in captivity—something she says has never been done before. If her effort is successful, she says, the animals could then be shown to the public to generate conservation efforts on the animals’ behalf. Adds Russell Mittermeier, a director of the World Wildlife Fund: “Who is to say sloths can’t be symbols of conservation every bit as effectively as chimps? Heidi Mosbacher’s valuable work can help do this by stimulating an awareness and interest in this little-known creature.”

As she struggles to protect the sloths, Mosbacher also has to contend with nighttime incursions by the jaguars, as well as by ocelots and anacondas that prey upon the sloths and on the chickens she keeps under the house. She says the predators have killed several sloths, and twice she has found anacondas at least 12 feet long coiled around ducks.

Her biggest worry, however, stems from the animosity of those whose profits depend on clearing the forests. “They think I’m strange because I’m trying to protect sloths,” she says. “But that’s become my mission in life.”

Mosbacher thinks that her passion for animals is in part the result of being denied pets as a child by her late father, a telegraph office supervisor. “I loved him, but he was very hard on me,” she says. “My mother died when I was 8, and he never remarried. So I stayed at home by myself and used to dream of having a pet. Finally, when I was 15, he gave me a tortoise, which I kept for seven years. Her name was Fifi, and one day I left her outside with my father for a few minutes. When I came back, he said he was sorry but she had wandered off. That hurt me deeply.”

As a teenager, Heidi was also forbidden to have boyfriends, a prohibition she chose to ignore once she enrolled at the University of Munich. “I love the outdoors, so we would go skiing and hiking,” she says of her dates with fellow students. “But I never had a serious friendship with a man because most of them were too conservative and interested in material things. They expected me to settle down and live what I think is a routine, boring life in the city.” Although she wanted to study biology, Mosbacher acceded to her father’s wish and majored in chemistry (“He said it was a more secure field”), receiving her bachelor’s degree in 1962.

In 1967, after two years of 9-to-5 lab work, Mosbacher joined a German overseas volunteer group as a soil analyst in Kenya. After three years she returned to West Germany and lab work, then in 1973 joined another West German technical assistance group in Manaus. Two years after meeting her first sloth, she moved into the jungle.

It’s late afternoon, and Mosbacher is toweling off after a quick swim with a pair of Amazon dolphins as companions. For her, the time is restful, peaceful. She says she has never been attacked by piranhas, caimans or poisonous water snakes; she thinks perhaps the dolphins keep them away. “I have this dream,” says Mosbacher. “I would like to have a boat where I could put my sloths. Make it something like an ark for sloths. Then I could show them all over the Amazon. And if people got to know them, maybe they wouldn’t kill them.” As dusk falls, she dips her paddle into the rain-swollen river and pushes toward home. Behind, in the canoe’s shimmering wake, the dolphins break the water’s surface one last time. Within minutes, darkness descends on the jungle.

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