Zebras line up for a drink at a watering hole in Namibia's Etosha National Park. John Isaac

At this very moment, John Isaac is probably somewhere in the brush of India’s Bandhavgarh National Park, waiting patiently for his beloved tigers to give him another photo op. He has lost count of the number of trips he has made in recent years from his home near New York City to the massive parks of his native India. But all those journeys will culminate in a monograph of Isaac’s tiger photographs to be published in late 2011. The trips have been completely self-funded, driven by Isaac’s wish to call attention to the almost irremediable damage that poaching has done to Earth’s most magnificent cat.

It helps this time that on his way to his appointment he had a paying assignment—to photograph the wedding of the Maharajah of Jodhpur, attended by the likes of Mick Jagger and Sting along with a host of Indian dignitaries. Isaac had mixed feelings about the job. “What a celebration,” he writes. “Seven days of feasting and parties and fun. But deep down my conscience was not so happy with all this glitter and glamour, since I know there are millions of Indians going hungry.”

That sensitivity to, and abiding awareness of, the suffering of others led Isaac to a dramatic career change in the late 1990s. Back then he was chief photographer at the United Nations, for which he had traveled to more than 100 countries over two decades to shoot the death and destruction of human conflict and natural disasters. He bore witness to Pol Pot’s Cambodian Killing Fields, the Iranian Revolution, and the Ethiopian famine of 1984. But the Rwandan genocide of 1994 pushed him over the edge—into an emotional abyss that made him realize he just couldn’t do that kind of photography anymore. Indeed, Isaac’s emotional involvement with his subjects, and his impulse to help them rather than use them as tools of photographic advocacy, may have made him less successful as a photojournalist. By his own admission, in tough situations he sometimes lacked the resolve to get the best picture at any cost that drives photojournalists such as Jim Nachtwey or even Sebastiao Salgado.

Not long after he resigned from the U.N., Isaac had a reawakening triggered by his lifelong love of the natural world. Shifting around the same time to digital capture, he began to photograph wildlife—perhaps an antidote to the toxins of human rancor that had built up in his psyche. With a few detours—among them to Kashmir, where he shot the daily life and natural landscape of that contested territory to show that peace is possible anywhere, work that was published in a 2008 book—he has been shooting wildlife for over ten years. His main camera in the last few has been the Olympus E-3, though he has switched recently to the new Olympus E-5, and confesses to using and loving the Olympus PEN for its light weight yet ability to take interchangeable lenses. “The Four Thirds system is great for wildlife because it doubles the effective magnifying power of my lenses compared to what I’d get with a full-frame camera,” he explains.

The gallery of Isaac’s wildlife photographs presented here is made up mainly of unpublished work, and celebrates his recent news that the George Eastman House will establish an archive of his life’s work. Isaac is also the subject of a feature in the January/February issue of American Photo, available now at newsstands. The profile tells the full story of Isaac’s journey into the darkness of human degradation, then back into the light of Mother Earth.

How about: John Isaac spent two decades as chief photographer for the United Nations, documenting some of the world’s most horrific events:

Refugees from the Rwandan genocide who have died from cholera are trucked away for burning, in Zaire, 1994.

An orphaned child with AIDS peers through a door at a UNICEF shelter in Windhoek, Namibia, 2002.

Rwandan refugee children scrape a barrel for food, 1994, from one of Isaac’s “saddest assignments.”

A young male tiger cools off in India’s Ranthambore National Park, where tigers now number less than 40 due to poaching. John Isaac
A “ten-point” elk in the safety of high grass at Yellowstone National Park, Wyoming. John Isaac
An elk sitting out the harsh Yellowstone winter. John Isaac
Bison butting heads in the snow at Yellowstone National Park, Wyoming. John Isaac
Sandhill cranes in flight at New Mexico’s Bosque del Apache National Wildlife Refuge, one of Isaac’s favorite places to photograp John Isaac
A puffin with its catch on Maine’s Machias Seal Island. “I was on my knees in the blind and spotted a bird sitting on a rock after a dive, but couldn’t get off a shot in time,” Isaac recalls. “Almost three hours later, he landed there again with a mouthful of fish. It was worth the wait.” John Isaac
An Alaskan bald eagle debating whether John Isaac is worthwhile prey. John Isaac
A bald eagle scooping a snack from icy Alaskan waters. John Isaac
A grizzly bear makes a perfect catch in Katmai, Alaska. John Isaac
A tigress and her cub cuddling in India’s Bandhavgarh National Park. The mother was later hit and killed by a jeep in the middle of the night, a suspicious incident still under investigation. John Isaac
A tiger cub bathing at India’s Ranthambore National Park. John Isaac
A Ranthambore tiger cub practices her stalk. Though two years old, she and two siblings were still being fed by her mother at the time of Isaac’s photograph. The mother was killed by poachers last summer after giving birth to another litter. John Isaac
A Ranthambore tigress cornering a sambar deer at the watering hole. John Isaac
A tiger owning the watering hole at Bandhavgarh National Park. “I always carry a wide-angle zoom along with my long lenses to capture overall scenes like this,” says Isaac. John Isaac
Proof that cats, here a tiger cub at Bandhavgarh, lick backwards to drink—scooping water into the bottom of their mouths. John Isaac
A tiger resting in the cool of evening, Bandhavgarh. “Late-day light is wonderful when you have a beautiful model posing for you,” says Isaac. John Isaac
A Bandhavgarh chital deer with its nursing baby, on edge because tigers are prowling nearby. John Isaac
A group of chital deer poses against the brushy palette of Bandhavgar. John Isaac
Bandhavgarh tigers after a mudbath. John Isaac
Namibian zebras race to the watering hole in the morning. John Isaac
Male zebras sparring near a watering hole in Etosha National Park, Namibia. John Isaac
Gemsbok locking horns in Etosha National Park, Namibia. John Isaac
An elephant strolls nonchalantly by the fight. John Isaac
A rhinoceros in Lake Nakuru National Park, Kenya. John Isaac
A crested crane feeds its offspring in Kenya’s Masai Mara National Reserve. “They use their beaks to strip the grass of its seeds, then put them in the baby’s mouth,” Isaac explains. John Isaac
Springbok and a giraffe under a cloudless Namibian sky. John Isaac
A young Springbok drinks as zebras wait their turn at a watering hole in Etosha National Park, Namibia. John Isaac
Zebras line up for a drink at a watering hole in Namibia’s Etosha National Park. John Isaac
A tiger scrutinizes a lizard at Bandhavgar National Park. “The lizard didn’t know who he was messing with,” says Isaac. “I was surprised the tiger didn’t swat him.” John Isaac
A young gazelle crosses an elephant’s path at Namibia’s Etosha National Park. John Isaac
Zebra friends at Kenya’s Masai Mara National Reserve. John Isaac
These baby langur monkeys “had just had a fight,” Isaac recalls. “One was comforting the other because he’d hit him hard.” John Isaac
A tag team of Namibian cheetahs. John Isaac
A cheetah blending in, Namibia. John Isaac
A Namibian cheetah speeds toward its prey. John Isaac
Cheetah portrait, Namibia. John Isaac
The red sand dunes at Sossusvlei, in the Namib desert, are over 300 feet high. John Isaac
A trio of Indian blackbuck antelope, endangered by human development. John Isaac
Migratory sandhill cranes perform their ritual dance at New Mexico’s Bosque del Apache National Wildlife Refuge, one of Isaac’s favorite places to photograph. John Isaac
The eagle is landing, Homer, Alaska. John Isaac
A young egret learning to fly in Florida’s Wakodahatchee Wetlands. “It took him a while to get his balance on that branch,” says Isaac, who has a long series of the struggling bird. “But eventually he was able to fly away.” John Isaac
Sandhill cranes in flight, Bosque. “I went the night before with all the other photographers to shoot the cranes by the moonlight, but the birds were just black silhouettes,” Isaac recalls. “So I went back early next morning as the sun was rising and the moon was setting.” John Isaac
A waterfall near Mount Fuji, Japan. “Instead of doing a wide shot, I took this with a 300mm lens and 1.4X converter—the equivalent of 840mm on my Olympus E-3,” says Isaac. “Sometimes a detail works better than the whole scene, even with big subjects.” John Isaac
Wild horses in Iceland. John Isaac
A cheetah yawns at Namibia’s Etosha National Park. John Isaac