A Mother's Love—Adrian Seymour

Photograph by Graham Hatherley

"The harpy eagle made my heart beat a little bit faster," filmmaker Adrian Seymour reports after 21 weeks spent filming a nest high in a tree in the Venezuelan jungle. "Climbing up and down to our arboreal camera platform, and then into the nesting tree itself, incurred the mother's wrath."

That wasn't good. The world's largest bird of prey, with a seven-foot wingspan and five-inch, razor-sharp talons, a harpy mother is a formidable foe. "She had precise knowledge of my field of vision and knew exactly when to strike. She was dead silent like an owl and very fast"—and she hit Seymour with the force of a baseball bat.

"Next thing I knew she had torn my shirt, though I was a little too heavy to carry," he says. "I was stunned by the power. Crying for my mom!"

Going With the Flow—Kenny Broad

Photograph by Wes Skiles

One of extreme cave diver Kenny Broad's closet calls came from one of the most mundane of activities: going to the bathroom.

Broad and his caving partner were in southern Mexico, more than 4,000 feet underground in one of the world's deepest caves. They camped for the night on scaffolding bolted to the cave's limestone walls, hanging 15 feet over the water, just out of the spray zone of a roaring waterfall.

When nature called, Broad got out of his slim hammock to relieve himself in a plastic bottle, which would be hauled out of the cave to prevent contamination. "With business done, I was getting back into my hammock, but my center of gravity must have been off, and instead of sinking downward into the mesh, I sat on the edge of the hammock and was flung backwards like a rag doll against the rock wall," he says. "My head whacked an outcropping and I plummeted between our bivy [bivouac] station and the solid wall into the water. The bad luck was cracking my head and falling in a dazed stupor to the water below. The good luck was that my arm caught one of the support ropes and it kept my head out of the water until I came to my senses and could slowly scramble my way back up to my home away from home. At least it was my head that hit."

One Night Stand—Amy Dickman

Photograph by Tim Laman, National Geographic

Few wildlife biologists working with Africa's big cats have been welcomed to the savanna in quite the way Amy Dickman was. "One very challenging incident happened on my very first night in the field," the veteran zoologist reports. "A big male lion came and slept right against my tiny one-man tent, nearly crushing me and making me very scared indeed!"

First Glance—Rory Wilson

Photograph by Javier Ciancio

Over the course of his varied career, British zoologist Rory Wilson has tracked leopards, been attacked by fur seals, and studied endangered species from the Equator to the Poles. But his most memorable experience remains his first glimpse of a wild penguin.

"I was sitting on the rear section of a fishing boat traveling up the Namibian coast," he recalls, still wincing at the memory of the seasickness he felt. "Then I saw a single, juvenile African penguin, in the water, rolled almost completely onto its back, concentrating wholly on preening feathers on its breast as it bounced around in the huge swell and vicious chop. Many would shriek in water like that, but my bird was as at home as a child listening to a goodnight story from the depths of its bed."

Sea of Love—Shannon Switzer

Photograph by Shannon Switzer

"A moment that will always be frozen in time for me occurred when I was photographing whale sharks in the Seychelles Islands," recalls photographer and ocean ecologist Shannon Switzer.

One of the gentle giants, the largest in the ocean, had suddenly disappeared into the gloom beneath her. So Switzer surfaced briefly in order to locate the rest of her team, which she saw swimming half a mile away. Plunging her head back underwater, she was stunned to find another whale shark so close beneath her she could have kicked it with her fins.

"I wasn't sure if it was the same one that had disappeared only seconds earlier, but this one seemed as interested in me as I was in him. We swam together slowly, side by side for nearly 20 minutes," Switzer recalls. "Fortunately, he was headed in the direction of my team. Once we had nearly reached them though, he paused. I stopped too, and he stared at me with his curious round eye and then turned and headed in the direction from where we had just come."

All Smiles—Martin Nweeia

Photograph by Steve Winter

"My favorite experience in the field came one night in a remote area of the Amazon," says Martin Nweeia. He had been conducting a dental study among the Ticuna Indians, but suspected that he was being viewed merely as a curiosity. "Then, one night, there were two children in an open hut who were spontaneously dancing and singing, and the child in me decided to join in. Time was lost as we continued to sing and dance, and the children became more animated and joyful, as did I. After what seemed like an hour or so, someone tapped me on the back and said, ‘Have you looked around the hut?' There in the surrounding darkness were the facial outlines of the entire village, quietly gathered to watch this display. From that day on, only smiles came from those who passed my way."

Perfect Timing—Lisa Dabek

Photograph by Ryan Hawk

Zoologist Lisa Dabek knew just about everything you could know about New Guinea's endangered Matschie's tree kangaroo without having seen one in the wild. When she finally got to the remote and mountainous region that is their home, however, she hiked for days in the rain forest, her eyes seldom leaving the trees. But she never saw one—until the very last day.

"I had always wondered why the tree kangaroo was red-orange in color," she recalls, "and then I saw that the moss in the trees was the same exact color. It was the most beautiful sight—perfectly camouflaged in the tree!"

Visions of the Fall—Stephen Sillett

Photograph by Michael Nichols, National Geographic

It was the "greatest tree in all the mountains of the world," a 3,200-year-old giant sequoia, and to botanist Stephen C. Sillett it was begging to be climbed.

He got the chance after teaming up with National Geographic photographer Nick Nichols, who hoped to photograph the huge tree. It was February, and the snows were deep in the Sierra Nevada. Sillett had to deploy an access rope on the farthest edge of the crown near the tip of the largest limb.

"The tree's largest limbs were covered with several feet of snow," Sillett says. "Moving through the frozen crown of this colossal tree required great care so as not to dislodge any snow, because documentation of the tree in full winter glory was Nichols's primary objective."

Eventually the botanist reached his objective, which was a dizzying 60 feet away from the main trunk. "The journey to this position, the view from there looking back on the mighty tree and its neighbors, and then rappelling 200 feet down from the limb into deep snow on the ground—I will never forget."

Sniff Test—Ben Horton

Photograph by Ben Horton

"My favorite experiences are when I have spent long enough in a place that I start to really connect with my subject," says Ben Horton, a National Geographic contributing photographer for whom the more remote that place is, and the wilder the subject, the better.

One such vivid experience occurred after having spent about a month in the Arctic. "I was sitting writing in my journal and seven wolves approached me," he says. "When I sat still, they came right up to me and started sniffing me up and down. It was easy to see they weren't being aggressive, but it was still a thrilling experience."

Dolphin Glow—Neil Losin

Photograph by Neil Losin

Toward the end of a long month vainly hunting among the forested islands of Indonesia for rare orioles, ornithologist Neil Losin was in a longboat one night crossing the sea to New Guinea's Raja Ampat archipelago. While disheartened by his lack of success and worried about the captain's navigational skills, something suddenly caught his eye.

"Our wake was glowing—not with reflected light from above, but with living light from below," he says. "Bioluminescent creatures flashed and blinked in the churning seawater. As I leaned over the bow, a huge bright shape materialized beneath us. It was unmistakably a dolphin, but all I could see in the darkness was a dolphin-shaped apparition: thousands of tiny, gelatinous creatures appearing and fading as the dolphin brushed by, leaving a glimmering afterglow in its wake. Seconds later, the dolphin overtook us and vanished below. It was an unforgettable moment!"

Cetacean Motivation—Diana Reiss

Photograph by John Hyde

Diana Reiss has spent countless hours exploring the psychology of dolphins and whales. But on at least one occasion her insights were put to a very real-world test, with all the world's news media watching.

"My favorite field experience," she says, "was the rescue of a humpback whale, Humphrey, after he wandered into the San Francisco Bay and traveled about 60 miles inland through an intricate set of waterways. We were able to lead him back out to sea by playing back sounds of other whales feeding in Alaskan waters. Luring him to follow us, we led Humphrey back out to sea. We saved a whale."

Local Critics—Joshua Howard

Photograph by Joshua Howard

While a member of an archaeological expedition in the Honduran jungle, photographer Joshua Howard lived with his colleagues among the Pech Indians of the Plátano River. The Indians served as guides and poled their guests upriver by dugout canoe to locate the petroglyphs they were hoping to find.

"In the evenings, after dinner, I would bring out my camera and take images of the night sky and the brilliant colors of the Milky Way that were visible due to how far off the beaten path we were," Howard remembers. "The camera was able to capture colors that the human eye could not see. The Pech Indians, young and old, would crowd behind my viewfinder to see the outcome of each exposure, expressing their excitement for a nice photo by patting me on the back, but then shaking their heads in disgust and laughing when a photo didn't turn out very well."