Joel Sartore has been a conservation photographer for more than 20 years, shooting primarily for National Geographic. About seven years ago, he brought his gear into a makeshift studio and began working with zoo-raised animals, most of which have biologists and handlers tending to their every need.

But even with lighting and trainers, he learned, things can go terribly wrong.

This is, after all, the animal kingdom.

A video on Mr. Sartore’s Web site documents his travels to, and trials at, zoos across the United States — concluding with a chimp who, somewhat gleefully, tears down the white background Mr. Sartore was using for the shoot.

“The chimp won,” Mr. Sartore said.

Mr. Sartore, who is 49 and based in Lincoln, Neb., has been photographing endangered species across America for “The Biodiversity Project,” which he hopes will include about 6,000 different creatures, about the number held in American zoos and aquariums. (So far, he has captured about 2,000.) He travels to zoos and aquariums in the United States – so far more than 60, all of them accredited.

“The goal,” he said, “is to get people to really think, ‘Wow, these animals are cool, and they’re worth looking at.’ ”

Joel Sartore

In 2010, Focal Point published the book, “Rare: Portraits of America’s Endangered Species,” which includes photos that first appeared in National Geographic in January 2009 when Mr. Sartore was asked to do a story on the Endangered Species Act of 1973.

But the project is continuing. Mr. Sartore’s hope is that it will provide a powerful, and beautiful, archive.

While it is clearly too late for some of the animals Mr. Sartore has documented (take the dusky seaside sparrow, for instance), underlying his hope is the belief that, for many of these species, it isn’t over.

For someone who has photographed animals in the wild for decades, the experience of photographing in the studio brought new meaning to the creatures.

“The whole point of this project is to really be able to look these creatures in the eye and get to know them,” he said. The animals are beautiful in their variation, their proximity yielding expressions most humans would interpret in emotional terms — anger, humor, pride.

Joel Sartore

Some animals probably won’t make it into the project. Zebras are too jumpy; kangaroos get nervous. Mr. Sartore is looking for a hand-raised bison. And he has yet to bring a mountain gorilla into the studio, although he photographed them in the wild for National Geographic’s November 2011 issue. (There are none in zoos; only lowland gorillas live in captivity.)

Of the millions of endangered species cataloged, he is capturing a tiny fraction – all in the U.S., in part because he’s financing much of the project himself and expanding it beyond American borders would be too expensive. National Geographic has helped, as has the sale of prints, which are available on his Web site.

Still, “each one is a work of art in its own way,” said Mr. Sartore, who sees the project as a sort of equalizer, in that it gives as much weight to an endangered mouse as to an endangered polar bear.

Yet he does have his favorites. Harapan, a Sumatran rhino, who at 4 years old, is among the last members of one of the world’s oldest mammal species. And the Budgett’s frog, which looks as if it is jumping for joy, laughing at something off-camera. The species is known for its vicious reaction to potential predators.

“He’s actually irritated — he’s growling at the lady who’s his keeper,” Mr. Sartore said of the portrait. “As soon as he got fed, he calmed down.”

Joel Sartore

Joel Sartore will be speaking about The Biodiversity Project at the Aspen Environmental Forum in June.

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