Photograph by Ronan Donovan, Nat Geo Image Collection
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Mr. Blue, a well-known wolf that has turned gray with age, looks at a camera trap near a drowned bison in Yellowstone National Park.

Photograph by Ronan Donovan, Nat Geo Image Collection

Rotting 'Carcass Cam' Gives Unique View of Hungry Wolves

Filming some of America's most iconic predators requires some clever thinking—like setting up a camera near a dead bison in Yellowstone.

A rotting carcass being picked away at by vultures may not seem like the ideal place for a photo shoot.

But if you’re hoping to catch gray wolves and other Yellowstone wildlife on camera, then setting up shop by one of their potential meals is a pretty good bet.

And that’s exactly how photographer Ronan Donovan found himself hunched over the body of a decomposing bison in the Yellowstone River in March 2016. Donovan was on assignment covering wolves for National Geographic magazine's Yellowstone issue.

Donovan installed a camera trap (aka carcass cam) near the dead bison, which had drowned during the harsh winter. Donovan did not move the carcass, but did touch it to ensure movement would trigger the camera trap.

We recently caught up with Donovan and asked him about his adventures filming some of America's most iconic predators. (Also see what it's like to be a vulture's lunch.)

Q: How did you use the dead bison to set up the “carcass cam?”

A: I had to set this camera trap up a little bit more in a non-traditional way, so to speak. I put it maybe 60 feet away from the carcass, whereas normally camera traps are close and wide. That's why you use them, so you can get an intimate image of a wild animal that you can't get when you have a camera in hand. But I was worried about the wolves being scared away if the camera was too close. I wasn’t worried about the bears being scared of the camera, because they're not scared of anything. (Related: "Capturing the Wildness of Wolves in Yellowstone.")

You had to touch the bison carcass—was that pretty gross?

It’s not so bad in winter because the scent is minimal. Summertime, it's pretty horrific and the smell really sticks to your clothes. But the changing temperature was a huge issue for the camera, freezing up and condensation and icing over. You'd have mornings that would be negative 20 degrees [Fahrenheit] and then it warms up to the teens or warmer when the sunlight is directly hitting the camera. I have 1,500 pictures from this camera of three wolves feeding on this carcass for 45 minutes, and maybe one photo is usable because the whole lens is iced up and looks like you're looking through a fogged-up window.

Camera traps, the majority of the time, [are] total heartbreak. But it's the only way to get these really incredibly close, intimate images. You've got to meditate on it before you go to the camera trap and keep your expectations reasonable.

Did you find that a little scary to be out there in wild Yellowstone by yourself?

EXCLUSIVE: 'Bear Bathtub' Caught on Camera in Yellowstone

It's just part of the job. It was a little bit tricky because the bison was across the river from the road. So I had to put on these chest waders, wade through with ice chunks floating by the Yellowstone River—in some places up to my chest—and it was a little bit sketchy at times to get over to this carcass. Over the two week period I had the camera trap running, I had to visit it four to five times to refresh batteries and check [memory] cards.

Another wild card was this giant male grizzly bear that kept visiting this carcass. One of the wolf biologists would be on watch from the road where she could see the whole hillside, because when I would cross the river, I couldn't see where this bear was. The bear had this routine where it would come down and eat and gorge himself for an hour and then go up over this little hill and take a nap for three, four hours. I would wait for him to leave and then quickly boogie across the river. One time was I just about to start work on the camera trap and I hear on the radio, 'Bear's coming! You've got to get out of there now!' (Explore an interactive of a bear's-eye view of Yellowstone.)

It definitely paid off. You got several beautiful photos, but there’s one that really stands out (below).

The image is a success, but it's just a split second of a moment in Yellowstone National Park with a wolf that has been through an incredible saga in his own life. He's eight years old, he used to be jet black and has turned white over the years as he's aged. He's had six different mates that have either been killed by hunters outside the park, or been lost from his pack, or they've been killed by a rival pack. (Read "The Yellowstone We Don't See: A Struggle of Life and Death.")

755M is his number, because he has a collar. Some people call him Mr. Blue because he's got that blue coat. But he represents a really unique aspect of Yellowstone, and the ability to watch a wolf from infancy all the way through its entire life—you can't do that anywhere else in the world.

This story was updated on May 17, 2017, to clarify the photographer's technique. The interview has been edited for length and content.

See more memorable moments from explorers in the field in our digital series, Expedition Raw.