Man left camera running in cave for 10 years and is shocked what he found after collecting it

If you left a camera in a cave for 10 years, what do you think you would find when you retrieved it?

Well, one man doesn't have to wonder about this question anymore, as he has done exactly that - and with some spectacular results.

Casey Anderson, 49, is a wildlife photographer based in the US who tracks animals in the American West.

He placed the camera inside a cave that he knew was being used as a bear den over a decade ago in the hope of catching the den being re-used.

But when he once again braved the grizzly bear den, he found that the camera had captured a whole lot more than just grizzly bears.

If you think about it, it's astonishing the camera lasted that long at all!

A mountain lion kept returning to the cave (Kathleen Reeder Wildlife Photography/Getty)

A video posted to Casey's Instagram page shows him finally returning to the camera after leaving it there all those years ago.

So-called 'camera traps' are a useful way for photographers to capture wildlife because they allow us to photograph animals behaving in a more natural way as there are no humans around to disturb them.

However as this case has shown they require a lot of patience, and there's no guarantee that after all that time you will find anything when you retrieve the camera, if the camera is even still intact!

But on this occasion, Casey struck gold.

"Not only had bears returned, but so had mountain lions, coyotes, and a surprising variety of smaller animals," he told Newsweek. "One mountain lion in particular kept returning again and again, almost obsessively."

Describing why he pursues this technique, he said: "This kind of discovery is what drives me. I've spent my life locating wild places and setting up cameras to quietly observe what unfolds when no one is around."

The den was used by grizzly bears (John Morrison/Getty)

The footage included a mountain lion, coyotes, and yes, grizzly bears.

But there was one question which was eating up people who saw the post of him going back to get the camera - how on earth did the battery last so long?

One person wrote: "Please tell me what batteries lasted 10 years!"

Casey replied: "I was shocked."

Replying to another post which said "So cool. Batteries lasted," Casey revealed that the camera had not been entirely undisturbed during its long watch.

He said: "Very cool. Bear knocked it over, so it was inactive for most of that time."

Nonetheless, it still managed to capture some remarkable footage during that time.