The caribou migration is a veritable feast for grizzly bears — if the bears can catch them. "American Arctic" premieres Wednesday, April 13 at 8/7c on PBS. [VID: Grizzly bears chasing a herd of caribou. Transcript: Away from the water, the caribou start to relax. It's a mistake. Caribou may be faster than bears on the open plain, but they must also rest the calves. Grizzlies and polar bears are almost the same species and increasingly overlap and interbreed, but grizzlies are a more serious thre

This is from the IMAX documentary: The Great North. William Reeves was the cameraman and Co. Director of the movie. He said, “I can verify that no human with a backpack, bicycle, black suit, or a black bear, was within 200 miles of this Caribou migration; The idea of a human chasing a herd that is running that fast is absurd. For non-believers, go there and try to get within 200 yards of a Caribou on foot, their survival instinct is more intelligent than a humans.” It doesn’t look like a person

The Porcupine Caribou herd is one of the largest herds in Alaska. With numbers nearing 170,000 animals. This herd also completes one of the longest migrations on Earth. | The Wonder Channel