Filmmaker Shane Moore and Assistant Cameraman Michael Mauntler recap on the time they spent on Alaska’s Admiralty Island and discuss the challenges and dangers that come with filming bears in their natural environment. A behind-the-scenes look at what goes into the making of a nature documentary.

Fortress of the Bears filmmaker Shane Moore reveals some of the filming techniques he used during his shoot on Alaska’s Admiralty Island. A behind-the-scenes look at what goes into the making of a nature documentary.

Part of the massive Tongass National Forest, Admiralty Island in southeast Alaska supports the largest concentration of bears anywhere in the world. Sustained by a wealth of salmon streams, isolated and protected by their environment, some 1,700 Alaskan brown bears are part of a unique circle of life that has played out here for centuries. Beginning in August, millions of salmon — pink and chum, coho and sockeye — return to the island to spawn, providing a feast for the bears, eagles, orcas, sea lions and even the trees. As long as the salmon continue to arrive, all is well. But this year, the salmon fail to arrive for the first time, and the bears get a bitter taste of what the future may hold.Buy the DVD. This film premiered on January 25, 2012. (Video limited to U.S. & Territories.)

Admiralty Island hosts the largest concentration of brown bears in the world. Watch video.

After a spring and summer with no sign of salmon, a mother bear is desperate to catch fish to feed her famished cub. Watch video.

It’s taken all spring and summer, but salmon finally return to Admiralty Island to spawn. Watch video.

Alaska’s Admiralty Island is home to an estimated 1800 brown bears, the largest concentration of bears in the world. Nearly 100 miles long and 20 miles wide, it is half the size of Yellowstone National Park, yet it sustains four times more grizzlies. The native Tlingít people call this island “Kootznoowoo,” meaning “Fortress of the Bears.” It is a place where bears depend on fish, fish depend on trees, and the trees depend on fish-eating bears to spread the nitrogen rich bodies of salmon throughout the forest. Everything depends on the annual salmon run. When a change in the weather keeps the salmon from arriving, the entire ecosystem is affected.

A La Niña winter has cooled the water to two degrees below normal, keeping the salmon out of the streams and delaying the run. It’s the worst salmon season in the last 40 years. As the bears wait for the salmon, they hunt and scavenge for anything they can find to supplement their unsatisfying diet of grass. The receding tide offers unique opportunities, and one young bear demonstrates a remarkable talent for clamming. But the feast is short-lived. With the passing season showing no sign of fish, the bears become increasingly gaunt and desperate. Will the salmon finally make their way up the streams of Admiralty Island? And will the bears survive until they do?

Fortress of the Bears enters a world shaped by bears, trees, and salmon, and explores the delicate balance of their interconnected lives. Fortress of the Bears premieres Wednesday, January 25 at 8/7 c.

I’ve been lucky enough to guide several polar bear viewing expeditions to Svalbard in the European high arctic. It is a wildly isolated and beautiful place. The amazing polar bear shots that Jenny Ross captured with her camera jolt us into thinking about the many hidden implications of climate change. So often we’re drawn to the big picture data, or the sweeping effects that our planet is undergoing – and rightly so. But I also like to dwell on the stories that bring climate change to life, through the eyes of individual animals and people. Each and every polar bear is facing increased every-day stress as a result of our warming planet. One year I saw a female and cubs on a chunk of ice the size of perhaps two football fields. It was the last ice of the season in a west coast inlet of Svalbard, and she was going to float it until it was gone.

Bottom line: polar bears need ice. And there is one reason for that – their prey need ice. Polar bears feed almost exclusively on seals, and those seals are what scientists call pagophilic (”ice-loving”). As the world’s frozen seas shrink, so do opportunities for polar bears to hunt these seals and make a living from a habitat that gets smaller every year. Some of them are forced to take extreme measures – in this case cannibalism. In 2006 I found the remains of a bear in Svalbard that could well have been the result of similar cannibalism (see picture) by desperate bears.

Polar bears elsewhere face similar pressures. Their future was never far from my mind when we filmed polar bears for Bears of the Last Frontier in northern Alaska. The Southern Beaufort Sea population is looking at a questionable future – sea ice will decline there by 6% per decade over the next 45 years. We stand to lose two thirds of the world’s polar bears by the year 2050 due to the effects of climate change. That’s 16,000 bears in 40 years, or an average of more than one bear every day. Although difficult when it comes to the future of the polar bear, I like to dwell on the side of optimism. This century’s polar bears will persist for longest in the high arctic archipelago of Canada and northern Greenland – a high latitude refuge for these super-specialists. They will exist in much smaller numbers than they do today, but my hope is that they will provide a constant reminder – as well as a beacon of hope – to do right by our environment, and ultimately to do right by ourselves.

Pictured: Chris Morgan with a polar bear skull in Svalbard. (Credit: Ellie Van Os)

The Arctic is changing. As temperatures slowly rise and the ice recedes, the shore is getting further away. Food sources that the polar bear have come to rely on are becoming less plentiful. In this changing climate, the polar bear is already showing signs of distress.

While polar bears struggle, opportunistic grizzlies fare well, as they benefit from the melting Arctic’s effects on its ecosystem. While the grizzly moves into newly opened territories, the polar bear can only wait for the freezing of its one-time kingdom. If the changing world proclaims the grizzly the new king of the Arctic, what will become of the polar bear?

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Online content for Arctic Bears was originally posted February 2008.