For generations, Yupik and Inupiat hunters have depended on the Pacific walrus. They ate the walrus' meat and whittled its bones into tools. Walrus skin covered their boats, and walrus intestines, stitched into raincoats, covered their backs. Today, the walrus is still an important part of the subsistence diet in villages along Alaska's Chukchi and Bering sea coasts, and Native Alaskans sell handcrafts made from walrus ivory.

But as the Arctic warms, the landscape upon which both walruses and people depend is changing.

The behavior of sea ice is no longer predictable. Perhaps the best illustration of that came in the summer of 2007, when the Arctic's sea ice cover hit a record low, shattering the previous record by 460,000 square miles -- an area the size of Texas and California combined.

Changing habits of polar bears have drawn most of the attention, but walruses, which depend on drifting summer sea ice as a base for hunting and transportation through the Bering Strait, are changing, too. They are sheltering more on land in Alaska and Siberia.

For Alaska's indigenous hunters, whose lives meld modern conveniences with their traditional subsistence culture, the change threatens a way of life.

"The elders have been coming to me and saying a lot of the old ways -- their many years of observations of how ice was forming and moved, which made them extremely accurate local forecasters -- all of a sudden, those old traditional knowledge ways weren't working, and aren't working," said Gary Hufford, regional scientist for the National Weather Service's Alaska region.

On St. Lawrence Island, just south of the Bering Strait, for example, elders report that the ice's character has changed.

"It's thinner than people are used to seeing, and there's less old, heavy ice," said Hajo Eicken, a University of Alaska sea ice scientist who has worked closely with native communities to understand those changes. "There's less ice to melt in the spring, which means it actually can retreat much more quickly."

Adventures of a 2-ton tap dancer

At the heart of the story is the walrus.

Weighing up to 2 tons, the animals are massive and blubbery on land, set apart by their prominent tusks. Scientists invariably describe them as "gregarious" and intelligent, with a distinct preference for the "broken pack" sea ice whose patches of open water afford them quick escape from polar bears.

"They're funny to watch, humorous animals. If you see a bunch of walruses, they just lie all over each other," said G. Carleton Ray, a marine ecologist at the University of Virginia who research focuses on marine mammals in the Arctic.

They're also noisy, he said, describing the walrus's mating song as "tap-tap-tap-tap, another tap-tap-tap, then a sort of 'boing,'" followed by a whistle.

But the tale is different in the water. There, the walrus is an efficient hunter, using its stiff, sensitive whiskers to root through sediment on the ocean floor for clams, worms, snails and other bottom-dwellers. The walrus dislodges its prey from the muddy seafloor by spitting out a powerful jet of water. Grasping the food in its jaws, the walrus sucks clams and snails right out of their shells, rather than cracking into them to get at the meat.

Still, the animals are limited to hunting in relatively shallow waters, normally diving 60 to 70 meters -- about 200 feet -- to nab their seafloor prey. Each dive lasts about seven to eight minutes.

"They're graceful, but they're not fast," Ray said. "They're not long-distance swimmers."

In recent years, weather conditions have sorely tested that swimming ability. The sea ice edge has retreated farther north during the annual summer thaw, past the edge of the continental shelf and into waters thousands of meters deep where walruses cannot forage.

"It's quite an abrupt change," said U.S. Geological Survey biologist Chad Jay, describing the seafloor's steep drop. "Walruses do all right when they're over the shelf, but in that deeper water it wouldn't take much -- they would spend most of their time swimming to the bottom and not have much time to feed."

A day at the beach may no longer be fun

As sea ice patterns have shifted, the animals have scrambled to adapt. In 2007, scientists were stunned to find thousands of walruses hauling out on beaches in Russia and Alaska, a scene that was repeated in 2009. That year, USGS reported 3,500 animals on the beach at Icy Cape, 140 miles southwest of Barrow. Anecdotal reports from Russia have estimated "tens of thousands" of walruses hauling out on short in Chukotka, according to the U.S. Fish and Wildlife Service's latest stock assessment.

Scientists do not know whether there is enough food in near-shore waters to support walruses over the long term. They are also concerned because the intensely social -- but easily frightened -- animals gather in larger numbers on land than they would on ice, and in combinations contrary to their normal community structure.

Female walruses and their young normally spend summers apart from males, but that has not been the case when a dearth of sea ice has forced the pinnipeds to seek refuge on land.

"When they haul out on shore, they're in very dense aggregations with adult males and females and young all mixed together," Jay said. "If there are any disturbances on the haul out, and walruses start to flee to the water, the younger animals get trampled and die."

Jay said he believes that's what happened in Icy Cape last year, when 131 walruses -- many of them young animals -- died. Similarly deadly stampedes have also been reported in Russia. Such reports helped prompt the Interior Department to consider protecting the Pacific walrus under the Endangered Species Act. The agency is expected to render its preliminary verdict next month.

Meanwhile, Ray said he's concerned that the diminishing spring and summer ice levels -- and the changing mix of different types of sea ice -- will impede walrus reproduction. Females walruses mate, give birth, nurse their young and molt on the ice, sticking with each pup for up to two years.

"The ice is forming about six weeks later in the fall and melting about six weeks earlier in the spring," he said. "That takes three months off the ice season. ... In the spring, with all those pups around, they're losing their ice."

Conventional wisdom thaws

But it's not just the walruses that are affected by the unpredictable Arctic ice. For hunters, the changes have made venturing out on ice or in small hunting boats more dangerous and more expensive, with less certain hope of returning home with walrus carcasses.

"As sea ice recedes, you're traveling further to find good ice," said Vera Metcalf, executive director of the Nome, Alaska-based Eskimo Walrus Commission. "That's a concern not only for safety but because it's very expensive to get prepared for any kind of hunting out in the waters. A lot of freight is shipped by airplane to the communities, and fuel is very expensive."

To help hunters in Alaska's coastal communities adapt to those changes, scientists with the University of Alaska and the National Oceanic and Atmospheric Administration have partnered up with village elders on a new type of climate forecast.

The project, whose initial run took place between April and June of this year, produced weekly forecasts of sea ice movement and melting with an eye to walrus hunting, rather than shipping or fishing.

But unlike the traditional model of scientific research, in which researchers arrive at a conclusion and communicate it to the public, the Sea Ice for Walrus Outlook was designed to incorporate detailed observations from expert hunters in participating Native communities, tapping generations of wisdom gleaned by those living closest to the ice. It's part of an emerging body of science that seeks to inform Western science using traditional knowledge.

In this case, that required reconciling two different approaches to Arctic ice, said the National Weather Service's Hufford. Scientists often focus on the Arctic as a region, while hunters are experts on the sea ice within about 50 miles of their villages.

"Many still hunt bowhead whale in skin boats made of walrus," he said. "They really know their local waters."

In Gambell, for instance, local hunters "have a vision of at least three or four waves of sea ice passing by in spring," said Igor Krupnik, a cultural anthropologist at the Smithsonian Institution who has worked closely with Alaska Natives to document their traditional environmental knowledge. "What scientists see as just ice breakup and retreat, to local people, it's a combination of four or five different events. It's a very different mechanism. They can see where the ice is coming from."

Enlisting hunters to keep watch

The project did hit some practical hurdles, such as figuring out how to transmit the forecasts to hunters who live in remote villages where access to the Internet can be slow and spotty. The scientists ended up putting the forecasts on the Web in regular and stripped-down "low-bandwidth" versions. They also faxed copies to village offices, harbor patrol offices and general stores.

The effort has already paid off for researchers, said Eicken, the University of Alaska scientist spearheading the forecast project. Reports sent in by Winton Weyapuk, an elder in the villages of Wales, show that the scientists' forecasting model "consistently" underestimated the wind speeds in the Bering Strait region, he said. That's important because wind, along with currents and sea surface temperatures, determines the motion of the ice.

Weyapuk has been working with Eicken and other scientists for several years. For the last four years, he has kept a daily log of weather and ice conditions at their request.

"It's a different world when you have someone like Winton working with you," said Krupnik, who has collaborated with Weyapuk on an illustrated dictionary of Inupiaq sea ice terms used in Wales. "We're learning a tremendous amount of new stuff."

Another hunter, Curtis Nayokpuk, sent in detailed reports on a peculiar ice formation -- what Eicken called an "ice nose" -- near his village, Shishmaref.

"This year the Wales Shoal shore ice is back!" Nayokpuk wrote in a dispatch included in the April 9 forecast. "Looks like it has frozen to historic size/thickness and winter/spring south winds have not chipped away at the shoal ice buildup. This means that the migrating sea mammals will be farther out from Shishmaref (direct route from Wales to Pt. Hope) and will require longer or more boat trips to find the walrus and Oogruk [bearded seal] this year."

Many scientists now predict the Arctic could see ice-free summers by 2040. That's not good news for the walruses. Jay's best guess is that over the next decade or so, years when the ice edge recedes above the continental shelf will become more frequent. What appeared to be aberrant behavior in the summer of 2007 -- walruses hauling out on land -- could become the rule.

"They can make use of some fairly sparse ice, but at some point, even that ice will disappear," he said.

How traditional Yupik and Inupiat hunting techniques will fare in the future is also an open question.

"People still hunt walrus on the ice or from boats," Krupnik said. "It's not damaging their lifestyle irreparably, but it is different now. They are doing it in May, not June. It's becoming very compact, two or three weeks instead of six weeks. Often, it's a week only. If something happens during that week -- if you have bad weather or strong winds -- you will be in trouble."

Click here to view the Sea Ice for Walrus Outlook.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500