In 1741 Vitus Bering sailed his 14-gun, 360-ton brig St. Peter along the southern edge of the sea that would later bear his name. After reaching Alaska’s coast earlier that summer, Bering was trying to get back to Russian Kamchatka, from which he had started in June, ahead of winter’s gales.

Wracked by scurvy and beset by autumn storms, Bering and his 76-man, mostly Russian crew picked their way along the 1,200-mile arc of volcanic islands that comprise the Aleutians. And they almost made it. That November, just 350 miles short of home, the St. Peter wrecked on a deserted island. Bering and 29 of his men soon perished; the remaining crew would manage to fashion a smaller vessel from the ship’s timbers and escape the island the following summer.

Among the survivors was Georg Steller, Bering’s German naturalist (who helped keep most of the sick and marooned crew alive by finding them roots and greens to eat). Steller returned home with a journal in which he’d recorded the incredible wealth of wildlife he’d seen on their journey—sea lions and seals, whales and sea otters, which were often the castaways’ only food. He described the gargantuan, manatee-like beast known today as Steller’s sea cow, 30 feet long and easy for starving men to harpoon. And the birds—birds in numbers beyond counting.

Today the sea cows are long gone—eaten into extinction by the Russian fur hunters who followed Bering and Steller. But the birds remain, part of an extraordinarily rich pocket of life cradled between Alaska and Russia, rimmed by the Aleutians to the south and all but pinched off to the north by the Bering Strait, where the two landmasses are only about 50 miles apart.

Nowhere else in North America, since the demise of the Passenger Pigeon, has it been possible to see so many birds. “Something like 80 or 85 percent of the United States’ seabirds nest in Alaskan waters, and most of those are in the Bering Sea,” said Nils Warnock, executive director of Audubon Alaska. In such a remote place, where researchers must travel thousands of miles by ship through choppy seas, it’s hard to nail down precise numbers. But by even the most conservative estimates, 40 million to 50 million seabirds nest here in more than 1,800 colonies. That total is believed to include 1.4 million Northern Fulmars, 6.7 million Fork-tailed and Leach’s Storm-petrels, 2.2 million Thick-billed Murres, 9 million Least Auklets, and more.

Come spring the volume doubles when an additional 40 million to 45 million seabirds, including Laysan Albatrosses from Hawaii and Short-tailed Shearwaters from Australia, arrive to feed during their non-breeding season.

Nourished by the waters’ abundant fish, squid, and other sea creatures, most of the Bering’s seabirds appear to be doing okay—at least for now. But across the world, seabirds are in trouble. One study published last year documented a nearly 70 percent decline in global populations between 1950 and 2010. Scientists worry that seabirds are especially sensitive to the threats of climate change, ocean acidification, commercial fishing, and shifts in marine ecosystems—threats that are only expected to intensify in the coming years.

A Northern Fulmar. Photo: Nick Cobbing

In this gateway to the Arctic, sea ice is already withdrawing north and disappearing more quickly; earlier open water, scientists know, means a reduction in the zooplankton at the base of the Bering Sea’s food chain. What’s more, less ice has allowed a greater volume of shipping traffic through the Bering Strait, increasing the chances that a ship will run aground and spill its load of heavy crude, or bring rats to a pristine island, already a concern in the Aleutians.

“So far, at least, the birds have been able to buffer themselves pretty well against changes, and they’ve remained pretty healthy and resilient,” said Heather Renner, supervisory wildlife biologist for the Alaska Maritime National Wildlife Refuge. “But we’re probably on the threshold of a lot of change.”

The Bering Sea region may provide the last, best chance to preserve the kind of natural wealth that once filled all the world’s oceans. Trouble is, the area is so far from anywhere that securing an accurate count to determine whether a species’ population is rising or falling—not to mention why, and what to do about it—is a Herculean task. And a very expensive one to boot. Just getting a team to a remote island like St. Matthew in the northern Bering Sea means chartering a ship from a community like Homer, 1,200 miles away, at a cost of tens of thousands of dollars each way, Renner said. Getting to the Diomede Islands, which sit an additional 400 miles farther north in the middle of the Bering Strait, home to some of the biggest seabirds colonies in the Arctic, just compounds the labor and expense.

With 10 to 15 years or more typically passing between scientific surveys, there are plenty of mysteries. Consider the Least Auklet, a charcoal and ivory bird the size of a pudgy starling, with white button eyes that look slightly manic. It is one of the most abundant seabirds in the Northern Hemisphere, yet research is so limited that scientists can say for sure only that Least Auklets breed by the millions in the Bering Sea—perhaps 500,000 on the Diomedes alone—feeding on copepods, shrimp, and other zooplankton in summer. What goes on the rest of the year, when the birds are at sea, is anybody’s guess. Meanwhile, no one has figured out how to even count the swarms of Northern Fulmars nesting on Chagulak Island in the Aleutians. Estimates have put the number of these gull-like relatives of shearwaters and albatrosses there at half a million, forming what is likely the largest fulmar colony in the world.

The Pribilof Islands, 300 miles off western Alaska, at least provide slightly better access to seabird colonies—if you don’t mind heights or seasickness. On land, biologists skirt the edges of windblown cliffs to survey the nests of Thick-billed and Common Murres perched on rocky ledges. On water, they travel in a tiny skiff, pitching in the frigid waves while trying to focus their binoculars on the million or more bowling-pin-sized birds crowding above.

On the Pribilofs, biologists are also attempting to track 200,000 Red-legged Kittiwakes—the largest such colony of these delicate, long-winged gulls, and one of just four colonies in the world, all in the Bering Sea. Jostling with them are Red-faced Cormorants—dark, goose-sized birds that have crimson skin around the eyes and seem far too large for the narrow ledges they balance on. These birds, likewise, are found nowhere else beyond the Bering Sea’s southern rim and adjacent areas, and yet the details about them are largely unknown.

Red-legged Kittiwakes. From Gerrit Vyn’s new book, The Living Bird. Photo: Gerrit Vyn

If counting birds on land is hard, it’s even tougher on the open ocean. Yet for more than three decades, George L. Hunt Jr., a research professor at the University of Washington, and his colleagues have conducted grueling at-sea surveys. They recognize the importance of searching beyond the nesting colonies, which hold only about two-thirds of any given population. The rest of the birds are at sea, Hunt said. Some are too young to breed; others tried to mate and failed, or skipped a year of nesting.

Discerning long-term population trends is further complicated because seabirds are exceptionally long-lived; puffins and murres, for example, can survive for 30 or 40 years. That means a colony can be suffering significant losses or poor breeding success for a long time before it finally shows.

The people who monitor the birds at sea are a particularly scrappy lot. They sit high above the waves on the bridge of a survey vessel, continually scanning the horizon several hundred yards out for flying or sitting birds, identifying and counting them while simultaneously entering the data into a laptop, even in rough seas. “Especially if you’re doing anything in the spring or fall, it can be horrible weather,” said Kathy Kuletz, a U.S. Fish and Wildlife Service seabird specialist based in Anchorage, who heads the at-sea surveys. Her crews average 12,000 miles of survey transects a year, and since 2006 they have logged a total of about 127,000 miles—a distance slightly more than halfway to the moon.

Hunt has done this more times than he can count. “So you’re in the wheelhouse or on the deck, sometimes 50 or 60 feet above the waves, trying to spot seabirds at up to 300 meters that are showing no more than six inches of body above the water. If it’s flat-ass calm—to use a nautical expression—you can see things pretty easily, but when there are little whitecaps you’re looking for black-and-white birds against a black-and-white ocean. And once you have combers—waves rolling down on themselves—you have to stop because you’re not getting good data.”

When the winds really roar, and the ship is rolling back and forth through 60 degrees of motion, Hunt said, “you don’t work. You strap yourself into your bunk so you don’t become airborne. And when it’s done, no matter how exhausted you are, you have to get up and go to work, because you have limited time and it costs a helluva lot of money to be out there.”

As punishing as they can be, the surveys have shown how some birds are reacting to changing conditions in the Bering Sea. Each year more and more albatrosses—Laysan and Black-footeds from Hawaii, and endangered Short-tailed Albatrosses from Japan—are found in the Bering Sea, according to Kuletz, who speculates that the shift may be tied to a northward movement of squid, a major food, in response to warming oceans. Plankton eaters like auklets and Ancient Murrelets are likewise moving north as the period of ice-free open water lengthens each year.

The at-sea surveys have also shown worrisome trends for those Northern Fulmars that no one can count at their immense breeding colonies. An analysis by Martin Renner (Heather’s husband, and a seabird expert in his own right) found that the number of Pelagic Fulmars counted at sea has been declining since the 1970s—and that these birds are similarly moving farther north into the Bering Sea.

Why? “I can only speculate on it,” Martin Renner said. Fulmars habitually follow fishing boats to feed on the bycatch and offal (if you’ve ever watched Deadliest Catch, you’ve seen plenty of fulmars); changes in regulations on how such waste is disposed of may be robbing the fulmars of a diet they’ve come to rely on. “Or it may have more to do with changes in the ocean ecosystem that are climate-driven,” he said.

There are other warning signs. Red-faced Cormorants have declined in the Pribilofs by about 70 percent since the 1970s, Heather Renner said. “That’s also true of the western Aleutians, which is really the core of their range. But in the rest of the Aleutians, they’ve been pretty stable.” Meanwhile, Aleutian Terns, whose white foreheads and darker gray plumage set them apart from more widespread (but also declining) Arctic Terns, have decreased in Alaska by 92 percent in the past three decades—“just huge, huge declines,” she said.

There are no clear answers as to why. Maybe it has to do with the cormorants not being long-distance fliers, making them less likely to adapt if prey move away from their island breeding colonies. As for the terns, some colonies have suffered from human disturbance, but Heather Renner suspects the trouble is tied to the disruption of their food web—perhaps on the wintering grounds near the Philippines and Indonesia, perhaps closer to home.

Red-legged Kittiwakes, like the ones on the ledges on St. George, are another species of conservation concern, ranked as “highly imperiled” in Alaska by the USFWS. In summer they feed at night on bioluminescent lampfish, which rise to the surface after dark, but in winter at least one group was shown to concentrate (for reasons still unknown) near the edge of the sea ice. “That means we would expect them to be one of the species most stressed by things like climate change,” Heather Renner said.

Having modeled fulmar trends, Hunt, Kuletz, Martin Renner, and others are now analyzing the immense, four-decade data set of at-sea observations to look at how Bering seabirds are faring as a whole. While they’re not yet ready to draw detailed conclusions about their findings, Hunt warned they might not be encouraging. “All I feel comfortable saying at this point is that it appears that there really are some humungous changes happening,” he said.

One certainty is that climate change is going to play a major role in the Bering marine system’s future. There seems to be a natural flip between several-year periods of slightly warmer and slightly cooler water, but scientists expect the warmer periods to lengthen, intensify, and come more frequently. Less sea ice and earlier ice melt affect the spring algal blooms, which affect the zooplankton blooms on which many of the smaller alcids like Least Auklets, and krill eaters like shearwaters, depend.

“If the future goes to more of these extended periods of warm years, I think we’ll see a diminishing of the seabirds in the Bering,” Hunt said. Those declines, Heather and Martin Renner suspect, would likely arise first with birds like Red-legged Kittiwakes and Black Guillemots that are closely associated with sea ice.

Stan Senner, who was the science coordinator for the Exxon Valdez Oil Spill Trustee Council and is now Audubon’s Pacific Flyway Vice President for Bird Conservation, noted with relief that Shell has withdrawn from its attempts at exploratory oil drilling in the Chukchi Sea, and that the Obama administration has frozen new oil and gas leases there for the next two years, although the long-term outlook is uncertain. Such drilling, he said, “has enormous potential, were there to be a catastrophic accident of some kind, to kill hundreds of thousands of birds. In that environment—cold air, cold water temperatures—a patch of oiled skin and feathers the size of a quarter is enough to kill a bird. You virtually assume that oil on a bird means death. And there’s no capacity to pick up and rehab birds in those settings anyway.”

Consider the 2010 BP blowout in the Gulf of Mexico, Senner said, when on peak days some 47,000 people, in more than 9,000 vessels, were working to contain the damage. Not even a fraction of that capacity exists among the tiny, scattered villages of the Arctic. “I’ve never heard the industry say how they’d respond” to a major spill, he said.

And it wouldn’t take a massive blowout. “A ship accident there would be a nightmare, and any spill up there would be devastating,” said Audubon’s Warnock, who has spent much of his career working with oiled birds in the aftermath of spills. For example, he said, every winter the entire world population of Spectacled Eiders—some 300,000 of these stunning, colorful sea ducks, which are already listed as a federally threatened species—concentrates in a single location, south of St. Lawrence Island in the northern Bering Sea. They pass the winter in open areas amid the sea ice, diving below the relatively shallow water for clams. No one even knew where these birds went for the winter until the dense flocks were discovered in the 1990s. Even a modest spill in that area at the wrong time could wipe out the entire species.

For now it’s impossible to say what tomorrow will bring. “There’s huge uncertainty when it comes to predictions,” Hunt said. “It’s hard enough to understand what’s going on right now and how things are working, much less predicting what it’s going to be like in the future.”

The cliffs on St. George, Chagulak, St. Lawrence, and a hundred other islands in the Bering Sea are silent now. Emptied by winter, they wait for spring and the promise of returning multitudes—a promise that has always been fulfilled, at least so far.