In 2016, tens of thousands of Common Murres washed up dead on beaches lining the Gulf of Alaska. Several more mass seabird die-offs have occurred in the region since then. Photo: Mark Thiessen/AP

Climate

In Alaska, Starving Seabirds and Empty Colonies Signal a Broken Ecosystem

Mass die-offs and breeding failures, now ongoing for years, have marine biologists worried that this is a new normal caused by climate change.

For thousands of years, tribal communities living on the inhospitable coast of Alaska and frigid islands of the Bering Sea have celebrated the arrival of spring by harvesting murre eggs. Every year Brandon Ahmasuk takes his family out to the cliffs, and just as he and his brother once did, his boys fight over who gets to scramble across the rocky outcroppings to collect the oblong, speckled eggs near their home in Nome, Alaska. On a single outing, Ahmasuk says he can usually count on gathering enough eggs to fill a 55-quart cooler.

But this year, when Ahmasuk’s brother took his annual trip out to the cliffs, he found a single egg. The breeding colony of several thousand Thick-billed and Common Murres was practically vacant.

Seabirds and their eggs are protected by the Migratory Bird Treaty Act, but Alaska’s native peoples can legally harvest these traditional foods as long as animal populations are healthy. And they need to: Due to the region's isolation, grocery items are expensive at rural stores. Ahmasuk, who is the subsistence director for Kawerak, Inc., an association of native villages in the Bering Strait Region, estimates it costs $8 or $9 for a gallon of milk in his town, where unemployment is high. Murres and other seabirds are a caloric lifeline, and their robust colonies have always been able to support the annual egg collections. That is, until recently. 

The murres' disappearance this year isn’t limited to Nome. Throughout Alaska’s coastal waters on the Bering and Chukchi Seas, Common and Thick-billed Murres failed to breed this year. Typically millions of the raucous black-and-white seabirds gather at some 170 colonies along Alaska’s coast to nest and raise their chicks together. But this year barely any birds showed up to their breeding grounds in May and June, and those that did arrived uncharacteristically late. Some birds in the Pribolof Islands in the Bering Sea were still sitting on eggs in mid-August, about a month later than normal.

At the same time, when Alaskan communities fringing the Bering and Chukchi Seas weren't finding live birds on nests, they were finding dead birds on beaches. From May through July, hundreds of emaciated Thick-billed Murres, Common Murres, Fork-tailed Petrels, Short-tailed Shearwaters, Black-legged Kittiwakes, and Northern Fulmars washed up on the Alaskan coast. Their cause of death? Starvation.

A single seabird die-off or breeding failure occasionally happens, and healthy, wild populations can absorb a bad year. But the two disruptive events have occurred together and for several years in a row, suggesting a new normal in the North Pacific and Arctic seas, says Max Goldman, a conservation biologist at Audubon Alaska. “It seems pretty clear that seabirds are dying from starvation and due to a few facets of climate change,” he says. Water temperatures are well above normal off the Alaskan coast, and this past winter, for the first time in known history, sea ice in the northern Bering failed to refreeze over the winter.

“It was shocking,” says Phyllis Stabeno, a physical oceanographer with the National Oceanic and Atmospheric Administration. “We’ve never seen this lack of ice before.”

The seabirds’ troubles add to the list of this summer's atypical events that are more likely to occur in a warmer atmosphere: wildfires have consumed the west since July; algae blooms are choking wildlife and making people sick in Florida, and some of the Arctic’s oldest sea ice that is always frozen, even at the peak of summer’s ice retreat, melted for the first time in recorded history. These sorts of events are projected to grow more frequent and extreme as climate change progresses, according to the Intergovernmental Panel on Climate Change.

Common Murres washed up on the state's southerly beaches lining the Gulf of Alaska in 2016. This summer, six species showed up dead but were more concentrated in northern Alaska offshore of the Bering and Chukchi Seas. Photo: Mark Thiessen/AP

The same changes affecting those systems—just a few extra degrees in temperature, really—are also reverberating throughout the North Pacific food web, from phytoplankton to fish and all the way up to apex-predator seabirds, which are struggling to find food in water warmer than they’re used to.

The biologists aren’t immediately concerned about the seabird populations; these species are long-lived, abundant, and widespread. Several years of die-offs and now breeding failures could put a “dent” in the populations, says Kathy Kuletz, a seabird biologist with the U.S. Fish and Wildlife Service (FWS), and especially in local populations. But for now, Kuletz and other researchers are more concerned about what these occurences foretell about the ecosystem’s health and its future.

A Fundamental Shift

Until about three years ago, Common and Thick-billed Murres had never failed to breed in Alaska since monitoring began in the 1970s, says Heather Renner, a seabird biologist with FWS. Other species, like kittiwakes, could be finicky from year to year, but murres were always steady breeders.

Then, in 2015, three Common Murre colonies monitored by FWS failed to produce chicks, with potentially more failures at unmonitored colonies. In 2016, every monitored murre (Common and Thick-billed) colony in the Gulf of Alaska and Bering Sea failed—something Renner had never seen before. In 2017, the birds bounced back slightly, but she says 2018 looks like another bad year, with low numbers of chicks hatched.

“Often when conditions are tough, [birds are] making the physiological choice not to breed,” Renner says, “because they can’t find enough food to forage for themselves or for a chick.”

Seabird die-offs are growing more frequent, too. This summer marks the seventh mass die-off in Alaska since 2013, says seabird biologist Julia Parrish, the director of Coastal Observation and Seabird Survey Team (COASST), a community-science project that tracks seabird populations and die-offs. COASST trains coastal residents, including those living in the remote villages where Ahmasuk works, to conduct regular surveys of their beaches. The community scientists then document any dead seabirds they find washed up onshore.

In the early years, die-offs affected a single species at a time, like Cassin’s Auklets, Tufted Puffins, or Common and Thick-billed Murres, and the carcasses tended to wash up in the same place over a short period of time. But the die-offs are now affecting more species across a wider geographical area. This year, six species were found dead, and not only species in the alcid family, like murres, which are mostly found in the North Pacific, but also birds in the tubenose family, like this year’s Northern Fulmars and Fork-tailed Storm Petrels, which range farther north into the Arctic. And this year the birds have also been found across a large area—from the mouth of the Chukchi Sea south to the northern Gulf of Alaska and west to St. Matthew Island—over a three-month window.

“All these things point to just a fundamental shift in that Arctic ecosystem,” Parrish says. “There’s lots of evidence that the system is shifting and not in ways that can support more of those upper-trophic organisms,” like salmon, marine mammals, and seabirds.

She notes that her volunteer army has so far counted fewer dead birds this year compared to other recent mortality events. But they can’t know the true scale of the die-offs for certain because birds might sink at sea and never be recovered.

According to Ahmasuk, the birds that do wash up are emaciated, with their breast bones showing, little fat on their bodies, and nothing in their stomach or intestines. 

“The diagnosis is starvation,” Parrish says. “The question is why.”

All Alaskan seabird die-off events, even going back to the 1970s, have been associated with warm water conditions, Kuletz says. Given recent evidence, Renner thinks warm temperatures are “very likely” responsible for the murres’ recent breeding difficulties as well.

For the past few years, scientists have blamed the seabird die-offs on the “the blob,” a localized patch of unusually warm water (also known as a marine heat wave) that sent water temperatures skyrocketing in the northern Pacific from 2013 to 2017. From a seabird’s perspective, the lens of warm surface water created what was essentially a marine food desert, spanning hundreds of miles or more. In their desperation, starving murres were documented flying inland and up rivers, where they would ordinarily never go, in search of food.

But the blob has largely dissipated, further suggesting that the events this year are part of a larger trend of ocean warming. In Alaska and around the world, sea surface temperatures have been warming for decades, and the Arctic is warming faster than anywhere else on Earth.

“The sea ice melting earlier and earlier—that was not produced by the heat wave,” Parrish says. “That’s a more general global ocean-warming signal.”

For people living on Alaska’s coast, these changes are impossible to miss. St. Lawrence Island, which is usually locked in a thick layer of ice during the coldest months, was surrounded by almost completely open water this past winter, says Ahmasuk. The Diomede Islands used to have a sea ice landing strip for small planes; now, they have to be visited by helicopter.

In June 2018, sea surface temperatures in the oceans around Alaska were warmer than usual, sometimes by 5°F, according to ocean temperature data from the National Oceanic and Atmospheric Administration (NOAA).

And in the ocean, especially the cold waters of the Arctic and sub-Arctic, a few degrees can mean a lot. “What I tell people is you’re like an ocean on the inside,” Parrish says. “If you experience a four-degree temperature shift, that would be a serious health problem, and the ocean is the same way.”

Change From the Bottom-Up

Seabird ecologists have spent decades working to understand the relationship between seabirds, their fishy food, and water temperatures to use them as biological indicators of ocean health. They’ve found that water temperature influences the type and quality of food available in the ecosystem, all the way up the food chain. Overall, cold water contains healthier food than warm water.

“As the planet warms up and as that affects ocean conditions, it seems like these high-latitude systems are going to become more like lower-latitude systems, which means overall less productive or at least differently productive,” says Kris Holdereid, a marine scientist at NOAA who studies algae and phytoplankton.

It starts at the microscopic level with phytoplankton, single-celled plant-like organisms, which bloom in the spring and summer off Alaska’s coast. All the animals that feed in Alaskan waters—fish, birds, marine mammals—eat phytoplankton or something that eats phytoplankton. “A lot rides on them,” says Suzanne Strom, a marine scientist at Western Washington University who studies plankton communities in the Gulf of Alaska.

In warm years, including the blob years, phytoplankton communities near Alaska resemble those typically seen further south. Instead of the fatty, high-calorie phytoplankton that bloom in colder water, Strom and her team found skinny, “needle-like” phytoplankton, which effectively put the entire ecosystem on a diet. This low-calorie food source, devoured by zooplankton and small fish, leads to less and lower-quality food for larger fish (including commercially important species), marine mammals, and birds. In short, warmer water led to less energy available in the system overall.

The research “really implicates the planktonic food web in that [seabird] die-off” in 2015 and 2016, Strom says. 

Lack of food is one problem for seabirds, but being unable to find it is another. Fish and plankton flee warm conditions by migrating into deeper, cooler waters, says Goldman from Audubon Alaska. Thick-billed Murres can easily dive to depths of 350 feet, or even 600 feet, but in warm years their food is often out of reach. Other times, food arrives but at the wrong time. Historically seabirds timed their arrival at their breeding grounds to overlap with maximum food. Now, birds are often arriving “to an empty fridge,” he says.

Northern Fulmar in the Pribilof Islands, Bering Sea. Its odd beak appendage is a salt gland that secretes excess salt taken in when drinking large volumes of seawater. Photo: Design Pics Inc/Alamy

Sea-ice melt compounds the birds’ struggles further. In the past, the annual phytoplankton bloom in the Bering Sea was tightly coupled to the springtime retreat of sea ice. During winter, algae grow on the bottom of the ice, and when it melts the algae sink to the ocean floor where zooplankton and small fish feast on it, Stabeno, the physical oceanographer, says. No sea ice means one fewer food resource supporting the base of the food web.

“Seabirds are kind of the sentinels of these ecosystems,” Strom says. If the birds are doing poorly, it’s an indication that everything else is struggling down through the food web.

Many factors influence the Alaskan coastal system: Arctic winds, Pacific currents, glacier melt, and even El Niño play a role. Most, if not all, are influenced by climate change. And the broad trends tell the same story: Each body of water surrounding Alaska—the Gulf of Alaska, the Bering Sea, the Chukchi Sea, and the Arctic Ocean—is showing signs of long-term warming. None of this bodes well for seabirds, or the communities who rely on them on the northern coast of Alaska, especially because it looks like Alaskan waters are going to continue warming.

"It’s such a dynamic system, it’s really hard to determine what’s going to happen next,” Stabeno says. 

For Ahmasuk and other native villagers who rely on the murre eggs for sustenance, such unpredictability is worrisome; human livelihoods are also at risk. “Seabirds are harvested for food by a lot of our communities,” he says, more than ducks, geese, or other bird species. If seabirds continue to decline, people will have to harvest more of other resources, like fish and wild game, though many of these Arctic animals are feeling similar pressures, too.

“It’s a big food-security issue,” Ahmasuk says. “We’re right at the forefront of climate change. It’s happening faster here than any place else.”

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