Research has no answers for continued seabird die-off
By Julia Lerner
St. Lawrence Island, home to two native villages in the region, is also the summer home of several migratory seabird species, including kittiwakes, auklets, murre and shearwaters.
Over the last several years, though, the bird colonies on the island have been shrinking, and no one has been able to determine why.
“They are literally seeing fewer birds on the cliffs, and they’re watching the birds fade away every year,” explained Alaska Sea Grant Marine Advisory Program Agent Gay Sheffield, based at UAF’s Northwest Campus in Nome. “These birds are a signal of the health of our ecosystem, and they’re also a food security item, so people have great interest. Why are birds here not in the best of health, and why are they dying?”
Across the region, dead seabirds have been washing up on shores in large numbers for several years now, and the problem seems to be getting worse.
“Starting in 2017, the northern Bering Sea has been experiencing seabird die-offs,” Sheffield explained. “Multi-species adults have been washing in dead, and that includes a variety of different types of birds. Typically, it has been shearwaters, murres, puffins, gulls, kittiwakes, and this year we had cormorants and loons wash up dead. It’s not normal.”
In addition to local subsistence hunter and beach goers finding dead birds on regional shores, the National Park Service recently conducted a survey of the Bering Land Bridge Preserve to study the seabird die-offs in the region. According to reporting from KNOM, they found upwards of 100 dead birds every four kilometers on some parts of the survey areas.
Researchers and scientists, including Sheffield, have posited theories about the seabird die-offs, known as wrecks in the scientific community, speculating disease, toxic algal blooms and food source scarcity, though scientists will have to do a lot more on-the-ground research before they can determine an official cause.
Since 2017, though, the majority of the dead seabirds have one thing in common. “Regardless of the species and regardless of the year, [the birds] have been documented in poor body condition, meaning they’re thin,” Sheffield explained. There are things that could make a bird thin. “One is: Is it sick with something, so it doesn’t feel good, and it doesn’t have the strength to go eat? The second would be: Is it being poisoned, so it doesn’t feel good, so it’s going to starve? Third, is it having trouble finding its food?,” said Sheffield.
“We’ve sent off numerous carcasses to the U.S. Fish and Wildlife Service for testing to see what the cause is,” said Brandon Ahmasuk, Kawerak Inc.’s Vice President of Natural Resources and acting Subsistence Resources Program Director. “The majority of test results just show that they’re starving. We’ve asked, ‘Why are they starving?’ and ‘Is it possible that they’re also being exposed to harmful algal blooms, toxins in the ocean?’”
Algal blooms occur naturally in the summertime but are becoming more frequent as the Bering Sea warms due to climate change. Blooms can produce toxins that poison fish, mammals and birds, according to the National Oceanic and Atmospheric Administration, though non-toxic blooms can be harmful, too. Non-toxic blooms can consume all the oxygen in the water, clog fish gills and smother bird food sources.
Researchers at the U.S. Fish and Wildlife Service, though, told Kawerak that bird metabolisms worked too quickly to test for algal poisoning, Ahmasuk said. Ahmasuk has been working with seabird wrecks for over a decade.
“It was 2011, and we were already getting reports of seabird die-off,” he told the Nugget. “Early on, it was mostly murres and shearwaters, but as time went on, the murres were still dying, but we began getting more reports of puffins and auklets. Other migratory birds, ducks, swans, cranes, appear to be doing fine. It appears to be all seabirds taking the hit.” Many of the bird species involved in the ongoing wrecks are harvested by subsistence hunters, meaning a decrease in food supply and quality for residents of the Bering Strait.
“There’s very little fat and very little meat on the birds, with the breastbones showing,” Ahmasuk said. “Communities are heavily reliant on these resources in the spring and summer to help offset grocery store costs. Across our region, over the last several years, residents haven’t been able to harvest eggs or seabirds like they used to.”
Ahmasuk and Sheffield have been collecting bird carcasses, freezing and shipping them to researchers at USFWS to try and find answers. When U.S. Fish and Wildlife receive the birds, they typically send them to the US Geological Survey National Wildlife Health Center in Madison, Wisconsin for necropsy.
“There, they conduct an examination of the body, and then they can do testing for disease, infectious and non-infectious diseases,” explained USFWS biologist Robert Kaler. “Ultimately, their goal is to determine the cause of death.”
Kaler, the USFWS biologist responsible for coordinating seabird die-off response in Alaska, says the state has been experiencing significant seabird wrecks over the last few years.
“We had a major die-off in the Gulf of Alaska [in 2016],” he told the Nugget. “We’ll never know exactly how many birds died, but there were probably upwards of 200,000 common murres that died, and there were other seabirds that were effected as well.”
When the USGS Wildlife Health Center conducted necropsies of those birds, they declared the cause of death: Emaciation.
In the following years, though, Kaler says scientists at USFWS and at the USGS Alaska Science Center detected trace amounts of toxic algal growths in Alaskan waters, which may have contributed to the murre emaciation.
“We don’t have a solid understanding of how even a low level of exposure to a biotoxin … will affect the bird or organism,” Kaler said.
Because the wrecks are occurring in several species of seabirds, there are more questions than answers right now.
“In almost all cases, the birds have been starved,” explained Kathy Kuletz, USFWS’s supervisory seabird biologist. “They’re emaciated, indicating starvation was the cause of death. That can’t completely discount that there might be harmful algal bloom toxins that made them too sick to eat, but it seems too pervasive and across the board in terms of number of species. The fact that they’re emaciated indicates a lack of food.”
“The big question right now,” Kuletz said, “is where is the food?”
In 2017, scientists discovered shrinking of the cold pool, a cold-water “curtain” that separates the cooler waters of the Northern Bering Sea from the warmer waters of the Southern Bering Sea. Over the years, the thermal barrier disappeared, meaning that northern waters warmed, fish moved north and competition for food resources began within the ecosystem.
“The sea ice used to be very stable and on a regular schedule, and created a nice thermal barrier,” Sheffield said. “The southern Bering Sea ecosystem is different than ours, and it is comprised of a lot of large bodied, predatory, commercially-viable fish stock, like Pollock and Pacific Cod.”
The disappearing sea ice means less productive algae growing to support existing marine life, and the emergence of larger, more predatory fish means more competition for the shrinking food stock of smaller prey fish.
“We have bigger fish in our waters and less ability to make food,” Sheffield said. “Is there enough food for the birds?”
Kaler has received reports of bird die-offs in the Bering Strait every year since 2017, he said, though this year the die-off spread further west.
“There have been annual die-offs of seabirds [in the region], and sometimes that die-off extends down into the Bristol Bay region,” he said. “This year, in 2021, it extended into the Aleutians. From St. Lawrence Island to Nome to Shishmaref, we’ve been getting reports.”
Lavrentiya, a small community in Chukotka on the opposite side of the Bering Strait from Wales, has seabirds washing ashore, too.
The first report this year came in May, when Kaler received details of two dead murres in the Bering Strait.
“These birds are food for people here,” Sheffield said. “Murres, puffins, cormorants, seagulls, are food for people in the region. They’re also a product of a healthy ecosystem.”
The Bering Strait ecosystem, then, is struggling.
“It’s alarming,” Kuletz said. “We have more and more observations of birds washing up. It’s still in the dozens to hundreds at any one given site or area, and of course it’s a huge area.”
Kuletz says the Bering Strait die-off is not considered a large one, as a major die-off can include thousands of birds in one spot. “Even so, it’s certainly concerning because it’s occurred multiple years in a row,” she said. “The fall always shows a bit of an uptick for seabird mortality. Part of that is because young birds are not very big and not very experienced at foraging, so if conditions are not really good, they might starve.”
The best way for locals to help, she says, is to continue reporting details of each dead seabird in the region to Sheffield, Ahmasuk and to USFWS.
USFWS does not have boots on the ground studying the seabird die-off in the Bering Strait. Kuletz said travel around the region has been complicated by the COVID-19 pandemic and relies heavily on on-site partners and volunteers to collect specimen for them.
“The people of this region, all of the community members, have continued to call in what they see and in a lot of cases, send in what they see,” Sheffield said. “It’s all a volunteer effort to find out what is wrong with our ecosystem and what is wrong with the birds.”