Researchers say they’ve further narrowed the possible explanations for a seabird die-off in the Bering Strait Region from 2018. Although thousands of dead seabirds were found emaciated and starved that summer, the cause may not be related to food shortages, but instead to some type of sickness.
“Red years, that’s 2018 and 2019, all (sea)birds are experiencing if not the highest, very close to the highest nutritional stress that we’ve ever seen.”– Alexis Will
Alexis Will is with the University of Alaska Fairbanks’ Institute of Arctic Biology and has been studying seabirds on St. Lawrence Island for years. At the end of March, Will unveiled her research during a UAF Strait Science presentation online hosted by the university campus in Nome.
Will has concentrated her research on five different species of birds, all found on the island – kittiwakes, least auklets, crested auklets, common murres, and thick-billed murres. Each species dives to a different depth, and therefore consumes various fish. However, the thick-billed murres, as Will puts it, eat everything from euphausiids to squid and a wide range in between.
Besides all five species experiencing high nutritional stress over the last couple of years, due to drastic shifts in the Bering Sea ecosystem, Will says the seabirds had other challenges.
“In those two years we also saw almost complete reproductive failure on the colonies, which is quite unusual for these birds. Neither least or crested auklets live for very long so they can’t really afford to lose a breeding season. They really put a big effort into breed(ing) every year. So, for these birds to miss two breeding seasons in a row is pretty significant.”
Will and her fellow researchers have been using a stress hormone called corticosterone to track how stressed these seabirds are. This is a reliable marker, according to Will, when the birds are tested at their colonies on St. Lawrence Island because there aren’t many other stressors present causing corticosterone to be produced in the seabirds.
Due to the high levels of nutritional stress found in all five species, Will says her research team predicted the data would show a lack of food available for them to eat. Instead, the research team observed completely different findings in the Bering Sea around St. Lawrence Island.
“So basically we see the opposite of what we predicted. We don’t see any increase in forage fish, we actually see what looks like a decline, and we don’t see any decrease in benthic fish.”
Forage fish would potentially be a food source for common murres and kittiwakes, however the researchers’ study showed common murres are choosing to eat benthic prey instead. Benthic fish refers to various species that live at the sea bottom, deep in the water column, which common murres and other birds eat.
Will points out that this is only the tip of the iceberg and researchers need more data and samples to get a fuller picture of what is causing seabirds in the Bering Sea region to starve to death.
But at this point, with indications that there are plenty of prey fish available for seabirds to eat, Will says they are eliminating “lack of food” as a cause for the 2018 die-off.
“Of course birds were starving so that may have been some sort of result, poor foraging ability may have been a result, but we’re looking a little bit more at ‘maybe they were sick.’ We found Avian influenza in just one bird, remember it was just one and it is possible that they picked it up on the wintering grounds. However, we don’t know how many birds were infected, or what the effect is of this particular strain on thick-billed murres.”
She would go on to say that they also don’t know what this means for the humans that eat these seabirds.
Despite the many unanswered questions, one Savoonga resident, who has been following Will’s research, says many on the island aren’t deterred from harvesting seabirds or their eggs.
“There’s still plenty of birds, I think they’re just…having trouble reproducing because of the lack of food maybe.”– Punguk Shoogukwruk
Punguk Shoogukwruk has worked with Will and her fellow researchers for the past couple of years. He is a resident guide for the team in Savoonga and he says he has observed a change in seabirds’ behavior from last year.
“The year started out okay, the birds were very active, they were laying eggs. And then as the year went by, the eggs started disappearing, there was no chicks. This was after egg harvest (around June or July)…But the birds gave up, they just gave up on laying their eggs.”
Savoonga elder Delbert Pungowiyi made the same observation last summer as he witnessed empty cliffs without the usual birds’ nests near his home.
Will says those observations were in line with the researchers’ findings when they came back to Savoonga in 2019.
“When we returned to do our normal field work and started counting birds on the cliffs, we found that there were 25% less birds on the cliff than there were before the die-off. These counts are really rough and they are not by any means a rigorous population estimate, but it does indicate that it’s possible there was a pretty significant impact on the breeding population of birds from this die-off event.”
Thick-billed murres, the only sampled species from St. Lawrence Island with a confirmed Avian flu strain of H10N6, will be the focus during this year’s research.
During the upcoming season Shoogukwruk will be collecting samples from thick-billed and common murres on Will’s behalf, as her work continues this summer under different circumstances.
“This year because of COVID-19 the scientists can’t come out here (to Savoonga), so they sent me a bunch of sample kits and I was to give them to the locals here, the local captains, and they’re allowed ten birds a piece.”– Punguk Shoogukwruk
Shoogukwruk says the research team pays him and other locals $18 for each bird they sample, with a cap of ten birds per person. Each sample kit comes with swabs, personal protective gear like gloves and goggles, as well as instructions on how to properly store the samples.
The research team hopes to gather more than 200 seabird samples this year with the help of Shoogukwruk and other Savoonga hunters. But it is unclear when the team will identify a direct cause for the Bering Sea-bird die-off in 2018, let alone the most recent one from last summer.
As they try to identify the reason for the die-off, Will says it is still safe to keep harvesting and eating seabirds for subsistence purposes, but St. Lawrence Islanders should continue to use their best practices for preparing and cooking the meat.
Image at top: File photo of seabirds flying at sunset. From the public domain, via Pixabay.