The carcass of a puffin is not a rarity in itself, but when hundreds are recovered – at a number 70 times normal – and many others are sick and emaciated, something peculiar is at play. The mass die-off occurred in the Bering Sea, turning St Paul Island into a feathered graveyard of sorts.
In the four months of survey in 2016, the team found 359 dead bodies, most of the tufted puffin variety, a species that seldom washes ashore. In the past decade, only around six have ever been recorded. Hundreds of tufted puffins – known for their white “face-masks” and blonde plumes that look like two slicked-back eyebrows – dead en masse startled the residents and scientists alike.
Not only that but those are just the ones the team found, marked and photographed for record-keeping purposes. The researchers estimate that around 3,150 to 8,800 birds died in total, with tufted puffins making up 87 percent, followed by crested auklets – those black birds with a plume sprouting up right between their eyes.
“Collected specimens were severely emaciated, suggesting starvation as the ultimate cause of mortality,” wrote the researchers in the open-source study published in PLOS ONE. “The majority of tufted puffins were adults regrowing flight feathers, indicating a potential contribution of molt stress."
The team believes elevated sea surface temperatures are the primary culprit, setting in motion a domino effect that saw shifts in plankton and forage fish distribution in the eastern Bering Sea. They believe this change in prey distribution combined with molt stress resulted in a mass die-off.
Puffins spend most of their life out in the open ocean, but return to shore during breeding season to nest and molt, replacing their all-black plumage with bright feathers that have garnered them the nickname “clowns of the sea”. Molting is an energy-consuming process for birds, with their ability to fly limited during this time. A combination of climate factors and molting season likely contributed to their demise. They just couldn’t get enough food in time.
The National Park Service (NPS) notes that Alaska has also been experiencing “extreme” seabird die-offs, with 2018 marking the third consecutive season of massive seabird deaths.
“Seabirds are good indicators of ocean ecosystem health,” noted NPS. “Recent mortality events are concerning in that they may be pointing to significant changes in marine ecosystems. Our northern oceans have been experiencing record-breaking, above-average sea surface temperatures.”
When temperatures rise on the sea’s surface, cold-water fish and plankton relocate or reproduce less often, making it difficult for seabirds that rely on them for nutrition to scrounge enough food to survive. On St. Paul Island, the puffin carcasses were collected with the help of citizen scientists as part of a program called COASST.
"This paper is a successful application of citizen science in the real world,” said Lauren Divine, from the Aleut Community of St Paul Island Ecosystem Conservation Office, in a statement. “Island residents collected high-quality data in real time and provided COASST with a detailed context for their analysis. Without the positive and mutually beneficial relationship built over years of collaboration, this massive die-off of Tufted Puffins would have gone unreported in the scientific community.”