Tufted puffins suffer mysterious mass death in Bering Sea

Global warming ‘increasingly linked with shifts in marine ecosystem processes and structure’, say researchers

Thousands of puffins died in a mass mortality event in Alaska, possibly due to climate change, scientists have said.

Up to 8,800 tufted puffins and other seabirds are thought to have died around St Paul Island in the Bering Sea between October 2016 and January the following year, according to a new study.

Researchers writing in the PLOS ONE journal said that such die-offs were “increasing in frequency and magnitude, potentially linked with ongoing climate change”.

Dead puffins found by scientists were “severely emaciated” and had likely starved, they wrote.

A series of extended warm spells have been linked with a decline in the abundance of prey species in the Bering Sea since 2000, according to the study.

Its authors wrote: “Bering Sea food webs are particularly sensitive to bottom-up climate effects, as changes in atmospheric forcing impacts sea ice, as well as the extent of the ‘cold pool’, a lens of cold near-bottom seawater that acts as a refuge for cold-water associated species.”

They added: “Climate change has been increasingly linked with shifts in marine ecosystem processes and structure.

“Although climate change is predicted to alter marine ecosystems globally, the effects of global warming are predicted to be the most extreme at higher latitudes.”

Exacerbating the issues of food was the fact that the puffins were thought to have been moulting at the time of their deaths.

The diving birds would have needed more energy than usual to regenerate their flight feathers, and could have been forced to use more of their reserves to power themselves through the water with a reduced wing surface.

There have been a string of similar mass die-offs in the northeast Pacific in recent years, the study said, which were “cumulatively suggestive of broad-scale ecosystem change”.