Climate change caused mass death among Alaskan puffins

Thousands of puffins have perished in recent years in the Bering Sea. Scientists have now pinpointed the reason for the mass die-off of the iconic black-and-white birds with their distinctive orange bills: it’s climate change.

In the fall of 2016 the bodies of several thousand tufted puffins washed up on the beaches of Saint Paul Island in Alaska in just a few months. Scientists estimated that anywhere between 3,150 and 8,800 birds, many of them puffins and crested auklets, died in the space of just two to three months.

Tufted puffins, which sport flamboyant white tufts of feather on their heads, spend cold winter at sea, but come ashore in spring and summer to nest in coastal colonies from California all the way to Alaska. Several species of puffin are listed as vulnerable.

The birds washed ashore at Saint Paul Island looked emaciated as if they had starved to death. At first experts were puzzled about the exact cause of the mass die-off. Subsequent research has revealed, however, that shifting weather patterns affected populations of fish in the area, which likely deprived migrant puffins of food during the precarious period when they began molting.

Nor has this event been a one-off. In coming years similar die-off may well become more common among birds, bats and other species. “Mass mortality events are increasing in frequency and magnitude, potentially linked with ongoing climate change,” the researchers write in a study published in the journal Plos One.

“These ‘massive mortality events’ — defined as catastrophic, but often short-lived, periods of elevated mortality — can affect substantial proportions of a population, occasionally with long-term consequences to population size,” they add.

They found that warming water temperatures drive local fish populations to decline, along with a decrease in the amount of zooplankton, which serve as food for many fish. With fewer fish around, puffins then began to starve en masse until they succumbed to malnutrition.

Similar climate change-driven mass die-offs of fish, birds and mammals have been occurring elsewhere as well. Although they were not unknown in past decades, they are becoming more common, experts say. That is alarming as species are disappearing at a much faster rate than ever before in human history.