Warm seas precede Alaskan bird die-off

Seabirds off the coast of Alaska are dying in large numbers. Starvation caused by warming sea water appears to be the culprit.

Warmer water is suspected of altering ocean currents that bring fish and fish food to the birds' feeding grounds.

Hundreds, perhaps thousands of emaciated Northern fulmars and short-tailed shearwaters are washing ashore on Bering Sea islands. Kittiwakes, murres and auklets also are turning up dead. Some birds are drowning because they are too weak to hold their heads out of the water.

The total number of dead birds is not known because much of the shoreline on islands and the mainland is inaccessible or rarely visited. Die-offs stretch to the Russian coast.

This was reported Sept. 11 in the Alaska Dispatch News, an Anchorage newspaper. A link to its online story was provided in a post to Birdchat, a national birding e-mail service. (http://bit.ly/2w5kvV1)

The U.S. Fish and Wildlife Service in Anchorage has examined the dead birds, finding empty stomachs and intestinal tracts, and little body fat.

"The new die-off follows a massive loss of common murres in 2015 and 2016, the biggest murre die-off on record in Alaska, and precursor to near-total reproductive failures for murres in the Gulf of Alaska and Bering Sea," reporter Yereth Rosen wrote in the Dispatch News.

Each death wave has been associated with unusually warm marine waters, Rosen wrote. This is the fourth consecutive year for an unusually warm Bering Sea. A climate scientist for the National Weather Service in Anchorage has called the water exceedingly warm.

One reason suggested for warming water is a shorter ice season. If ice on the Bering Sea melts early in the spring, the open water will absorb more heat. Eventual cooling is expected, but future temperature events are unknowable.

The waves of dead seabirds are unprecedented, according to Julia Parrish, executive director of the Coastal Observation and Seabird Survey Team at the University of Washington, Seattle.

Parrish said that the pattern of seabird deaths is moving north.

"Recent history suggests that several species, including murres, crested auklets, tufted puffins, Northern fulmars and shearwaters, have had trouble in the warmer waters," she wrote in an e-mail.

Current losses for fulmars and shearwaters probably will be absorbed by the normally large populations of those species, Parrish wrote. The most common shearwater there is the short-tailed, with a population in the millions.

Fulmars and especially shearwaters are known "wreck" species — species that occasionally die in droves, she wrote. Their numbers recover from those events.

"Keep in mind," she wrote, "that we have seen a cascade of seabird die-offs annually starting in 2014. This has occurred at a rate, magnitude and geographic scope unprecedented in the decades beached-bird programs have been extant along the West Coast.

"The northeast Pacific marine heat wave also has been unprecedented," she wrote. "The ocean surface in the Northeast Pacific has been warmer for longer than anywhere in the world."