The shores of Alaska’s Prince William Sound are littered with the carcasses of tens of thousands of seabirds after a mass die-off that scientists say could be caused by climate change. Federal wildlife officials say the birds, all of a species known as the common murre, starved to death. That’s a clear indication that their food supply has been disrupted, but even the experts aren’t exactly sure why.

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When a large number of a single species dies at the same time, scientists are quick to investigate the causes. At this time, experts believe rising global temperatures are the primary suspect in the deaths of the seabirds. Because the birds apparently died of starvation, logic follows that the birds were unable to find appropriate food. For these birds, that would be ocean herring and other fish whose populations are known to be in decline. It’s worth noting that herring numbers in particular have been low since the 1983 Exxon Valdez oil spill, which occurred in the sound. What we see here is another example of how human activity has interrupted the ecosystem, breaking a link in the food chain and causing havoc among fragile species.

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The population of common murres has been known to suffer even with just a slight increase in water temperature. Indeed, the waters off Alaska’s southern coast—southeast of Anchorage—have been warmer than usual for the last two years. This year’s strong El Niño has caused that trend to continue. Researchers working on the investigation aren’t ready to link the die-off to climate change definitively, though. “We know they are starving. Their stomachs are empty,” said Robb Kaler, a seabird biologist with the U.S. Fish and Wildlife Service in Anchorage. “But we don’t yet know what the mechanism is.”

Around this time last winter, researchers in San Francisco were investigating the troubling death of several hundred seabirds. That die-off was thought to be tied to a translucent ‘goop’ of unknown origin. Other mysterious mass die-offs have also been reported in the past year, like the 85,000 saiga antelopes in Kazakhstan who may have succumbed to a bacterial infection. Around the globe, these events have wildlife scientists concerned about the future of the Earth’s animal populations, including our own.

Via Washington Post

Images via Shutterstock (1, 2) and FWS