Dead starfish line the shore of the German island of Sylt. Mass wildlife die-offs have been interpreted as omens of an impending environmental collapse. PHOTOGRAPH BY DANIEL FRIEDERICHS

Mass-mortality events are sudden, unusual crashes in a population. If you think that you are hearing about them more often these days, you’re probably right. (Elizabeth Kolbert described frog and bat die-offs in a 2009 article; her subsequent book won a Pulitzer Prize recently.) Even mass-mortality experts struggle to parse whether we’re witnessing a genuine epidemic (more properly, an epizootic) of these events. They have also raised another possibility: that we are in the throes of what one researcher called an “epidemic of awareness” of spooky wildlife deaths.

The Internet has offered a wellspring of speculation about mass wildlife deaths. A case in point: more than four thousand red-winged blackbirds are found dead on New Year’s Day, 2011, in Beebe, Arkansas. As the story spreads, news of other die-offs is reported from around the world. Dead jackdaws in Sweden. Dead velvet swimming crabs in the U.K. More dead blackbirds in Louisiana. Dead snapper in New Zealand (“many with their eyes missing”). Five days after the initial event, a Washington Post blogger dubs it “the Aflockalypse.” The name sticks, and so does the implication. The Web is soon abuzz with commentators linking these occurrences to end-is-near prophecies, secret government experiments, and the threat of ecological collapse. The National Wildlife Health Center ultimately diagnoses the probable cause of the die-off as avian panic, most likely triggered by loud noises—possibly fireworks—too close to the birds’ nighttime roost. Of course, nobody can say for sure.

Wildlife die-offs are an ancient phenomenon. One fossil site in Chile revealed recurring mass marine-mammal deaths, most likely from toxic algae blooms, dating back at least nine million years. Aristotle, in his “Historia Animalium,” in the fourth century B.C., remarked on mass dolphin strandings as simply something that the animals were known to do “at times.” The earliest written record in American history, from 1542, by the Spanish explorer Álvar Núñez Cabeza de Vaca, appears to indicate that Native Americans on Tampa Bay, in Florida, understood fish die-offs—which still occur in the area today—as typical of certain seasons.

At least in some quarters, the sudden death of large numbers of wild animals has been read as a dire message to humanity: scientists have pointed out that the first biblical plague of Egypt, a fish die-off in a blood-red Nile, is an apt description of the effects of the acidification of the river’s water. Yet the widespread interpretation of such events as signs, whether ecological or divine, that humankind’s abuse of the planet has gone too far appears to be relatively new.

Read  more on what mass mortality holds for us here in The New Yorker.