It’s still too soon to say what has caused a mass mortality of several bird species in the eastern U.S. over the last month or two. But a bird ecologist with the Smithsonian Migratory Bird Center told NPR on Monday that the recent emergence of Brood X cicadas may be involved.
Reports of large numbers of dead and sick birds first came to light in late May in Washington, D.C. The birds that were alive were often blind with crusty eyes and were disoriented or shaking.
The most reported species have been Blue Jays, Common Grackles, European Starlings, American Robins, as well as Carolina Wrens, Gray Catbirds, House Sparrows, Northern Cardinals, and Northern Flickers.
The Smithsonian’s Brian Evans told NPR’s Ari Shapiro that more than 600 birds have been brought to wildlife rehab centers in the D.C. area. And he noted that number is “a poor representation of the total number of birds impacted.”
The die-off has since been found as far away as Indiana, Kentucky, and Ohio.
Shapiro asked Evans how the cicada emergence may be involved.
“What we know is that the spatial extent, the area, of the mortality event, and the timing of the mortality event, largely matches the emergence of the Brood X cicadas,” Evens said. “But that’s entirely correlation. We don’t know directly whether it’s causative, and we’re trying to investigate the potential links that might be there.”
He said it’s possible that a fungus that affects cicadas could have negatively impacted birds, but that’s only a “a potential cause” at this point.
“Pesticides are of course a potential cause,” he added. “Cicadas have lived underground right underneath us for 17 years and could have been accumulating toxins like pesticides or heavy metals that then the birds could be exposed to in really high concentrations, just because they’ve switched their diet over to cicadas.”
Notably, Evans added that the bird die-off appears to be in decline as the cicada emergence is wrapping up.
“The birds could take a once-every-17-year hit on their populations,” he said, “but on the other hand, this could be the start of something else entirely.”
The Smithsonian is looking for accounts of sick or dead birds in the area, so if you’ve encountered any, report what you’ve seen here. And if you have seen birds eating cicadas, researchers want to hear from you.