Update on Mysterious Bird Deaths

This summer, sick and dying birds were documented in several states in the Mid-Atlantic, Midwest, and South. The main symptom was swollen, crusted-over eyes in fledglings of blue jays, robins, grackles, and several other species.

Biologists, wildlife agencies, and conservation organizations, including the National Wildlife Federation, recommended that folks proactively take down bird feeders and baths, places where birds congregate that could be contributing to the spread of whatever was causing this mysterious illness.

Now, there’s some good news: according to the latest update from the Cornell Wildlife Health Lab, it seems this bird mortality event is beginning to subside without significant impact to bird populations overall. However, though several diseases and pathogens have been ruled out, after much testing we still don’t know exactly what the cause of this outbreak actually was.

One theory is that because the documentation of sick and dead birds overlays with the timeframe and geographic distribution of the periodical cicadas of Brood X that emerged this year, it seems likely that there’s a connection. It could be some natural illness caused by ingesting cicadas or possibly secondary effects of pesticides that people sprayed on the cicadas (which is absolutely the wrong thing to do). It’s important to note, however, that this cicada connection is still just speculation.  

With all of this in mind, it should be ok to put bird feeders and baths back out. It’s still important to regularly clean and disinfect feeders and baths to prevent the spread of disease. That should be part of your regular practice if you are putting out feeders and baths for the birds.

As always, if you find a sick or dead bird, report it to your local or state wildlife agency for documentation.

UPDATE/CLARIFICATION 8/11/21:
My suggestion in the video and post above that it should be ok to put bird feeders and baths out could be premature. As of this update, the recommendation to halt feeding and offering baths has not been updated by the agencies conducting the research into this illness and mortality event.
–Naturalist David Mizejewski

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