Mystery illness strikes down birds across US south and midwest

A mysterious illness is killing birds across several states in the south and midwestern US, and wildlife scientists are rushing to try to find the cause, with many victims suffering from crusty eyes, swollen faces and the inability to fly.

Wildlife managers in Washington DC, Virginia, Maryland and West Virginia first began receiving reports of sick and dying birds with eye swelling and crusty discharge, as well as neurological signs in late May, according to a statement from the US Geological Survey, which added: “No definitive cause of death is identified at this time.”

Related: Mass die-off of birds in south-western US 'caused by starvation'

In Kentucky, the department of fish and wildlife resources is asking the public to report encounters with sick and dead birds through a new online reporting system. They say the species affected thus far have included blue jays, common grackles and European starlings, but other species may also be affected. More than 20 samples have been sent out for testing.

In Ohio, the Ohio Wildlife Center posted on Facebook that it has been admitting songbirds with eye issues and is working with authorities to help determine what might be causing local birds to become sick. Indiana wildlife officials said they tested the birds for avian influenza and west Nile virus, and the samples came back negative.

According to the USGS, birds congregating at feeders and baths can transmit disease to one another. They recommend that people cease feeding birds until this mortality event has concluded, clean feeders and baths with a 10% bleach solution, and avoid handling birds.

While it’s not known if the mortality is linked to bird baths, the Centers for Disease Control and Prevention warned in April about a salmonella outbreak linked to wild songbirds across several states. The outbreak killed eight people.

In this new disease outbreak, people report that the birds are behaving as though they are blind, and are not avoiding humans.

According to a report from NBC News, wildlife biologist Laura Kearns of the Ohio division of wildlife has expressed that infectious disease, pesticides and even the cicada outbreak are suspects. Even cicadas have been plagued this year, with their 17-year waiting period interrupted by a fungus that alters their behavior and causes part of their body to rot away.

Bird mortality events are not all that uncommon. Last year, hundreds of migratory birds dropped dead in New Mexico in a massive die-off. After analyzing samples and testing theories, the New Mexico department of game and fish eventually concluded that the birds had died from starvation and unexpectedly bad weather.

“Migrating birds entered New Mexico in poor body condition and some birds were already succumbing to starvation,” the agency wrote. “The unusual winter storm exacerbated conditions, likely causing birds to become disoriented and fly into objects and buildings. Some were struck by vehicles and many landed on the ground where cold temperatures, ice, snow and predators killed them.”

According to a 2007 study, mass mortality events are often tied to weather.

This new disease-fueled die-off comes at a time when birds are facing unprecedented challenges. The US has lost more than a quarter of bird populations in just the last 50 years, according to a 2019 study. The study authors write: “This loss of bird abundance signals an urgent need to address threats to avert future avifaunal collapse and associated loss of ecosystem integrity, function, and services.”