Mystery disease kills songbirds

Hundreds of songbirds have died in a disease outbreak affecting more than 10 US states, and experts have no idea what's killing them. But, just as social distancing was adopted against the COVID-19 pandemic, they are playing safe.

The experts are telling homeowners to remove bird feeders and birdbaths to lessen contact among birds and slow the spread of the disease that is striking them down.

Wildlife experts say the mysterious ailment seems to affect juvenile birds more than adults, and no effects on humans, livestock or poultry have been reported.

Dead birds found in states have been tested for "every known pathogen of birds", said Patrick Comins, the executive director of the Connecticut Audubon Society, and nothing has been found.

David Stallknecht, director of the Southeastern Cooperative Wildlife Disease Study at the University of Georgia, Athens, said: "We're still scratching our heads on this one." His group is involved in the effort.

Among the known bird diseases and viruses that have been ruled out so far are salmonella, avian influenza, West Nile virus, Newcastle disease viruses, herpes and pox viruses and Trichomonas parasites.

"We haven't ruled out pesticides," Comins said. "One of the initial hypotheses was that the deaths corresponded with cicadas that had been sprayed. Or this could be a novel pathogen that we haven't seen before."

The emergence of the cicadas aligns with the timing and range of the bird illness. Allisyn Gillet, an ornithologist with Indiana's Natural Resources department, said there's a correlation there, but a link hasn't yet been established.

Since it was first detected in May in Washington DC, the disease has been reported in Pennsylvania, Delaware, Florida, Indiana, Kentucky, Florida, Maryland, Ohio, Virginia and West Virginia.

Affecting species

The illness is affecting species that are typically seen in backyards: common grackles, blue jays, European starlings, American robins, cardinals, house finches, house sparrows, eastern bluebirds, red-bellied woodpeckers, Carolina chickadees and Carolina wrens, according to wildlife experts.

Gillet said the symptoms seem to remain consistent among affected birds: crusty discharge and swelling of the eye area and neurological signs, such as rapid eye activity and uncoordinated movements.

She said the birds were also disoriented and exhibited unusual behavior, including walking in strange ways and stumbling around. They had little control of their limbs and would do things like kick their legs up while on their backs.

Gillet said the mortality rate of the illness appears high, as most of the birds are dying shortly after they are reported to officials.

Wildlife veterinarian Christine Casey of the Kentucky Fish and Wildlife Resources Department said residents had reported online 1,400 sick or dead birds as of July 2. Laura Kearns, a wildlife biologist with the Ohio Division of Wildlife, said hundreds of birds have been found dead in the state.