"Mass bird die-offs can be caused by starvation, storms, disease, pesticides, collisions with man-made structures or human disturbance," says Greg Butcher, Audubon's director of bird conservation.
"Scientists are still investigating what happened to the birds in Louisiana and Arkansas, but initial findings indicate that these are isolated incidents that were probably caused by disturbance and disorientation."
The birds that died - Red-winged Blackbirds, Common Grackles, Brown-headed Cowbirds and European Starlings - are abundant species that flock together in large nighttime roosts during the winter months. Roosts can contain from tens of thousands to 20 million individuals or more.
"We do need to keep a close watch to see if a pattern develops," says Melanie Driscoll, Audubon's director of bird conservation for the Mississippi River Flyway. "But if these incidents are isolated, they do not represent a significant threat to our native bird populations. Far more concerning in the long term are the myriad other threats birds face, from widespread habitat destruction and global climate change to inappropriate energy development and invasive species."
Butcher adds, "Data drawn from Audubon's Christmas Bird Count Audubon has already confirmed that many of our most familiar and beloved birds are in a state of population decline, due in large part to human activities."
"Even if this is an isolated incident," says Audubon President David Yarnold, "It is vital for people to pay attention because so often the fate of birds is linked to our own. Birds breathe the same air we do, and they are part of the same food web that sustains us all."
Read more in David Yarnold's Opinion piece on CNN.
Related link: Audubon's Christmas Bird Count.