So it turns out those bird deaths in Arkansas on New Year's Eve was a case of mass suicide -- well, sort of. Experts did say their fatal wounds were self-inflicted.
Experts from the Southeastern Cooperative Wildlife Disease Study conducted autopsies on more than a dozen of the upwards of 5,000 that fell from the sky, and determined that their injuries were "consistent with blunt trauma."
The report went on to say:
In most instances, such traumatic injuries in wild birds are due to flying into stationary objects such as trees, houses, windows, power lines, towers, etc.
This matches reports from eyewitnesses, who said "the birds were hitting mailboxes, cars, basketball goals, houses, trees," Keith Stephens of the Arkansas Game and Fish Commission told the New York Daily News. "The trauma shows that they were in flight when they collided with something that killed them."
It is theorized that fireworks confused the birds, including red-winged blackbirds, which do not see well at night.
Tests also ruled out bacteria, viruses, heavy metals, pesticides and bird-killing chemicals called avicides as the cause of death.
So this mystery appears to be solved -- the birds did it to themselves. But the causes of the rash of other bird and fish deaths remain unknown.