US scientists believe fireworks may have caused thousands of birds to fall dead from the sky over an Arkansas town on New Year's Eve.
The BBC reports Karen Rowe, of the Arkansas Game and Fish Commission, as saying that the red-winged blackbirds probably flew low to avoid explosions and collided with objects.
She stopped short, however, of declaring the mystery solved, saying further tests on the dead birds are planned.
Officials say more than 3000 birds fell over the city of Beebe. The few that survived the fall stumbled around like drunken revellers, according to some witnesses.
A county wildlife officer, Robby King, says birds were "littering the streets, the yards, the driveways, everywhere...it was hard to drive down the street in some places without running over them."
Residents report hearing loud fireworks just before the birds started raining from the sky. The AFGC says initial laboratory reports show they died from trauma.
Severe weather another possible cause
Severe weather could also be the cause. Tornadoes swept through Arkansas and neighbouring states on 31 December, killing seven people.
The birds are reported to have started flying into one another, as well as hitting homes, cars, trees and other objects. Some could have flown straight into the ground.
Ms Rowe, an ornithologist, says they were flying at rooftop level instead of treetop level to avoid explosions above: "Blackbirds have poor eyesight, and they started colliding with things."
City authorities have hired a specialist waste disposal firm to remove the dead birds from gardens and rooftops.