A worker collects dead birds from the backyard of a home in Beebe, Ark., on Jan. 2. ((Stephen B. Thornton/Arkansas Democrat-Gazette/Associated Press) )

The carcasses of some of the nearly 2,000 red-winged blackbirds that inexplicably fell on Beebe, Ark., on New Year's Eve night will be sent for testing to determine the cause of death.

The Arkansas Game and Fish Commission says the state Livestock and Poultry Commission Lab and the National Wildlife Health Center Lab in Madison, Wis., will examine the dead birds, starting Monday.

Commission spokesman Keith Stephens said the birds fell in an area about 1.5 kilometres long and three-quarters of a kilometre wide. He said it's not the first time birds have dropped from the Arkansas sky.

Environmental workers finished picking up the carcasses on Sunday.

Commission ornithologist Karen Rowe said the flock could have been hit by lightning or high-altitude hail, or may have been startled by fireworks.

Several hundred thousand red-winged blackbirds have used a wooded area in the town as a roost for the past several years, Mayor Mike Robertson said. He and other officials went to the roost area over the weekend and found no dead birds on the ground.

"That pretty much rules out an illness" or poisoning, the mayor said.

Beebe is about 60 kilometres northeast of Little Rock.