© AP PhotoHundreds of dead birds lay along the side of the highway in Pointe Coupee Parish, Louisiana, about 300 miles south of the thousands dead in Arkansas
Scientists said that New Year's Eve fireworks might have been to blame for the 3,000 blackbirds that died in a small town in Arkansas.
But they were forced to order more tests last night after 500 birds plummeted to the ground 360 miles away in Louisiana on Monday and dozens more died in Kentucky.
And just a 100 miles away from the Arkansas mass bird kill, at least 83,000 dead and dying fish washed ashore - possibly as many as 100,000.
The Internet has been abuzz with conspiracy theories about secret government testing and a looming Armageddon.
Experts insist a link between the bizarre incidents is unlikely.
© AP PhotoAssistant State Veterinarian Dr. Brandon Doss examines dead red-winged blackbirds at the Arkansas Livestock and Poultry Commission Diagnostic Laboratory in Little Rock. Further testing will be back next week
But that doesn't explain why more than 500 birds dropped dead from the sky in Louisiana on Monday or why a Kentucky woman found dozens of dead birds in her yard.
Louisiana state biologists are trying to determine what led to the deaths of the hundreds of red-winged blackbirds and starlings on highway La. 1 on Monday.
State Wildlife Veterinarian Jim LaCour said lab tests could take several weeks to come up with an explanation for the deaths, and he declined to speculate on possible causes.
But he did say massive bird deaths have been known to occur in the state in the past, albeit in smaller numbers.
© Daily MailSummary of recent events
The bird carcasses were lying with many clumped in groups, some face down, some with wings outstretched.
Necropsies are being performed and samples are being sent to multiple institutions for disease testing.
And in Kentucky a woman told a local television station she found dozens of dead birds in her yard on Monday.
It is unclear what if anything is happening with the Kentucky carcasses.
Up to 100,000 dead and dying drum fish washed up along a 20-mile stretch of the Arkansas River, about 100 miles west of Beebe.
Wildlife officials say the fish deaths are not related to the dead birds, and that because mainly one species of fish was affected, it is likely they were stricken by an illness.
Had it been an environmental cause, other kinds of fish would be dead, too.
Full test results on the fish could take up to a month.
A little further north the Maryland Department of the Environment said that tens of thousands of small fish have died in the Chesapeake Bay.
© Daily MailAs many as 100,000 drum fish washed up dead from the Arkansas River
In Arkansas one dead bird struck a woman walking her dog and another hit a police vehicle.
Birds were 'littering the streets, the yards, the driveways, everywhere', said Robby King, a county wildlife officer in Beebe, a community of 5,000 north east of Little Rock.
'It was hard to drive down the street in some places without running over them.'
For some people, the scene evoked images of the apocalypse and cut short New Year celebrations. Many families phoned police instead of popping champagne.
'I think the switchboard lit up pretty good,' said Beebe police captain Eddie Cullum. 'For all the doomsdayers, that was definitely the end of the world.'
© European Pressphoto AgencyResidents examine a dead bird on the Beebe street as another can be seen in the background. Witness described dead birds raining down on cars and homes. One hit a woman walking her dog
Scientists now say that the fireworks appeared to have frightened the birds into such a frenzy that they crashed into homes, cars and each other. Some may have flown straight into the ground.
'The blackbirds were flying at rooftop level instead of treetop level' to avoid explosions above, said Karen Rowe, an ornithologist with the Arkansas Game and Fish Commission.
'Blackbirds have poor eyesight and they started colliding with things.'
But Ms Rowe stopped short of declaring the mystery solved, saying labs planned to test bird carcasses for toxins or disease.
© ReutersA few birds survived their falls and stumble around, but most died of 'massive trauma' upon hitting each other and then the ground below
A few stunned birds survived their fall and stumbled around like drunken revellers.
There was little light across the countryside at the time, save for the glimmer of fireworks and some lightning on the horizon. In the tumult, many birds probably lost their bearings.
'I turn and look across my yard, and there's all these lumps,' said Shane Roberts, who thought hail was falling until he saw a dazed blackbird beneath his truck.
Paul Duke filled three five-gallon buckets with dead birds on New Year's Day. 'They were on the roof of the house, in the yard, on the sidewalks, in the street,' said the school supervisor.
Red-winged blackbirds are among North America's most abundant birds, with somewhere between 100 million and 200 million nationwide, according to the Cornell Lab of Ornithology in Ithaca, New York.
Ms Rowe put the number of dead in Beebe at 'easily 3,000'. Thousands can roost in one tree.
The Game and Fish Commission shipped carcasses to the Arkansas Livestock and Poultry Commission and the National Wildlife Health Centre in Madison, Wisconsin.
© AP PhotoCleanup is underway. Here is bucket of bird carcasses. Some are being sent out to Wisconsin and Georgia for more tests
Test results could be back in a week.
A few grackles and a couple of starlings were also among the dead. Those species roost with blackbirds, particularly in winter.
'They died from massive trauma,' said Game and Fish Commission spokesman Keith Stephens.
Residents heard loud fireworks just before the birds started hitting the ground.
'They started going crazy, flying into one another,' Mr Stephens said. The birds apparently also hit homes, trees and other objects, and some could have been killed by flying hard into the ground.
The area where the birds fell is too large to determine if any specific blast rousted the birds, Police chief Wayne Ballew said.
'It was New Year's Eve night. Everybody and their brother was shooting fireworks,' he said.
Comment: For more information and additional analysis of the strange events in Arkansas read
And They March! The Strange Tale of the Beebe Blackbirds