Arkansas wildlife officials are struggling to explain the recent, sudden deaths of tens of thousands of creatures. Late on New Year's Eve, nearly 5,000 blackbirds fell dead from the sky in the small northeastern town of Beebe in an incident "straight from a Hitchcock movie." A few days earlier, nearly 100,000 dead drum fish floated to the top of the Arkansas River just 125 miles west of Beebe. (Watch a CNN report about the incidents.) Authorities say the two instances of mass animal death are likely unrelated. At least five explanations have been suggested:

1. Weather
Recent bursts of hail and lightning may explain the death of the birds, says Keith Stephens, a spokesman with the Arkansas Game and Fish Commission, as quoted by Reuters. That said, no physical injuries have yet been detected on the birds' corpses.

2. New Year's Eve fireworks
"Revelers shooting off fireworks in the area may have startled the birds from their roost," reads a Game and Fish Commission news release, as quoted in the Arkansas Times. "The birds may have died from [resulting] stress."

3. Poison
While some residents initially suspected that the birds, whom some consider a nuisance, had been poisoned, officials have questioned that explanation. "Since it only involved a flock of blackbirds... it is unlikely they were poisoned," says Karen Rowe of the Game and Fish Commission, as quoted in the Daily Mail. "But a necropsy is the only way to determine if the birds died from trauma or toxin."

4. Disease
In the case of the fish, the simultaneous death of such a large group might suggest a pollutant was to blame. But the fact that the vast majority of casualties were from one species argues against that theory. "If it was from a pollutant, it would have affected all of the fish, not just drum fish," Stephens tells MSNBC. Some form of disease may be the real culprit.

5. The laws of nature
A population boom, coupled with the cold weather, could be to blame for all the fish popping up dead, Andrew Goodwin, associate director of the University of Arkansas' Aquaculture and Fisheries Center, tells AOL News. If too many fish were competing for food, a sizable proportion may not have been in good condition. In such a situation, the already weak fish would have had their immune systems further compromised by a sudden cold snap and been unable to fight off an infection.