© Katty Bell
Prince William County police spokesman Jonathan Perok said it happened about 2 p.m., near Aden Grocery.
Police, animal control and crews from the Virginia Department of Transportation were called to the area, where witnesses said they were shoveling dead birds off the road.
It was unclear Thursday night what type of birds they were, and what caused them to die.
Several people reported seeing large numbers of birds gathered on power lines in the area earlier in the day.
Kevin Rose, a wildlife biologist with the Virginia Department of Game and Inland Fisheries, said mass bird die-offs are usually the result of lightning or some sort of trauma. That trauma often includes birds in flight striking power lines.
"Without a few samples we can't really tell," Rose said in an email. "Unless it starts happening more, we are not concerned."
Though strange and somewhat eerie, mass bird die offs aren't all that uncommon, according to the U.S. Geological Survey's Wildlife Health Center.
On New Year's Eve in 2011, as many as 5,000 birds die en massed in Arkansas, literally raining from the sky.
The USGS worked with Arkansas wildlife officials to determine what killed the birds, most of them red-winged blackbirds, and found they died of impact trauma.
"Field observations ... suggested these birds were roosting for the night, were startled from their perches by loud noises in the area, and because of their very poor night-vision, the birds may have flown into stationary objects such as power lines, telephone poles, houses, mailboxes, tree branches, etc.," the USGS report said.
Loud fireworks were heard in the area prior to the bird die-off.
That same year, the National Wildlife Heath Center also worked with the Louisiana Department of Wildlife and Fisheries to investigate a similar though smaller scale event involving about 500 red-winged black birds, starlings, brown-headed cowbirds and grackles.
"The necropsy findings from these birds were also consistent with 'trauma,'" the USGS reported. "Many of these birds appear to have collided with a power or fence line."
"...mass bird deaths aren't all that uncommon..." Really? Thought we were told the opposite not too long ago, but now that it is the norm, perhaps it isn't any longer? I wonder when the same will be said about mass human deaths? Though that is already the norm in many countries we seek to 'liberate'.