Feb. 18 -- Straight out of an eerie scene from a Hitchcock movie, scores of birds suddenly out of nowhere could be seen falling from the sky on a fairly calm day, many plummeting to their death.
The strange event was captured on a home security camera in the city of Cuauhtemoc in Chihuahua, Mexico. The footage showed a rush of hundreds of yellow-headed blackbirds in a flash spiraling out of control to the ground in a residential neighborhood during the early-morning hours of Feb. 7.
Many of the discombobulated birds were able to quickly gain flight again and take off, but others died after crashing into houses, cars and each other or hitting the pavement hard with great speed.
Residents came out of their homes later that morning to find to their surprise dozens of dead bird carcasses littering the street in the Alvaro Obregón neighborhood. People immediately began posting videos of the dead birds on social media.
It remains a mystery as to what exactly caused scores of birds to suddenly drop in a flash from the sky, although many locals and experts have speculated what might have disoriented or scared the birds to such an extent.
The weather at the time of the incident was rather calm with temperatures in the mid-40s.
A local veterinarian who was called in by authorities to examine the scene speculated that the birds may have become overwhelmed and disoriented from inhaling toxic fumes or coming into contact with electrical power lines that overloaded and unleashed a massive "electric discharge," forcing them to plummet, according to local media outlet Reporte Cuauhtémoc.
A radio station in Mexico, La Ranchera de Cuauhtemoc, reported that the birds were apparently flying at a high speed when they lost stability and collided into one another, causing blows strong enough to kill some of them.
Dr. Andrew Farnsworth, a senior research associate at the Cornell Lab of Ornithology, said he believes a more plausible explanation is that a predator or a loud disruptive sound spooked the birds.
What caused the birds to behave so wildly, an event he called "fascinating and frightening," may be something biological, chemical or environmental in nature.
There's also "a slim chance it's meteorological, like a microburst. But the biological, chemical, meteorological, and electromagnetic explanations are likely to be far far less likely than the predator attack, or the disruptive sound," Farnsworth told AccuWeather, adding that "given the response and speed of the birds' behaviors," a predator is the most likely culprit.
But, he maintained, "the event is so extreme and odd that's it's hard to explain."
This species of blackbirds, about 8 to 10 inches in length, is known to migrate from northern Canada to northern Mexico where they spend the winter. And they're known to form huge flocks, hence the large number of birds falling from the sky in the video.
Such incidents of mass bird deaths are not uncommon, according to the U.S. Geological Survey, and occur at least once a week. Most notable are the deaths that occurred at least three consecutive years on New Year's Eve between 2009 and 2011 when thousands of red-winged blackbirds dropped from the sky, both times in Beebe, Arkansas. In the 2009 incident, a state ornithologist reviewing radar images determined that rogue, professional-grade fireworks in neighborhood celebrations were the cause, The Christian Science Monitor reported.