This is the moment thousands of migratory blackbirds plummet from the sky in a huge mass, leaving over 100 dead on the ground. 

The dead birds were found in the area of Alvaro Obregon in Cuauhtemoc, a city in the Mexican state of Chihuahua, on the morning of 7th February. 

Hundreds of yellow-headed blackbirds (Xanthocephalus xanthocephalus), which travel south to Mexico from Canada in the winter, fell from the skies in mysterious circumstances. 

The footage shows thousands of birds suddenly dropping from the sky in a huge mass. Most of them apparently manage to take flight again, while around 100 remain motionless on the street. 

Another clip shows the motionless birds lying on the side of the street as someone with a broom sweeps them into piles. 

Local residents were stunned to find the migratory birds littering the city streets in the morning and informed the local authorities. 

Officers attended the scene at around 8.30am and found the dead blackbirds scattered on the ground. 

Ricardo Abel Soto Cruz of the Faculty of Zootechnics and Ecology at the Autonomous University of Chihuahua told the news site Meteored that the birds could have become disorientated after inhaling toxic fumes coming from a nearby building or after receiving an electric shock if they had stopped to rest on power cables prior to the incident. 

The dead birds were removed from the streets, and tests are taking place to establish their exact cause of death. 

The investigation in Mexico is ongoing, but a more straightforward explanation has been offered by avian specialists. 

Dr Richard Broughton, an ecologist with the UK Centre for Ecology & Hydrology, told The Guardian that small birds had simply been chased by a predator. 

"This looks like a raptor like a peregrine or hawk has been chasing a flock, like they do with murmurating starlings, and they have crashed as the flock was forced low," he said. 

"You can see that they act like a wave at the beginning, as if they are being flushed from above." 

Dr Alexander Lees from Manchester Metropolitan University agreed and said the bird's natural behaviour was a much more likely cause than any outside interference. 

"There always seems to be a kneejerk response to blame environmental pollutants, but collisions with infrastructure are very common. In a tightly packed flock, the birds are following the movements of the bird in front rather than actually interpreting their wider surroundings, so it isn't unexpected that such events happen occasionally."