Hundreds of birds fell from the sky in Mexico. Here’s why.

On the morning of February 7, residents in the Álvaro Obregón section of Cuauhtémoc in northern Mexico woke up to a horrible sight. In the early hours of the day, a flock of birds suddenly fell from the sky, and over a hundred of them dropped dead on the streets, a local news website reported.

The victims in this mysterious incident were the yellow-headed blackbirds, which belong to the Xanthocephalus species. Native to northern America and Canada, these birds migrate to the southwestern parts of the continent during winters. When the residents reported the matter, the local police arrived to find about a hundred birds dead on the streets. 

A local veterinarian who visited the site after a request from the police attributed the bird deaths to inhalation of toxic smoke, possibly from a nearby heater, while media reports suggested that the birds were possibly victims of air pollution due to heaters, agrochemicals or they may have been electrocuted by an overload on the power lines. And a video captured by a security camera is the only evidence of the incident. 

Another prediction is that there might be a predatory bird involved with the case, experts told The Guardian. Although no such bird is seen in the video, Dr. Richard Broughton, an ecologist with the UK Centre for Ecology & Hydrology is certain that a predatory bird was responsible for pushing the flock of birds towards the ground. 

As seen in the video above, the birds descend from the sky as a unit, a phenomenon called "murmuration", often seen in starlings. Broughton is confident that the flock reacted to the predator in this fashion but was forced too close to the ground where some of them crashed, and never was able to recover. Even after the flock moved away, many birds can be seen taking to the skies from the ground. 

Dr. Alexander Lees from Manchester Metropolitan University in the U.K. also agreed with this explanation and added that the collision with infrastructure was quite common in birds. 

In December 2019, 225 starlings were mysteriously found dead on a road in Anglesey, Wales. Their deaths were also attributed to a predator that likely forced them to crash on the tarmac, The Guardian reported.