This is the eerie moment hundreds of black birds swarm over city streets and fly around in circles, causing concerns among many online users of an oncoming natural disaster.

The ominous sight was filmed by an unnamed resident over the sky of Ulanhot, in northern China’s Inner Mongolia region, on the evening of 20th October.

Phone footage shows what looks to be hundreds of birds densely packed in a flock and flying at a low altitude over the street.

Dozens more have gathered on top of a near building and all over treetops as the rest circled around street lights.

Birdwatchers described the birds emitting beautiful and haunting chirps as they circled low in the sky, forming a massive cloud of black feathers.

The event sparked widespread speculation and curiosity on Douyin, China’s version of TikTok, with many users fearing it might be a bad omen.

One user titled ‘African little white face y’ commented: “Where the crows fly, people will die.”

And user ‘Shallow thoughts’ wrote: “Mankind continues to be bad, and calamities will be inevitable.”

While experts said the phenomenon might be a migrational behaviour of a particular bird species, a magnificent scene was created during their directional adjustments and team integration while heading south for warmer habitats.

While this occurrence is intriguing, experts urged the public to remain calm, reminded everyone that it is a part of bird migration, and advised caution to prevent unnecessary traffic congestion or safety hazards during observation.