Crows are swirling in large flocks over Kyiv—what's the reason? Watch the video to find out.

In Kyiv, a massive gathering of birds was observed over Bereznyaky and Rusanivka. Thousands of feathered creatures were circling above the buildings and streets. Social media users referred to the birds as crows, adding that their flight was quite shocking and resembled scenes from horror films.

Experts quickly corrected this, stating that the flock of birds was not crows, but rooks. They noted that there was nothing terrifying about it; it was simply the daily movement of rooks that had remained for the winter.

As reported by TSN.ua, according to Anatoliy Poluda, head of the Ukrainian Bird Ringing Center, last week in the evening near the capital's zoo, several large flocks of rooks, totaling between 5,000 to 10,000, could be seen. They were performing a "carousel," circling at an altitude of 200-300 meters before flying towards Khreshchatyk.

"There is nothing frightening about the birds circling; on the contrary, it is a mesmerizing sight, and passersby enjoyed watching the rooks. As for their presence in Bereznyaky, it's hard to say whether the rooks have chosen this area for roosting. They may gather in Bereznyaky and Rusanivka before heading to their roosting place. During the day, they circle the area, perch on trees and rooftops, and then, as dusk approaches, they gather together and fly to their roosting site. In the previous 3-5 years, the roosting area was in Vydubychi, but now it has changed," said the head of the Ukrainian Bird Ringing Center.

He added that a few days ago, one of the amateur ornithologists recorded the movement of thousands of rooks heading north, along the Dnipro River above Hydropark and Trukhaniv Island.

"I do not rule out, and it is most likely the case, that the rooks that were circling over Bereznyaky in the evening took off and might subsequently fly to roost in the Obolon area, at 'Natalka' park, or on the islands near the left bank, around the Northern Bridge. For rooks, the absence of people is not crucial; what matters is that there are trees where they can roost. At one time, a large gathering of rooks, up to 50,000, was recorded in Hydropark over several years, and they were even visible from the subway train. Then they chose another 'backup' location – the territory of the capital's zoo. From there, they were driven away, and they moved to the former Pushkin Park. Three years ago, almost all the rooks from Kyiv flew to roost in the Vydubychi area, but now something has changed, and it seems they are roosting in Obolon. Why? There is no answer to this; only the rooks know," noted Anatoliy Poluda.

The ornithologist explained that rooks in Kyiv operate on a specific schedule: in the morning, they disperse throughout the city, spread out, and search for food. Around 3:00-4:00 PM, they gather in large groups in certain locations in the capital, such as Bereznyaky, and at dusk, they take off towards their roosting site.

"By the way, the number of rooks gathering in Bereznyaky, judging by the photos, is quite significant – approximately 10,000. Overall, in recent years, about 60-80 thousand rooks winter in Kyiv. The general trend is that the breeding population of rooks in Ukraine is declining. Specifically, in Kyiv region, according to our studies, the number of breeding rooks has decreased more than tenfold over the last 30-40 years," noted Anatoliy Poluda.

The ornithologist added that one of the main reasons for this decline is the use of seed materials, most often corn, treated with hazardous pesticides.

"Rooks come to Kyiv for the winter from eastern Ukraine, the southern part of the European territory of Russia, and even from western Kazakhstan. It's hard to say exactly how many are wintering in Kyiv this year, but it is no less than 50-60 thousand. In the 1980s-1990s, their numbers were around 120-140 thousand. To get a more or less accurate figure of the rooks wintering in the city, we need to engage a dozen observers and 'position' them in places where the main corridors of daily bird movements are. After all, the birds arrive at their roosting sites from different directions, and it's difficult for one person to track everything," concluded Anatoliy Poluda.

This large gathering of birds is called murmurations – a phenomenon of coordinated flight of a large flock of birds (starlings, jackdaws, crows, etc.) that form dynamic, three-dimensional shapes of varying density.

Understanding how the behavior algorithm of an individual bird leads to such a phenomenon is aided by computer modeling. It has shown that the mechanism of murmurations plays a role in protecting the flock from predators.

Similar phenomena are demonstrated by large schools of fish.