Raindeer are into some weird behavior now and then. Like panicking together in circles.

A raindeer not panicking. Photo: Are G Nilsen
When reindeer are threatened, they stampede in a circle, making it extremely difficult to target an individual from the herd. Fawns are in the middle of the swirling mass.
Footage showing these “raindeer cyclones” on on Russia’s Kola Peninsula near the Arctic Circle has gone viral on the Internet in the last few days, and it is easy to see why. The sight of the circling reindeer is indeed breathtaking.
“It’s a defense strategy, designed to confuse any predator,” PBS said in a documentary featuring a reindeer cyclone. “Whether wolf, bear, or Viking – achieving a clean kill in a swirling melee like this is difficult.”
As you can see in the documentary, the Viking hunter has a hard time picking an animal from the herd.
Similar defensive formations have been observed in fish, IFL Science notes. They form into a large ball or tornado-like schools, scaring off even large predators.
Nature is truly amazing.