Vikings hunting reindeer in Norway were once confounded by "reindeer cyclones"; a threatened herd would literally run circles around the fierce hunters, making it nearly impossible to target a single animal.

Filmmakers recently captured incredible aerial footage of one of these reindeer cyclones, which aired Feb. 13 on PBS in the documentary "Wild Way of the Vikings," a program about Vikings and the wilderness they inhabited around A.D. 1000. [Photos: Ancient Arrows from Reindeer Hunters Found in Norway]

One of the documentary's most striking scenes shows a re-enactment of a Viking hunt interspersed with real footage of reindeer herds. Reindeer were important to the Vikings for their meat, hides, antlers and bones, according to the film.

In the cyclone scene, a lone hunter (an actor playing a Viking) approaches the herd; he notches and releases an arrow. The footage that follows shows an actual herd of reindeer running in circles. As the swirling mass of bodies thunders along a circular path, an overhead camera reveals that the herd's momentum follows a spiral shape, drawing tightly toward the cyclone's "eye" at the center.

Faced with this spinning reindeer stampede, any predator — wolf, bear or human — would have a very tough time targeting and overpowering a single reindeer, making this a formidable defense strategy, according to a statement from PBS.

This behavior is also practiced by reindeer kept in corrals, occurring in groups of at least 20 to 25 animals, researchers wrote in a 2002 study published in the journal Rangifer. Penned reindeer formed "cyclones" and were observed to run "invariably" in a counterclockwise direction, the scientists reported.

A herd of reindeer moves through snow-covered mountains in Norway. (Image credit: Copyright Maramedia, photo by Fergus Gill)

Opportunistic hunters

Vikings were opportunistic hunters who preyed on reindeer, birds, fish, seals, walruses and possibly even whales, Albína Hulda Pálsdóttir, a doctoral candidate with the Centre for Ecological and Evolutionary Synthesis at the University of Oslo in Sweden, told Live Science.

"The Vikings really adapted to making use of everything that they could," she said.

Scientists know that Vikings hunted with bows and arrows, and used ropes and nets for fishing "and possibly birding," said Pálsdóttir, a zooarchaeologist and science adviser for the film.

However, archaeologists know little about the details of their hunting techniques, as Vikings crafted tools primarily from organic materials such as wood, rope and hide, which don't preserve well.

But in recent years, many of these ancient relics have emerged from melting ice and permafrost. This is particularly true in Norway, where ice patches — regions of long-frozen snow — are rapidly disappearing, providing archaeologists with access to Viking objects that were preserved in ice for more than a millennium, Pálsdóttir said.

"It's really adding to our understanding of their material culture, and what they may have used to hunt reindeer," she added.

You can watch the entire episode of "Wild Way of the Vikings" on the PBS website.

Originally published on Live Science.