Pack of Female Wolves Destroys Enemy Intruder in Brutal Fight (Video)
A pack of female wolves defends its den from an intruder in a new PBS documentary.
Credit: Nature: Arctic Wolf Pack/WNET

Moms are fierce — especially when they're wolves.

In a dramatic new video from an upcoming PBS documentary on Arctic wolves, a pack of female wolves defends its den from a bedraggled, strange wolf who attempts to make a meal of the pack's defenseless cubs.

Well, defenseless except for their mother and her three female packmates.

In a snarling, brutal sequence, the pack drags, bites and pulls the invader away from the pups. Within moments, the pups are safe from danger, and the stranger is on the run. [In Photos: Adorable Baby Wolves]

The footage is part of a new episode in the series "Nature." The episode, "Arctic Wolf Pack," airs on PBS on Jan. 17. The documentary follows a pack of Arctic wolves (Canis lupus arctos) living only 500 miles (800 kilometers) from the North Pole. The snowy-furred canines birth their fuzzy, blind pups in dens burrowed into the Arctic tundra. Their mother, dubbed Snow White, isn't alone in caring for them. Her packmate, Black Spot, nurses Snow White's pups — a mysterious behavior never before captured on film. To make milk, Black Spot must have recently given birth herself, but the fate of her mate and her own litter is a mystery.

Arctic wolves are found in Greenland and the far northern reaches of Canada. It's the only subspecies of gray wolf that is not threatened by hunting or loss of habitat, according to the World Wide Fund (WWF) — an advantage it gains by living so far north that it rarely encounters humans.

Beyond its white fur, the Arctic wolf's short muzzle and small ears distinguish this subspecies from its more southerly gray cousins. These adaptations make it easier for the wolves to retain body heat, according to the WWF. The wolves live off of Arctic hares, caribou and musk ox, the latter of which grow to at least 10 times the wolves' weight. With such large prey, survival is a matter of cooperation between packmates — whether that means banding together to hunt or to protect the next generation.

The documentary "Nature: Arctic Wolf Pack" from THIRTEEN premieres Wednesday, Jan. 17, at 8 p.m. on PBS.

Original article on Live Science