Their spine-tingling howl, which they use to communicate with each other.
Between 124 and 211cm from head to tip of tail.
Wolves are mostly meat-eaters. They’ll tuck into anything from deer and wild boar, to smaller animals.
Grey wolves live in wilderness areas where there aren’t many people. They can be found in parts of Europe (not the UK), as well as North America, Alaska and Asia.
Nobody knows exactly how many grey wolves there are.
Wolves have got a bad reputation for being a threat to humans and domestic animals, and many of them have been poisoned or shot. Changes in the use of land also threaten their habitat.
Grey wolves are members of the dog family and are the largest of all wild dogs.
Watch some grey wolves in a video from our friends at Arkive.