Gray wolves are the largest canines and once ranged over much of the Northern Hemisphere, although they are now limited to parts of North America, Asia and Europe. They are also highly social animals, living and hunting in groups called packs.
As the largest members of the dog family, gray wolves range between 60 and 175 pounds and anywhere from 4 1/2 to 6 feet long. Despite the name, gray wolves come in a variety of colors such as white, gray, brown, cinnamon and black. Although most gray wolves only live between six and eight years in the wild, they mature quickly and mate for life. When a female gives birth to a litter, the entire pack helps to raise the pups, an early interaction that teaches the young wolves about their roles in the group. Highly social, wolves communicate with each other in a variety of ways from howling, barking and whining to scent making.
Gray wolves once roamed throughout North America from Canada and Alaska to the lower contiguous United States. However, hunting completely eradicated the wolves from all the United States except for Alaska. In 1995, experts reintroduced gray wolves to Yellowstone National Park, where they are thriving as of 2015.