For 60 years there had been no wolves in Yellowstone National Park. Government trappers and poisoners made sure of that. But last March, amid considerable outcry from area ranchers, biologists loosed 14 Canadian gray wolves in three packs into the park as part of a larger plan to reintroduce the animal to the northern Rocky Mountains. Like a watch, an ecosystem works better when you have all the pieces, says Ed Bangs of the U.S. Fish and Wildlife Service. The wolves have a cleansing effect on the big-game herds. If you look at a deer being swift or an elk being so surefooted--they’re the magnificent animals they are largely because of the constant honing effect of wolves. The three new Yellowstone packs have so far stayed in or near the park, have had two litters of pups--and haven’t killed any livestock. Wolves are the only land mammals that were present in Yellowstone when Columbus stepped ashore that weren’t there a year ago, says Bangs. Now that we have them back, millions of people have the opportunity to experience a completely wild land--and possibly hear wolves howl, which is one of the greatest experiences you’ll have in your life.