On a cold morning in January of 1995, a stock truck crossed the Roosevelt Arch carrying fourteen gray wolves from Alberta. They were held for ten weeks in chain-link pens on the northern range so they would settle before they ran. Seventeen more came the next winter. The plan had been argued over in hearings for two decades, sued into the courts twice, and rewritten until nobody could recall the original. A ranger who was there said the wolves did not bolt when the gates opened. They stood, looked, and walked out at their own pace.

The elk noticed first. Herds that had grazed the valley floors in plain view quit doing it. Their numbers on the northern range, near twenty thousand at the peak, fell by three quarters over fifteen years. Willow came back along the creeks where the elk no longer stood all day. Beaver, which want willow to eat and to build with, followed the willow. A single colony on the northern range in 1996 became a dozen. Songbirds moved into the new cover. Ravens, eagles and bears grew fat on what the packs left on the snow.

A short film later told the world the wolves had rerouted the rivers. Working biologists have spent years walking that back. Drought did some of it. Hunting outside the park did some. Grizzlies eating elk calves did a share. Some valleys recovered and some did not, and the arguing continues in the journals. On one point there is no argument. The park is louder than it was, and the sound comes from the wolves.

The people who carried the idea for twenty years were told it would fail at every turn. The ranchers would never stand for it. The animals would not survive the trip. The ecosystem had moved on and could not take them back. They kept filing the paperwork and driving to the hearings. Fourteen animals and a great deal of patience put back what took seventy years to remove.

Good work often looks like that from inside it. Long stretches where nothing seems to move, and then a gate opens and the whole valley begins to change.