Long TextExercise 76 of 83

In the winter of 1995, fourteen grey wolves were transported from Canada to Yellowstone National Park in the United States, marking the beginning of one of the most ambitious and controversial wildlife reintroduction programmes in modern history. The wolves had been absent from the park for nearly seventy years…

• Why had wolves disappeared from Yellowstone before the reintroduction programme?
• What effect did the return of wolves have on the park's vegetation?