How did the decline in the wolf population in Yellowstone national park leed to a decline in beaver population?

The decline of the wolf population in Yellowstone National Park led to an increase in elk and deer populations, as there were fewer natural predators to keep their numbers in check. This surge in herbivore populations resulted in overgrazing of vegetation along riverbanks, which negatively impacted the habitat for beavers. Beavers rely on the presence of healthy riparian vegetation for food and building materials; thus, their population declined as their habitat deteriorated due to the increased herbivory.