The bears of Yellowstone National Park in Wyoming are eating better than usual these days, and they have their neighbors the wolves to thank for it. Specifically, the bears are once again feasting on berry shrubs, which had grown scarce 20 years ago due to elk overfeeding on them. The wolves, however, are now eating some of the elk before those elk have a chance to eat all the berries. The bears come out ahead, with more berries to be had. In turn, the bear’s numbers grow—researchers have counted three to four times as many bears in the park today compared to earlier years.

 

Human officials reintroduced the wolves to the park in the 1990s in hopes that they might bring down the elk population, which at that time had grown too big for the park’s limited living space in the absence of any natural predators to thin out their herds.