This article was originally published on National Geographic.


“…“Trophic cascade” is the term used for the effects of an apex predator, like a wolf, on the landscape. Explain what that means—and describe how the reintroduction of wolves in Yellowstone led flora and fauna to flourish.

When they brought wolves back, it quickly changed and improved the landscape in ways that even the biologists didn’t anticipate. First and foremost, Yellowstone had way more elk than it could reasonably accommodate. Wolves brought that number back down to what it historically had been prior to Europeans arriving in Yellowstone.

They also began to see other species flourishing. The elk were no longer able to gather in the valleys in huge numbers and browse at their leisure; they had to be much warier and spend more time at higher elevations.

One of the effects was that streamside vegetation began to rebound. Aspen and willow returned, which in turn encouraged beavers to return to the park, as willow is their main food source. Beavers change the profile of a river, making it deeper by creating dams and pools, which in turn is healthier for fish.

Wolves also reduced Yellowstone’s coyote population, which was the densest in North America. Because of this, the rodent population had been kept artificially low. Once the wolves started to kill off some of the coyote population—not to eat them but to defend their own territories—there was a huge rebound in the rodent population.

As a result of that, other animals that eat rodents also rebounded, like large birds of prey, raptors, foxes, and badgers. The renaissance of all these species was a direct result of restoring the top predator…”

Read on at: National Geographic.