In 1995, then-Interior Secretary Bruce Babbitt, center, and others deliver the first gray wolf for release into Yellowstone National Park. The film explores this and other issues about such predators. (Pool/AFP/Getty Images)

Wolves. Grizzlies. Mountain lions. Yellowstone National Park is full of natural predators — animals that help keep the area’s fragile ecosystem in balance.

But past wildlife management reduced their numbers, triggering a cascade of unintended consequences through the park. Without natural predators to reduce their numbers, animals such as elk flourished in Yellowstone. They ravaged delicate wildlife with winter browsing and reduced habitat for other animals, such as beavers and birds.

In recent years, however, predators’ numbers have soared. The documentary “Epic Yellowstone: Return of the Predators” sees the park through their eyes.

On Saturday, the film will have its world premiere screening at 7 p.m. at the Smithsonian National Museum of Natural History. On Sunday, it will air on the Smithsonian Channel at 9 p.m. It’s part of the 2019 Environmental Film Festival, an annual event that brings hundreds of films to the nation’s capital. The festival runs from Thursday to March 24.

“Epic Yellowstone” follows predators over the course of a year in the park. It covers what it takes for the animals to survive, raise their young and protect their territory in an ecosystem that is still recovering from years of predator control that allowed elk herds to balloon and forced songbirds to disappear, among other effects.

The reintroduction of wolves in the park was controversial.

Starting in 1995, the park introduced the first wolves to roam Yellowstone since they were hunted out of existence in the 1920s. Protested by hunters and local ranchers, the move is credited with benefiting other species such as eagles and bears that feed off carrion killed by wolves. But researchers are unsure whether the park’s ecosystem will ever be restored.

After the screening, producers Eric Bendick, Tria Thalman and Tom Winston will participate in a Q&A.

Tickets are free, but reservations are required.

Go to Dceff.org/festival for the festival schedule and to bit.ly/predatorfilm to RSVP for the Yellowstone film.