This story originally appeared on Vox and is part of the Climate Desk collaboration.
In the early 1900s, long before smartphones and selfie sticks, tourists flocked to Yellowstone National Park—not for the geysers or scenery, but for a grotesque show: a nightly spectacle of grizzly bears raiding cafeteria scraps from open-pit landfills like desperate, starving pirates.
The bears were in dangerous proximity to humans: Hungry bears tore at open car windows. Tourists posed a little too close with their film cameras. Yellowstone park rangers logged dozens of injuries each year—nearly 50 on average.
Eventually, the Park Service ended the nightly landfill shows: Feeding wild animals human food wasn’t just dangerous, it was unnatural. Bears, ecologists argued, should eat berries, nuts, elk—not leftover Twinkies. In 1970, the park finally shut down the landfills for good.
By then, though, grizzlies were in deep trouble. As few as 700 remained in the lower 48 states, down from the estimated 50,000 that once roamed the 18 western states. Decades of trapping, shooting, and poisoning had brought them to the brink. The ones that clung to survival in Yellowstone National Park learned to take what scraps they could get and when they were forced to forage elsewhere, it didn’t go so well.
More bears died. Their already fragile population in the Yellowstone region dipped to fewer than 250, though one publication says the number could have been as low as 136, according to Frank van Manen, who spent 14 years leading the US Geological Survey’s grizzly bear study team and now serves as an emeritus ecologist.
The Yellowstone bears had been trained to rely on us. And when we cut them off, their population tanked.
And so in 1975, the US Fish and Wildlife Service placed grizzly bears on the endangered species list, the country’s most powerful legal mechanism to stave off extinction.
The grizzly’s place on the list afforded them some important protections under the Endangered Species Act (ESA). Hunting was off-limits, as was trapping or poisoning, and the listing included rigorous habitat protections. Grizzlies slowly came back.