The grizzly bear is one of the most iconic species in Yellowstone National Park. When the U.S. Fish and Wildlife Service took steps to remove bears near the park from the endangered species list last year and began to allow limited hunting in the area, animal rights activists were outraged.

Now, a federal judge’s ruling puts Yellowstone’s grizzlies back on the endangered species list. A decision issued by Montana Judge Dana Christensen Monday stated that in delisting Yellowstone grizzlies from the endangered list, the Fish and Wildlife Service had acted “arbitrarily and capriciously,” disregarding the long-term health of grizzly bear populations.

Why were Yellowstone grizzly bears considered endangered in the first place?

Grizzly bears in Yellowstone were first added to the endangered species list in 1975. At their peak, the population numbered more than 50,000, but aggressive hunting over the first few decades of the 20th century caused a steep decline.

Today, that population is roughly five times larger, and many consider the comeback a conservation success story.

State officials first attempted to delist the grizzlies in 2007, saying populations were healthy and stable. That decision was struck down by a court in 2009 after a review of the delisting found that whitebark pine seeds, one of the bears' biggest food sources, was in decline because of warming temperatures.

Why did the Fish and Wildlife Service try again last year?

Last June, Interior Secretary Ryan Zinke announced that officials yet again intended to remove the Endangered Species Act regulations protecting Yellowstone area grizzlies from activities like hunting. The Fish and Wildlife Service supported the move, saying the bear population could support small, limited hunting and that issues concerning whitebark pine seeds had been addressed.

"As a kid who grew up in Montana, I can tell you that this is a long time coming and very good news for many communities and advocates in the Yellowstone region," Zinke said in a statement.

The move also received support from pro-hunting groups like the National Rifle Association and some locals who said that bears were increasingly encroaching on their property, killing livestock, and sometimes endangering people.

"This decision is extremely premature and could set grizzly bear recovery in the Yellowstone region back by decades," Bonnie Rice, with the Sierra Club's grizzly bear program in Bozeman, Montana, told National Geographic in 2017.

Both the Sierra Club and Center for Biological Diversity at the time noted they were considering legal action.

Why did this case get struck down?

The aforementioned wildlife organizations partnered with a number of Native American tribes to file a lawsuit against the administration's decision.

“Fish and Wildlife has been moving in this direction under pressure of the states,” says EarthJustice's Tim Preso, the attorney who represented the plaintiffs.

The population of grizzly bears living in and around Yellowstone National Park currently doesn't intermingle with the population living closer to the Canadian border. The geographical distinction means the ESA can list a Yellowstone population differently than those farther north. Grizzly populations in Alaska, for example, have never been on the endangered list.

Grizzly Bear 101 Grizzly bears are at the top of the food chain, but much of their diet consists of fruit, roots and grasses.

Yet in his court ruling, Judge Christensen said the state had not considered the longterm genetic health of the Yellowstone population. The lack of connectivity with other bear groups, his ruling stated, leaves the Yellowstone grizzlies genetically vulnerable.