Lawmakers in several states, led by Republican politicians, are now looking to trim those protections, arguing that the endangered species law is an impediment to economic growth, costly to taxpayers, and long on regulation but short on results. The species of greatest concern are those that live largely on private lands, such as the grizzly bear in Wyoming.

The Trump administration has also repeatedly taken aim at the ESA since January, with critics charging that strict government regulations are hindering development and standing in the way of “energy domination.” This year, the administration signed executive orders instructing government agencies to rewrite ESA rules in ways that could speed up fossil fuel projects and skirt the kinds of environmental reviews the law typically demands.

Rep. Rob Bishop (R-Utah), chairman of the House Natural Resources Committee, said in a statement earlier this year that the ESA was supposed to be “an insurance policy against species loss” but had become “a perpetual admission ticket to the endangered species ‘Hotel California.’”

Critics like Burgum have described the ESA as a failed bureaucracy, pointing to a small percentage of species that have been removed from the endangered list in recent decades. Burgum also says the law’s rigid rules do little to help species recover. Supporters say the issue isn’t the ESA, but a history of chronic underfunding and inconsistent political support.

“The picture is a lot grimmer if you take away the successes of the ESA,” said David Wilcove, a professor of ecology and evolutionary biology at Princeton University. “We continue to wait until species are in dire straits before we protect them, and that makes recovery far more difficult and expensive.”

A Track Record of Prevention, Not Just Recovery

Supporters and experts point out that the ESA has been largely successful at its original aim of preventing mass extinction. Since 1973, only 26 species on the federal list have gone extinct. At least 47 species are believed to have disappeared before they could be placed on that list.

“The ESA works more like a critical care unit than a hotel,” Wilcove said. “It’s as though we built a great hospital but never funded enough doctors or equipment.”

The ESA’s biggest success story is also one of its most recognizable: the bald eagle. In the 1960s, after widespread use of the pesticide DDT and habitat destruction left only a few hundred nesting pairs in the lower 48 states, the majestic bird became the first species listed in the modern era of the ESA. DDT was eventually banned and, after protections under the ESA in 1978, the bald eagle’s numbers steadily rebounded. The bird was eventually delisted in 2007, with nearly 10,000 pairs thriving nationwide.

Species such as the American alligator and the Steller sea lion have also recovered from low points and have been removed from the endangered list. Conservationists argue the ESA has helped thousands of other plants and animals by protecting their habitats and keeping them off the endangered list in the first place.

Challenges on Private Lands

The ESA’s regulatory authority over private as well as public property has long been a source of conflict with landowners. The vast majority of species on the endangered list—more than two-thirds—depend on private lands for survival, and about 10 percent live only on those lands.

“There’s no doubt about it,” said Jonathan Adler, an environmental law professor at the William & Mary University School of Law. “Your ability to use that land is going to be limited, and you can be prosecuted. That’s one reason it discourages landowners from cooperating.”

Research has suggested that rule can create “perverse incentives” on private land. One study of the red-cockaded woodpecker, for instance, found that timber was harvested in privately owned, old-growth forests early in a forest’s life if the bird was present, likely to skirt federal habitat restrictions.

Congress over the years has also created a series of incentives, such as tax breaks and conservation easements, which allow landowners to receive money or tax credits in exchange for habitat protection. The acreage enrolled in those programs has declined in recent years, a trend that has alarmed many conservationists.

For years, the Endangered Species Act had widespread bipartisan support but in recent years has become one of the most litigated environmental laws in the country. Efforts to roll back the ESA have emerged under several administrations, with reversals when leadership changed.

Today, conservationists are particularly concerned that the Trump administration’s aggressive regulatory rollback, combined with a more conservative-leaning Supreme Court, could permanently narrow the ESA’s authority. It also comes as climate change and habitat loss are putting increasing pressure on more species to potentially endangered levels.

Andrew Mergen, a law professor at Harvard Law School who previously spent 20 years litigating ESA cases at the Department of Justice, says the focus should be on ramping up resources for recovery rather than deregulation. “The law has prevented extinctions,” he said. “The real challenge is to commit enough funding and political will to help species recover, not to dismantle the protections that keep them alive.”

Hope on the Horizon

Politics aside, conservationists and biologists point to recent news stories as a sign of what the ESA is still capable of doing. In July, the U.S. Fish and Wildlife Service removed the Roanoke logperch, a freshwater fish, from the endangered species list. Burgum hailed the announcement as “proof positive” the ESA was no longer a “Hotel California.”

But in this case, conservationists note, the recovery came after more than three decades of dam removals, wetland restoration, and expensive reintroduction efforts, all of them launched well before the Trump administration. (Related: “Rarities Helped by ‘Hotel California’ Return from ‘Biochemical Dead’”)

“The optimistic part is that we know how to save species when we actually invest in them,” Wilcove said. “The question is whether we’ll make that commitment.”