The ESA, signed into law by President Richard Nixon, has long been a target of the Trump administration, which has sought to reduce its regulations as “draconian” and an impediment to development. Since January, the administration has issued executive orders telling agencies to rewrite ESA rules in ways that would speed up fossil fuel projects, often skirting required environmental reviews.

The president has been joined by Burgum and others in the conservative movement who have declared the law a failure because its strictures do little to promote recovery.

Scientists and conservation attorneys counter that the fault lies not with the ESA but with underfunding and inconsistent political will. “We continue to wait until species are in dire straits before we protect them,” said David Wilcove, a professor of ecology and evolutionary biology at Princeton University. “That makes recovery far more difficult and expensive.”

While some critics on the right have panned the ESA for allowing 99 percent of protected species to remain listed, experts emphasize that many have not yet gone extinct due to the law. Since 1973, only 26 federally monitored species have been delisted due to extinction. At least 47 are believed to have disappeared on waiting lists for listing consideration, according to Wilcove.

“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.”

One of the most celebrated successes of the ESA has been the recovery of the bald eagle. As development and the pesticide DDT decimated populations in the 1960s, only a few hundred nesting pairs were left in the lower 48 states. After the chemical was banned and the bird given ESA protections in 1978, numbers improved each year. By 2007, the bald eagle was delisted, with nearly 10,000 pairs thriving.

American alligators and Steller sea lions are other examples of successful species recovery thanks to the ESA and related protections.

The ESA has long drawn controversy over its inclusion of private lands under its protections. Roughly two-thirds of listed species live, at least in part, on private property, and about 10 percent are found there exclusively.

“The government is saying, ‘Your ability to use that land is going to be limited, and you can be prosecuted,’” said Jonathan Adler, an environmental law professor at the University of William & Mary. “That discourages landowners from cooperating.”

In some cases, studies show the law’s rules can create “perverse incentives.” A red-cockaded woodpecker study, for example, found that timber was thinned or clear-cut earlier in stands where the bird was known to live, possibly to sidestep future federal habitat protections.

Over the years, lawmakers have introduced various incentives, such as tax breaks and conservation easements, to compensate private landowners who work to protect habitats. But such programs have dwindled in recent years, stoking conservationists’ fears.

The Future of the ESA

The ESA once had widespread bipartisan support, but has become one of the most litigated environmental laws in U.S. history. Presidents Ronald Reagan and George H.W. Bush proposed major changes to it; the Clinton administration rewrote others to soften its impacts.

Congress has also introduced major changes, including new rules for critical habitats that would ease or eliminate the obligation to consult with other agencies before approving actions that would destroy them.

Some experts fear that the Trump administration’s aggressive loosening of ESA protections and rules, combined with a Supreme Court with several conservative justices, will diminish the law’s reach for years to come. At the same time, the accelerating rate of climate change and ongoing habitat destruction threaten to put more species in dire straits than ever before.

Harvard Law School’s Andrew Mergen, who spent more than two decades litigating ESA cases as a government attorney, argues the law is strong and that efforts should be focused on resources, not deregulation. “The law has prevented extinctions,” Mergen said. “The real challenge is committing enough funding and political will to help species recover, not dismantling the protections that keep them alive.”

Politics aside, recent news offers a reminder of what’s possible. Last month, the U.S. Fish and Wildlife Service declared that the Roanoke logperch, a freshwater fish, has recovered sufficiently to be taken off the endangered list, the first such case in North Carolina in a decade. Burgum touted it as “proof” the ESA is no longer “Hotel California.”

But conservationists caution the fish’s recovery took more than three decades of dam removals, wetland restoration and other costly reintroduction efforts that often involved transporting them to new habitats—all of which began long before Trump took office.

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