The ESA has come under repeated attack since January from the Trump administration, which claims the law’s strictures overreach and prevent “energy domination” by inhibiting development. The executive orders the president signed this year charge government agencies with rewriting the ESA’s rules to facilitate fossil fuel projects more quickly by bypassing environmental reviews.

Conservatives like Burgum characterize the law as ineffective, arguing the rigidity of its rules do little to further species’ recoveries. But many scientists and legal scholars say the problem is not the ESA itself but the chronic underfunding and political whiplash the law has experienced over the years.

“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.”

The ESA Prevents Extinctions, but Recovery Is Slow

Environmental law experts note that the ESA’s record extends beyond species recoveries, to preventing far worse losses. Since the law’s passage in 1973, only 26 federally monitored species have gone extinct after they were listed. At least 47 other species are thought to have disappeared while still on the waiting list, according to one estimate.

“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 bald eagle has long been one of the most heralded recovery success stories of the ESA. As the nation’s official bird, it’s been a high-profile symbol for the act. In the 1960s, the bird faced steep declines caused by habitat loss and the pesticide DDT. Widespread use of the chemical in the years after World War II led to nearly 100 percent mortality for eagle eggs and wiped out large populations across the country. By the mid-1960s, only a few hundred pairs were thought to nest in the lower 48 states.

After Congress banned DDT in 1972 and the eagle was given ESA protections in 1978, their numbers slowly began to rebound. By 2007, thanks to habitat protections, the bird was delisted, with close to 10,000 pairs found nesting across the U.S.

A host of other species have similarly benefited from the targeted protections. The American alligator and Steller sea lion are just two of many others.The ESA’s protections have applied to both public and private lands, which for decades has been a source of tension. Private lands are home to more than two-thirds of all listed species. In fact, about 10 percent of all listed species occur only on private property.

“The biggest concern for landowners is that your ability to use that land is going to be limited and you can be prosecuted,” said Jonathan Adler, a law professor specializing in environmental policy at the William & Mary law school. “That has the effect of discouraging landowners from being cooperative.”

The restrictions “seem to create perverse incentives,” Adler added, pointing to studies that have found that in some cases, logging was increased in places where threatened species were found to preempt federal habitat restrictions.

Legislators over the years have sought to ease those tensions through tax breaks and other conservation easements that provide compensation for landowners who take steps to help protect at-risk species and their habitats. But programs have decreased in recent years, sources for conservationists to worry about.

The ESA’s Uncertain Future

Once a bipartisan cause, the Endangered Species Act is now one of the most litigated environmental laws in the U.S. Many efforts to roll back its reach have been launched over the years under various administrations, only to be reversed when the White House changed hands.

But this time could be different, experts say. The Trump administration’s aggressive attack on the ESA’s habitat and listing protections combined with a conservative-leaning Supreme Court could permanently scale back the act’s reach, many fear. And while political battles play out, climate change and habitat loss threaten to push an increasing number of species toward the brink.

“I think the larger worry is that with climate change, habitat loss, and all of these other things … we’re not just going to be listing fewer species,” said Andrew Mergen, a senior lecturer at Harvard Law School who worked for more than 20 years at the Interior Department litigating ESA cases. “We’re going to be listing species later and later in their decline, and that’s only going to make recovery more difficult. The real challenge is not necessarily deregulation but having the resources to actually implement the law as it’s been written.”

Proof the ESA Works … or Proves the ESA Works

Amidst all the political posturing and blame game, recent events have offered at least a glimmer of hope for conservationists. In July, the U.S. Fish and Wildlife Service announced that a freshwater fish, the Roanoke logperch, had bounced back from perilous levels and could be taken off the endangered species list. Burgum took to Twitter soon after, calling the delisting “proof” the ESA was no longer “Hotel California.”

But as Wilcove noted, the recovery is the product of more than three decades of dam removals, wetland restoration, and other efforts to return critical habitat, not to mention an expensive reintroduction and breeding program. The work began long before the Trump administration.

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