The Trump administration adopted a rule Tuesday that could shrink the historic habitats of plants and animals threatened with extinction, an action that opponents say will make it more difficult for them to recover.

On their way out of office, the directors of the U.S. Fish and Wildlife Service and the National Marine Fisheries Service established a rule that changed the definition of what determines a habitat under the Endangered Species Act. It was the second major rollback the administration has made to the signature wildlife protection law.

Under the new definition, only “critical habitat” that can sustain the species in question can be protected, as opposed to a broader habitat the plant or animal might one day occupy if it is suitable.

“This action will bring greater clarity and consistency to how the Service designates critical habitat,” Rob Wallace, assistant secretary for fish and wildlife and parks, said in a statement. “Making the Endangered Species Act more effective at conserving imperiled wildlife and more transparent and user friendly for stakeholders represents a win-win for everyone.”

Conservationists immediately denounced the change as favoring developers over wildlife that has been put at risk by human activity.

Under the previous rule, the immediate living space of species designated as endangered or threatened was protected. It also could include areas that species once inhabited but that became unsuitable after development or climate impacts altered the ecology — these were recognized as areas that scientists could try to restore. But the new rule will is more likely to open such areas to agriculture, logging or other development.

“This is yet another blow to endangered species from an administration that subscribes to a ‘death by a thousand cuts’ approach to bedrock wildlife laws,” said Jamie Rappaport Clark, president and chief executive of Defenders of Wildlife, a liberal conservation group. “This clearly favors developers and industry, making it easier for the most vulnerable wildlife to slip through the cracks.”

Two years ago, the Interior Department made key changes to the act, including allowing officials to consider economic impacts such as losses of jobs and revenue in deciding whether a species should be classified as endangered or threatened.

Clark, a director of the Fish and Wildlife Service under President Bill Clinton, said the new definition of habitat contradicts the purpose of the Endangered Species Act of 1973, which seeks to save wildlife from extinction by preserving and restoring existing and historic habitats.

Other groups joined Clark in saying they would press the incoming Biden administration to review and change the rule. It takes about a year to draft a rule, propose it, seek public comment, address concerns and write a final draft.

The conservation group Earthjustice said the new rule was hastily created and would be challenged in federal court. Environmental groups have been largely successful in challenging rules adopted since 2017 by the Interior Department, which oversees the Fish and Wildlife Service.

“The Trump administration finalized this rule just under the wire to make it harder for species to survive and recover — the exact opposite of what we should be doing under the Endangered Species Act,” said Earthjustice’s Addie Haughey. “We urge President-elect Biden … to take a hard look at this anti-science rule next year.”

But the Trump administration said the reason for the rule change is far more complicated than how opponents characterize it.

The administration says that in making the change, policymakers responded to a 2018 Supreme Court decision that found that protection of endangered habitats went too far. The court ruled that critical habitat should be narrowly defined so that it doesn’t unnecessarily intrude on the rights of farmers, home builders, loggers and landowners.

“Today’s final definition of habitat will continue to improve implementation of the ESA and will address a 2018 Supreme Court ruling in a case regarding dusky gopher frog critical habitat that any area designated as critical habitat must also be habitat for the species,” according to a statement provided by the Fish and Wildlife Service.

“They’re obligated to do this rule under the Supreme Court decision,” said Michael Mittelholzer, assistant vice president for regulatory affairs for the National Association of Home Builders.

In Weyerhaeuser v. the Fish and Wildlife Service, a developer argued that it was being harmed by an endangered habitat designation aimed at benefiting the gopher frog, which wasn’t present on the land and had not been for decades. A divided court ruled in favor of the developer.

“The Endangered Species Act regulates what critical habitat is, but there is no limiting factor on what’s noncritical habitat,” Mittelholzer said. “As much as the other side wants to do this, it was not Congress’s intent when it established the act. The way we’re impacted when we’re doing normal land development activities is we become subject to the ESA if a species is not there and will never be there.”

Jonathan Wood, a senior attorney at the conservative Pacific Legal Foundation, which supported the rule change, said it will force officials to consider whether designating an area as critical habitat is likely to contribute to the recovery of a species.

“The new definition rightly excludes areas that are not currently habitat but merely could become habitat with substantial effort by landowners,” Wood said. Critical habitat designations “dramatically reduce land values,” whether it rightly falls under the category or not, and “landowners won’t invest time and energy into habitat restoration. The available evidence suggests that critical habitat designations have failed to encourage species’ recovery on private land.”

But dismissing a species habitat simply because the animal or plant is no longer present is unfair, conservationists say, arguing that human development fragmented the land, driving away wildlife or dividing their populations, which hampered their ability to mate and reproduce.

“Our most vulnerable species are barely clinging to survival after being forced from their homes into smaller and smaller spaces,” Stephanie Kurose, a policy specialist for the Center for Biological Diversity, said in a statement. “We can’t expect them to ever recover if we don’t protect the areas [where] they once lived.

“President Trump has cemented his legacy as the most anti-wildlife president in history,” Kurose said. “Today’s rule will have devastating consequences for some of America’s most iconic species, including the grizzly bear, whooping cranes and Pacific salmon.”