A one-word Endangered Species Act change turns habitat science into the next extinction fight

The Trump administration has finalized a rule that removes the federal government’s long-standing regulatory definition of “harm” under the Endangered Species Act, a narrow-sounding legal change with a big scientific consequence: habitat destruction that injures or kills protected wildlife will no longer be named in the rule itself as illegal “take.”

The final rule, issued by the U.S. Fish and Wildlife Service and the National Marine Fisheries Service and scheduled for publication in the Federal Register on July 14, rescinds the definition of “harm” from federal regulations at 50 CFR parts 17 and 222. The Interior Department announced the decision on July 10, saying the change “restores clear ESA enforcement” and returns the law to its “actual text and original intent.” Conservation groups say the move strips away one of the law’s most practical tools: protecting the places endangered and threatened species need to feed, breed, shelter and recover.

This is a science story because the dispute is not only over statutory wording. It is over whether extinction risk can be managed by protecting individual animals while weakening protection for the ecological systems that keep those animals alive. The answer from decades of conservation biology is blunt: for most imperiled species, habitat is not scenery around the problem. Habitat is the problem.

The Endangered Species Act bars the “take” of endangered wildlife. Congress defined “take” to include actions such as harassing, harming, pursuing, hunting, shooting, wounding, killing, trapping, capturing or collecting protected wildlife. Since the 1970s, federal regulations have defined “harm” to include some forms of habitat modification or degradation when that habitat damage actually kills or injures wildlife by significantly impairing essential behaviors, including breeding, feeding or sheltering.

The new final rule removes that regulatory definition. In the agencies’ words, the rescission “removes the regulatory definition of ‘harm’ from the Code of Federal Regulations.” The rule does not erase the word “harm” from the statute, and it does not repeal the ESA’s separate requirements for federal agencies to avoid jeopardizing listed species or destroying or adversely modifying designated critical habitat. But it does change the enforcement terrain for habitat damage, especially where private or non-federal actions are involved.

Interior Secretary Doug Burgum framed the move as a property-rights and regulatory-certainty measure. “For years, federal agencies abused the ESA to obstruct lawful land use and burden American families and businesses,” Burgum said in the Interior Department’s July 10 announcement. Commerce Secretary Howard Lutnick said the administration was returning the ESA to “its foundational purpose” without “sacrificing economic growth and American prosperity.”

The agencies also argue that existing permits and incidental-take statements will remain valid and unchanged. In the final rule, they say previously issued permits will not have to be reevaluated solely because of the rescission, and they state that disturbing those settled decisions would be “highly disruptive.”

That is the administration’s case. The scientific concern is what happens next.

A central finding of modern conservation research is that species usually slide toward extinction because their habitat has been destroyed, degraded, fragmented or made unusable. A 2019 paper in Conservation Science and Practice, “Temporal analysis of threats causing species endangerment in the United States,” reviewed listing decisions for species protected under the ESA from 1975 through 2017 and found habitat modification was the dominant recurring threat. The authors reported that 81% of listed species were affected by habitat modification, while only 17% were affected by overutilization such as hunting, collecting or direct exploitation.

A broader 2022 study in the same journal, “The greatest threats to species,” examined the International Union for Conservation of Nature Red List database and found habitat loss threatened more species than any other category it measured. Its abstract reports that, among 20,784 threatened species with available data, 88.3% were affected by habitat destruction. That finding matters here because the ESA fight is not happening in a vacuum. It sits inside a global biodiversity crisis driven heavily by land-use change, freshwater disruption, coastal development, pollution, invasive species and climate pressure.

Put more plainly: if a protected bird needs an old-growth forest cavity to nest, a protected salmon needs cold connected streams to spawn, or a protected turtle needs intact beach and nearshore habitat to reproduce, the line between “killing the animal” and “destroying what keeps it alive” can be biologically artificial. The law may separate categories. The organism does not.

That was the reasoning behind the regulatory approach upheld by the Supreme Court in 1995 in Babbitt v. Sweet Home Chapter of Communities for a Great Oregon. In that case, a majority allowed the government to keep treating significant habitat modification that actually kills or injures wildlife as “harm” under the ESA. The new final rule leans instead on a narrower reading, citing legal arguments about the ordinary meaning of “take” and the Supreme Court’s 2024 decision in Loper Bright Enterprises v. Raimondo, which ended Chevron deference to agency interpretations of ambiguous statutes.

The administration’s position is that the old rule expanded “take” beyond what Congress meant and turned section 9 of the ESA into a sweeping land-use regulation. The final rule says FWS’s 1975 and 1981 definitions transformed a prohibition on killing, injuring or capturing protected animals into a habitat-modification regime. The agencies argue that section 7 of the ESA already governs federal actions affecting critical habitat, while section 5 allows the government to acquire land for conservation.

Conservation scientists and wildlife advocates counter that those tools do not substitute for the practical reach of the “harm” definition. Section 7 applies to federal actions. It does not automatically cover every private development, logging project, water diversion, mining operation, coastal dredging project or other activity that may damage habitat. Land acquisition can help, but it is slow, expensive and incomplete. Many species need connected landscapes, seasonal corridors or water conditions that do not fit neatly inside a purchased parcel.

Defenders of Wildlife said July 10 that it intends to sue, calling the rescission an attempt to eliminate the interpretation that habitat destruction leading to death or injury of protected species constitutes illegal take unless authorized. “The law, the science and the American public’s opinion do not support this decision,” Jane Davenport, a senior attorney at the group, said in the organization’s statement.

The group’s response should be read as advocacy, not neutral analysis. But the science point it raises is independently supported: habitat loss is a primary driver of extinction risk. The policy argument is over how much of that risk the ESA should regulate, who bears the cost, and whether agencies can keep using a definition the current administration says was legally overbroad.

The agencies say the rule does not remove all species protection. Directly killing or injuring listed wildlife remains prohibited. Existing permits remain in place. Federal agencies still have duties under section 7. The final rule also says the Services used a National Environmental Policy Act categorical exclusion, rather than preparing a full environmental impact statement, because they view the rule as a legal interpretation rather than a specific on-the-ground project.

That NEPA point will likely become one of the legal pressure points. Commenters argued during rulemaking that the Services should analyze environmental effects because changing the definition could alter what habitat-damaging activities are treated as unlawful. The agencies responded that they had independently evaluated NEPA and determined the rule qualified for a categorical exclusion. In practical terms, that means the government is making a national habitat-protection change without first producing the kind of public environmental analysis usually associated with major federal actions.

The effect will not be uniform across species. Some listed animals face acute direct-killing threats: poaching, vehicle strikes, deliberate persecution, accidental capture in fishing gear. Others face threats that are overwhelmingly habitat-based. Northern spotted owls depend on old-growth forest structure. Southwestern willow flycatchers need riparian habitat. Desert tortoises are shaped by desert land disturbance, disease, drought and development pressure. Salmon and steelhead are tied to stream temperature, flow, sediment, barriers and spawning habitat. Florida manatees depend in part on seagrass availability and water quality.

The rule also lands as climate change makes habitat protection more complicated. Species ranges are shifting. Drought, wildfire, heat extremes, sea-level rise and marine heat waves can make old habitat less suitable and push species into new areas. If the legal system protects only the animal in the moment and is less able to address habitat conditions that injure it, conservation work gets narrower just as ecological risk gets wider.

That does not mean every habitat dispute has an easy answer. Landowners, utilities, local governments, ranchers, fishing fleets and builders often face real compliance costs. Habitat conservation plans and incidental-take permits can take time and money. Some communities experience ESA enforcement as remote federal control over local land and water choices. A serious news account should not flatten those concerns into caricature.

But the evidence also does not support pretending that species can recover without habitat. The ESA’s own stated purpose is to provide a way to conserve the ecosystems on which endangered and threatened species depend. That ecosystem language is not decorative. It is the scientific premise of the law.

The regulatory rollback may also shift more decisions into litigation. Without a regulatory definition, developers and agencies may face new uncertainty about what “harm” means in enforcement, while conservation groups will test whether courts accept the administration’s narrower reading after Loper Bright. The final rule says agencies will rely on the statutory text going forward. Courts will now have to decide how much room remains for habitat-based harm claims when a project damages the conditions a listed species needs to survive.

For readers, the cleanest way to understand the stakes is this: the administration says the change ends an unlawful expansion of federal power and keeps direct species protections intact. Conservation biologists warn that direct protection is often too late if the nest, stream, beach, wetland, forest or feeding ground is already gone.

That is why a one-word change belongs on the science desk. It is not only a Washington rulemaking story. It is a test of whether U.S. endangered-species policy will continue to treat habitat as biological infrastructure, or whether it will draw a sharper legal line between an animal and the living system that makes its survival possible.

What is known

• The final rule rescinds the regulatory definition of “harm” under the Endangered Species Act from FWS and NMFS regulations.
• The rule was announced July 10 and is scheduled for Federal Register publication July 14.
• The administration says direct killing or injury of listed wildlife remains prohibited and existing permits remain valid.
• Conservation research repeatedly identifies habitat loss and degradation as a leading driver of species endangerment and extinction risk.
• Defenders of Wildlife and other conservation advocates say they plan to challenge the rule in court.

What remains uncertain

• How courts will interpret “harm” after the regulatory definition is removed.
• How quickly developers, landowners and agencies will change behavior in response to the rule.
• Which species and habitats will see the first practical impacts.
• Whether Congress, future administrations or courts will restore a habitat-based definition.

Sources

• U.S. Fish and Wildlife Service and National Marine Fisheries Service, final rule: “Rescinding the Definition of ‘Harm’ Under the Endangered Species Act,” public inspection PDF, scheduled for Federal Register publication July 14, 2026: https://public-inspection.federalregister.gov/2026-14195.pdf
• U.S. Department of the Interior, “Department of the Interior Restores Clear ESA Enforcement by Rescinding Misguided ‘Harm’ Definition,” July 10, 2026: https://www.doi.gov/pressreleases/department-interior-restores-clear-esa-enforcement-rescinding-misguided-harm
• The Conversation, Mariah Meek and Karrigan Börk, “How redefining one word strips the Endangered Species Act’s ability to protect vital habitat,” July 2026 update: https://theconversation.com/how-redefining-one-word-strips-the-endangered-species-acts-ability-to-protect-vital-habitat-287348
• Scheele et al., “Temporal analysis of threats causing species endangerment in the United States,” Conservation Science and Practice, 2019: https://doi.org/10.1111/csp2.78
• Jaureguiberry et al., “The greatest threats to species,” Conservation Science and Practice, 2022: https://doi.org/10.1111/csp2.12670
• Greenwald et al., “Extinction and the U.S. Endangered Species Act,” PeerJ, 2019: https://doi.org/10.7717/peerj.6803
• Babbitt v. Sweet Home Chapter of Communities for a Great Oregon, 515 U.S. 687 (1995): https://supreme.justia.com/cases/federal/us/515/687/
• Defenders of Wildlife, “Trump Administration Rescinds ‘Harm’ Definition, Defenders Prepares for Court,” July 10, 2026: https://defenders.org/newsroom/trump-administration-rescinds-harm-definition-defenders-prepares-court-0