In part two of this three-part series, Defenders of Wildlife’s Biodiversity Law Center looks at regulations under Section 4 of the Endangered Species Act (ESA). Section 4 covers the first and last steps in a species’ protection under the ESA: (1) adding a species to the endangered or threatened species list for protection, (2) identifying the “critical habitat” that supports the species, and (3) removing species and their critical habitat from protection when the species has recovered and no longer needs those protections. Each of these processes received heavy revisions undermining conservation in 2019. In the most recent regulatory amendments for 2024, some of the problems created in the 2019 amendments were completely eliminated, while other fixes were only partial and left problematic provisions in place. As such, we think of these section 4 regulations as “the middling” in this series on “the good, the middling, and the ugly.”
How are species listed and unlisted?
The protections of the ESA only apply to species that have been formally listed as endangered—meaning at risk of extinction, or threatened—meaning likely to become endangered within the “foreseeable future. 16 U.S.C. § 1532(6), (20). Section 4 of the ESA tells the Fish and Wildlife Service—or National Marine Fisheries Service for marine species—to consider five factors to decide whether a species is at risk of extinction: (1) risk to habitat, (2) overuse by humans, (3) disease or predation, (4) the impact of (or lack of) existing protections, and (5) other factors. 16 U.S.C. § 1533(a)(1).
The goal of the ESA is to recover species to the point of no longer needing protection. 16 U.S.C. § 1531(b). When conservation succeeds, the Services evaluate the same five factors to determine whether the species is no longer at risk of extinction. If so, the Services remove the species from the list and the ESA no longer protects the recovered species.
What is critical habitat?
The ESA recognizes that species cannot survive and recover if they have no place to live. For that reason, in addition to protecting species, the ESA also protects “the ecosystems upon which endangered species and threatened species depend.” 16 U.S.C. § 1531(b). To achieve that purpose, the ESA directs the Services to designate “critical habitat” for listed species. 16 U.S.C. § 1533(a)(3). That critical habitat then receives protection from the ESA, which prohibits federal agency actions from destroying or adversely modifying critical habitat. Critical habitat designations are an important part of the ESA’s recovery strategy. While critical habitat is supposed to be designated for each species when it is listed, there are exceptions that are narrowly delineated under the statute. If interpreted too broadly, however, the exceptions can hamstring the effectiveness of critical habitat protection.
What regulatory changes have been made regarding listing, delisting, and critical habitat?
The 2019 regulations made multiple changes which would prevent species from being listed, prevent critical habitat from being designated, and allow for species to be delisted—losing ESA protection—before they are truly recovered. These changes each undermined conservation. The 2024 regulatory changes sought to fix these gaps. Many fixes are great successes, but others only achieve partial success and fall short of meeting the purpose of the ESA.
Listing/Delisting
- Removing economic considerations from listing. Under the ESA, the decision whether to list a species as endangered or threatened is a purely science-based decision that does not involve economic considerations. Yet many industries seek to insert their economic interests into the process. Responding to this interest, the 2019 regulations removed an explicit prohibition against considering factors as part of the listing process. In a conservation win, the 2024 regulations restored that prohibition, realigning the regulations with the statute itself.
Determining how far the “foreseeable future” covers when listing threatened species. The term “foreseeable future” is an important part of ESA implementation because threatened species are defined under the ESA as species likely to become endangered within the foreseeable future. See 16 U.S.C. § 1532(20). The way that the Services define the term “foreseeable future” therefore influences whether a whole suite of species receives ESA protection. Since 2009 the Services have relied on a robust internal policy for determining what the “foreseeable future” is for any given species under review. The 2019 regulations added a regulatory definition under which the Services look only as far as impacts to species are “reasonably determinable” to be “likely.” By using the term “likely,” the 2019 definition appeared to jettison a longstanding practice of using extrapolation and scientifically grounded prediction, based upon available scientific data, to assess foreseeable future threats to species. The 2024 regulations updated this regulatory definition to be better in-line with the existing practice. Under the new definition, the foreseeable future extends as far the Services can “reasonably rely” on the information before it–an approach that allows for predictive modelling rather than waiting to extend protections only when endangered status is imminent and certain.
Critical Habitat
- Designating unoccupied areas as critical habitat. The ESA recognizes that both occupied habitat and unoccupied habitat can be critical for a species recovery. A very imperiled species may only occupy a portion of its historic range, and will need to expand beyond currently occupied areas to fully recover. Moreover, in a time of climate change many species will need to move to new areas (for example, upslope or further north) as ecosystems shift. The 2019 regulations created significant limits on designating unoccupied habitat in a way that contradicts the statute. Specifically, the 2019 regulations required that, before unoccupied critical habitat is designated, the agencies first determine that occupied areas would be inadequate for species conservation. The 2024 regulatory amendments removed this unlawful additional hurdle to establishing unoccupied areas as critical habitat.
- Setting the standard for when designating critical habitat is “not prudent.” The ESA tells the Services to establish critical habitat “to the maximum extent prudent and determinable.” 16 U.S.C. § 1533(a)(3)(A). Determining that a designation is “not prudent” is one of the limited exceptions to critical habitat designation. Originally, the phrase only applied where critical habitat would “not benefit” a species, such as when critical habitat designation might draw illegal collectors to the locale of rare plants or insects. The 2019 regulations removed the “not benefit” standard and replaced it with one that allows for not designating critical habitat where habitat destruction “is not a threat” to a species. This exception threatens to swamp the rule. In a time of climate change, many species may face numerous threats other than habitat destruction—but this makes it even more important that their habitat be protected through the critical habitat designation process. For example, the newly enlarged exception made a big impact in the Service’s choice not to designate critical habitat for the rusty patched bumble bee, whose primary threats come from pesticide use and invasive parasites rather than habitat loss. Critical habitat is still important for these bees, however, as they are better equipped to deal with the pressures of pesticides and invasives if they can inhabit areas that meet all their nutrition and nesting needs. Nonetheless, the 2024 regulations failed to restore the more-protective “not benefit” standard.
- Designating critical habitat for species that live mostly outside the U.S. The 2019 regulations also added—and the 2024 regulations retained—a new set of circumstances under which critical habitat designation can be avoided as “not prudent”: where a species that lives in multiple countries has its secondary habitat in the U.S. This exception threatens to undermine species conservation and recovery by failing to protect habitat that may not be primary, but nonetheless may play an important role in supplementing or connecting other habitat areas. For example, the jaguar lives primarily in Mexico, but uses areas of the Southwest to spread out and hunt. Under the new regulations, that secondary habitat may not be designated as critical habitat and may not receive protection under the ESA.
Author
![Ellen Richmond](/sites/default/files/styles/square/public/2021-05/Ellen%20Richmond.jpeg?h=c240dbc4&itok=M_8y0Nsu)
Ellen Richmond
Areas of Expertise: Litigation, National Environmental Policy Act, Endangered Species Act, FOIA
Ellen Medlin Richmond advocates to protect imperiled species and their habitat across the West
![Daniel Franz headshot](/sites/default/files/styles/square/public/2024-08/2025-725%20-%20Daniel%20Franz%20-%203-%20square%20crop_0.jpg?itok=ERlkr937)
Daniel Franz
Daniel’s litigation and legal advocacy work involves the protection of endangered species and their habitat across the country.
Before joining Defenders, Daniel was an environmental
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