# Endangered and Threatened Wildlife and Plants; Reclassification of the Hawaiian Stilt (Kukuluae'o or Ae'o) From Endangered to Threatened With a Section 4(d) Rule > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/fr%3A2026-14550 ## Record - **Collection:** Federal Register - **Document type:** Rule - **Published:** July 20, 2026 - **Citation:** 91 FR 45480 ## Text DEPARTMENT OF THE INTERIOR Fish and Wildlife Service 50 CFR Part 17 [Docket No. FWS-R1-ES-2020-0079; FXES1113090FEDR-267-FF09E22000] RIN 1018-BE02 Endangered and Threatened Wildlife and Plants; Reclassification of the Hawaiian Stilt (Kukuluae'o or Ae'o) From Endangered to Threatened With a Section 4(d) Rule AGENCY: Fish and Wildlife Service, Interior. ACTION: Final rule. SUMMARY: We, the U.S. Fish and Wildlife Service (Service), are reclassifying the Hawaiian stilt (kukuluae'o or ae'o, Himantopus mexicanus knudseni; a subspecies of the black-necked stilt ( Himantopus mexicanus )) from endangered to threatened (downlist) under the Endangered Species Act of 1973, as amended (Act). This action is based on our evaluation of the best scientific and commercial data available, which indicates that the subspecies' status has improved such that it is not in danger of extinction throughout all or a significant portion of its range, but that it is still likely to become so within the foreseeable future. We also finalize protective regulations under the authority of section 4(d) of the Act that are necessary and advisable to provide for the conservation of the Hawaiian stilt. We recognize the Hawaiian names kukuluae'o and ae'o as additional common names. DATES: This rule is effective August 19, 2026. ADDRESSES: This final rule is available on the internet at https://www.regulations.gov. Comments and materials we received are available for public inspection at https://www.regulations.gov at Docket No. FWS-R1-ES-2020-0079. Availability of supporting materials: Supporting materials we used in preparing this rule, including the 5-year review and the recovery plan, are available at https://www.regulations.gov at Docket No. FWS-R1-ES-2020-0079. FOR FURTHER INFORMATION CONTACT: Direct all questions or requests for additional information to: Aaron Nadig, Deputy Field Supervisor, U.S. Fish and Wildlife Service, Pacific Islands Fish and Wildlife Office; telephone 808-792-9400, aaron_nadig@fws.gov. Individuals in the United States who are deaf, deafblind, hard of hearing, or have a speech disability may dial 711 (TTY, TDD, or TeleBraille) to access telecommunications relay services. Individuals outside the United States should use the relay services offered within their country to make international calls to the point-of-contact in the United States. SUPPLEMENTARY INFORMATION: Executive Summary Why we need to publish a rule. Under the Act, a species warrants reclassification from endangered to threatened if it no longer meets the definition of an endangered species (in danger of extinction throughout all or a significant portion of its range). The Hawaiian stilt is listed as endangered, and we are reclassifying (downlisting) the Hawaiian stilt as threatened. We have determined that the Hawaiian stilt does not meet the Act's definition of an endangered species, but it does meet the definition of a threatened species (likely to become an endangered species throughout all or a significant portion of its range within the foreseeable future). Reclassifying a species as a threatened species can be completed only by issuing a rule through the Administrative Procedure Act rulemaking process (5 U.S.C. 551 et seq. ). What this document does. This rule reclassifies the Hawaiian stilt from endangered to threatened with a rule issued under section 4(d) of the Act, based on the subspecies' current status. Additionally, this rule formally recognizes the Hawaiian names for the Hawaiian stilt as additional common names: “kukuluae'o” or “ae'o” for short. The basis for our action. Under the Act, we may determine that a species is an endangered species or threatened species because of any of five factors: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) overutilization for commercial, recreational, scientific, or educational purposes; (C) disease or predation; (D) the inadequacy of existing regulatory mechanisms; or (E) other natural or manmade factors affecting its continued existence. We may reclassify a species if the best scientific and commercial data available indicate the species no longer meets the applicable definition in the Act. Based on the status review, the current threats analysis, and evaluation of conservation measures discussed in this rule, we conclude that the Hawaiian stilt no longer meets the Act's definition of an endangered species and should be reclassified to a threatened species. The Hawaiian stilt is no longer in danger of extinction throughout all or a significant portion of its range but is likely to become so within the foreseeable future. We have determined that the Hawaiian stilt is a threatened species due to the following threats: predation, overgrowth of nonnative plants, inappropriate water levels ( i.e., too high or too low) that do not support Hawaiian stilt nesting, disease (primarily botulism), urban development, water extraction and diversion, and environmental contaminants. Sea level rise resulting from climate change is an emerging threat and is projected to impact the Hawaiian stilt's population within the foreseeable future. Previous Federal Actions On March 25, 2021, we published a proposed rule to reclassify the Hawaiian stilt from endangered to threatened (86 FR 15855). The proposed rule opened a 60-day public comment period, ending May 24, 2021. During that open comment period, we received a request for a public hearing, and on June 23, 2021, we reopened the public comment period for an additional month and announced a public informational meeting and a public hearing to allow the public an additional opportunity to provide comments (86 FR 32857). We held a virtual public hearing on July 7, 2021. Please refer to the proposed rule to reclassify the Hawaiian stilt (86 FR 15855) for a description of Federal actions related to this subspecies that occurred prior to the proposed rule's publication. Peer Review In accordance with our joint policy with the National Marine Fisheries Service on peer review that published in the Federal Register on July 1, 1994 (59 FR 34270), and our August 22, 2016, memorandum updating and clarifying the role of peer review of listing and recovery actions under the Act ( https://www.fws.gov/sites/default/files/documents/peer-review-policy-directors-memo-2016-08-22.pdf ), we solicited independent scientific review of the scientific data and interpretation contained in our proposed rule. We sent the proposed rule to five independent peer reviewers and received four responses. The peer reviews can be found at https://www.regulations.gov at Docket No. FWS-R1-ES-2020-0079. In preparing this final rule, we incorporated the results of these reviews, as appropriate. A summary of the peer review comments and our responses can be found in the Summary of Comments and Recommendations below. Summary of Changes From the Proposed Rule We made several changes in this final rule in response to public comments we received on the March 25, 2021, proposed rule (86 FR 15855). In incorporating the primary changes resulting from public input, we: • Completed minor editorial changes and reorganized various sections of the rule to increase readability. • Updated the following sections to incorporate the most recent data from peer review publications and species expert comments on the proposed rule: Range, Abundance, and Population Trends; Criterion 3 for Downlisting; Criterion 4 for Downlisting; and Current Voluntary and Regulatory Conservation Efforts. • Updated figures and text to reflect newly received survey data and associated analyses, including updated (with the inclusion of 2016-2023 census data) population trend analyses (Gorresen et al. 2024, entire). • Updated the following discussions under Summary of Biological Status and Threats: Predation, Sea Level Rise, Tropical Cyclone Intensity and Frequency, Ground and Surface Water Alterations Resulting from Urban Development, and Environmental Contaminants to incorporate the most current peer reviewed research and information received through peer review and species expert comments on the proposed rule. • Added kukuluae'o as an official Hawaiian common name for the subspecies, as well as retaining the corrected short form of this name, ae'o, as outlined in the proposed rule. • Changed the foreseeable future timeframe from present-to-2040, to present-to-2080, based primarily on increased confidence in regional sea level rise projections, and on the newly published, updated, and peer-reviewed population viability analysis (PVA) which projects Hawaiian stilt viability through 2080. • Revised table 1 to provide more details (where available) regarding the types of management implemented at each of the core wetlands, the year the core wetland received protection, and details regarding methods of each type of management. • Added an exception for take under the 4(d) rule that was accidentally overlooked in our proposed downlisting rule. This take exception under 50 CFR 17.31(b) allows any employee or agent of the Service, any other Federal land management agency, the National Marine Fisheries Service, a State conservation agency, or a federally recognized Tribe, who is designated by their agency or Tribe for such purposes, when acting in the course of their official duties, to take Hawaiian stilt without a permit if such action is necessary to aid a sick, injured, or orphaned Hawaiian stilt, dispose of a dead Hawaiian stilt, or salvage a dead Hawaiian stilt specimen that may be useful for scientific study. In addition, any employee or agent of the Service, of the National Marine Fisheries Service, or of a State conservation agency that is operating a conservation program pursuant to the terms of an approved cooperative agreement with the Service that covers the Hawaiian stilt in accordance with section 6(c) of the Act, who is designated by their agency for such purposes, may, when acting in the course of their official duties, also take Hawaiian stilt. • Removed proposed take exception (3) of the 4(d) rule that specifically applied to State and local government law enforcement for the take of Hawaiian stilts for the purposes of aiding or euthanizing sick, injured, or orphaned Hawaiian stilts, because any person who finds a sick, injured, or orphaned endangered migratory bird may, without a permit, take and possess the bird in order to immediately transport it to a permitted rehabilitator, according to 50 CFR 17.21(c)(7). • Made minor edits to the final 4(d) regulatory text for clarity, which did not result in any changes to its substance or intent. The information we received during the comment period for the proposed rule did not change our previous analysis of the magnitude or severity of threats facing the subspecies or our determination that the Hawaiian stilt is no longer an endangered species but meets the Act's definition of a threatened species. Summary of Comments and Recommendations In the proposed rule published on March 25, 2021 (86 FR 15855), we requested that all interested parties submit written comments on the proposal by May 24, 2021. We also contacted appropriate Federal and State agencies, scientific experts and organizations, and other interested parties and invited them to comment on the proposal. Newspaper notices inviting general public comment were published in the Honolulu Star Advertiser. We received a request for a public hearing, held a virtual public hearing on July 7, 2021, and reopened the public comment period from June 23, 2021, to July 23, 2021 (86 FR 32857). We reviewed all comments provided during the comment periods and the public hearing to identify substantive information. All substantive information has either been incorporated directly into this final determination or is addressed below. Peer Reviewer Comments As discussed in Peer Review above, we received comments on the proposed rule (86 FR 15855, March 25, 2021) from four peer reviewers. We reviewed all comments we received from the peer reviewers for substantive issues and new information. Peer reviewer comments are addressed in the following summary and were incorporated into this final rule as appropriate. The changes we made as a result of peer review consisted of adding new peer-reviewed data published since the proposed rule regarding reproductive success, management efficacy, and threats (predation and sea level rise); clarifications and corrections, including typographical edits; revising descriptions of our analysis; and expanding some risk information related to predation, sea level rise, tropical cyclone intensity and frequency. The reviewers' comments did not result in changes to our resiliency analysis or conclusions. (1) Comment: All four peer reviewers reiterated that the Hawaiian stilt is mangement dependent in that it relies on human intervention to mitigate threats (particularly predation by nonnative mammals, birds, and reptiles; overgrowth of nonnative plants; inappropriate water levels; avian botulism; and sea level rise). Our Response: We agree that management is essential for long-term viability of the Hawaiian stilt. Our goal is to work with partners to maintain our current adaptive management efforts while simultaneously increasing our understanding and application of effective management tools, particularly in response to sea level rise. (2) Comment: Two peer reviewers commented that the reclassification of the Hawaiian stilt may be premature and could result in decreased public interest, protection, and conservation efforts for the subspecies, ultimately resulting in an increase in threats and subsequently a decline in population viability. Our Response: We are aware of the perception that conservation benefits afforded to the Hawaiian stilt would be reduced as a result of this final reclassification to threatened with an associated 4(d) rule. However, the determination to downlist a species from endangered to threatened status must be based solely on the best scientific and commercial data, which for the Hawaiian stilt indicates that the subspecies is not currently in danger of extinction (endangered) but is likely to become endangered within the foreseeable future (threatened). In addition, the combined purpose of these rules is to provide the Hawaiian stilt continued protections, while also facilitating conservation of Hawaiian stilt and furthering its recovery by giving our conservation partners management flexibility to more efficiently implement predator control and habitat management intended to benefit the subspecies via the 4(d) rule. Upon the effective date of this final reclassification and associated 4(d) rule, Hawaiian stilts will still receive protection under the Act. Section 4(d) rules do not change the consultation requirements under section 7 of the Act. Section 7(a)(2) of the Act requires Federal agencies, including the Service, to ensure that any action they authorize, fund, or carry out is not likely to jeopardize the continued existence of any endangered species or threatened species or result in the destruction or adverse modification of designated critical habitat of such species. These requirements are the same for a threatened species regardless of what is included in its 4(d) rule. Although this final 4(d) rule allows for select exceptions to prohibitions, as outlined under Protective Regulations Under Section 4(d) of the Act, this rule only addresses requirements under the Act, and does not change the Hawaii Endangered Species Law. Current State of Hawaii law (Hawaii Revised Statutes (HRS) section 195D-4) requires the issuance of a temporary license for the take of endangered and threatened animal species, if the activity otherwise prohibited is for scientific or conservation purposes or incidental to an otherwise lawful activity. As a result, upon the effective date of this final 4(d) rule, certain activities excepted under the Act remain subject to State law prohibitions and so State authorization will continue to be required. Please see Final Rule Issued Under Section 4(d) of the Act for more details on State law and associated requirements ( e.g., license, permit, Safe Harbor Agreement, Habitat Conservation Plan). (3) Comment: Two peer reviewers commented that downlisting the Hawaiian stilt may be premature as the subspecies will require an increase in conservation planning and actions to mitigate for habitat loss and degradation resulting from sea level rise. Both peer reviewers cited a recent scientific paper (Harmon et al. 2021a, entire) published since publication of the proposed rule that indicates that a 3.3 feet (ft) (1 meter (m)) rise in sea level by 2100 will result in a 27 percent (4,564 acre (ac) (1,847 hectare (ha))) loss of potential waterbird nesting habitat due to marine inundation, and a 2 percent (336 ac (136 ha)) loss of potential nesting habitat due to groundwater inundation, for a total of 29 percent loss of potential waterbird nesting habitat across the Hawaiian Islands. Further, all core wetlands on Kauai, Oahu, Maui Nui, and Hawaii outlined in the recovery plan are projected to be fully or partially inundated due to sea level rise by 2100 (Harmon et al. 2021a, entire). Our Response: We have revised our discussion on sea level rise under Summary of Biological Status and Threats to reflect recently published reports ( e.g., Harmon et al. 2021a, entire; Intergovernmental Panel on Climate Change (IPCC) 2022, entire; National Oceanic and Atmospheric Administration (NOAA) 2022, entire). The Hawaiian stilt demonstrates plasticity with a high tolerance to salinity, a broad range of foraging habitat, relatively substantial movement between islands, a current population range that includes all of the main Hawaiian Islands (except Kahoolawe), and a relatively stable population since 2005. Further, we do not expect the estimated current vital rates reported in the updated PVA to change considerably within the foreseeable future (present through 2080). Therefore, we conclude that with ongoing management in collaboration with Federal and State partners, and some private partners, the Hawaiian stilt is not currently at risk of extinction but is at risk of extinction within the foreseeable future due to ongoing threats and future threats associated with sea level rise. (4) Comment: One peer reviewer commented that a full assessment of the risks of climate change has not been carried out for the Hawaiian stilt; in particular, the likely effects of salinification in wetlands due to climate change is a risk factor that was not assessed in the downlisting proposal. Our Response: In this final rule, we revised our discussions on Sea Level Rise and Tropical Cyclone Intensity and Frequency under Summary of Biological Status and Threats to incorporate recently published scientific findings relevant to the Hawaiian stilt and its habitat from climate change, and to provide additional information requested by peer reviewers. Regarding salinification, Hawaiian stilts use a wide range of water salinity ranging from 0 to 200 parts per thousand (ppt) ( e.g., Hono'uli'uli Unit at Pearl Harbor National Wildlife Refuge (NWR)) (Coleman 1981, p. 48; Reed et al. 2011a, p. 4; Nadig 2017, pers. comm.). Because of its tolerance for a wide range of salinities, salinification of wetlands due to sea level rise is unlikely to occur to such a great extent and at such a rapid rate in the near-term future to put Hawaiian stilt populations at risk. Therefore, while the impact of salinification on Hawaiian stilt viability in the longer-term future is more difficult to project, we do not anticipate salinity to be a substantial factor influencing the near-term extinction risk for the Hawaiian stilt. (5) Comment: One peer reviewer commented that our discussion on tropical cyclone intensity and frequency in the proposed rule did not provide any information about the effects of hurricanes on the stilt population size, even though population data exist. The reviewer notes that whether there is an effect on stilt numbers is ultimately what matters and, thus, is more important than any habitat effects. Our Response: We revised Tropical Cyclone Intensity and Frequency under Summary of Biological Status and Threats to incorporate a more thorough discussion on the history of hurricanes and tropical storms in Hawaii and the Hawaiian stilt population index values following hurricane and tropical storm events since 1986 (the year the Hawaii Department of Land and Natural Resources, Division of Forestry and Wildlife (DOFAW) Annual Waterbird Survey became standardized). (6) Comment: Two peer reviewers commented that recovery criterion 1, which states that all core wetlands be protected and managed for threats to the subspecies, has not been met and recommended that the Service postpone the reclassification of the Hawaiian stilt until this criterion has been fully met. One of these peer reviewers cited the lack of protection and management of core wetlands in accordance with management practices outlined in the recovery plan. Examples given included all wetlands on Niihau (lack of protection and management), Kakahai'a NWR on Molokai (lack of management), and Kawai'ele Waterbird Sanctuary on Kauai (not all recovery plan management practices being implemented). Further, both peer reviewers cited new data that show all core wetlands on Kauai, Oahu, Maui Nui, and Hawaii outlined in the recovery plan are projected to be fully or partially inundated due to sea level rise by 2100 (Harmon et al. 2021a, entire). Our Response: Recovery plans provide roadmaps to species recovery but are not required in order to achieve recovery of a species or to evaluate it for delisting. In addition, recovery plans are also nonbinding documents that rely on voluntary participation from landowners, land managers, and other recovery partners. A determination of whether a valid, extant species should be delisted is made solely on the question of whether it meets the Act's definitions of an “endangered species” or a “threatened species.” We have determined that Hawaiian stilt meets the definition of a threatened species. (7) Comment: Two peer reviewers commented that we should provide more details regarding the progress cited for recovery criterion 1 (all core wetlands are protected and managed). One of these peer reviewers specifically requested that the Service include more information regarding the methods used for predator control and habitat management activities at each of the core wetlands, as well as provide an overview of the data on efficacy of each method and the year such actions were initiated at each of the core wetlands. Our Response: We have updated table 1 to distinguish between vegetation control and water level control management at each of the core wetlands. We do not have a comprehensive dataset on all predator control methods and habitat management methods implemented in all managed core wetlands, nor do we have the temporal data for the year that individual methods were initiated or their subsequent frequency of implementation across core wetlands. In summary, predator control is most effective if implemented during the nesting season, and the control of rats, cats, and mongooses has increased nest success at multiple sites (Underwood et al. 2013, entire; Underwood et al. 2014, entire). Kauai and Oahu support the largest amount of wetland habitat and receive the most wetland management, followed by Maui, Molokai, and Hawaii, respectively. We are unaware of predator control and habitat management activities on Niihau. Wetland management addresses three key threats (predator control, overgrowth of vegetation, and water levels), as well as botulism outbreaks when they arise. However, not all of these actions are implemented at all of the core wetlands that receive management, nor are they implemented all of the time. The recovery plan outlines the total area of core wetlands on each island as well as the total area of managed core wetlands. Although we did not have available all the information required to conduct an analysis as suggested, Hawaiian stilts are resilient and rebound after a stochastic disturbance (Reed et al. 1998a, p. 43). For example, Keālia NWR is one of the most important core wetlands for Hawaiian stilt nesting habitat. Since management efforts to eliminate nonnative feral pigs and axis deer, both of which began heavily degrading nesting habitat and threatening eggs during the nesting season, were initiated in 2018, Keālia has supported a large number of Hawaiian stilts. This example demonstrates how Hawaiian stilts are highly plastic and respond positively to management. Lastly, Hawaiian stilts are believed to have reached a population equilibrium with respect to the available area of nesting habitat (van Rees et al. 2020, p. 217; Paxton et al. 2021, p. 434). As such, in order to increase the population size, we must first increase the available area of protected and managed nesting habitat, which we intend to facilitate with this downlisting's accompanying 4(d) rule that allows for increased flexibility for management strategies that benefit Hawaiian stilts. (8) Comment: Two peer reviewers commented that recovery criterion 2, which states that at least 50 percent of supporting wetlands should be protected and managed in accordance with management practices outlined in the recovery plan, has not been met, and that 11 supporting wetlands are projected to be fully or partially inundated by sea level rise (Harmon et al. 2021a, entire). Our Response: We acknowledge that criterion 2 from the recovery plan has not yet been achieved. Recovery plans provide guidelines for possible pathways toward recovery, but meeting recovery criteria and accomplishing recovery actions are not required in order to achieve recovery of a species, or to evaluate it for downlisting or delisting. While supporting wetlands are important because they provide habitat for smaller Hawaiian stilt populations, or are seasonally important, the Hawaiian stilt has demonstrated flexibility regarding requirements for foraging habitat (Kawasaki et al. 2020, entire), moves freely between islands, and has maintained a stable population under ongoing management of core wetlands (Paxton et al. 2021, p. 432; DOFAW 2022, unpaginated). Despite the protection and management goals defined in criterion 2 being only partially achieved, landowners are increasingly engaging in conservation (Goodale 2021, pers. comm.), and we are constantly seeking new conservation partnerships with private and government (State and Federal) landowners and offer several competitive funding sources for such landowners to carry out beneficial management actions for both core and supporting wetlands. We and our conservation partners are actively working toward solutions to maintain and expand Hawaiian stilt nesting habitat in the face of sea level rise, as well as the other threats outlined in this final rule (see Current Voluntary and Regulatory Conservation Efforts ). Further, we are aware that 29 percent of potential waterbird nesting habitat may be partially or fully inundated by marine and groundwater inundation by 2100 (Harmon et al. 2021a, entire). While sea level rise may cause some wetlands to expand, and new wetlands may be formed as a result of marine and groundwater inundation, urban development and uncertainty regarding landowner interest and willingness to implement management for waterbirds in areas into which wetlands may migrate may obstruct the management of newly formed wetland areas. However, because the greatest impacts to the Hawaiian stilt associated with sea level rise are a decade or more away, we do not consider them immediate threats to the subspecies. We therefore conclude that reclassification of the Hawaiian stilt from endangered (at risk of extinction) to threatened status (at risk of becoming endangered within the foreseeable future) is warranted, and accounts for the future impacts of sea level rise to habitat. (9) Comment: Two peer reviewers commented that the PVA does not adequately demonstrate that the Hawaiian stilt population has achieved long-term viability, and that the subspecies has not met the population threshold for reclassification that was identified in the recovery plan. Our Response: The PVA included a sensitivity analysis to the vital rates used in the PVA. The sensitivity analysis showed that the most important predictors of extinction were adult mortality, juvenile mortality, percent of adult females breeding, and nest failure. These analyses showed rapid change in the probability of extinction if these parameters changed even a small amount. The PVA is an optimistic best-case scenario, and we focused on the qualitative nature of the results (meaning the relative proximity of differential vital rates to thresholds of population decline or extinction) (van Rees and Reed 2021, in litt.). This highlights a somewhat fragile aspect of the Hawaiian stilt's long-term viability. While we recognize this fragility and the conservation reliance of the Hawaiian stilt and the nature of future threats associated with sea level rise and climate change, the population has remained relatively stable since approximately 2005 (after increasing previously) and is unlikely to change in the immediate future as current management continues. Because of the threats we have outlined in this final rule, we conclude that the Hawaiian stilt meets the definition of a threatened species and not that of an endangered species. Long-term Hawaiian stilt viability will require continued management, which will include the implementation of management techniques to address future threats associated with sea level rise. Further, the PVA found that the Hawaiian stilt has reached a population equilibrium constrained by available managed wetland habitat across the main Hawaiian Islands and that, in order for the Hawaiian stilt population to increase and sustain a population of 2,000 birds or greater, we must increase the amount of managed wetland habitat for the Hawaiian stilt. Both the Service and DOFAW are actively working to expand management in core wetland habitat across the main Hawaiian Islands ( e.g., James Campbell NWR and Mānā Plains Wildlife Sanctuary). (10) Comment: Two peer reviewers commented that the preliminary results from the PVA cited in the proposed rule concluded that the Hawaiian stilt population is currently not at risk of extinction, and that to be at risk of extinction, mortality rates would have to be at or above 20 percent for adults and 40 percent for juveniles, and nest failure rates would have to be at or above 50 percent. They disagree that the Hawaiian stilt is not at risk of extinction, pointing out that the probability of extinction reaches 1 (100 percent likelihood of extinction) when these rates reach or exceed 34 percent, 79 percent, and 75 percent, respectively. Our Response: The PVA quantified Hawaiian stilt viability by employing Hawaiian stilt vital rates from managed wetlands (van Rees et al. 2022, p. 11) and concluded that Hawaiian stilt viability is sensitive to changes in estimated vital rates, meaning that changes in these vital rates could increase the model's outcomes on probability of extinction by 2100 (van Rees et al. 2022, p. 9). We acknowledge that several of the key vital rates (as derived from best-case-scenario estimates on managed populations) are close to levels that could result in simulated extinction (van Rees and Reed 2021, in litt.), and that vital rates can vary widely among nesting sites and nesting years. However, most successful breeding attempts occur in managed wetlands, and the PVA indicates that the likelihood of extinction is very low for the Hawaiian stilt based on vital rates from managed wetlands. Managed wetland habitat has enabled the Hawaiian stilt population to remain relatively stable since 2005, and we do not expect a significant change in the estimated current vital rates in the near future given ongoing management. However, we recognize that current vital rates could change in the foreseeable future in response to the threats affecting the subspecies, but the subspecies' threatened status accounts for potentially reduced viability in the foreseeable future. (11) Comment: One peer reviewer commented that the initial (Reed et al. 1998a, entire) and 2019 (Reed and van Rees 2019, entire) PVAs used a juvenile mortality rate that was a 2-year mean of juvenile mortality measured from the point at which chicks were banded to the point at which they reached 2 years of age (which is a time period with comparatively higher survival than the period prior to banding). The reviewer therefore states that the juvenile mortality input values included in the PVA do not account for mortality that occurs before the chicks are large enough to band (which is a time period during which chicks appear to experience very high mortality). Our Response: Hawaiian stilt, like many other avian species, experience high mortality prior to reaching banding age (approximately 10 days old for Hawaiian stilt) (Goodale 2021, pers. comm.). However, mortality prior to banding age was built into the van Rees et al. (2022) updated PVA model, which starts with brood size data in the stochastic reproductive modeling step rather than with clutch size. Thus, the loss of eggs due to hatching failures and loss of chicks prior to banding age are implicit in the model (van Rees and Reed 2021, in litt.). We also note that despite high rates of chick mortality in the first 10 days of life, the Hawaiian stilt has maintained a relatively stable population since 2005. (12) Comment: Two peer reviewers commented that stochastic events, such as botulism outbreaks or hurricanes, were not built into the PVA. The reviewer stated that botulism is an ongoing source of adult mortality in Hawaiian stilt, though it is highly variable among sites. Our Response: According to the authors of the PVA, catastrophic events, such as disease outbreaks or hurricanes, are unlikely to be as influential as sea level rise (van Rees and Reed 2018, entire; Reed and van Rees 2019, entire) on the Hawaiian stilt's viability. While botulism and hurricanes occur in Hawaii and may result in loss of individual birds, particularly chicks, data suggest that neither of these have a catastrophic effect on the Hawaiian stilt population (van Rees et al. 2022, p. 10; Uyehara 2018, in litt.). The PVA model is stochastic, individual-based, and has environmental stochasticity explicitly built into its simulations (van Rees and Reed 2021, in litt.; van Rees et al. 2022, p. 4). However, quantitative outputs of the study warrant caution and should be taken only as a best-case scenario, and reduced management actions would result in less favorable vital rates and therefore a greater extinction risk (van Rees and Reed 2021, in litt.). The sensitivity analysis in the updated PVA shows that a small change in vital rates would increase the probability of extinction. However, with ongoing management, and substantial impacts associated with sea level rise still a decade or more away, we conclude that such a change in vital rates is not likely to occur in the near future, as the subspecies has maintained a relatively stable population since 2005 under current management. (13) Comment: Two peer reviewers commented that recovery criterion 4 has not been met and that reclassification should not occur until the subspecies has multiple self-sustaining breeding populations on the island group of Kauai and Niihau; the island of Oahu; the island group of Maui, Molokai, and Lanai; and the island of Hawaii. The reviewers state that the population of the Hawaiian stilt is not self-sustaining or thriving and that the lack of change in overall reproductive success over time, the stabilization of the population at roughly between 1,600 and 2,000 individuals over the last 15 years, and the results of the 2019 updated PVA all suggest that the population may be limited by habitat availability and limitations to reproductive output as a result of predation. Our Response: The recovery plan defines a self-sustaining breeding population as a population that is large enough to make extirpation from stochastic forces unlikely and that is able to remain stable or grow with little human intervention except for predator control and vegetation management (Service 2011, p. 121). There are relatively larger, self-sustaining (albeit conservation-reliant) breeding populations of Hawaiian stilt on Kauai, Oahu, and Maui, with smaller, self-sustaining populations on the islands of Lanai, Molokai, and Hawaii (see Range, Abundance, and Population Trends ). In addition, the broad distribution of Hawaiian stilts across multiple islands provides the subspecies with the resiliency and redundancy necessary to withstand stochastic ( e.g., single wetland) or catastrophic ( e.g., islandwide) events, respectively, which was the overall intent of criterion 4 of the recovery plan. The Hawaiian stilt population has remained relatively stable since 2005 under current management, with population growth primarily limited by available managed wetland habitat. The Hawaiian stilt is density-independent below a population threshold of approximately 900 to 1,000 birds but reaches a State-wide equilibrium population below the recommended target of 2,000 birds listed in the recovery plan. Therefore, in order to increase the Hawaiian stilt population size, we must increase management within managed wetlands and initiate management at currently unmanaged wetlands. (14) Comment: Two peer reviewers commented that new preliminary research indicates that even with improvement in predator control and vegetation management techniques since the 1970s, overall reproductive success has not changed over time on Oahu (Idle 2023, p. 16). One reviewer also stated that this fact, when coupled with the stabilization of the adult population reported by the DOFAW annual counts, indicates that reproductive success may be a limiting factor toward population growth. Our Response: We agree that reproductive success may be a limiting factor toward population growth. Recent data indicate that the Hawaiian stilt has reached a population equilibrium with the current amount of available managed wetlands (Reed and van Rees 2019, entire; van Rees et al. 2020, p. 217; van Rees et al. 2022, p. 11; Paxton et al. 2021, p. 434). Hawaiian stilts are territorial during their nesting season and, as a result, the population becomes density-dependent as it exceeds approximately 1,000 birds, and reaches a population equilibrium under 2,000 birds, within the currently available managed habitat. As such, if reproductive success were to improve by means of nest success, chick survival, or recruitment (or any combination thereof), the Hawaiian stilt population would still face limited nesting habitat and may not increase in size until the amount of managed nesting habitat is expanded. The 4(d) rule component of this final rule is intended to make implementing predator control and habitat management for the Hawaiian stilt more streamlined for our conservation partners, so that together we can continue to improve the status of the Hawaiian stilt and further its recovery. (15) Comment: One peer reviewer commented that the winter counts in the DOFAW Waterbird Population Index Database in 2018 and 2019 have fallen below 1,500 Hawaiian stilts and that most recent data show a consistent downward trend in numbers, which should be grounds to delay the downlisting of this subspecies until the downward trend is shown to have reversed for several years. Our Response: An early release of data from DOFAW's Annual Waterbird Survey data for the 2018 and 2019 surveys was missing important count data from several NWRs due to government shutdowns in January 2018 and January 2019. The survey data have since been updated and are provided in figure 1. Depending on the winter or summer survey, the raw count data for these years are either right around or below 1,500 individuals. However, we do not yet have the state-space modeling results available for the raw count data, which is therefore not corrected for imperfect detectability. As such, these raw data represent a minimum population count. The recent model represents the best available information regarding the Hawaiian stilt population size and supports our conclusion that the Hawaiian stilt population is currently just under 2,000 individuals (Paxton et al. 2021, p. 434). (16) Comment: One reviewer commented that based on annual waterbird counts, the updated PVA, and the protection status of core and supporting wetlands in Hawaii, the conditions for the Hawaiian stilt population are the same as when the 2011 recovery plan was created ( i.e., the population is in the same state as it was in 2011). The reviewer claims that the criteria established within the 2011 recovery plan are still relevant and warrant actions to meet those criteria in order to recover this population, and that none of the 2011 recovery plan criteria have been met completely. Our Response: Part of our rationale for downlisting the Hawaiian stilt is the observed stability of the population since 2005 (figure 1). In 2011 when the recovery plan was finalized, long-term stability of the population had not yet been confirmed. Further, since 2011, a PVA (van Rees et al. 2022; van Rees and Reed 2021, in litt.) and other analyses described in this rule, such as those related to carrying capacity (van Rees et al. 2020, entire), have further refined our understanding of Hawaiian stilt recovery needs. The Hawaiian stilt appears to have reached a population equilibrium under current available managed habitat conditions, and we and our partners are actively working to restore wetland habitat to expand the population and further the recovery of the subspecies (see Current Voluntary and Regulatory Conservation Efforts ). (17) Comment: Two peer reviewers commented that the number of feral cats on the landscape has increased. They further state that weak laws and/or lack of enforcement allow for the feeding of feral cat colonies, often near core and supporting wetlands, and that many endangered waterbirds are lost to predation by feral cats annually. They state that at the Hanalei NWR, in a 4-year period from 2014 to 2018, over 250 native waterbirds were killed by feral cats. They state that if not mediated, feral cats will continue to have a direct and negative impact on stilt populations. Our Response: We agree that feral cats will continue to have direct and negative impacts on Hawaiian stilts in wetlands lacking mammalian predator-proof exclosures. The Service and DOFAW are actively working to address predation of the Hawaiian stilt. For example, mammalian predator-proof fences at the Hono'uli'uli Unit of Pearl Harbor NWR, the Ki'i Unit of James Campbell NWR, the Kanahā Wildlife Sanctuary (Maui), and Pouhala Marsh (Oahu) will help reduce predation on Hawaiian stilts from feral cats and other mammals. In addition, the threat to the subspecies from predation was factored into our status determination. (18) Comment: One peer reviewer commented that the cumulative threats to the Hawaiian stilt should be included in the decision-making process. Our Response: We agree with the commenter and have considered in our status determination the cumulative nature of the threats to the Hawaiian stilt, as discussed under Cumulative Effects. State Agency Comments (19) Comment: The Office of Hawaiian Affairs (OHA) stated that the proposed downlisting does not include an assessment of the impacts of climate-associated environmental changes such as sea level rise, reduced rainfall trends, and more frequent extreme weather events on the Hawaiian stilt or its habitat, or recent management challenges such as the adoption and promotion of trap-neuter-release as the sole means of feral cat control despite the threat to Hawaiian stilt from feral cat predation. Our Response: We recognize that there will be management challenges to maintain safe nesting habitat to support a viable Hawaiian stilt population in light of sea level rise and that ongoing and future threats, such as an increase in hurricane frequency and intensity, compound the threats to the Hawaiian stilt. The Service is actively working with multiple partners to identify the best conservation decisions to help native habitats and species adapt to these threats and to manage predation, including that from feral cats. We have incorporated new scientific data acquired since the publication of the proposed rule into this final rule related to threats to the Hawaiian stilt and its habitat, including an updated analysis on sea level rise and other effects of climate change (see Summary of Biological Status and Threats). (20) Comment: The OHA shared that the Hawaiian stilt has a unique cultural significance to Native Hawaiians (OHA 2021, in litt.) and suggested that the Service consider its historical and cultural significance in our decision-making process and consult and collaborate with Native Hawaiian and local communities with regard to the proposed 4(d) rule. They also stated that restoring Hawaiian wetland agro-systems (lo'i) could help compensate for projected losses of wetland habitat due to sea level rise and potentially aid in the recovery of the Hawaiian stilt. They requested that we include an exception in the final 4(d) rule for take related to Native Hawaiian resource management techniques. Our Response: The Service appreciates the cultural significance of the Hawaiian stilt and values Native Hawaiian resource management techniques, and it is our goal to include demonstrated traditional ecological knowledge in our decision-making processes. We met with several Hawaiian traditional agroecology practitioners who view the presence of Hawaiian stilts in their farms as a symbol of ecosystem health, and these practitioners shared no interest in such a take exception out of concern for the stilt. (21) Comment: OHA suggested that the Service consider recognizing the Hawaiian stilt by its full name in the Hawaiian language, the kukuluae'o, as opposed to the shortened version of this word, ae'o. Our Response: While the name “ae'o” has been used consistently in most of our past documents, as well as in State and other partner documents regarding this subspecies, we note that both “ae'o” and “kukuluae'o” are found in the Hawaiian Dictionary (Pukui and Elbert 1986, pp. 4, 178) as Hawaiian names for the bird. To avoid any confusion that may arise from changing the widely recognized Hawaiian name (ae'o) for the bird, including its use in the recovery plans for the subspecies, upon the finalization of this rule, both “kukuluae'o” and “ae'o” will be entered as the official Hawaiian names for the subspecies on the Federal List of Endangered and Threatened Wildlife (50 CFR 17.11). (22) Comment: The DOFAW commented that recovery criterion 3 states that an updated PVA should be conducted to demonstrate a stable or increasing population of Hawaiian stilts above 2,000 birds. They stated that the proposed rule references an unpublished updated PVA, but that they did not have an opportunity to review it and therefore could not comment on the population stability or extinction risk of the Hawaiian stilt based on the current analysis. Additionally, they commented that the Service has not yet defined the population size deemed necessary for long-term survival of the subspecies and that although State-wide trends over the past 31 years show an increasing population trend, the data are not sufficiently robust to define a trend for the past 11 years with any confidence (Paxton et al. 2021, entire). They also stated that while populations on Kauai and Molokai (representing 30 percent of the population) are increasing, the population trend of the other 70 percent of the population occurring on other islands is either unknown or decreasing. They stated that although State-wide populations appear to be close to 2,000 individuals, the apparent downward trends on some islands, including Oahu, are concerning. Our Response: With respect to earlier access to the updated PVA, all references cited in the proposed rule, including the 2019 PVA, are posted to https://www.regulations.gov under the docket number provided in the proposed rule (FWS-R1-ES-2020-0079). With regard to a minimum viable population (MVP) size and analysis of short-term and long-term population trends for the Hawaiian stilt, please see revised discussions under Criterion 3 for Downlisting, Criterion 4 for Downlisting, and Range, Abundance, and Population Trends. While the 2019 PVA did not explicitly state an MVP, 1,000 individuals is the recommended MVP size perceived to be adequate to allow for retaining evolutionary potential for fitness in perpetuity (Frankham et al. 2014, entire), and we have concluded that it is reasonable to apply this MVP for the Hawaiian stilt. Further, the updated PVA (van Rees et al. 2022, entire) determined that the carrying capacity for the Hawaiian stilt is likely closer to 1,500 individuals, and that the 2,000-individual recovery target is likely unattainable given current habitat availability (van Rees et al. 2022, table 2, p. 11). While population trends have generally been increasing over time, they appear to have plateaued, indicating that the Hawaiian stilt may have reached its carrying capacity in existing wetlands. Further, the suggestion that the Hawaiian stilt population may have reached population equilibrium is in alignment with the recent density dependent analysis (van Rees et al. 2020, entire). We acknowledge that the short-term population trend is slightly declining, but the long-term trend is still increasing. Though short-term trends have fluctuated, the population has remained relatively stable since approximately 2005 (Gorresen et al. 2024, table 3, figure 4). (23) Comment: The Hawaii DOFAW commented that populations of the Hawaiian stilt may have reached the carrying capacity of existing available and adequately managed habitat, and therefore, additional acres of habitat in protected wetlands will need to be restored and managed to increase Hawaiian stilt populations and achieve long-term recovery. Our Response: We agree that there is more conservation work to do to advance recovery of the subspecies. This final reclassification and the associated 4(d) rule are expected to provide our conservation partners increased flexibility to implement predator control and habitat management aimed at furthering the recovery of the Hawaiian stilt. Public Comments (24) Comment: Multiple commenters stated that our sea level rise analysis in the proposed rule was incomplete, that sea level rise is a substantial threat, and that anticipated habitat loss should warrant keeping the subspecies listed as endangered versus threatened. Several commenters stated that an increase in the frequency and intensity of hurricanes and tropical depressions will threaten the viability of the Hawaiian stilt and that there will be more breaches that inundate Hawaiian stilt habitat. They stated that Hawaiian waterbird habitat is limited, questioned whether there would be space for new wetlands to form through natural or human-induced processes (Harmon et al. 2021a, entire), and asked whether or not there are plans in place to acquire suitable lands to mitigate this loss. Our Response: A thorough analysis of wetland loss and gain across the main Hawaiian Islands resulting from sea level rise has not been conducted. However, we updated our discussion under Sea Level Rise to include the most recent findings and our interpretation of how this threat will impact Hawaiian stilt viability. Climate data predict an increase in intensity and frequency of hurricanes (tropical cyclones) and tropical storms that will result in high surf that breaches sand berms around the lower elevation wetlands within the foreseeable future. To date, while hurricanes and tropical storms can result in nest failure and chick mortality, we are unaware of data that show that hurricanes or tropical storms currently influence the population trend for the Hawaiian stilt. Please see Sea Level Rise for more information, and for mitigation efforts in response to sea level rise, please see Current Voluntary and Regulatory Conservation Efforts. While we acknowledge that sea level rise may result in decreased viability for the Hawaiian stilt in the foreseeable future, sea level rise is not currently a threat to the viability of the subspecies. Therefore, we determined in this final rule that there will likely be negative impacts to Hawaiian stilt viability due to sea level rise impacts in the foreseeable future, which supports our determination that the Hawaiian stilt is threatened (likely to become endangered within the foreseeable future) rather than endangered (at risk of extinction). (25) Comment: Several commenters noted the shortcomings of the DOFAW Annual Waterbird Survey. They noted several problems with the count data, specifically that the data is not a true census but instead representative of population trends, and that the quality of the count data and how it affects the sensitivity of the PVA models should be considered. Another commenter stated that the DOFAW Annual Waterbird Survey lacks the level of accuracy needed to downlist the subspecies. Commenters cited Camp et al. (2014, entire) and stated that there are other methods that are used for seabird and shorebird counts that balance statistical precision with limitations in available survey effort. Our Response: We agree that the DOFAW Annual Waterbird Survey is valuable as an index of the population trend but should not be considered a true estimate of population size. We discuss this, as well as the value of a new model (Paxton et al. 2021, entire) that accounts for error and bias associated with count data (Camp et al. 2014, entire) to develop a more accurate estimate, under Range, Abundance, and Population Trends. Despite its limitations, the survey data, especially when coupled with a modeling approach that compensates for some of its inadequacies, represents the most useful and best scientific and commercial data available at this time for determining approximate minimum population size and general short-term and long-term population trends, and indicates that the Hawaiian stilt population is stable at just under 2,000 individuals. (26) Comment: One commenter stated that in the section of the proposed rule titled Range, Abundance, and Population Trends, we describe population trends but do not describe trends in reproductive success. They state that reproductive success is an indicator of the health of the population and that it should be considered in our decision to downlist the Hawaiian stilt. Our response: The updated PVA included reproductive data collected primarily in protected and managed core wetlands and can be found in the cited publications (Reed et al. 1998a, entire; Reed and van Rees 2019, entire; van Rees et al. 2022, entire). Additionally, we have incorporated recent research and information (Christensen et al. 2021, entire; Goodale 2021, pers. comm.; Harmon et al. 2021b, entire; Idle 2023, entire) into our discussions regarding Hawaiian stilt reproductive success under Predation and throughout the document as appropriate. (27) Comment: One commenter stated that Hawaiian stilt reproduction had been monitored at Keālia Pond NWR from at least 1995 to 2013 and that nesting attempts at this site have been declining since 2008. Our Response: We have reports regarding Hawaiian stilt reproduction at Keālia Pond NWR through 2014, and these data were included in our analyses, as well as the updated 2019 PVA. The PVA incorporated numerous Refuge reports, as well as all other available sources on reproductive data for the Hawaiian stilt ( e.g., Pittman-Robertson reports) (Reed et al. 1998b, entire; Reed and van Rees 2019, entire; van Rees et al. 2022, entire). (28) Comment: Two commenters stated that additional details about the type and intensity of management occurring at each managed wetland ( e.g., staffing levels at refuges, acreages within each wetland being managed with each management type) should be added to the rule and that management is not consistent across the entirety of each, or among the various, managed wetland site(s). Our Response: Not all of the information that the commenters requested is currently available. However, we updated table 1 with available data regarding management type and methods. Further, we are aware that not all managed wetlands are managed for all Hawaiian stilt threats with the same intensity at all times. However, as this variation in management efforts has existed in the past and will likely continue to exist into the foreseeable future, it does not change our assessment regarding the status of the Hawaiian stilt as threatened or endangered under the Act. (29) Comment: A commenter perceived there were errors in the 2019 PVA (Reed and van Rees 2019, entire) related to details provided by the authors about Hawaiian stilts at Keālia Pond NWR, such as locations of nesting sites, and a large chick mortality event that the commenter claims did not occur at Keālia Pond NWR. Our Response: The updated PVA (van Rees et al. 2022, entire) has now been peer reviewed and published and is referred to in this final rule as such. The PVA represents some of the best scientific and commercial data available regarding Hawaiian stilt population viability. However, we do not base our decision to reclassify the Hawaiian stilt from endangered to threatened solely on the PVA. We also base our decision on the DOFAW Annual Waterbird Survey, the recent modeling by Paxton et al. (2021, entire), and our confidence in continued management of core wetland habitat. Further, we investigated the chick mortality error that the commenter referenced and found that the 50 dead Hawaiian stilt chicks were documented at Pearl Harbor NWR (not Keālia Pond NWR) and were a result of high nesting density (Nadig 2021, pers. comm.). (30) Comment: One commenter stated that the proposed rule implies that the quality and quantity of managed wetlands has been maximized and that any additional management implemented at this point would not have any additional effect on the Hawaiian stilt. They requested we clarify why we claim that Hawaii's wetland habitats have reached carrying capacity for the Hawaiian stilt while also stating that the population may be slightly increasing. They also asked that we address whether or not Hawaiian stilt numbers will decline if wetlands, which are already at carrying capacity, are flooded by sea level rise. Other commenters also stated that there are data suggesting that current population levels are not stable but declining, demonstrating the need for more conservation management measures and protections instead of fewer. Our Response: The best available scientific and commercial data indicate that the Hawaiian stilt population has currently reached a population equilibrium under the current amount of available habitat. The State-wide Hawaiian stilt population is stable at just above 1,500 individuals and likely won't increase to 2,000 individuals without an increase in the availability of managed habitat. As such, the best way to increase the population size is to increase the amount of managed wetland habitat. Further, this final downlisting rule is aimed at encouraging and facilitating additional management efforts by maximizing the ease at which management actions beneficial to the Hawaiian stilt can be carried out via the 4(d) rule associated with this downlisting. In regard to the population's response to sea level rise, we acknowledge in our discussion under Sea Level Rise that there is uncertainty surrounding how this threat will impact Hawaiian stilt viability and that it does not currently appear to be impacting Hawaiian stilt viability. However, we also state that we expect that sea level rise could lead to population-level impacts resulting from habitat loss for the Hawaiian stilt in the foreseeable future and therefore contributes to its threatened status. (31) Comment: Several commenters stated that the PVA considered populations and reproductive success but is missing critical analyses such as impacts from botulism, sea level rise, and other variables associated with climate change. Our Response: The updated PVA employs the best available information and is based on a best-case scenario that depends upon the Hawaiian stilt population maintaining current vital rates (Reed and van Rees 2019, entire; van Rees and Reed 2021, in litt.; van Rees et al. 2022, p. 9). The population has remained relatively stable with current vital rates since approximately 2005 under current management (Paxton et al. 2021, p. 432; DOFAW 2022, unpaginated). Sea level rise was intentionally left out of the updated PVA (van Rees et al. 2022, entire) for reasons outlined in our revised discussion under Sea Level Rise. In short, there were multiple reasons sea level rise was not incorporated into the PVA, in part related to the uncertainty about how sea level rise will affect overall wetland habitat availability (gain and loss) in the future, and in part related to how sea level rise will impact the Hawaiian stilt given the subspecies' frequent movement among wetlands, habitat plasticity, and tolerance to salinity. The authors of the PVA reasoned that to make a more accurate statement of extinction risk, a more in-depth analysis that was spatially explicit would be necessary, including site-specific vital rates for different types of habitats ( e.g., refuges, taro lo'i, unmanaged areas); average estimates of annual movement rates between those habitats, especially movement related to breeding; and an accurate, defensible, and mechanistically modeled estimate of the changes in breeding habitat availability and quality given future sea level rise (van Rees and Reed 2021, in litt.). Much of these data are not available, to our knowledge. However, a recent PVA on the Hawaiian common gallinule ( Gallinula galeata sandvicensis ), a more vulnerable species with less plasticity than the Hawaiian stilt, included habitat loss associated with sea level rise and found that this more vulnerable species is not likely to be extirpated due to habitat loss associated with sea level rise even by 2160 (van Rees and Reed 2018, entire). Although we do not anticipate that the estimated current Hawaiian stilt vital rates for managed habitats employed in the PVA will change in the near future, the threatened determination for the Hawaiian stilt accounts for potential impacts to habitat from sea level rise in the foreseeable future. (32) Comment: Several commenters stated that nonnative plants are a threat to Hawaiian stilt nesting habitat and that more nonnative plant management is needed to improve habitat conditions for the subspecies. Our Response: We agree that invasive plants are a threat to Hawaiian stilts and that an increase in vegetation control across wetlands in Hawaii is needed to improve habitat conditions for this subspecies. We are actively working with partners to restore wetlands, which includes vegetation management. Further, the intent of the 4(d) rule associated with this downlisting is to facilitate and, thereby, increase management activities that promote Hawaiian stilt viability. (33) Comment: Several commenters stated that an increase in the intensity and duration of drought may threaten the Hawaiian stilt by negatively altering core and supporting wetland habitat. Our Response: While Hawaii has been experiencing severe drought conditions, especially since the turn of the century (Eischeid et al. 2022, p. 3997), the Hawaiian stilt population has remained relatively stable during that period despite those conditions (Paxton et al. 2021, p. 432). To date, drought has not been mentioned frequently in the body of literature, nor during meetings with species and subject matter experts, as one of the viability-altering threats to the Hawaiian stilt. Because the incidence and duration of drought may increase in the foreseeable future due to climate change, we consider drought a threat that may impact the Hawaiian stilt in the foreseeable future, which supports our finding that the Hawaiian stilt is a threatened species ( i.e., at risk of becoming endangered within the foreseeable future). (34) Comment: A few commenters expressed concern that the proposed downlisting will impact funding of current and future site management. Our Response: We have no reason to believe that there will be a decrease in funding for wetland habitat management as a result of this final rule to downlist the Hawaiian stilt. The threatened status affords the Hawaiian stilt all of the same protections ( e.g., under section 7) as that of an endangered status, but in addition, the 4(d) rule that accompanies the threatened status includes exceptions for take associated with predator control and habitat management that have a net benefit to the subspecies. As such, upon finalization of this reclassification and 4(d) rule, our conservation partners will have greater flexibility to implement essential habitat management and predator control, and therefore, we expect an increase in conservation management efforts for the Hawaiian stilt. Because the downlisting of the Hawaiian stilt does not dramatically decrease protections, and implementation of predator and habitat management practices will become more streamlined and likely increase with the 4(d) rule, we have no reason to expect a decrease in funding or management for the subspecies. (35) Comment: Many commenters stated that downlisting the Hawaiian stilt is premature because none of the four recovery criteria have been fully met. Some of these commenters requested that the final rule to downlist the Hawaiian stilt be delayed. Our Response: Please see our revised discussion of our progress related to the criteria outlined in the recovery plan under Recovery Criteria. As outlined in the proposed rule and this final rule, recovery criteria are guides to recovery and represent conditions that would likely accompany the recovery of the species, as best we can determine at the time of creating the recovery plan. Regarding the perceived disparity between the recovery criteria and the definition of endangered, a decision to revise the status of a species is ultimately based on an analysis of the best scientific and commercial data available to determine whether a species is no longer an endangered species or a threatened species, regardless of what guidelines are outlined in the recovery plan. Recovery may be achieved without all of the criteria in a recovery plan being fully met. For example, one or more criteria may be exceeded while other criteria may not yet be accomplished, or new information received since the creation of the recovery plan may indicate that some targets originally outlined in the plan are not as appropriate as other targets to demonstrate recovery. Data show that Hawaiian stilt has maintained a relatively stable population since 2005 under current management (Paxton et al. 2021, p. 432; DOFAW 2022, unpaginated), and we do not anticipate the estimated current vital rates used in the PVA within managed habitats to change in the near future. Our conclusion that the data show the status of the Hawaiian stilt has improved so that it no longer meets the definition of an endangered species, but rather that of a threatened species, does not mean that we think the species has fully recovered and no longer warrants protection or management, only that the species is no longer at risk of extinction presently, although it remains at risk of extinction ( i.e., becoming endangered) in the foreseeable future. In addition, through the 4(d) rule finalized here, we have made all of the protections available to endangered species applicable to the Hawaiian stilt as a threatened species, with exceptions for take only for those activities that support important conservation efforts for the benefit of the subspecies. (36) Comment: One commenter requested that we designate critical habitat for the subspecies and improve habitat quality prior to downlisting. Our Response: Critical habitat is outside the scope of this rulemaking, and though we are not designating critical habitat at this time, we may do so in the future. This final rule will provide immediate benefits to the Hawaiian stilt by giving our conservation partners the flexibility they need to more efficiently implement beneficial predator control and habitat management actions directed at protecting the subspecies. This flexibility is achieved through the section 4(d) rule that applies to threatened species but not to endangered species. The final downlisting with a 4(d) rule is intended to make management practices that are essential to the recovery of this management-dependent subspecies easier to implement and conservation outcomes more readily achieved ( e.g., by facilitating the development and protection of additional habitat for the Hawaiian stilt). Final Reclassification Determination Background Only those topics directly related to downlisting the Hawaiian stilt are discussed in this rule, and, as a result, our citations do not represent the entire body of literature pertaining to the subspecies. Our comprehensive review of the biological information on the Hawaiian stilt including taxonomy, life history, ecology, and conservation activities, as well as threats facing the subspecies or its habitat, is presented in our recent Hawaiian stilt 5-year status review (Service 2020, entire) and the Recovery Plan for Hawaiian Waterbirds (Service 2011, entire), which are available at https://www.regulations.gov under Docket No. FWS-R1-ES-2020-0079. We prefer to, and will, include Hawaiian language spellings, including diacritical marks, to the degree possible and appropriate in the preambles of our Federal Register documents. For the text to be codified in the Code of Federal Regulations (CFR), however, we will omit diacritical marks to ensure that no errors are inadvertently incorporated during the codification process. Further, for consistency, we will use Hawaiian stilt throughout the preamble of this final rule due to the use of Hawaiian stilt as the common name used in the preamble of the proposed rule. Taxonomy and Species Description The Hawaiian stilt (kukuluae'o or ae'o, Himantopus mexicanus knudseni ) is a waterbird endemic to the Hawaiian Islands (Stejneger 1887, entire). The Hawaiian stilt is widely recognized as a subspecies of the black-necked stilt ( Himantopus mexicanus) (American Ornithology Union 1998). The Hawaiian stilt is black and white with long, pink legs (Bryan 1901, p. 26; Shallenberger 1977, p. 24), slender in appearance, and grows to about 16 inches (in) (40 centimeters (cm)) in height. Plumage is black on the back and white on the front and underside of the bird. Juveniles have a brownish back and more extensive white on the cheeks and forehead than adults. Chicks are well camouflaged in a downy plumage that is tan with black speckling (Coleman 1981, pp. 33, 35, 86-87). The Hawaiian stilt is a long-lived vertebrate, as the life span can reach at least 30 years (Reed et al. 2014, p. 4). Range, Abundance, and Population Trends Hawaiian stilts were historically known from the main Hawaiian Islands ( i.e., Niihau, Kauai, Oahu, Maui, Molokai, and Hawaii) except Lanai (until recently) and Kahoolawe. Hawaiian stilts move between islands, resulting in sudden large increases in numbers at certain sites (from several hundred to a thousand or more) and concurrent decreases at other sites (Engilis and Pratt 1993, pp. 142, 156, 148; Banko 1988, p. 6). Hawaiian stilts began colonizing the island of Lanai in the 1980s, following construction of a water treatment plant that provided foraging and breeding habitat (Engilis and Pratt 1993, p. 147; Pyle and Pyle 2017, unpaginated). The subspecies currently consists of one single population dispersed across the main Hawaiian Islands (except Kahoolawe), and individuals move freely between wetlands and islands (Munro 1944, pp. 59-60; Telfer and Burr 1979, p. 8; Coleman 1981, pp. 7-8; Reed et al. 1998a, pp. 36, 38; Reed et al. 1998b, pp. 791-796; Battista 2008, p. 2; Nishimoto 2014, p. 3; Paxton and Kawasaki 2015, in litt.; Dibben-Young 2017, in litt.). Hawaiian stilts disperse readily, exploit seasonally flooded wetlands, and readily colonize newly restored or created habitats (van Rees et al. 2020, p. 3). The population naturally fluctuates according to climatic and hydrologic conditions (Banko 1988, pp. 2-7; Engilis and Pratt 1993, pp. 145, 147; Reed et al. 1998b, pp. 791-797). Because the subspecies consists of one large population, any discussion regarding the subspecies' needs (below) also addresses the population's needs. The Hawaii DOFAW, conducts a biannual waterbird population index (count), and those data offer the best available information to assess population trends and relative abundance for the Hawaiian stilt (DOFAW 2022, unpaginated). Count data from these surveys can indicate presence and relative abundance of the subspecies but importantly cannot be used to produce a true population estimate (Paxton et al. 2021, pp. 434-435). Data from this ongoing survey effort were available from 1986 through 2016 for our analysis in the proposed rule. Since the publication of the proposed rule, data for the 2017 through 2023 survey years have also been analyzed (Gorresen et al. 2024, entire). Winter and summer surveys for Hawaiian stilt show a fluctuating population, which generally increased from 1987 to 2005, and since then has been roughly stable at 1,500 to 2,000 individuals (Paxton et al. 2021, p. 432; Gorresen et al. 2024, figure 4). Years where counts surpassed 2,000 individuals have been followed in the subsequent year by a decrease of 300 to 700 birds (DOFAW 2022, unpaginated). In the proposed downlisting rule, we reported long-term (1986 through 2016) and short-term (2006 through 2016) population trend analyses (Paxton et al. 2021, entire) that indicate that the 5-year minimum average population estimate for Hawaiian stilts was 1,932 birds [1,552-2,385] from 1986 to 2016 (Paxton et al. 2021, p. 430). This analysis has since been updated with data from 2016 to 2023 and indicates that while the short-term (2013-2023) trend shows a modest decline, the long-term trend is still increasing (figure 1; Gorresen 2024 et al., table 3 and figure 4), with the 5-year minimum average abundance estimate at 1,511 birds (Gorresen 2024 et al., table 1 and figure 2). ER20JY26.026 This model supports our conclusion that the Hawaiian stilt population is stable between 1,500 and 2,000 birds. Further, the Hawaiian stilt population is unlikely to increase over 2,000 birds until there is an expansion of managed wetland habitat because the subspecies has likely reached a population equilibrium ( i.e., the population size that the landscape can currently support) within existing managed wetland habitat (van Rees et al. 2022, p. 11; Paxton et al. 2021, p. 434). Under current management efforts on core and supporting wetlands, the updated PVA suggests that the State-wide carrying capacity for the Hawaiian stilt is below 2,000 individuals and likely closer to 1,500 individuals (van Rees et al. 2022, table 2). With regard to future trend projections, the updated PVA indicates that if current management practices continue and environmental conditions are relatively stable over the course of the projection, and if all other model assumptions and parameter estimates are correct, the Hawaiian stilt has almost no chance of extinction, and the mean population size will be just under 1,600 individuals by 2100 (van Rees et al. 2022, p. 7). However, the authors of the 2019 PVA performed a sensitivity analysis for the vital rates used in the PVA, and their analysis showed a rapid change in the probability of extinction if these parameters changed a small amount (van Rees et al. 2022, p. 10). As such, the 2019 PVA authors note that the current vital rates are very close to the thresholds of population decline or extinction, which highlights the fragile nature of the Hawaiian stilt's long-term viability (van Rees and Reed 2021, in litt.). Habitat and Life History Requirements The Hawaiian stilt primarily occurs from sea level up to 656 feet (ft) (200 meters (m)) in elevation, in natural and human-made lowland coastal wetlands (Perkins 1903, p. 452; Shallenberger 1977, pp. 23-25; Coleman 1981, pp. 8-18; Griffin et al. 1989, p. 1169; Engilis and Pratt 1993, pp. 155-156; Evans et al. 1994, p. 6; Service 2005, p. 31; Service 2011, pp. 50-60). However, Hawaiian stilts are not restricted to lowland coastal wetlands, as they have been observed at slightly higher elevations and outside of coastal wetlands, such as foothill impoundments, reservoirs, and other wetlands (Service 2005, pp. 28-29; Kawasaki et al. 2020, p. 431). Hawaiian stilts use areas of sparse, low-growing (up to 18 in (46 cm) tall) perennial vegetation or exposed tidal flats for nesting and breeding, and sometimes foraging (Smith and Polhemus 2003, p. 61; United States Department of Agriculture—Natural Resources Conservation Service (USDA-NRCS) 2009, p. 5 and Appendix B; Gee 2007, pp. 70-71). The most common foraging depth for adults appears to be 5 in (13 cm) or less below the surface of the water (Ohashi and Burr 1977, p. 3; Smith and Polhemus 2003, pp. 60-61; Gee 2007, p. 62; Reed et al. 2011a, pp. 3-4). Shallow water (approximately 2-3 in (7.6 cm)) and wet mudflats are particularly important for foraging chicks (Morin 1998, p. 11; USDA-NRCS 2009, p. 4; Reed et al. 2011a, p. 4; Reed 2017, in litt.). Hawaiian stilts use a wide range of water salinity ranging from zero to 200 ppt ( e.g., Waiawa Unit at Pearl Harbor NWR (Coleman 1981, p. 48; Reed et al. 2011a, p. 4; Nadig 2017, pers. comm.)). While adults have a tolerance to salinity, young Hawaiian stilt chicks that are unable to fly require a nearby freshwater source (Nadig 2022, in litt.). There are many freshwater springs scattered along the coastlines of the main Hawaiian Islands, particularly on the island of Oahu, which are adjacent to or within wetlands, that provide chicks with fresh water (Nadig 2022, in litt.). Hawaiian stilts typically begin breeding at age 2 (Reed et al. 1998a, p. 36). Nests are simple scrapes on the ground (Coleman 1981, p. 53; Smith and Polhemus 2003, p. 61; Gee 2007, p. 98). Pairs usually lay three to four eggs that are incubated for approximately 24 days (Coleman 1981, p. 56; Chang 1990, p. 43). Chicks are precocial, leaving the nest within 24 hours of hatching. Within a few hours after the last chick hatches, parents lead their brood to shallow feeding areas (Coleman 1981, p. 77). Foraging areas may be directly adjacent to the nest site or a distance away (Coleman 1981, p. 77; Engilis and Pratt 1993, pp. 155-156; Reed and Oring 1993, p. 57), depending in part on food availability (Reed and Oring 1993, p. 57). Adults with 3-day-old chicks have been observed foraging 0.3 mile (0.5 kilometer) from the nest site (Reed and Oring 1993, p. 57). Chicks fledge (can fly) approximately 28 days post-hatching (Reed et al. 1999, p. 478), but young may remain with both parents for several months after hatching (Coleman 1981, pp. 83-84). Hawaiian stilts are opportunistic feeders that eat a wide variety of invertebrates and other aquatic organisms found in shallow water and mudflats (Perkins 1903, p. 452; Shallenberger 1977, pp. 23-25; Robinson et al. 1999, pp. 8-9; Service 2011, p. 58). Managed wetlands with desirable water depth are common foraging sites (Underwood et al. 2013, p. 6). They also sometimes forage in grasslands adjacent to wetlands. Hawaiian stilts move intra-island and inter-island as they exploit food resources (Engilis and Pratt 1993, pp. 155-156). The specific breeding and rearing conditions described above are necessary to both individuals and to the subspecies as a whole. The Hawaiian stilt is a conservation-reliant subspecies (Reed et al. 2012, p. 888; Underwood et al. 2013, p. 1), meaning that it will require active management into perpetuity because of our inability to eliminate the dominant threats, which include introduced predators and invasive vegetation (Scott et al. 2005, pp. 383-389; Scott et al. 2010, pp. 92-93; Goble et al. 2012, pp. 869-872). It is also considered conservation-reliant because it relies almost solely upon managed wetlands for successful nesting and breeding (Reed et al. 2012, p. 888; Underwood et al. 2013, p. 1). The accepted management regime for creating and maintaining optimal Hawaiian stilt breeding and rearing habitat has three major components: control of predators; control of invasive introduced plant species; and manipulation of water levels to mimic natural hydrological processes and meet life-history needs (Service 2011, pp. 163-169; Underwood et al. 2014, p. 32 and supporting references). More information on the subspecies' management dependency is presented in the Summary of Biological Status and Threats, below. Recovery Criteria Section 4(f) of the Act directs us to develop and implement recovery plans for the conservation and survival of endangered and threatened species unless we determine that such a plan will not promote the conservation of the species. Under section 4(f)(1)(B)(ii), recovery plans must, to the maximum extent practicable, include objective, measurable criteria which, when met, would result in a determination, in accordance with the provisions of section 4 of the Act, that the species be removed from the Lists of Endangered and Threatened Wildlife and Plants. Recovery plans provide a roadmap for us and our partners on methods of enhancing conservation and minimizing threats to listed species, as well as measurable criteria against which to evaluate progress towards recovery and assess the species' likely future condition. However, they are not regulatory documents and do not substitute for the determinations and promulgation of regulations required under section 4(a)(1) of the Act. A decision to revise the status of a species, or to delist a species, is ultimately based on an analysis of the best scientific and commercial data available to determine whether a species is no longer an endangered species or a threatened species, regardless of whether that information differs from the recovery plan. There are many paths to accomplishing recovery of a species, and recovery may be achieved without all of the criteria in a recovery plan being fully met. For example, one or more criteria may be exceeded while other criteria may not yet be accomplished. In that instance, we may determine that the threats are minimized sufficiently and that the species' viability is such that it no longer meets the definition of an endangered species or a threatened species. In other cases, we may discover new recovery opportunities after having finalized the recovery plan. Parties seeking to conserve the species may use these opportunities instead of methods identified in the recovery plan. Likewise, we may learn new information about the species after we finalize the recovery plan that may change the extent to which existing criteria are appropriate for identifying recovery of the species. The recovery of a species is a dynamic process requiring adaptive management that may, or may not, follow all of the guidance provided in a recovery plan. For the purposes of this discussion, we assess the progress of Hawaiian stilt recovery relative to recovery targets in the second revision of the Recovery Plan for Hawaiian Waterbirds (Service 2011, entire). The 2011 revision included specific recovery recommendations for the Hawaiian stilt and modified population target levels. In developing recovery criteria for the Hawaiian stilt, we used a 1998 PVA for the subspecies (Reed et al. 1998a, entire) as the basis for population target levels. For Hawaiian stilt recovery criteria, we also assessed and categorized wetlands on each island into core and supporting wetlands. Core wetlands provide habitat essential for the larger populations of Hawaiian waterbirds that comprise the bulk of the numbers recommended for recovery. Supporting wetlands are additional areas that provide habitat important for smaller populations or provide habitat needed seasonally by segments of the population during part of their life cycle. Wetlands identified as “protected” (whether core, supporting, or neither) are those considered secure from development. In general, protected wetlands are NWRs, State-owned wildlife sanctuaries, or mitigation wetlands, where the primary purpose of management is wildlife conservation or does not conflict with the goal of wildlife conservation. The core and supporting wetlands identified in the 2011 recovery plan are the sites on each island that provide the greatest potential for recovery of the Hawaiian stilt (Service 2011, p. 114; Service 2020 pp. 2-3). The overall goal for recovery of the Hawaiian stilt is to restore and maintain multiple self-sustaining breeding populations within the subspecies' historical range (Service 2011, p. 120). The plan provides four criteria for reclassifying the Hawaiian stilt from endangered to threatened status and two additional criteria for delisting the subspecies. We describe and assess the recovery criteria as they relate to evaluating the status of the Hawaiian stilt below. Criterion 1 for Downlisting Criterion 1 states that all core wetlands on the island groups of Kauai-Niihau, Oahu, Maui-Molokai, and Hawaii are protected and managed in accordance with the management practices outlined in the recovery plan (Service 2011, pp. 124, 126, 163-165). The plan states that it is crucial for wetlands at these sites to be secure from conversion to non-wetland conditions and to have sufficient enduring management to recover waterbirds in Hawaii. Currently, of the recovery plan's 17 identified core wetlands, 14 are protected from development and have some predator and habitat management activities in place. Three core wetlands lack protection from development and predator and habitat management (table 1). Table 1—Status and Characteristics of Core Wetlands Identified for the Recovery of the Hawaiian Stilt Wetland name/ location Island Hectares (acres) Protected 1 Managed Water management infrastructure 2 Responsibility 3 Year protected/management initiated (if known) Kaloko-Honokōhau, National Historic Park Hawaii 22 (55) X predators and habitat partial NPS 1978. Loko Waka Ponds Hawaii 10 (24.5) partial Private Hanalei NWR Kauai 371 (917) X predators and habitat yes Service 1979 (hau control, water infrastructure, but not managed wetlands); 1989 (opportunistic predator control in response to sightings and bird kills). Hulē'ia NWR Kauai 98 (241) X predators and habitat partial Service 2006 (began to open up units for managed wetlands; some predator control). Lumaha'i Valley Wetlands Kauai 51 (125) partial Private Mānā Plains Forest Reserve (formerly Kawai'ele Wild Bird Sanctuary) Kauai 14 (35) X predators and habitat yes DOFAW 2003. Kanahā Pond Wildlife Sanctuary Maui 59 (145) X predators and habitat partial DOFAW 1951. Keālia Pond NWR Maui 280 (692) X predators and habitat partial Service 1992. Kakahai'a NWR Molokai 18 (45) X predators and habitat partial Service 1977. 'Ōhi'apilo Pond Bird Sanctuary Molokai 10 (25) X predators and habitat partial County Playa Lakes (wetland complex) Niihau 769 (1,900) no Private Hāmākua Marsh Waterbird Sanctuary Oahu 35.6 (88) X predators and habitat partial DOFAW 1997. James Campbell NWR, Ki'i and Punamanō Units Oahu 66 (164) X predators and habitat partial Service 1976. Kawainui Marsh Oahu 304 (750) X predators and habitat partial DOFAW 2007. Marine Corps Base Hawaii, Nu'upia Ponds Oahu 196 (483) X predators and habitat no MCBH 1982. Pearl Harbor NWR, Hono'uli'uli and Waiawa Units Oahu 25 (61) X predators and habitat yes Service 1972. Pouhala Marsh Waterbird Sanctuary Oahu 28 (78) X predators and habitat partial DOFAW 1995. Legend: 1 Protected refers to wetland areas that are secure from development. 2 Water level control capacity varies between core wetlands. In some core wetlands, control of water output (withdrawal) and flood (input) can be implemented with water control structures like impoundments, but these may or may not have the capacity for water input. Some core wetlands have access to pull water from wells, some have access to pull from rivers, while some rely solely on surface waters. For example, at James Campbell NWR, the Punamanō Unit is combined with the Ki'i Unit. However, Ki'i has full water management capabilities (withdrawal and input), while the Punamanō Unit does not. Both Hāmākua (U.S. Army Corps of Engineers ponds) and Keālia NWR (fish ponds) have full management in smaller impoundments, but the larger main ponds do not. 3 Responsibility: DOFAW = Hawaii Division of Forestry and Wildlife; MCBH = Marine Corps Base Hawaii; NPS = National Park Service; Service = U.S. Fish and Wildlife Service; County = County Government; State = State Government entity; Private = private landowner(s). For example, the Playa Lakes (Lake Hālālai'i and Lake Halulu) on the island of Niihau make up the largest of the core wetlands (table 1) and is one of the three core wetland sites that lack protections. These wetlands, dependent upon rainfall, are considered ephemeral and are inaccessible for monitoring and management even though pigs, sheep, cattle, and other exotic animals reportedly roam the island (Niihau Cultural Heritage Foundation 2022, entire). As such, while the Playa Lakes are thought to have a substantial role in the viability of the Hawaiian stilt, their current conservation value to the subspecies is unknown due to inaccessibility. Although Criterion 1 has not been fully achieved as originally defined in the recovery plan, we have made substantial progress in protecting and managing core wetland areas. The ongoing management on core wetlands has contributed toward the stabilization of the Hawaiian stilt population and helped to further the recovery of the subspecies, as evidenced by its total population range-wide remaining stable at between 1,500 and 2,000 birds over the past 20 or more years (Paxton et al. 2021, p. 432; DOFAW 2022, unpaginated). Criterion 2 for Downlisting Criterion 2 states that at least 50 percent of the supporting wetlands on the islands of Kauai, Oahu, Maui-Molokai-Lanai, and Hawaii are protected and managed in accordance with the management practices outlined in the recovery plan. The plan states that protection and management of these wetlands is required to recover waterbirds in Hawaii, but there is more flexibility regarding which sites must be managed, as it is possible that other sites may fulfill the same needs as those identified. The recovery plan identified 34 sites as supporting wetlands throughout the State; of these, 15 are protected, 11 have predator or habitat management or both (4 of which are not protected), and 7 of the 34 supporting wetlands are in protective status with some form of management (table 2). Therefore, this criterion has been partially met. Table 2—Supporting Wetlands and Characteristics Identified for Recovery of the Hawaiian Stilt Wetland name/location Island Hectares (acres) Protected 1 Managed Responsibility 2 Kealakehe (Kona) Sewage Treatment Plant Hawaii 12 (30) predators County. Ke'anae Pond (Kea'au/Shipman) Hawaii 2.9 (7.2) X Private. Keanakolu Road Stock Ponds (1-5) (Part of Kohala-Mauna Kea Ponds and Streams) Hawaii 18+ (45+) Private/State. 'Ōpae'ula Pond Hawaii 3 (7.5) Private. Waiākea Pond Hawaii 16 (39.5) State/County. Waimanu Valley Hawaii ( * ) County. Waipi'o Valley Hawaii ( * ) X County. Hanalei Trader Taro Fields (Hanalei River and Taro fields that are not part of Hanalei NWR) Kauai 40.4 (100) Private/State. Hanapepe Salt Ponds Kauai 20 (50) Private/DOFAW. Mānā Base Pond and Wetlands (Part of Mānā Plain) Kauai 81 (200) X predators and habitat Private/State. 'Ōpaeka'a Marsh Kauai 20 (50) Private/DOFAW. Smith's Tropical Paradise Kauai 1.9 (4.7) X Private/State. Wailua River Bottoms Kauai 20 (50) Private/State. Waimea River System Kauai 64 (158) Private/State. Wainiha Valley River and Taro Fields Kauai 44 (109) Private/County. Waitā Reservoir Kauai 151 (373) Private. Lāna'i Sewage Treatment Ponds Lanai 3 (7.4) predators Private/County. Ke'anae Point Maui 1.5 (3.7) X State. Waihe'e Coastal Dunes and Wetlands (Waihe'e Refuge) Maui 101 (250) X predators and habitat Private. Kaunakakai Wastewater Reclamation Facility Ponds Molokai 1.5 (3.7) X predators County. Kualapu'u Reservoir Molokai 30 (74) X State. Paialoa Fish Ponds Molokai 2 (5) Private. Hale'iwa Lotus and Taro Fields Oahu 4.2 (10.6) Private/County. Hale'iwa Waialua Lotus Fields Oahu 30 (75) Private. He'eia Marsh Oahu 162 (400) X predators and habitat DOFAW. Ka'elepulu Mitigation Pond (Enchanted Lake) Oahu 2.2 (5.6) X predators and habitat Private. Kahuku Prawn Farm (Includes Amoriant and Kahuku Aquaculture Farms) Oahu 41 (100) Private. Lā'ie Wetlands Oahu 81 (200) X Private. Lualualei RTF, Niuli'i Ponds Oahu 16 (40) X predators and habitat USN. Paikō Lagoon Wildlife Sanctuary Oahu 13 (33) X predators and habitat DOFAW. Punaho'olapa Marsh Oahu 41 (100) X Private. Turtle Bay, Kuilima Wastewater Treatment Plant Oahu 5 (12.4) X Private. 'Uko'a Marsh Oahu 122 (300) predators and habitat Private. Waihe'e Marsh Oahu 10 (25) predators and habitat Private. Legend: 1 Protected refers to wetland areas that are secure from development. 2 Responsibility: DOFAW = Hawaii Division of Forestry and Wildlife; USN = U.S. Navy; County = County Government; State = State Government entity; Private = Private Landowner(s). * Large area of intermixed wetlands, agricultural lands, and/or upland habitat, where habitat area extent cannot be determined. Criterion 3 for Downlisting Criterion 3 states that a PVA should be conducted to update the findings of Reed et al. (1998a, entire) and determine the population size necessary for long-term viability of the Hawaiian stilt, and that the State-wide surveyed number of the Hawaiian stilts indicates a stable or increasing trend and has not declined below 2,000 birds (or an alternative target based on the updated PVA) for at least 5 consecutive years. The Hawaiian stilt PVA was updated in 2019 (van Rees et al. 2022, entire) using multiple modeling techniques to analyze data collected since 1998 and by incorporating additional peer-reviewed data on adult survival rates, variances in adult and juvenile survival rates (Reed et al. 2014, entire), and individual movement patterns (Reed et al. 1998b, entire). While the 2019 PVA did not explicitly establish a MVP for the Hawaiian stilt, it did conclude that the 2,000-individual target identified in the recovery plan (Service 1978, entire; Service 2011, entire) is inappropriate, as there is a very low (approximately 3 percent) probability that the 2,000-individual target could be attained given the amount of suitable habitat currently available (van Rees et al. 2022, table 2). The 2019 PVA estimated that the carrying capacity (or population equilibrium size) for the Hawaiian stilt is fewer than 2,000 individuals and may be closer to 1,500-1,600 individuals (van Rees et al. 2022, tables 1 and 2). In general, 1,000 individuals is a commonly recommended MVP, as it is perceived to be the smallest number of individuals required to retain evolutionary potential for fitness in perpetuity, though the MVP may vary by species (Frankham et al. 2014, entire). Genetic diversity is an important factor to consider when determining MVP: when low, the MVP is likely to be greater than 1,000 individuals, but if genetic diversity is moderate or high, 1,000 is likely adequate (Frankham et al. 2014, entire). While there are no genetic studies for the Hawaiian stilt, genetic studies have been conducted on the Hawaiian coot ('alae ke'oke'o, Fulica americana alai ), which is another endemic waterbird in Hawaii that has experienced simultaneous population declines over 100 or more years, and thus may serve as a surrogate for the Hawaiian stilt. The Hawaiian coot exhibits low levels of structure at microsatellite loci but high gene flow among islands (Sonsthagen et al. 2018, p. 863). If we use the Hawaiian coot as a surrogate species for the Hawaiian stilt, as both the Hawaiian stilt and Hawaiian coot have similar abundance (just under 2,000 individuals) and move between islands (Riggs 2016, entire), we can reasonably assume that the Hawaiian stilt is not at increased risk of the loss of genetic diversity. We conclude that an MVP size of 1,000 individuals (Frankham et al. 2014, entire) is an appropriate MVP for the Hawaiian stilt given adequate genetic diversity within the subspecies. Further, density-dependent population dynamics on managed wetlands affects Hawaiian stilt population growth beginning at approximately 1,000 individuals (Reed and van Rees 2019, entire; van Rees et al. 2020, entire). The Hawaiian stilt population was increasing from 1986 to 2004 but appears to have plateaued since 2005, indicating that the subspecies has reached carrying capacity within managed wetland habitat (Paxton et al. 2021, pp. 432, 434; Gorresen et al. 2024, figure 4). The 5-year estimated average abundance reported as the minimum size of the Hawaiian stilt population in 2016 was 1,932 birds (Paxton et al. 2021, pp. 430), and that estimate for the 2019-2023 time period was 1,511 birds (Gorresen et al. 2024, table 1). We therefore conclude that Criterion 3 ( i.e., to update the PVA, reassess the population size needed for long-term viability, and show that stable State-wide survey trends do not decline below an appropriate target based on the updated PVA for 5 consecutive years) has been met. As described in the recovery criterion, a new PVA has been produced that indicates that the carrying capacity for the subspecies is fewer than 2,000 individuals and likely closer to 1,500-1,600 individuals. The Hawaiian stilt population has been roughly stable at a minimum of 1,500 individuals since 2004 (Paxton et al. 2021, p. 432; Gorresen et al. 2024, figure 4), and we've determined that an appropriate MVP for the subspecies is closer to 1,000 individuals than 2,000 (and that the subspecies is currently in population equilibrium). Criterion 4 for Downlisting Criterion 4 states that there should be multiple self-sustaining breeding populations on at least the following: the island group of Kauai and Niihau; the island of Oahu; the island group of Maui, Molokai, and Lanai; and the island of Hawaii. Because the Hawaiian stilt exists in one intermixed population, we refer to breeding populations solely to distinguish groups of Hawaiian stilts that breed at a specific wetland on a specific island at any given time. The recovery plan defines a self-sustaining breeding population as a population that is large enough to make extirpation from stochastic forces unlikely, and that is able to remain stable or grow with little human intervention except for predator control and vegetation management (Service 2011, p. 121). The recovery strategy further strengthens this concept by incorporating the need to satisfy two widely recognized and scientifically accepted goals for promoting viable self-sustaining breeding populations: (1) By increasing the population size and distribution across the islands, a single or series of catastrophic events will not result in the extinction of the subspecies; and (2) increasing the population size throughout its range to a level where the threats of genetic, demographic (population dynamics), and normal environmental uncertainties are diminished (Service 2011, p. 112). As previously summarized, the State-wide population was stable or slightly increasing through approximately 2004 and has remained relatively stable since 2005 (Service 2011, pp. 48-49; Service 2020, pp. 5, 18; van Rees et al. 2020, p. 3; DOFAW 2022, unpaginated; Paxton et al. 2021, p. 432). Hawaiian stilt breeding population sizes fluctuate, and some wetlands are favored over others during different years; therefore, monitoring such trends is important to understanding the conservation needs of the subspecies. Hawaiian stilt populations trends on each of the islands that support at least one breeding population fluctuate in the short-term, but the long-term (1986 to 2016) population trends are increasing on all islands except for Oahu (where the long-term trend is indeterminate) (table 3). In addition, the State-wide population is also increasing in the long-term trend (Paxton et al. 2021, p. 430). Table 3—Summary of Island-Specific Hawaiian Stilt Population Short-Term and Long-Term Index Trends [Paxton et al. 2021, p. 431] Island Short-term (2006-2016) trend Long-term (1986-2016) trend Kauai Increasing Increasing. Oahu Decreasing Indeterminant. Lanai Decreasing Increasing. Molokai Increasing Increasing. Maui Indeterminant Increasing. Hawaii Decreasing Increasing. The establishment, protection, and active management of wetlands for waterbirds is likely the largest contributor to the marked increase in abundance in Hawaiian stilt and the other listed waterbirds species since the late 1980s; however, these increases appear to have plateaued or may even be reversing recently, which may indicate that the population has reached its carrying capacity within existing managed wetlands (Paxton et al. 2021, p. 434; Rounds 2020, in litt.). Present distribution of the Hawaiian stilt encompasses all islands where they were historically known (Niihau/Kauai, Oahu, Maui, Molokai, and Hawaii), as well as the island of Lanai due to the expansion in range that occurred in the mid-1980s from the development of the Lanai wastewater treatment facility. There are multiple breeding populations on each of the islands/island groups outlined in the recovery plan (Oahu, Hawaii, Kauai/Niihau, and Maui/Molokai/Lanai), and long-term population trends are increasing in each of these areas except for Oahu (where the trend is indeterminate) (Paxton et al. 2021, p. 431). Even though we lack data demonstrating that breeding populations in each of these areas are stable ( i.e., “self-sustaining”) as specifically targeted in the recovery plan, the State-wide population was stable or slightly increasing through approximately 2005 and has remained relatively stable since (Service 2011, pp. 48-49; Service 2020, pp. 5, 18; van Rees et al. 2020, p. 3; DOFAW 2022, unpaginated, Paxton et al. 2021, p. 432). The wide distribution of the Hawaiian stilt population, spread out across the multiple islands, provides the subspecies with the resiliency and redundancy necessary to withstand a stochastic ( e.g., single wetland) or catastrophic ( e.g., islandwide) event, respectively, which was the intent of this recovery criterion. As such, we conclude that the specific targets outlined in the recovery plan for this criterion have been at least partially satisfied, and that the overall intent of this recovery criterion has been achieved. Discussion/Summary of Downlisting Criteria Assessment The downlisting criteria in the recovery plan (Service 2011, entire) represented our best assessment at the time of conditions that would result in a determination that the Hawaiian stilt could be considered for reclassification under the Act as threatened rather than endangered. While achieving each of the downlisting criteria in a recovery plan is not required for downlisting, we have made substantial progress on those recovery criteria: (1) Ongoing management is occurring at most core wetlands (Criterion 1); (2) protection has been secured for about 40 percent of supporting wetlands, and about 33 percent of the supporting wetlands are being managed (Criterion 2); (3) an updated PVA was performed and reassessed population targets are being met (Criterion 3) (van Rees et al. 2022, entire); and (4) the range-wide population has been stable to increasing from 1986 through 2019, with relatively large and stable breeding populations on most of the historically-occupied islands, indicating adequate resiliency and redundancy to withstand stochastic and catastrophic events (Criterion 4). However, it appears that the population has likely reached equilibrium (van Rees et al. 2020, entire; van Rees et al. 2022, p. 11; Paxton et al. 2021, p. 434), and other factors may be contributing toward a plateau in population trend (Christensen et al. 2021, entire; Harmon et al. 2021b, entire; Paxton et al. 2021, p. 434). Additionally, we recognize the need to continue recovery actions to further improve the status of the Hawaiian stilt across its range. Delisting Criteria We provided two delisting criteria in our recovery plan. The first delisting criterion aims for protection and management in accordance with the management practices outlined in the recovery plan be in place for at least 85 percent of the supporting wetlands on the islands of Kauai, Oahu, Maui-Molokai-Lanai, and Hawaii. The second delisting criterion is defined as the State-wide surveyed number of Hawaiian stilts having a stable or increasing trend and not having declined below 2,000 birds (or some alternative target based on an updated PVA) for at least 10 consecutive years. The information presented above for the downlisting criteria indicates that the criteria for delisting have not yet been fully met, and we provide a summary of information relating to the delisting criteria below. With regard to Criterion 1, the Service finds that progress towards securing management actions on supporting wetlands has been made and is showing success, but the criterion has not been fully realized to date. For supporting wetland sites, producing long-term and sustained Hawaiian stilt habitat management is complicated by the following factors. First, many supporting wetlands are owned or managed by multiple entities, which complicates coordination and intensity of management efforts. Additionally, the primary purpose of many of these sites is not waterbird conservation, but instead purposed for water reclamation facilities, wastewater retention, taro production, and flood control, and, therefore, management for conditions conducive to Hawaiian stilt breeding is secondary. Finally, long-term management efforts on many of these sites are more tenuous than at core and supporting sites owned by Federal and/or State conservation agencies; this is due to a general lack of secured and dedicated funding sources and lack of internal operational capacity. Partnerships at supporting wetland sites have contributed to recovery progress for the Hawaiian stilt and other waterbirds (see Current Voluntary and Regulatory Conservation Efforts ). Progress toward achieving this criterion is ongoing but not yet at a level of permanency or extent that would achieve the greatest conservation outcomes targeted by this criterion. With regard to delisting Criterion 2, winter and summer surveys for the Hawaiian stilt show a fluctuating population, which generally increased from 1986 to 2004 and has been roughly stable at 1,500 to 2,000 individuals since 2005 (see Range, Abundance, and Population Trends ). An updated PVA indicates that the carrying capacity (and therefore an appropriate abundance target) for the Hawaiian stilt is fewer than 2,000 individuals and likely closer to 1,500 individuals (van Rees et al. 2022, table 2). Because the Hawaiian stilt population has been essentially stable at or above 1,500 individuals since 2005, delisting Criterion 2 has been fulfilled. As previously described, recovery of a species may be achieved without all of the criteria in a recovery plan being fully met. We may learn new information about the species after a recovery plan is finalized, and the new information may change the extent to which the originally defined recovery criteria are appropriate for identifying recovery of the species. Therefore, we use the regulatory definitions of the Act when determining the appropriate classification of a species listed under the Act. Regulatory and Analytical Framework Regulatory Framework Section 4 of the Act (16 U.S.C. 1533) and the implementing regulations in title 50 of the CFR set forth the procedures for determining whether a species is an endangered species or a threatened species, issuing protective regulations for threatened species, and designating critical habitat for threatened and endangered species. On April 5, 2024, jointly with the National Marine Fisheries Service, we issued a final rule that revised the regulations in 50 CFR part 424 regarding how we add, remove, and reclassify endangered and threatened species and what criteria we apply when designating listed species' critical habitat (89 FR 24300). On the same day, we published a final rule revising our protections for endangered species and threatened species at 50 CFR part 17 (89 FR 23919, April 5, 2024). These final rules are now in effect and are incorporated into the current regulations. Our analysis for this final decision applied our current regulations. Given that we proposed downlisting this species under our prior regulations (revised in 2019), we have also undertaken an analysis of whether our decision would be different if we had continued to apply the 2019 regulations; we concluded that the decision would be the same. The document comparing the analyses under the regulations currently in effect and the 2019 regulations are available on https://www.regulations.gov at Docket No. FWS-R1-ES-2020-0079. The Act defines an “endangered species” as a species that is in danger of extinction throughout all or a significant portion of its range and a “threatened species” as a species that is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range. The Act requires that we determine whether any species is an endangered species or a threatened species because of any of the following factors: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) Overutilization for commercial, recreational, scientific, or educational purposes; (C) Disease or predation; (D) The inadequacy of existing regulatory mechanisms; or (E) Other natural or manmade factors affecting its continued existence. These factors represent broad categories of natural or human-caused actions or conditions that could have an effect on a species' continued existence. In evaluating these actions and conditions, we look for those that may have a negative effect on individuals of the species, as well as other actions or conditions that may ameliorate any negative effects or may have positive effects. We consider these same five factors in downlisting a species from endangered to threatened. We use the term “threat” to refer in general to actions or conditions that are known to or are reasonably likely to negatively affect individuals of a species. The term “threat” includes actions or conditions that have a direct impact on individuals (direct impacts), as well as those that affect individuals through alteration of their habitat or required resources (stressors). The term “threat” may encompass—either together or separately—the source of the action or condition or the action or condition itself. However, the mere identification of any threat(s) does not necessarily mean that the species meets the statutory definition of an “endangered species” or a “threatened species.” In determining whether a species meets either definition, we must evaluate all identified threats by considering the species' expected response and the effects of the threats—in light of those actions and conditions that will ameliorate the threats—on an individual, population, and species level. We evaluate each threat and its expected effects on the species, then analyze the cumulative effect of all of the threats on the species as a whole. We also consider the cumulative effect of the threats in light of those actions and conditions that will have positive effects on the species, such as any existing regulatory mechanisms or conservation efforts. The Secretary determines whether the species meets the definition of an “endangered species” or a “threatened species” only after conducting this cumulative analysis and describing the expected effect on the species. The Act does not define the term “foreseeable future,” which appears in the statutory definition of “threatened species.” Our implementing regulations at 50 CFR 424.11(d) set forth a framework for evaluating the foreseeable future on a case-by-case basis, which is further described in the 2009 Memorandum Opinion on the foreseeable future from the Department of the Interior, Office of the Solicitor (M-37021, January 16, 2009; “M-Opinion,” available online at https://www.doi.gov/sites/doi.opengov.ibmcloud.com/files/uploads/M-37021.pdf ). The foreseeable future extends as far into the future as the Service can make reasonably reliable predictions about the threats to the species and the species' responses to those threats. We need not identify the foreseeable future in terms of a specific period of time. We will describe the foreseeable future on a case-by-case basis, using the best scientific and commercial data available and taking into account considerations such as the species' life-history characteristics, threat-projection timeframes, and environmental variability. In other words, the foreseeable future is the period of time over which we can make reasonably reliable predictions. “Reliable” does not mean “certain”; it means sufficient to provide a reasonable degree of confidence in the prediction, in light of the conservation purposes of the Act. Analytical Framework To assess Hawaiian stilt viability, we used the three conservation biology principles of resiliency, redundancy, and representation (Shaffer and Stein 2000, pp. 306-310). Briefly, resiliency is the ability of the species to withstand environmental and demographic stochasticity (for example, wet or dry, warm or cold years), redundancy is the ability of the species to withstand catastrophic events (for example, droughts, large pollution events), and representation is the ability of the species to adapt to both near-term and long-term changes in its physical and biological environment (for example, climate conditions, pathogens). In general, species viability will increase with increases in resiliency, redundancy, and representation (Smith et al. 2018, p. 306). Using these principles, we identified the species' ecological requirements for survival and reproduction at the individual, population, and species levels, and described the beneficial and risk factors influencing the species' viability. Summary of Biological Status and Threats In this discussion, we review the biological conditions of the Hawaiian stilt and its resources, and the threats that influence the subspecies' current and future condition, in order to assess the subspecies' overall viability and the risks to that viability. In addition, the 5-year review (Service 2020, entire) documents our comprehensive biological status review for the subspecies, including an assessment of the potential threats to the subspecies. The sources cited in this final rule represent the best scientific and commercial data available concerning the current status of the subspecies, including the past, present, and future threats. We used this information to evaluate the current and future resiliency, redundancy, representation, and viability of the Hawaiian stilt. (See Regulatory and Analytical Framework.) The effects of conservation actions were also assessed as part of the current condition of the subspecies. We note that overutilization for commercial, recreational, scientific, or educational purposes (Factor B) was not identified as a threat at the time of listing, and we have no additional information to suggest it is currently, or will become, a threat in the foreseeable future; hunting of the subspecies has been prohibited since the 1940s. Furthermore, in this final rule, we consider regulatory mechanisms (Factor D) with respect to how both regulatory and volunteer conservation measures might reduce or ameliorate threats to the subspecies, rather than in the context of a potential stand-alone threat. Threats to the subspecies are reduced by voluntary and regulatory actions initiated by the Service, Federal agencies, DOFAW, and voluntary actions by a large network of organizations interested in wetland and waterbird conservation range wide. A summary of these efforts is found in Current Voluntary and Regulatory Conservation Efforts. We assessed the impact of threats on the Hawaiian stilt into the foreseeable future. The foreseeable future is the extent into the future for which we can make reasonably reliable predictions about the threats to the Hawaiian stilt and its response to those threats. In the proposed rule, we considered the foreseeable future timeframe to extend out to 2040 primarily due to uncertainty related to physical processes ( e.g., changes in Greenland and Antarctic ice sheets) and future societal actions employed to reduce greenhouse gas emissions (global warming), and because climate models in earlier IPCC reports begin to diverge considerably around this year depending on the greenhouse gas emission scenario (IPCC 2014, pp. 9, 11). However, since the drafting of the proposed rule, the IPCC has published updated reports using the most current climate data, and subsequently, NOAA published revised sea level rise scenarios with increased confidence in regional projections (IPCC 2021 SPM-15, entire; NOAA 2022, entire). Both the updated IPCC and NOAA reports show increased confidence in climate and sea level rise projections through the near-term (2050) and long-term (2100). Though we now have increased confidence in sea level rise projections out to 2100, we have less confidence in the subspecies' response to the climate-related threats to their habitat that far out into the future. Hawaiian stilt resiliency currently relies greatly on habitat management activities, and it will continue to rely on habitat management especially under future sea level rise scenarios. Our confidence in the continuation of habitat management activities into the future is more limited than our confidence in sea level rise projections into the future. However, we are reasonably confident that we can project Hawaiian stilt resiliency further out into the future than 2040, to approximately 2080, based on: the most recently published sea level rise data (NOAA 2022, p. 60) which lends higher confidence to both shorter- and longer-term sea level rise projections in Hawaii; the most recently published, updated, peer-reviewed PVA (van Rees et al. 2022, entire) which projects the probability of extinction of the Hawaiian stilt through 2100; and the more limited reliability of the continuation o [Text truncated at 120,000 characters. The full text is on the page linked above.] --- Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2026-14550. Public record. Not legal advice.