USFWS Rejects Bid to List Research Macaques, Citing Lack of Science

WASHINGTON, DC – July 14, 2026 – The U.S. Fish and Wildlife Service (USFWS) has once again rejected a petition to list the long-tailed macaque under the Endangered Species Act (ESA), a decision that highlights the intense conflict between biomedical research needs and animal protection advocacy. In its finding, the agency determined that the petition, filed by People for the Ethical Treatment of Animals (PETA) and other groups, failed to provide substantial scientific evidence to warrant further review.

This marks the second time in three years that the USFWS has turned down such a request, reaffirming its position that the data presented does not justify classifying the species as threatened or endangered. The decision is a significant victory for the biomedical community, which relies heavily on the primate for preclinical research, but a major setback for animal welfare organizations that argue the species is in peril.

A Science-Based Rejection

According to the USFWS, PETA's petition did not present “substantial scientific information warranting further review.” Agency officials clarified that while the petition documented potential harm to individual animals, it lacked the credible, population-level data required to justify an ESA listing. The first petition, rejected in October 2024, was dismissed on similar grounds.

The National Association for Biomedical Research (NABR), which represents over 280 institutions involved in animal research, praised the agency’s consistency.

“NABR commends USFWS for conducting a thorough, science-based review of the petition submitted by activist groups and for its determination that LTM monkeys do not warrant listing under the ESA,” said Matthew R. Bailey, president of NABR. Bailey accused the petitioners of misusing environmental laws to achieve other goals.

“It is clear from the record that activist groups like PETA have attempted to weaponize the ESA and other environmental processes to block or hinder medical research in the United States and around the world,” Bailey added. “Doing so not only jeopardizes human health and safety, but it undermines the value of these environmental processes when they are used as tools to further political agendas.”

The Conservation Controversy

At the heart of the dispute is a fundamental disagreement over the conservation status of the long-tailed macaque (Macaca fascicularis). Animal welfare advocates point to the International Union for Conservation of Nature (IUCN), which elevated the species’ status from “Vulnerable” to “Endangered” in 2022 and reaffirmed it in 2025. The IUCN’s assessment projects a population decline of 50-70% over three generations, citing threats from habitat loss, human-macaque conflict, and overutilization for research and the pet trade.

PETA’s petition referenced these findings, along with a study suggesting macaque populations in their native Southeast Asia are 80% smaller than previously thought. “This decision defies both evidence and common sense,” said a PETA science advisor in a statement, arguing that the purpose of the ESA is to prevent extinction, not to “prop up profits for the experimentation industry.”

However, the biomedical research community fiercely disputes the IUCN’s classification. NABR has challenged the assessment, alleging it contains scientific errors and potential conflicts of interest. The organization cites a 2024 review in the American Journal of Primatology by researchers Ray Hilborn and David R. Smith, which argues that studies claiming an extinction risk for macaques often lack supporting data. The review posits that the species is highly adaptable, thrives in human-altered environments, and can rebound quickly from low population numbers, making its extinction highly improbable.

Indispensable for Medical Advancement

For the scientific community, the stakes of the USFWS decision are enormous. Long-tailed macaques, which share approximately 92% of their genes with humans, are considered an essential model for developing and testing new drugs and therapies before they reach human clinical trials.

“Due to their physiological and biological similarities with humans, LTM monkeys are a crucial resource for pre-clinical biomedical research,” explained Bailey. “They have been instrumental in the development, and in safety and efficacy assessment, of many of today's medicines and treatments.”

Their contributions are wide-ranging. The primates were pivotal in accelerating the development of COVID-19 vaccines and have been vital in creating treatments for HIV/SIV, cancer, and hypertension. Research involving macaques has led to numerous monoclonal antibody drugs used for asthma, rheumatoid arthritis, and preventing organ transplant rejection. According to industry data, six of the 25 most commonly prescribed drugs were developed with their help. This reliance has been strained by a global supply shortage, intensified by China’s 2020 export ban, which threatens to slow future medical progress.

The use of these animals is governed by a strict regulatory framework in the U.S., including the Animal Welfare Act and oversight by Institutional Animal Care and Use Committees (IACUCs), which enforce the principles of Replacement, Reduction, and Refinement of animal use.

The Future of Research: A Shift Toward Alternatives

While the debate over macaques continues, the broader landscape of biomedical research is undergoing a significant transformation. Spurred by ethical concerns and technological innovation, a major push is underway to develop and adopt New Approach Methodologies (NAMs) that can reduce or replace the need for animal models.

These alternatives include sophisticated in vitro models like organs-on-a-chip—microfluidic devices lined with human cells that mimic organ function—and 3D organoids grown from stem cells. Computational modeling and artificial intelligence are also being used to predict drug toxicity and efficacy in silico. This technological shift has gained powerful legislative and institutional support.

The FDA Modernization Act 2.0, passed in 2022, removed the federal mandate for animal testing in drug development, allowing companies to submit data from NAMs. The National Institutes of Health (NIH), a primary funder of research, has also begun shifting its priorities, launching a Human-Based Science Initiative and announcing it will no longer fund studies focused exclusively on animal models of human disease. While these alternatives cannot yet fully replicate the complex interactions of a living organism, their rapid advancement signals a clear trend toward more human-relevant and less animal-dependent science.