WASHINGTON, Oct. 13, 2025 /PRNewswire/ — The International Union for Conservation of Nature (IUCN) issued a decision on October 9, 2025, to retain the “Endangered” status determination for long-tailed macaque (“LTM”) monkeys (Macaca fascicularis).
The latest issuance by the IUCN follows a 2023 petition filed by the National Association for Biomedical Research (NABR) challenging the IUCN status determination. NABR’s petition demonstrates that reviews by Hansen et. al., which the IUCN has used as the basis for its status determinations, misrepresent existing scientific data.1 More information regarding the NABR petition is available online at www.nabr.org.
A separate petition filed with the IUCN by Dr. Hank Jenkins asserts that the Hansen et al. authors possess conflicts of interest that require further investigation by the IUCN. It is unclear if such conflicts exist, or if the authors of the IUCN review possess conflicts requiring disclosure or recusal.
On October 7, 2024, the U.S. Fish and Wildlife Service (“the Service”) rejected a petition filed by advocacy groups to list “LTM” monkeys under the Endangered Species Act (“ESA”). The petition contains the same information submitted to the IUCN which is the basis for the IUCN’s current assessment. In rejecting the petition, the Service stated “the petition did not present credible information to support impacts to populations or the species as a whole.” The full findings from the Service on the petition to list long-tailed macaques under the U.S. Endangered Species Act is published in the Federal Register and is located here: “LTM_Petition.pdf.” No government in the world considers “LTM” monkeys to be endangered. Peer-reviewed scientific publications demonstrate the latest IUCN determination, and information used in the determination, are flawed and unsupported.2
“The NABR scientific review team is disappointed that the IUCN has failed to objectively consider scientific information that has been presented,” stated Dr. Ray Hilborn, a world-renowned scientist and member of NABR’s scientific review team.
“The lack of data on trends in abundance, and misrepresentation of data that do exist, raise serious questions about the scientific process employed by the IUCN to reach this determination,” added Dr. Hilborn.
“LTM” monkeys are used extensively throughout the world in biomedical research given their physiological and genetic similarities with human beings. Five of the 20 most used prescription drugs were developed with the help of long-tailed macaques. Research with “LTM” monkeys has been crucial for advances in regenerative medicine, immunology, cancer, vaccine development, and pharmacology, as well as development of the COVID-19 vaccine.3 The National Institutes of Health (NIH) recently published a review confirming the importance of “LTM” monkeys in conducting biomedical research.
“NABR is disappointed that in the face of overwhelming scientific evidence, the IUCN has bowed to pressure from animal activists to suggest the ‘LTM’ monkey as at risk,” said Matthew R. Bailey, president of NABR. “Available scientific information clearly shows this species is not at risk and in fact is considered to be invasive in several countries. It is beyond comprehension that the IUCN claims the species is at risk while simultaneously claiming it is one of the world’s most invasive species. NABR will continue to educate policy makers and the public on these issues to protect public health and the integrity of the scientific process.”
According to a publication entitled “100 of the World’s Worst Invasive Alien Species,” “LTM” monkeys are recognized by the IUCN to be an “invasive” species.4
The conservation status of “LTM” monkeys and PETA’s involvement in government programs was recently the subject of a U.S. House of Representatives Oversight Committee hearing in September 2024. Witnesses at this hearing testified that PETA and other animal advocacy groups have improperly attempted to influence government investigations of private parties and foreign governments for political reasons.
About the National Association for Biomedical Research
Founded in 1979, NABR is the only 501(c)(6) non-profit association dedicated to sound public policy for the humane use of animals in biomedical research, education, and testing. Members include more than 340 universities, medical and veterinary schools, teaching hospitals, pharmaceutical and biotechnology companies, patient groups, and academic and professional societies who rely on humane and responsible animal research to advance global human and animal health. Learn more about us at www.nabr.org.
1 See Hilborn, R., & Smith, D. R. (2023). Is the long‐tailed macaque at risk of extinction? American Journal of Primatology, e23590. (Available at https://doi.org/10.1002/ajp.23590).
2 See Hilborn, R., & M. Chaloupka (2025). Estimating the abundance of widely distributed primates. American Journal of Primatology (accepted for publication).
3 See Albrecht, L., E. Bishop, B. Jay, B. Lafloux, M. Minoves, C. Passaes (2021). COVID-19 Research: Lessons from Non-Human Primate Models (2021) doi: 10.3390/vaccines9080886 (available at www.ncbi.nlm.nih.gov/pmc/articles/PMC8402317/.
4 See IUCN, 100 of the World’s Worst Invasive Alien Species (available at www.iucngisd.org).
Contact: Eva Maciejewski
emaciejewski@nabr.org
(202) 967-8305
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