Concerns Raised Over IUCN's Decision on Long-Tailed Macaques Status

In a recent resolution dated October 9, 2025, the International Union for Conservation of Nature (IUCN) reaffirmed the endangered status of the long-tailed macaque (Macaca fascicularis). This decision has stirred controversy, following a petition submitted by the National Association for Biomedical Research (NABR) in 2023, which challenged the validity of this classification. The NABR argues that the IUCN's basis for this determination, specifically the studies by Hansen et al., misrepresent existing scientific data.

Dr. Ray Hilborn, a prominent scientist and member of the NABR’s scientific review team, expressed disappointment over the IUCN's failure to objectively appraise the scientific data presented to them. He stated, “The lack of data regarding the population trends combined with the misrepresentation of existing information raises serious doubts about the scientific process employed by the IUCN in reaching this decision.”

Supporting this claim, the U.S. Fish and Wildlife Service rejected a petition to list long-tailed macaques under the Endangered Species Act, saying it lacked credible information about the impact on the species populations. Their complete response was made available in the Federal Register, indicating that no credible evidence supported the designation of these primates as endangered.

The ongoing debates are not limited to the status of these macaques but also raise ethical questions about research practices and animal welfare. In fact, long-tailed macaques are paramount in biomedical research due to their physiological and genetic similarities to humans. They play a crucial role in developing essential medications, including five of the top twenty most commonly prescribed drugs. Their contributions have been pivotal, particularly in advancing fields like regenerative medicine, immunology, and cancer research—highlighted in a recent NIH report emphasizing their ongoing importance in biomedical research.

Despite this, Matthew R. Bailey, the NABR president, voiced his concerns about the IUCN yielding to pressure from animal welfare advocates, who seek to label the long-tailed macaque as endangered. He insisted that overwhelming scientific evidence indicates this species is neither endangered nor at risk, and noted that in some regions, they are even considered invasive. “It’s perplexing how the IUCN can classify the species as endangered while simultaneously recognizing it as one of the world's most invasive species,” Bailey stated.

The IUCN's classification has also sparked significant discussions in the U.S. government. A hearing by the U.S. House oversight committee revealed allegations of inappropriate influences by groups like PETA over governmental investigations into private entities and foreign nations for political reasons.

The NABR continues to advocate for the secure and humane use of animals in biomedical research, calling for heightened transparency in discussions surrounding animal welfare and scientific progress. Founded in 1979, it remains the sole nonprofit organization dedicated to promoting sound public policies that favor humane animal research practices across universities, medical institutions, and pharmaceutical companies.

In conclusion, as the debate over the long-tailed macaque’s status unfolds, it encapsulates a broader challenge of ensuring that scientific integrity prevails in conservation efforts while balancing ethical considerations regarding animal welfare. The NABR is committed to enlightening policymakers and the public about these vital issues to safeguard public health and uphold the scientific process's integrity.