Long-tailed macaques, monkeys native to Southeast Asia, have been listed as endangered on the IUCN Red List since 2022 after their populations declined by at least 50% over 30 years. Yet, the U.S. Fish and Wildlife Service (FWS) has twice now declined to consider protecting the species under the domestic Endangered Species Act. The most recent decision was announced on July 14, 2026. Such a listing would have restricted the primate’s import for biomedical research, one of the biggest threats to its population.
Mongabay asked FWS for comment but did not receive a response by publication.
Long-tailed macaques (Macaca fascicularis) can live in a wide variety of habitats, from riverbanks and mangroves to rainforests and, even, cities. Despite their adaptability, populations of the medium-sized primates have declined sharply due to habitat loss, climate change, hunting and trade, primarily for biomedical research, according to the IUCN, the global wildlife conservation authority.
A 2025 study found that macaques poached from the wild are likely supplementing the breeding farms in Cambodia, Laos and Vietnam that supply laboratories abroad.
Lisa Jones-Engel, chief scientific advisor for primate experimentation with People for the Ethical Treatment of Animals (PETA), said trapping macaques for medical testing is the biggest factor in their population decline.
