Reassessment is Key
Recognizing the Issue
While presenting on the “World’s 25 Most Endangered Primates” in 2008, the co-founder of the International Primate Protection League Ardith Eudey expressed concerns about the declining populations and increasing threats to long-tailed macaques. These worries were later elaborated in the paper The crab-eating macaque (Macaca fascicularis): widespread and rapidly declining by Eudey (2008).
Years later in 2015, at another meeting of the International Primatological Society, she brought attention again to the long-tail macaques, highlighting how the species classified as Vulnerable under the IUCN Red List.
In 2021, three of the nine subspecies became Vulnerable under the IUCN Red List — namely the Macaca F. Fascicularis, the Con Son Long-tailed Macaque M. F. Condorensis, and the Nicobar Islands Long-tailed Macaque M. F. Umbrosa. The remaining six subspecies, all located on islands, were listed as Data Deficient (as shown in the table below).
The new IUCN update for the long-tail macaque has the potential to raise awareness to the burgeoning plight of the species and, in that, gather the funding needed for urgent research initiatives and conservation measures.
The Species Survival Network (2012) indicated that several populations across the range of long-tailed macaques, especially island populations, risk being decimated. As such, a core part of The Long-Tailed Macaque Project is to seek a clearer picture of the true distribution of this species in Southeast Asia.
Research and individual reports suggest that long-tailed macaque populations are decreasing in various parts of their range. The species is still perceived as abundant, but researchers speculate that their presence in human-inhabited areas leads to an overestimation of their population size.
Systematic surveys are therefore needed to assess their accurate size and distribution in order to ensure that policymakers are correctly informed in their management plans for the species.
Table 1 from Hansen, M. et al. 2021
Current (lack of) Information
The long-tailed macaque is distributed across Southeast Asia.
Previously grouped in ten subspecies, the Philippine Long-tailed Macaque, M. F. Philippinensis was sufficiently genetically similar to M. F. Fascicularis.
Information on the population size and distribution, as well as genetic and cultural diversity is currently insufficient on all nine remaining subspecies, but fundamental for effective conservation measures.
Due to their synanthropic nature, long-tailed macaques are distributed in both anthropogenic and non-anthropogenic areas, and therefore don’t occupy protected areas. From a practical perspective, conservation initiatives must target the smaller geographical scales — including the seven insular subspecies.
For the species’ global distribution, we still largely rely on the maps published by Fooden in the 90s, themselves based on surveys from the 70s and 80s. The range map below is used by the IUCN Red List and represents an updated version of the Fooden map.
No better or more recent distribution map is presently available.
In summary, we seek to assess the population size and distribution of long-tailed macaques across Southeast Asia and create an improved distribution map.
For that, we collect published data through databases, social media as well as unpublished data through direct contact with researchers.
We also create and train an international team who conducts census surveys in their own countries, using line-transect distance sampling. For more information, see Methods and Analysis used in Hansen et al. 2019.
Adapted from Hansen, M. F., Gill, M., Nawangsari, V. A., Sanchez, K. L., Cheyne, S. M., Nijman, V., & Fuentes, A. (2021). Conservation of Long-tailed Macaques: Implications of the Updated IUCN Status and the CoVID-19 Pandemic. Primate Conservation, 35, 1-11.