Populations

Reassessment is Key

In 2008, Ardith Eudey, co-founder of the International Primate Protection League and long-time chair of the Asia section of the IUCN Primate Specialist Group, raised concerns at the International Primatological Society’s presentation of the “World’s 25 Most Endangered Primates” regarding the declining populations and increasing threats to long-tailed macaques Macaca fascicularis. This was consolidated and expanded upon in a paper “The crab-eating macaque (Macaca fascicularis): widespread and rapidly declining” published by Eudey in Primate Conservation in 2008. In 2015, she again raised the alarm bells at another meeting of the International Primatological Society, and it is now recognized that, as a species, long-tailed macaques meet the criteria for them to be listed as Vulnerable on the IUCN Red List. In January 2021, three of the nine M. fascicularis subspecies were also listed as Vulnerable on the IUCN Red List—the nominate subspecies Macaca f. fascicularis, the Con Son long-tailed macaque M. f. condorensis, and the Nicobar Islands longtailed macaque M. f. umbrosa. The remaining six, all island forms, were listed as Data Deficient (see table below).  The new IUCN update for this species has the potential to increase attention to the burgeoning plight of the species and, with that, the funding needed for urgent research initiatives and conservation measures. on measures. Research and anecdotal evidence suggest that long-tailed macaque populations are decreasing in various parts of their range. The species is still perceived as abundant, but researchers have speculated that the presence of long-tailed macaques in anthropogenic areas may lead to overestimation of their population size. Systematic surveys are needed to assess their true population size to ensure that policymakers are correctly informed when creating management plans for the species. 

Table 1 from Hansen, M. et al. 2021

The long-tailed macaque is distributed across Southeast Asia. Formerly with 10 subspecies, the Philippine long-tailed macaque, M. f. Philippinensis was found to be insufficiently genetically differentiated and is now considered to be a junior synonym of M. f. fascicularis. Information on population size and distribution and genetic and cultural diversity is insufficient or lacking for the nine remaining subspecies, yet highly needed to ensure effective conservation measures. Due to their synanthropic nature, long-tailed macaques are distributed in both anthropogenic and non-anthropogenic areas, and therefore often not reliant on protected areas. From a practical and management perspective, conservation initiatives will also have to be targeted at the smaller geographical scales including the seven insular subspecies and otherwise geographically restricted regions. For the species’ global distribution, we still largely rely on the maps published by Fooden in 1995, which were based on field surveys in the 1970s and 1980s and, for many areas, on museum collections. The range map shown below is used by the IUCN Red List is an updated version of the Fooden map. A more recent distribution map is not available. Additionally, the Species Survival Network (2012) indicated that several populations across the range of long-tailed macaques, especially island populations may well be decimated. As such, a part of The Long-Tailed Macaque Project’s mission is to have a clearer picture of the true distribution of this species in Southeast Asia.

Image Credit: IUCN Red List

In summary, we plan to assess the population size and distribution of long-tailed macaques across Southeast Asia and the create a distribution map. We will conduct online data collection using databases and social media and contact researchers for unpublished data. We will also create and train an international team, who will conduct census surveys in their own countries using line-transect distance sampling referring to 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 Conservation35, 1-11.

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