Advancing conservation of threatened primates
LUCIANA OKLANDE R * 1 , 2 ,ANDI E ANG3 and RAC H E L ASHE G BOFE IKEMEH4 Our closest living relatives—the non-human primates—are in trouble. Approximately 64% of the 536 currently recog- nized species are included in one of the threatened categor- ies of the IUCN Red List, with 16% categorized as Critically Endangered. How did this happen? Many factors combine to threaten primates: deforestation and habitat fragmenta- tion reduce resources and restrict dispersal and gene flow; encroachment and urban expansion into primate habitats extend the human–wildlife interface, heightening the poten- tial for conflicts and pathogen transmission; and extraction of primates for biomedicine, consumption and the pet and wildlife trade (notably for rituals and so-called medicine) re- duces populations and affects demography. These threats drive mortality, decrease adaptability and lead to local extinctions, with profound—and potentially irreversible— effects on primates and the ecosystems they inhabit. Unsurprisingly, all articles in the primate conservation theme in this issue of Oryx concern threatened species. Primates have long generation times (e.g. 22 years for gor-
illas; 12 years for howlermonkeys and langurs; 6 years for ta- marins), advanced ages at first reproduction, long lifespans and low fertility. Their conservation thus requires amatching long-term vision sustained by continuous efforts and re- sources. But, as Hameed et al. (2024) note in their review of primates in India,monitoring of primate populations is often short-lived and limited in geographical coverage. Further hindrances to primate conservation include
challenges of financing and logistics for environmental edu- cation, community conservation initiatives, maintenance of study sites, surveys and ranger patrols. Some logistical pro- blems, however, are now being addressed by the application of technologies such as camera traps, acoustic monitoring and drones, improving the efficiency of data collection, es- pecially for arboreal or cryptic species: unoccupied aerial ve- hicles have been used to survey the Critically Endangered cao vit gibbon Nomascus nasutus in China and Viet Nam (Wearn et al., 2024); the northern muriqui Brachyteles hy- poxanthus and buffy-headed marmoset Callithrix flaviceps, both Critically Endangered, have been detected in Caparaó National Park, Brazil, using arboreal infrared camera traps (Kaizer et al., 2022); occupancy-based camera-trap surveys have been used to assess the Critically Endangered Celebes
*Corresponding author,
lula_ok@yahoo.com.ar 1Grupo de Investigación en Genética Aplicada, Instituto de Biología Subtropical, Universidad Nacional de Misiones—Consejo Nacional de Investigaciones
Científicas y Técnicas, Argentina 2Neotropical Primate Conservation, Argentina 3Mandai Nature, Singapore 4SW/Niger Delta Forest Project, Nigeria
crested macaque Macaca nigra across its range in North Sulawesi, Indonesia (Johnson et al., 2020); and multi-strata camera traps have been used to examine habitat use by the Endangered dryas monkey Chlorocebus dryas in the Democratic Republic of the Congo (Alempijevic et al., 2022). We cannot develop conservation plans for threatened primates without accurate population assessments (Rylands et al., 2020). These novel studies, together with more traditional research— such as for the Endangered ring-tailed lemur Lemur catta in Madagascar (Randrianjaka et al., 2024), the Endangered gold- en monkey Cercopithecusmitis kandti in Rwanda (Tuyisingize et al., 2023), the Critically Endangered Vieira’stiti monkey Plecturocebus vieirai in Brazil (Costa-Araújo et al., 2022), and the Critically Endangered Delacour’slangur Trachypithecus delacouri in Viet Nam (Nguyen et al., 2022)—all deal with surveys and the provision of essential baseline data. A further challenge is ensuring that evidence from re-
search is used appropriately and promptly by policymakers for management and conservation purposes. An example of a success story in this respect is the marked increase in the population size of the Critically Endangered white-headed langur Trachypithecus leucocephalus in China (Tang et al., 2024) following government intervention to reduce poach- ing. Population surveys conducted in 2010/2011 and 2020/ 2021 in the Chongzuo White-Headed Langur National Nature Reserve, Guangxi Province—home to 95% of the few known individuals—recorded an increase in the num- ber of both individuals and groups over this period. Poaching for food and traditional medicine is no longer the main threat to these langurs, although forest loss and fragmentation continue. Like other animals, primates do not respect national boundaries, and threatened species that occur in more than one jurisdiction potentially face additional problems from uneven conservation efforts. Transboundary collabo- ration and coordination are key in such situations. For ex- ample, the only known population of the cao vit gibbon occurs along the border between China and Viet Nam, and the home ranges of groups often span the two countries. Collaborative transboundary censuses in the Bangliang Gibbon National Nature Reserve in China and Trung Khanh Cao Vit Gibbon Species and Habitat Conservation Area in Viet Nam demonstrated a slow increase in this population from 2007 to 2016 (Ma et al., 2020).Amemoran- dum of understanding between the two countries for co- operative conservation of the cao vit gibbon, along with a transboundary action plan, collaborative approaches to counter hunting, and informal meetings on the border have all facilitated the conservation of this species. But as
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (
http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited. Oryx, 2024, 58(2), 137–138 © The Author(s), 2024. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605324000371
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