Mandrills (Mandrillus sphinx) are enigmatic primates endemic to central Africa and are threatened by habitat loss and hunting. However, effective management of this species is limited by insufficient information about their numbers in the wild, since population size can impact viability and genetic diversity. Here, we used for the first time a non-invasive genetic approach to estimate the census and effective population size (N_c and N_e respectively) of a wild mandrill horde in Lopé National Park (Gabon). We amplified a total of 232 unique genotypes using a panel of 16 microsatellite loci from mandrill fecal samples collected over three years (2016–2018). Using the single sample estimator in CAPWIRE, we obtained an estimate for N_c of 989 (95% CI 947–1399) individuals which was close to that obtained from the multiple sample estimator implemented in the program MARK [992 (95% CI 708–1453)]. These estimates approximately correspond with previous visual counts obtained from the same horde. Based on a model implemented in the program NeOGen, when samples were pooled across all three sampling sessions, statistical power was sufficient for a robust N_e estimate. Using the three one-sample estimators in the NeESTIMATORV2 program and the one in COLONY, Ne was estimated at 292 (95% CI 239–370) and 135 (95% CI 108–176) individuals respectively, indicating that N_e is between 13.6 and 29.5% of N_c. This study showed that non-invasive genetics is an effective tool for providing accurate estimates of horde sizes of mandrills and other elusive primates, provided enough samples and hypervariable loci are genotyped.

山魈（Mandrillus sphinx）是中非特有的神秘灵长类动物，受到栖息地丧失和狩猎的威胁。然而，由于种群规模会影响生存能力和遗传多样性，因此对其在野外数量的信息不足，限制了对该物种的有效管理。在这里，我们首次使用非侵入性遗传方法来估计洛佩国家公园（加蓬）野生山魈部落的人口普查和有效种群规模（分别为N _c和 N _{e ）。}我们使用三年（2016-2018 年）收集的山魈粪便样本中的 16 个微卫星基因座，扩增了总共 232 个独特的基因型。使用 CAPWIRE 中的单样本估计器，我们获得了 N _{c的估计值}989 (95% CI 947–1399) 个体的结果接近于从程序 MARK [992 (95% CI 708–1453)] 中实施的多样本估计器获得的结果。这些估计与从同一部落获得的先前视觉计数大致对应。基于程序 NeOGen 中实施的模型，当样本在所有三个采样会话中汇集时，统计能力足以进行稳健的 N _e估计。使用 NeESTIMATORV2 程序中的三个单样本估计器和 COLONY 中的一个，估计 Ne 分别为 292 (95% CI 239–370) 和 135 (95% CI 108–176) 个体，表明 N _e在 13.6 之间和 29.5% 的 N _c. 这项研究表明，如果对足够的样本和高变位点进行基因分型，非侵入性遗传学是准确估计山魈和其他难以捉摸的灵长类动物群规模的有效工具。