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Status of the northern muriqui (Brachyteles hypoxanthus) in the time of yellow fever


Understanding the impact of zoonotic diseases on wild primate populations is important for assessing local extinction risks and for evaluating potential mitigating factors. Comparative data on demographic changes in two isolated populations of the northern muriqui (Brachyteles hypoxanthus) during a severe yellow fever outbreak in southeastern Brazil provide unique insights into the potential effects of this disease in this Critically Endangered species. From October 2016 to April 2017, the muriqui population at the Reserva Particular do Patrimônio Natural—Feliciano Miguel Abdala (Caratinga) lost 31 of its 324 members, or nearly 10%, whereas the population at the Reserva Particular do Patrimônio Natural—Mata do Sossego (Sossego) declined from 34 to 25 individuals, or 26%. Greater per-capita risks to muriquis in the Sossego population could be related to ecological and anthropogenic differences, including a wetter climate and an absence of sympatric howler monkeys (Alouatta guariba), which may have directly or indirectly buffered the Caratinga muriquis. Although we lack definitive confirmation that the muriqui population declines were caused by yellow fever, the timing and magnitude of the losses strongly implicate the disease. We highlight the risks of catastrophic population declines in small populations and emphasize the value of long-term demographic monitoring studies.

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We thank the Brazilian government, Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), and the Sociedade para a Preservação do Muriqui for permission to conduct research at the RPPN Feliciano Miguel Abdala. The research here was supported with funds from the Vilas Research Professorship and the Graduate School of the University of Wisconsin-Madison to KBS, with logistical and administrative support provided by Preserve Muriqui and Conservation Internacional-Brasil. Andreia Maria da Silva, Luana Vinhas, Leticia Almeida, José Gustavo Adler, Renan César, Joice Lima, and Valeria Ribeiro helped with the demographic monitoring of the Caratinga muriquis during the present study. Other funding sources and contributors to the long-term database can be found at the Strier lab website, We also thank the Primate Action Fund/Conservation International and the Fundação Grupo Boticário de Proteção à Natureza for supporting the activities of the Projeto Muriquis do Sossego, and Fundação Biodiversitas, Muriqui Instituto de Biodiversidade (MIB), Mineração Curimbaba, the Associação dos Amigos do Meio Ambiente (AMA), Sr. Franscisco Portes, and Eduardo Bazém for logistical support. Sr. Jairo Joaquim de Andrade, Adriana Milagres, and Mateus Melo Dias helped with the demographic monitoring of the Sossego muriquis during the present study. We are grateful to Júlio César Bicca-Marques, Marco Antonio Barreto de Almeida, and an anonymous reviewer for their constructive comments, which have greatly improved our manuscript, and especially to Marco Antonio Barreto de Almeida for guiding us to key literature on yellow fever.

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Correspondence to Karen B. Strier.

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Strier, K.B., Tabacow, F.P., de Possamai, C.B. et al. Status of the northern muriqui (Brachyteles hypoxanthus) in the time of yellow fever. Primates 60, 21–28 (2019).

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  • Disease
  • Epizootic event
  • Demographic changes
  • Primate population
  • Atlantic forest