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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.

Demographic data are essential to assessments of the status of endangered species. However, establishing an integrated monitoring program to obtain useful data on contemporary and future population trends requires both the identification of priority areas and populations and realistic evaluations of the kinds of data that can be obtained under different monitoring regimes. We analyzed all known populations of a critically endangered primate, the muriqui (genus: Brachyteles) using population size, genetic uniqueness, geographic importance (including potential importance in corridor programs) and implementability scores to define monitoring priorities. Our analyses revealed nine priority populations for the northern muriqui (B. hypoxanthus) and nine for the southern muriqui (B. arachnoides). In addition, we employed knowledge of muriqui developmental and life history characteristics to define the minimum monitoring intensity needed to evaluate demographic trends along a continuum ranging from simple descriptive changes in population size to predictions of population changes derived from individual based life histories. Our study, stimulated by the Brazilian government's National Action Plan for the Conservation of Muriquis, is fundamental to meeting the conservation goals for this genus, and also provides a model for defining priorities and methods for the implementation of integrated demographic monitoring programs for other endangered and critically endangered species of primates.

Assessments of the status of endangered species have focused on population sizes, often without knowledge of demographic and behavioral processes underlying population recovery. We analyzed demographic data from a 28-year study of a critically endangered primate, the northern muriqui, to investigate possible changes in demographic rates as this population recovered from near extirpation. As the population increased from 60 to nearly 300 individuals, its growth rate declined due to increased mortality and male-biased birth sex ratios; the increased mortality was not uniform across ages and sexes, and there has been a recent increase in mortality of prime-aged males. If not for a concurrent increase in fertility rates, the population would have stabilized at 200 individuals instead of continuing to grow. The unexpected increase in fertility rates and in adult male mortality can be attributed to the muriquis' expansion of their habitat by spending more time on the ground. The demographic consequences of this behavioral shift must be incorporated into management tactics for this population and emphasize the importance of understanding demographic rates in the recovery of endangered species.

Social, ecological, and historical processes affect the genetic structure of primate populations, and therefore have key implications for the conservation of endangered species. The northern muriqui (Brachyteles hypoxanthus) is a critically endangered New World monkey and a flagship species for the conservation of the Atlantic Forest hotspot. Yet, like other neotropical primates, little is known about its population history and the genetic structure of remnant populations. We analyzed the mitochondrial DNA control region of 152 northern muriquis, or 17.6% of the 864 northern muriquis from 8 of the 12 known extant populations and found no evidence of phylogeographic partitions or past population shrinkage/expansion. Bayesian and classic analyses show that this finding may be attributed to the joint contribution of female-biased dispersal, demographic stability, and a relatively large historic population size. Past population stability is consistent with a central Atlantic Forest Pleistocene refuge. In addition, the best scenario supported by an Approximate Bayesian Computation analysis, significant fixation indices (Φ(ST) = 0.49, Φ(CT) = 0.24), and population-specific haplotypes, coupled with the extirpation of intermediate populations, are indicative of a recent geographic structuring of genetic diversity during the Holocene. Genetic diversity is higher in populations living in larger areas (>2,000 hectares), but it is remarkably low in the species overall (θ = 0.018). Three populations occurring in protected reserves and one fragmented population inhabiting private lands harbor 22 out of 23 haplotypes, most of which are population-exclusive, and therefore represent patchy repositories of the species' genetic diversity. We suggest that these populations be treated as discrete units for conservation management purposes.

The size and composition of primate groups affect dispersal and reproductive opportunities, and thus have implications for the conservation and management of endangered species. Group fissions that increase dispersal options can reduce close inbreeding, particularly in small, isolated populations that are candidates for translocation and other forms of management. While the impact of group size on permanent group fissions has been well documented in matrilocal societies, less is known about the process of permanent fission in patrilocal primates. Here, we use social network analyses of four years of scan-sample data (2011–2014) to retrospectively investigate whether membership in a newly fissioned group of northern muriquis (Brachyteles hypoxanthus) at the Reserva Particular do Patrimônio Natural – Feliciano Miguel Abdala, Caratinga, Minas Gerais, Brazil, could be predicted from prior social relationships. Modularity metrics indicated the start of the Matão group fission during the 2012–2013 mating season, with a distinct subgroup of individuals that formed the new Nancys group being evident. Dyadic associations were significantly stronger and eigenvector centrality values were significantly higher among the individuals that formed the Nancys group than among those that remained in the Matão group. One mother and her four adult sons were among the founders of the Nancys group, but other mother-adult son families did not fission together. Our analyses add to the literature on permanent fissions in patrilocal societies. They also suggest that the modularity metric of social network analyses can be useful in identifying the best timing for implementing management programs that take social preferences into account. Such considerations can contribute to informed decisions about translocations, reintroductions, and the rehabilitation of groups or subgroups in the conservation management of endangered primates such as muriquis. [ABSTRACT FROM AUTHOR]

Citizen Science (CS) is a process that engages members of the public in the collection and interpretation of scientific data in collaboration with scientists. It is especially useful for monitoring biodiversity over extended periods and at larger scales than most researchers can cover themselves. Here we present preliminary insights from a project initiated to evaluate the potential of a systematic CS program to monitor primates in small fragments of Atlantic Forest surrounding the Reserva Particular de Patrimônio Natural Feliciano Miguel Abdala (RPPN-FMA), in Caratinga, Minas Gerais, Brazil. This region was near the center of a severe yellow fever outbreak that peaked in late 2016 and early 2017, which coincided with steep declines in the known populations of the four species of primates that occur sympatrically in the RPPN-FMA (Alouatta guariba, Brachyteles hypoxanthus, Callithrix flaviceps, and Sapajus nigritus). Nothing, however, was known about the status of these species in the surrounding forest fragments. To gain rapid insights into the status of primates in these fragments and at the same time to assess the feasibility of developing a more systematic CS program in the future, we visited 54 landowners within 6 km of the reserve, 49 of which agreed to participate by sharing their perceptions of primate presence or absence before and after the yellow fever outbreak, and in the subsequent potential recovery period. Consistent with the decline in primate populations in the RPPN-FMA and another region in southeastern Brazil, participants residing around the reserve perceived the greatest declines in populations of Alouatta and Callithrix, followed by Sapajus, with a comparatively small decline in Brachyteles. Participant perceptions, reflected in their monthly reports from June 2018 to June 2020, suggest that the presence of Alouatta (detected significantly more often by auditory cues) and Callithrix returned to pre-yellow fever levels, while that of Sapajus (detected more by visual cues) exceeded pre-yellow fever levels. The only species with seasonal variation in participant perceptions was Callithrix. Although systematic censuses are needed to calibrate participant reports, there is clear potential for the development of a more comprehensive CS program as part of conservation efforts to monitor primate species in this region. [ABSTRACT FROM AUTHOR]

National action plans for the conservation of threatened fauna species (PANs) are instruments to promote the implementation of global biodiversity targets on a national scale. In Brazil, 74.8% of threatened animal species were covered with PANs by the end of 2019. In this study we evaluate the contribution of these PANs as tools for species conservation and for attaining Aichi targets. Between 2004 and 2019, 38 PANs were concluded, and 42.76% of the 2,044 actions, included in the PANs, were achieved. These actions promoted a series of conservation measures that contributed to 10 of the 20 Aichi targets, resulting in direct benefits for the target species. [ABSTRACT FROM AUTHOR]

Many arboreal primates descend to the ground, a custom that may occur more frequently in disturbed habitats, and in the presence of researchers to whom the primates are habituated. In this paper, we describe opportunistic observations of ground use in two groups of northern muriquis (Brachyteles hypoxanthus) at the RPPN Feliciano Miguel Abdala, Minas Gerais, Brazil. Members of both groups were observed drinking, resting, feeding, playing, and traveling on the ground to different degrees, and variation in the levels of habituation of the two groups may be responsible for the differences in the distribution of their terrestrial activities. The potential increase in vulnerability to predation or disease owing to ground use has implications for the conservation of this critically endangered species. Am. J. Primatol. 69:706–712, 2007. © 2007 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

The northern muriqui (Brachyteles hypoxanthus) is a critically endangered species endemic to the Atlantic Forest of southeastern Brazil. Long‐term observational studies of wild muriquis have provided many insights into the behavioral ecology and life history of this species. However, nearly everything that is currently known about the northern muriqui's behavioral endocrinology has come from combining our respective expertise in noninvasive field and laboratory research. Here, we reflect on the history of our collaboration, focusing on major challenges, key scientific findings, and factors that contributed to its success. Challenges included insuring the reliable collection of frequent fecal samples from a large enough number of known individuals over extended periods of time, preserving the steroids in the field and transporting them, developing and validating the fecal steroid assays, and interpreting the hormonal profiles within the behavioral and ecological contexts of the study subjects. Major findings included our thorough description of the fecal progesterone and estradiol profiles associated with muriqui ovarian cycling and gestation, the seasonal resumption of cycling, its onset during puberty of dispersing females, and the differences between fertile and infertile cycles. We also documented the relationship between fecal cortisol and testosterone in sexually active males across breeding and nonbreeding seasons, and sex differences in cortisol levels across the mating and conception seasons. We attribute the success of our collaboration to a number of factors including our mutual appreciation for one another's high standards for ethics, data quality, and data interpretation. [ABSTRACT FROM AUTHOR]