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Habitat fragmentation due to human activities is one of the principal threats to all primates and is particularly so for arboreal platyrrhines. Its impact has been extreme in the Brazilian Atlantic forest, where most primate populations have been severely reduced in numbers and their distributions restricted, resulting in low probabilities of long-term persistence. One of the most severely affected species is the northern muriqui (Brachyteles hypoxanthus), which today has fewer than 1,000 individuals distributed over only a dozen populations and is considered to be Critically Endangered. Most of these populations are isolated and smaller than 50 individuals, including the population inhabiting the Sossego Forest in Simonésia, Minas Gerais. With fewer than 30 individuals associating in one social group, the Sossego muriqui population is doomed to extinction unless emergency management measures are implemented to protect it. We monitored the demography of the Sossego muriquis to evaluate the impacts of the introduction of a reproductive-aged female that was translocated into this population in December 2006. Data were collected on all individuals, identifiable from their natural markings, during 3 to 12 monthly surveys conducted each year from July 2012 to June 2020. They revealed that the population grew from 32 individuals in July 2012 to a peak of 38 in September 2015, but then declined to a low of 22 individuals in September 2017, coinciding with a yellow fever outbreak in the region. As of June 2020, there were 24 individuals present. Four of the surviving individuals were the translocated female and three of her five offspring. One of her daughters was confirmed to have emigrated to another forest fragment and a second daughter has not been seen since March 2019 and is suspected to have emigrated. During the eight years of monitoring, we recorded 17 births (11 females and six males) and 25 disappearances involving 17 females, including the female confirmed to have dispersed, and eight males. Our results emphasize the risks of demographic stochasticity in small, isolated populations. The confirmed emigration of one dispersal-aged female that failed to locate a group to join, and the absence of any immigrants, call attention to the demographic implications of translocation as a potential conservation tool for small, isolated populations of species such as the northern muriqui in which female dispersal and male philopatry are typical. [ABSTRACT FROM AUTHOR]

Interest in intraspecific behavioral variation has grown with concerns about the ability of primates to adapt to the rapidly changing ecological and demographic conditions that threaten their survival. Now, in addition to identifying the causes and phylogenetic distribution of normative, species-specific behavior patterns for interspecific comparisons, there is widespread recognition of the need to incorporate intraspecific variation. This variation is evident across groups and populations of the same species as well over the long histories of single groups of long-lived, socially complex animals with overlapping generations. Yet, analyses of both cross-sectional and longitudinal data require explicit criteria about how to classify and interpret behavioral variation, and must be sensitive to the limitations of space-for-time substitutions in these comparisons. Current approaches have made great advances, but there remains an urgent challenge of understanding intraspecific variation in a way that will facilitate the development of new predictive models to assess population resilience and extinction risks in the face of climate change and other anthropogenic influences. [ABSTRACT FROM AUTHOR]

Understanding variation in habitat quality, diet, and behavioral patterns is fundamental for the development of conservation strategies for threatened primates. From June-August 2013, we conducted a preliminary study of four northern sportive lemurs (Lepilemur septentrionalis)-Critically Endangered, solitary-foraging primates living in different forest fragments in Montagne des Français, Madagascar. We sought to obtain the first systematic data on the behavior and feeding ecology of this species in the wild, and identify potential differences in habitat characteristics. The four individuals in our study are estimated to represent approximately 8% of the known population of this species, about which very little else is known. Our data showed that the variety of plant parts consumed did not differ among the four individuals despite differences in habitat as determined by measures of anthropogenic disturbance, tree density, species diversity, total tree basal area, and presence of invasive species. The data suggest, however, that individuals in areas that suffer more anthropogenic threats spent slightly more time feeding, devoted a greater percentage of feeding time to fruit than to leaves, and had larger home ranges than those in areas with fewer different anthropogenic activities. Our results suggest that the ability of the northern sportive lemur to adjust its behavior under different environmental conditions may be beneficial to their ability to persist in degraded habitats. [ABSTRACT FROM AUTHOR]

Long-term field studies of wild primates can have far-reaching impacts that transcend their contributions to science. These impacts can benefit not only the study animals, study areas, and local human communities, but they can also have unintended, potentially negative consequences. Examples of some of the positive impacts from the Northern Muriqui Project of Caratinga, in Minas Gerais, Brazil, include contributions to conservation efforts on behalf of this critically endangered species, capacity building through the training of Brazilian students, and employment opportunities for local people through our collaboration with a locally administered NGO that is facilitating ecotourism, education, and reforestation programs. Some concerns about unintended consequences of the research include the effects of our trails and trail traffic on surrounding vegetation and other aspects of the environmental “footprints” that both long-term researchers and short-term visitors may leave. In addition, although precautions against potential health risks from routine exposure to human observers are now standard protocol, little is known about the other ways in which our long-term research presence can affect the primates' experiences or alter their perceptions of their social and ecological environments. Risk analysis, which weighs both the positive and negative impacts can provide useful perspectives for addressing the ethical considerations that can arise during long-term field studies. Am. J. Primatol. 72:772–778, 2010. © 2010 Wiley-Liss, Inc. [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 taxonomy of muriquis, the largest extant primates in the New World, is controversial. While some specialists argue for a monotypic genus (Brachyteles arachnoides), others favor a two‐species classification, splitting northern muriquis (Brachyteles hypoxanthus) from southern muriquis (B. arachnoides). This uncertainty affects how we study the differences between these highly endangered and charismatic primates, as well as the design of more effective conservation programs. To address this issue, between 2003 and 2017 we collected over 230 muriqui fecal samples across the genus' distribution in the Brazilian Atlantic Forest, extracted DNA from these samples, and sequenced 423 base pairs of the mitochondrial DNA (mtDNA) control region. Phylogenetic and species delimitation analyses of our sequence dataset robustly support two reciprocally monophyletic groups corresponding to northern and southern muriquis separated by an average 12.7% genetic distance. The phylogeographic break between these lineages seems to be associated with the Paraíba do Sul River and coincides with the transition between the north and south Atlantic Forest biogeographic zones. Published divergence estimates from whole mitochondrial genomes and nuclear loci date the split between northern and southern muriquis to the Early Pleistocene (ca. 2.0 mya), and our new mtDNA dataset places the coalescence time for each of these two clades near the last interglacial (ca. 120–80 kya). Our results, together with both phenotypic and ecological differences, support recognizing northern and southern muriquis as sister species that should be managed as distinct evolutionarily significant units. Given that only a few thousand muriquis remain in nature, it is imperative that conservation strategies are tailored to protect both species from extinction. Research Highlights: Phylogenetic analysis of mitochondrial DNA from "northern" and "southern" muriquis identifies these primates as falling into two reciprocally monophyletic lineages. These taxa also differ phenotypically, ecologically, and possibly behaviorally.While dated mitochondrial and nuclear DNA phylogenies suggested the divergence between the two Brachyteles species around the start of the Pleistocene (ca. 2.0 mya), the coalescence times for both the northern and southern lineages are much more recent (ca. 120–80 kya).Together, these data support the recognition and conservation management of northern and southern muriquis as distinct species. [ABSTRACT FROM AUTHOR]