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The main factors influencing feeding competition among members of diurnal primate groups are the distribution, availability, and quality of food resources. Socioecological models predict that temporal availability of preferred resources, such as fruit, can influence intragroup feeding competition, which is expected to affect rates of agonism and intragroup spatial patterns. We evaluated the effects of temporal variation in fruit availability on the degree of frugivory (i.e., the proportion of time spent feeding on fruit in relation to total food consumption) and the effects of fruit availability and degree of frugivory on rates of agonistic interactions, and intragroup proximity in two wild groups of gray woolly monkeys (Lagothrix lagotricha cana) in southwestern Brazilian Amazonia. We recorded 227 agonistic interactions via the all occurrences method and 3549 records of spacing via scan sampling during an 8-mo field study from March to October 2017. We found that fruit availability showed a positive relationship with the woolly monkeys' degree of frugivory, which in turn showed a positive relationship with the rates of agonism. We also found that degree of frugivory positively affected intragroup proximity in periods of lower fruit availability, and that agonistic interactions and proximity covaried positively. Conversely, as the degree of frugivory increased, monkeys exhibited greater interindividual distances and, consequently, lower rates of agonism, consistent with lower levels of feeding competition in periods of higher fruit availability. Therefore, we suggest that intragroup contest competition for fruits is an important cost of group living even for generalized, opportunistic frugivorous primates, such as woolly monkeys. [ABSTRACT FROM AUTHOR]

We collected systematic data on the home range and day ranges of one group of 57-63 muriquis (Brachyteles arachnoides hypoxanthus) at the Estação Biológica de Caratinga, Minas Gerais, Brazil from September 1998-July 1999, and compared them with similar data collected 15 years ago when the 23-27 individuals in the group traveled together as a cohesive unit. Home range size increased from 168 ha to 309 ha, reflecting an expansion into areas of the forest that were previously unutilized and consistent with the positive relationship predicted between group size and home range size. By contrast, muriquis exhibited remarkable seasonal and interannual stability in their day ranges. Day ranges, which were calculated from 144 days with ≥8 h of observation, averaged 1,313 ± 573 m (median = 1,206 m). Day ranges did not vary with the size of subgroups, defined as independent individuals that traveled with one another out of contact with other group members. Subgroups were significantly larger during the rainy season (mean = 41.8 ± 12. 7, median = 46.0 individuals, n = 72) than the dry season (mean = 36.6 ± 13.25, median = 39.5 individuals, n = 72). Subgroups were also larger than the size of the entire group during the previous study, yet their day ranges are indistinguishable. The stability in muriqui day ranges is consistent with predictions for folivorous primates in which other indicators of intragroup feeding competition, such as female dominance relationships, are also absent. We attribute the transition from cohesive to fluid grouping patterns to limits on the number of individuals that can coordinate their movements when they spread out while foraging and suggest that seasonal differences in subgroup sizes without corresponding adjustments in day ranges reflect seasonal differences in the distribution of preferred foods coupled with the effects of reproductive seasonality on muriqui grouping patterns. [ABSTRACT FROM AUTHOR]

We documented four adolescent female transfers—two emigrations, two immigrations—during a 12-month study from August 1994 to July 1995 on one group of muriquis (Brachyteles arachnoides) at Estação Biológica de Caratinga in Minas Gerais, Brazil. Intergroup transfers occurred throughout the year independent of season. A total of 613 focal samples of 10-min duration conducted on six adolescent females (5–9 years of age) revealed significant differences in the behavior of migrant versus natal resident females. During the seasons encompassing their respective group transfers, both emigrants and immigrants devoted more of their time to resting than resident females belonging to the same age cohorts did. Time spent feeding on mature fruit was higher for one emigrant and lower for both immigrants compared to the two resident females. Emigrant females had fewer neighbors within a 1-m radius than resident females did, whereas immigrant females were within a 1-m radius of adult females and within a 5-m radius of adult males more often than resident adolescent females were. Adolescent females were displaced on 26 occasions. Displacements occurred mainly during the dry seasons (n = 21) and mainly at food sources (n = 21). Using the number of focal samples conducted on each female as an estimate of observation time, immigrant females were displaced at twice the rate of residents. However, like other behavioral differences detected between resident and migrant adolescent females, differences in individual displacement rates were evident only during the season in which each of the immigrants joined the group. Collectively, our findings imply that female intergroup transfer in this population involves relatively mild, short-term costs. [ABSTRACT FROM AUTHOR]

Reports on the demography and behavioral patterns of muriquis or Brachyteles arachnoides. Nine-year monitoring at Fazenda Montes Claros, Minas Gerais, Brazil; Group size and composition; Home range; Grouping patterns; Implications for muriqui social structure; Future perspectives for the Matao group.

Habitat loss and fragmentation are known to restrict the movements of primates, including their ability to expand their home ranges. These effects are especially strong at high densities, where home range overlap can result in high rates of agonistic intergroup encounters over range defense. We investigated habitat use and range defense in a population of northern muriquis (Brachyteles hypoxanthus) at the Reserva Particular do Patrimônio Natural – Feliciano Miguel Abdala, in Minas Gerais, Brazil from August 2010 to July 2013. The four groups in this isolated population used 878 ha of forest, with home ranges exhibiting high interannual fidelity in location and low intergroup overlap. Core areas represented 13–29% of the respective home ranges and, except for one group, showed only moderate to low interannual fidelity in successive years. Of 130 intergroup encounters recorded in 2010–2011, significantly more occurred in core areas that overlapped with the range of another group than in areas of home range overlap or areas used exclusively by one group. Daily path lengths of the one group used in assessing range defensibility varied little (1075–1132 m) across years and relative to home range diameter did not meet the criteria for defensibility. However, the occurrence of independent subgroups, combined with a mean monthly detection distance of 242 m, provides strong evidence of range defensibility. These findings point to the importance of fission–fusion dynamics for intergroup range defense, particularly in primates living at high densities in fragmented habitats. [ABSTRACT FROM AUTHOR]

Primate research and conservation may inadvertently reproduce neocolonial dynamics when primatologists from affluent, imperialist nations conduct studies in primate habitat countries. Here, we consider how interrogating the positionality of both foreign researchers and range-country collaborators can strengthen primatology. Such consideration may help us to better understand where each member of the collaboration is coming from, both figuratively and literally, and how those situated perceptions shape the research process. Centering the perspectives of the range-country collaborators, whose perspectives are infrequently voiced within the primatology literature, may illuminate challenges in cross-cultural communication and imbalances of knowledge and power. Here, we explore how positionality shapes collaborative research through the narratives of two foreign/range-country collaborator teams doing primate research and conservation in Africa and South America. Our goal is to provide examples that consider the positionalities of range-country collaborators relative to both foreign researchers and local community members, and that serve as models for primate researchers as they consider their own research teams' positionalities. These narratives highlight how prioritizing the perspectives of range-country and local collaborators when they differ from those of foreign collaborators can strengthen future research and conservation efforts. [ABSTRACT FROM AUTHOR]

We examined the relationship between food patch size and feeding party size with comparative data from two populations of muriquis ( Brachyteles arachnoides) in the 37,797-ha forest at the Parque Estadual de Carlos Botelho (PECB), São Paulo, and the 800-ha forest at the Estação Biológica de Caratinga (EBC), Minas Gerais. Precipitation was more abundant and less seasonal at PECB than EBC, and the density of large trees (>25.0 cm) was higher at PECB (206 ha [sup -1] ) than at EBC (132 ha [sup -1] ). At both sites, the size of feeding parties is positively related to the size of food patches. As predicted, food patches at PECB are significantly larger than those at EBC for both fruit and leaf sources. Contrary to expectations, feeding parties were larger at EBC than PECB. The higher population density of muriquis and sympatric primates at EBC may make large associations more advantageous to these muriquis than to muriquis living at lower population densities in PECB. [ABSTRACT FROM AUTHOR]