With approximately 30% of nonhuman primate species listed as critically endangered, the window of opportunity to conserve primates is closing fast. In this article, we focus on the degree to which publications in field primatology are biased in favor of particular taxa and field sites. We examined more than 29,000 peer‐reviewed articles and identified 876 field visits to 349 field sites. We found a highly clumped distribution by site and species. We also examined publication ethical statements and the extent to which they acknowledged local human communities (<5%). Due to a lack of consistency across publications, we provide recommendations for improving ethical statements and for evaluating research impact. Given the plight of primate biodiversity, these results suggest broader coverage of primate species and geographies, as well as more attention to the local human communities whose support is necessary if the intent is to have primate species in the wild in the 22nd century.

Ultimately, these methods will help researchers identify more precisely how primate gait kinematics respond to the complexity of arboreal habitats, furthering our understanding of the adaptive context in which primate quadrupedalism evolved.

The grasping capabilities and gait kinematics characteristic of primates are often argued to be adaptations for safely moving on small terminal branches. The goal of this study was to identify whether Eastern gray squirrels (Sciurus carolinensis) -arboreal rodents that frequently move and forage on small branches, lack primate-like grasping and gait patterns, and arguably represent extant analogs of a stem primate ancestor -adjust gait kinematics to narrow and non-horizontal branches. We studied locomotor kinematics of free-ranging and laboratory-housed squirrels moving over various substrates. We used high-speed video to film 1) a population of free-ranging squirrels moving on natural substrates and 2) laboratory-housed squirrels moving on horizontal poles. Substrates were coded as small, medium, or large relative to squirrel trunk diameter, and as inclined, declined, or horizontal. Free-ranging squirrels used more gallops and half-bounds on small and medium sized substrates, and more high-impact bounds, with reduced limb lead durations, on declined substrates. Laboratory squirrels moved at higher speeds than free-ranging squirrels and responded to decreasing diameter by using more gallops and half-bounds, lowering speed, and -controlling for speed -increasing mean duty factor, mean number of supporting limbs, and relative forelimb lead duration. Our inability to detect substantial diameter or orientation-related gait adjustments in the wild may be due to a limited accounting of confounding influences (e.g., substrate compliance).Ultimately, studies assessing stability measures (e.g., center of mass fluctuations, peak vertical force) are required to assess whether primates' enhanced grasping and gait patterns engender performance advantages on narrow or oblique substrates.

Arboreal environments present considerable biomechanical challenges for animals moving and foraging among substrates varying in diameter, orientation and compliance. Most studies of quadrupedal gait kinematics in primates and other arboreal mammals have focused on symmetrical walking gaits and the significance of diagonal sequence gaits. Considerably less research has examined asymmetrical gaits, despite their prevalence in small-bodied arboreal taxa. Here, we examined whether and how free-ranging callitrichine primates adjust asymmetrical gait kinematics to changes in substrate diameter and orientation, as well as how variation in gait kinematics affects substrate displacement. We used high-speed video to film free-ranging Saguinus tripartitus and Cebuella pygmaea inhabiting the Tiputini Biodiversity Station, Ecuador. We found that S. tripartitus used bounding and half-bounding gaits on larger substrates versus gallops and symmetrical gaits on smaller substrates, and also shifted several kinematic parameters consistent with attenuating forces transferred from the animal to the substrate. Similarly, C. pygmaea shifted from high-impact bounding gaits on larger substrates to using more half-bounding gaits on smaller substrates; however, kinematic adjustments to substrate diameter were not as profound as in S. tripartitus. Both species adjusted gait kinematics to changes in substrate orientation; however, gait kinematics did not significantly affect empirical measures of substrate displacement in either species. Because of their small body size, claw-like nails and reduced grasping capabilities, callitrichines arguably represent extant biomechanical analogs for an early stage in primate evolution. As such, greater attention should be placed on understanding asymmetrical gait dynamics for insight into hypotheses concerning early primate locomotor evolution.

Who do we aim to educate with primate conservation education programs (PCEPs)? In a commentary published in a recent AJP, Annette Lanjouw suggested that many efforts to “educate” habitat‐country communities can be neocolonial in their approaches. Forest destruction and habitat loss are a result of global consumption and expansion. We therefore need to approach conservation education from many angles including local stakeholders, policy makers, government officials, and the humans living in industrialized nations who are major consumers of the items that shrink primate habitats. In this review, we investigate PCEPs to determine if the conservation education goals, education methods, and assessment processes are proceeding within a neocolonial context. We reviewed the last 20 years of primate conservation literature and looked for publications that were focused on education programs. We found that in 50 of 52 publications published between 2001 and 2021, the education programs take place in habitat‐country local communities. We also reviewed primate field researcher and field site websites, and in most cases, education programs were also focused on educating local communities living near or in nonhuman primate habitats. Exceptions were student clubs, zoo programs, and a high school outreach program. Many PCEP providers presented a list of “lessons learned” and we compiled their wisdom in combination with our experience to provide a framework for moving forward. We conclude that as conservation primatologists, we must think beyond our field sites to create opportunities for educational outreach. We can reach global consumers by linking to zoos, television/motion picture, print media, social media, and working with schools on curricula. Primatologists can engage our undergraduates to establish clubs and create meaningful assignments that reach beyond the classroom. We encourage primatologists from the Global North to consider their positionality and the history of conservation exclusion in their attempts to conserve primates.

Objectives: Primate diagonal sequence (DS) gaits are often argued to be an adaptation for moving and foraging in the fine-branch niche; however, existing data have come predominantly from laboratory studies that are limited in taxonomic breadth and fail to account for the structural and ecological variation of natural substrates.We test the extent to which substrate diameter and orientation influence gait sequence type and limb phase in free-ranging primates, as well as how phylogenetic relatedness might condition response patterns. Materials and methods:We filmed quadrupedal locomotion in 11 platyrrhine species at field sites in Ecuador and Costa Rica and measured the diameter and orientation of locomotor substrates using remote sensors. We quantified limb phase values and classified strides by gait sequence type (N = 988 strides). Results:Our results show that most of the species in our sample consistently used DS gaits, regardless of substrate diameter or orientation; however, all taxa also used asymmetrical and/or lateral sequence gaits. By incorporating phylogenetic eigenvectors into our models, we found significant differences in gait sequence patterns and limb phase values among the major platyrrhine clades, suggesting that phylogeny may be a better predictor of gait than substrate diameter or orientation.Discussion: Our field data generally corroborate locomotor patterns from laboratory studies but capture additional aspects of gait variability and flexibility in response to the complexity of natural environments. Overall, our results suggest that DS gaits are not exclusively tailored to narrow or oblique substrates but are used on arboreal substrates in general. K E Y W O R D Sarboreal quadrupedalism, locomotion, phylogenetic eigenvector, platyrrhine

No abstract

Wild primates encounter complex matrices of substrates that differ in size, orientation, height, and compliance, and often move on multiple, discontinuous substrates within a single bout of locomotion. Our current understanding of primate gait is limited by artificial laboratory settings in which primate quadrupedal gait has primarily been studied. This study analyzes wild Saimiri sciureus (common squirrel monkey) gait on discontinuous substrates to capture the realistic effects of the complex arboreal habitat on walking kinematics. We collected high-speed video footage at Tiputini Biodiversity Station, Ecuador between August and October 2017.Overall, the squirrel monkeys used more asymmetrical walking gaits than symmetrical gaits, and specifically asymmetrical lateral sequence walking gaits when moving across discontinuous substrates. When individuals used symmetrical gaits, they used diagonal sequence gaits more than lateral sequence gaits. In addition, individuals were more likely to change their footfall sequence during strides on discontinuous substrates. Squirrel monkeys increased the time lag between touchdowns both of ipsilaterally paired limbs (pair lag) and of the paired forelimbs (forelimb lag) when walking across discontinuous substrates compared to continuous substrates. Results indicate that gait flexibility and the ability to alter footfall patterns during quadrupedal walking may be critical for primates to safely move in their complex arboreal habitats. Notably, wild squirrel monkey quadrupedalism is diverse and flexible with high proportions of asymmetrical walking. Studying kinematics in the wild is critical for understanding the complexity of primate quadrupedalism. K E Y W O R D S arboreal locomotion, asymmetrical walking, positional behavior, squirrel monkeys, wild primates