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Subadult female Angola black and white colobus monkey (Colobus angolensis palliatus) feeding from a seated position in the Diani Forest, Kenya
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In this project I studied black and white colobus monkeys (Colobus angolensis palliatus) inhabiting the Diani Forest of south coastal Kenya to test whether activity budgets, positional behavior, and support use differed among individuals in three age categories (juveniles, subadults, and adults). Data for three habituated groups were collected from...
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Preuss’s red colobus is critically endangered and endemic to Cameroon and Nigeria. It is one of the least studied red colobus species and therefore further knowledge about the species is crucial for conservation work. Activity budget of Preuss’s red colobus was carried in the southern part of Korup National Park, South West region of Cameroon for 1...
Citations
... Studying postural behavior in primates can provide important data for a deeper understanding of their morphological anatomy, ecology, and environmental adaptations [2,4]. Primate postural behavior is not only influenced by their morphological structure [5][6][7], physiological characteristics [8,9], and individual developmental characteristics [9,10] but also influenced by their habitat's structure [1,11,12], spatial distribution patterns of food resources, and their seasonal variations [13][14][15], as well as temperature [16]. ...
The feeding posture of a group of François’ langurs in Fusui County, Guangxi, was studied using instantaneous scan sampling from January to December 2016 to explore how the species adapts to karst limestone forests by collecting data on feeding posture, forest strata height, and substrate use. The results showed that leaves were the main food type of the François’ langurs, with young leaves accounting for 64.97% ± 19.08% of the food composition, mature leaves accounting for 11.88% ± 12.09%, fruits accounting for 12.96% ± 12.89%, flowers accounting for 4.16% ± 4.06%, and other food types, including stems, petioles, and other unknown parts of the tree, accounting for a total of 6.03% ± 9.09%. The François’ langurs had four main postures during feeding, of which sitting and bipedal standing feeding accounted for the largest proportions, at 85.99% ± 5.97% and 12.33% ± 6.08% of the total records, respectively. Quadrupedal standing and suspending were rarely observed and only appeared occasionally during feeding activities at the peak resting period, the two postures together accounting for 1.39% ± 1.59% of the total records. The feeding postures of the langurs had marked seasonal variation, as evidenced by the fact that seated feeding accounted for a significantly higher proportion of the total behavioral records in the rainy season than in the dry season, whereas feeding while standing bipedally was significantly more frequent during the dry season. Correlation analyses showed that feeding posture was correlated with food composition, showing a positive correlation between the proportion of bipedal standing feeding and mature leaf consumption. François’ langurs preferred to forage in the lower and middle forest layers, with the lower forest layer accounting for 55.93% ± 16.50% of the total number of recordings and the middle forest layer accounting for 33.63% ± 18.33%. Langurs were less likely to forage on the ground (rocks), accounting for only 6.79% ± 4.78% of the records. The frequency of langurs feeding in the upper part of the forest layer was the lowest at 3.65% ± 2.73%. Additionally, in the dry season, langurs utilized the lower forest layer more but used the middle forest layer less than in the rainy season. This study demonstrates that the spatial distribution of foods in the limestone forest has an important effect on the feeding posture of François’ langurs and their forest layer utilization.
... food carrying, display, investigation, social greetings, etc.) as well as to negotiate arboreal environments (e.g. Bailey et al., 2020;Dunham, 2015;Isler and Grüter, 2006;Thorpe and Crompton, 2006;Zhu et al., 2015). While body plans can be adapted to specific locomotor modes and capacities (e.g. ...
We investigated how baboons transition from quadrupedal to bipedal walking without any significant interruption in their forward movement (i.e. transition ‘on the fly’). Building on basic mechanical principles (momentum only changes when external forces/moments act on the body), insights into possible strategies for such a dynamical mode transition are provided and applied first to the recorded planar kinematics of an example walking sequence (including several continuous quadrupedal, transition and subsequent bipedal steps). Body dynamics are calculated from the kinematics. The strategy used in this worked example boils down to: crouch the hind parts and sprint them underneath the rising body centre of mass. Forward accelerations are not in play. Key characteristics of this transition strategy were extracted: progression speed, hip height, step duration (frequency), foot positioning at touchdown with respect to the hip and the body centre of mass (BCoM), and congruity between the moments of the ground reaction force about the BCoM and the rate of change of the total angular moment. Statistical analyses across the full sample (15 transitions of 10 individuals) confirm this strategy is always used and is shared across individuals. Finally, the costs (in J kg−1 m−1) linked to on the fly transitions were estimated. The costs are approximately double those of both the preceding quadrupedal and subsequent bipedal walking. Given the short duration of the transition as such (<1 s), it is argued that the energetic costs to change walking posture on the fly are negligible when considered in the context of the locomotor repertoire.
... We also found no differences in positional behavior between adults and subadults, suggesting that Tibetan macaques adopt a similar approach to support body weights between 12 and 18 kg in body size. Some researchers have argued that, due to the morphological limitations of individual development, it is challenging to discover differences in positional behavior between primate subadults and adults [21,50]. Therefore, Prediction 1 was not supported. ...
... Given the discontinuity of the arboreal support and the fragility of the terminal branches [10,21], we expected adults to be more active on the ground and coarse branches, and that other age-sex groups would be more active on trees and twigs. Infants and juveniles foraged significantly more frequently than adults, and subadults foraged on the terminal branches; however, there were no differences between adults and subadults. ...
Body size and individual development significantly affect positional behavior and substrate use. However, only a few studies have been conducted on immature wild macaques. We studied wild Tibetan macaques (Macaca thibetana) inhabiting Mt. Huangshan, China, to explore the degree of interspecific variation in positional behavior in relation to body weight and individual development. From September 2020 to August 2021, we used instantaneous scan sampling (duration 5 min, interval 10 min) to record age–sex groups, locomotions, postures, and substrate attributes. The results showed that Tibetan macaques used terrestrial substrates in nearly two-thirds of the recorded observations. The main postural modes were sitting and quadrupedal standing. The main locomotor modes were quadrupedal walking and climbing among all age–sex group records. Positional behavior and substrate use in adults only significantly differed from those in juveniles and infants. Although adult males were larger than the other age–sex groups, they did not climb and bridge more frequently than the other age–sex groups. The frequency of climbing, leaping, and suspension was significantly higher in juveniles than in adults. In addition, adult males used terrestrial and larger substrates more frequently, while juveniles and infants used arboreal substrates and terminals more frequently than adult males during traveling and feeding. We hypothesize that the more positional behavioral spectrum of Tibetan macaque juveniles’ may be related to rapid skeletal muscle development. These results suggest that differences in interspecific positional behavior may be caused by the individual development and survival needs of individuals, rather than just body size.
... In addition to what is known about below-branch locomotion in adult primates, there has been a recent influx of ontogenetic studies of primate locomotion (e.g., Covert et al. 2004;Dunham 2015;Workman and Covert 2005). The juvenile period is described as being the "golden age" in primate locomotion, as the locomotion repertoire expands in both terrestrial and arboreal environments (Dunbar and Badam 1998). ...
... For example, juveniles in two species that primarily use quadrupedal behaviors, Trachypithecus delcouri and T. hatinhensis, exhibit more suspensory locomotion (5.8% and 5.9%, respectively) than adults (<1% and 2%, respectively) (Workman and Covert 2005). Smaller-bodied primates (juveniles and subadults) can also use smaller substrates, allowing them to exploit more areas of the canopy (Dunham 2015;Young and Shapiro 2018). ...
... This is similar to most other cercopithecids, in which juveniles exhibit higher diversity of all locomotor categories than adults, including more frequent suspensory behaviors (Workman and Covert 2005). Juvenile Colobus angolensis palliates also have a more diverse locomotor repertoire than adults and use bimanual suspension, unlike adults (Dunham 2015). This difference between juveniles and adults can be explained by juveniles having more flexible joints, smaller body size, and being able to exploit all areas of their environment (Dunbar and Badam 1998). ...
Across the primates, larger body mass often necessitates below-branch locomotion (such as arm-swinging or brachiation). While colobines are typically considered arboreal quadrupeds, Pygathrix exhibits a high degree of arm-swinging behavior in captivity (ca. 50% of locomotion time). However, little is known about their behavior in the wild. We examined two questions about the locomotion of Pygathrix nemaeus in the wild: 1) What is the proportion of arm-swinging in the locomotor repertoire? 2) Given the difference in sizes between the sexes and age categories in this species, do adult males, adult females, subadults, and juveniles differ in arm-swinging frequency? Based on the hypothesis that increased body mass is typically associated with below-branch locomotion, we predict adult males will arm-swing the most, followed by adult females with a ventral infant, adult females without an infant, subadults, and then juveniles. We recorded data between November 2016 and April 2017 in Son Tra Nature Reserve, Da Nang, Vietnam. This time frame encompasses the wet and dry seasons. We video-recorded P. nemaeus between dawn and dusk, 5 days a week, and recorded behavioral data from the footage. We found that juveniles used arm-swinging the most (34.3%), followed by subadults (21.7%), adult females (17.6%), adult females carrying infants (15.5%), and then adult males (9.8%). These results do not support the hypothesis that larger bodied individuals engage more in below-branch locomotion. It is not uncommon for colobine juveniles to show higher proportions of arm-swinging than adults, but more research is needed to understand the relatively high proportions of arm-swinging in adult P. nemaeus.
... Most notably, these methods require daily access to electricity for charging cameras and equipment and uploading video clips-a condition not found at all field sites. Furthermore, quantifying substrate characteristics is more time consuming than the more or less instantaneous assessments of substrate size and orientation angle typical of most positional behavior studies (Dunham, 2015;McGraw, 1998;Youlatos, 1999). Recording substrate compliance is particularly time consuming (i.e., may require several minutes per substrate). ...
Objectives:
Laboratory studies have yielded important insights into primate locomotor mechanics. Nevertheless, laboratory studies fail to capture the range of ecological and structural variation encountered by free-ranging primates. We present techniques for collecting kinematic data on wild primates using consumer grade high-speed cameras and demonstrate novel methods for quantifying metric variation in arboreal substrates.
Materials and methods:
These methods were developed and applied to our research examining platyrrhine substrate use and locomotion at the Tiputini Biodiversity Station, Ecuador. Modified GoPro cameras equipped with varifocal zoom lenses provided high-resolution footage (1080 p.; 120 fps) suitable for digitizing gait events. We tested two methods for remotely measuring branch diameter: the parallel laser method and the distance meter photogrammetric method. A forestry-grade laser rangefinder was used to quantify substrate angle and a force gauge was used to measure substrate compliance. We also introduce GaitKeeper, a graphical user interface for MATLAB, designed for coding quadrupedal gait.
Results:
Parallel laser and distance meter methods provided accurate estimations of substrate diameter (percent error: 3.1-4.5%). The laser rangefinder yielded accurate estimations of substrate orientation (mean error = 2.5°). Compliance values varied tremendously among substrates but were largely explained by substrate diameter, substrate length, and distance of measurement point from trunk. On average, larger primates used relatively small substrates and traveled higher in the canopy.
Discussion:
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.
... However, in some instances, small body size can also provide beneficial opportunities to juveniles, permitting them to access regions of the habitat not available to larger adult group mates (Bezanson & Morbeck, 2013;Bezanson, 2017). For instance, field studies of primate locomotor ontogeny have found that the smaller body size of infants and juveniles allows them to engage in more acrobatic arboreal locomotion and move on smaller substrates than adults (Bezanson, 2006(Bezanson, , 2009Doran, 1992Doran, , 1997Dunbar & Badam, 1998;Dunham, 2015;Fan, Scott, Fei, & Ma, 2012;Sarringhaus, MacLatchy, & Mitani, 2014;Sugardjito & van Hooff, 1986;Wells & Turnquist, 2001;Workman & Covert, 2005;Wright, 2005;Zhu, Garber, Bezanson, Qi, & Li, 2014). These observations illustrate the importance of body size in determining the "locomotor niche" available to an animal, particularly when arboreal (Fleagle & Mittermeier, 1980;Jenkins, 1974). ...
The importance of locomotion to evolutionary fitness has led to extensive study of primate locomotor behavior, morphology and ecology. Most previous research has focused on adult primates, but in the last few decades, increased attention to locomotor development has provided new insights toward our broader understanding of primate adaptation and evolution. Here, we review the contributions of this body of work from three basic perspectives. First, we assess possible determinants on the timing of locomotor independence, an important life history event. Significant influences on timing of locomotor independence include adult female body mass, age at weaning, and especially relative brain size, a significant predictor of other primate life history variables. Additionally, we found significant phylogenetic differences in the timing of locomotor independence, even accounting for these influences. Second, we discuss how structural aspects of primate growth may enhance the locomotor performance and safety of young primates, despite their inherent neuromotor and musculoskeletal limitations. For example, compared to adults, growing primates have greater muscle mechanical advantage, greater bone robusticity, and larger extremities with relatively long digits. Third, focusing on primate quadrupedalism, we provide examples that illustrate how ontogenetic transitions in morphology and locomotion can serve as a model system for testing broader principles underlying primate locomotor biomechanics. This approach has led to a better understanding of the key features that contribute to primates’ stride characteristics, gait patterns, limb force distribution, and limb postures. We have learned a great deal from the study of locomotor ontogeny, but there is much left to explore. We conclude by offering guidelines for future research, both in the laboratory and the field.
... In contrast, the ontogenetic differences seen in locomotor modes across all behaviours suggest that indeed there are some physical or behavioural differences that prevent juvenile Javan slow lorises from fully mirroring adults within the same environment. Researchers working on ontogeny and positional behaviour, cite exploratory behaviour, changing musculoskeletal systems and varying environmental pressures as explanations for significant differences in locomotor behaviour between juveniles and adults (Workman and Covert, 2005;Bezanson, 2009;Dunham, 2015). The morphometric scaling reported in this study highlights how vertical clinging and gum feeding are essential aspects of Javan slow loris survival and allows juveniles to access tree trunks the way adults do. ...
Animals of all ages need to access essential food resources, either on their own or with the assistance of conspecifics. Rapid physical and behavioural development is one strategy to help young animals reach adulthood. Specialized gum-feeding mammals exploit a food type that is relatively difficult to access and digest and must possess the appropriate adaptions to access large vertical substrates, i.e. tree trunks. Unlike other gum feeding mammals, the Javan slow loris (Nycticebus javanicus) lacks physical structures, such as keeled nails or claws, which animals commonly use to secure themselves to large vertical substrates. To understand how slow lorises of all ages exploit gum, we examined their vertical gouging posture, locomotor behaviour, habitat use during feeding, and their morphometric measures across three age classes (adult, sub-adult, juvenile). Using data collected in Cipaganti, Java, Indonesia between April 2012 and April 2016, we found that individuals of N. javanicus rely on their hand, foot, and limb morphology to maintain vertical gouging postures, in place of claws or keeled nails. Locomotor behaviour, position in tree, and tree DBH showed no significant difference across age classes while feeding. Juveniles were indistinguishable from adults and sub-adults in regards to limb proportion indices, lower leg length, hand span and foot span. Some morphometric measures scaled isometrically e.g. arm length, but those highlighted during prolonged vertical postures scaled allometrically e.g. leg, hand, and foot measures. These findings suggest that the rapid behavioural and physical development of key features may act as an ontogenetic adaptation to facilitate access to a stable food resource at a young age. The Javan slow loris exemplifies the complex relationship that exists between an animal’s diet and the specializations that facilitate access to these food resources.
... The forest measures ca. 4.6 km 2 and is composed of patches of intact forest interspersed with highly degraded areas (Anderson et al. 2007a;Dunham 2015;Dunham and McGraw 2014). The climate is characterized by two rainy seasons, with short rains from October to December and long rains generally occurring from March to June (Mwamachi et al. 1995). ...
Behavioral and dietary flexibility permits primates to survive in variable environments. It is clear that some species cope with habitat disturbance and fragmentation better than others. I examined the dietary flexibility of Colobus angolensis palliatus by studying three groups inhabiting structurally distinct ranges in Kenya’s Diani Forest. I predicted that the two groups inhabiting more disturbed areas would have reduced food availability and would respond by increasing dietary diversity and consuming greater proportions of lianas and exotic plant species compared to the group inhabiting the more intact area. Forest composition and overall plant part availability differed among home ranges; however, group diets did not differ in their proportions of different plant parts, nor did groups select plant parts in proportion to their availability. Diets differed dramatically with regard to species-specific plant parts, i.e., mean monthly dietary overlap among groups = 10.4%. Contrary to my predictions, all three groups exhibited considerable dietary diversity, i.e., 63–76 plant species, and relied heavily on lianas, i.e., 20.8–38.4% of the diet, and exotic plant species, i.e., 30.1–40.3% of the diet. The presence of exotic plant species in all three ranges suggests that even the most intact areas of the Diani Forest are perturbed and should be classified along a spectrum of habitat disturbance rather than intact vs. degraded. Nonetheless, this study emphasizes that diets can vary considerably among groups living in the same forest, and this degree of dietary flexibility likely enables C. a. palliatus to survive within increasingly disturbed habitats.
... 9 Morbeck (1977); values represent percentage of 10-s instantaneous scan samples; site: Limura, Kenya. 10 Gebo & Chapman (1995); percentage of total positional bouts, continuous random focal sampling; site: Kibale Forest, Uganda. 11 Dunham (2015); percentage of total positional bouts, rotating instantaneous focal sampling of adults in all contexts; site: Diana Forest, Kenya. 12 McGraw (1998a,b); percentage of instantaneous focal sampling in all contexts; site: Tai Forest, Ivory Coast. ...
Apes, members of the superfamily Hominoidea, possess a distinctive suite of anatomical and behavioral characters which appear to have evolved relatively late and relatively independently. The timing of paleontological events, extant cercopithecine and hominoid ecomorphology and other evidence suggests that many distinctive ape features evolved to facilitate harvesting ripe fruits among compliant terminal branches in tree edges. Precarious, unpredictably oriented, compliant supports in the canopy periphery require apes to maneuver using suspensory and non-sterotypical postures (i.e. postures with eccentric limb orientations or extreme joint excursions). Diet differences among extant species, extant species numbers and evidence of cercopithecoid diversification and expansion, in concert with a reciprocal decrease in hominoid species, suggest intense competition between monkeys and apes over the last 20Ma. It may be that larger body masses allow great apes to succeed in contest competitions for highly desired food items, while the ability of monkeys to digest antifeedant-rich unripe fruits allows them to win scramble competitions. Evolutionary trends in morphology and inferred ecology suggest that as monkeys evolved to harvest fruit ever earlier in the fruiting cycle they broadened their niche to encompass first more fibrous, tannin- and toxin-rich unripe fruits and later, for some lineages, mature leaves. Early depletion of unripe fruit in the central core of the tree canopy by monkeys leaves a hollow sphere of ripening fruits, displacing antifeedant-intolerant, later-arriving apes to small-diameter, compliant terminal branches. Hylobatids, orangutans, Pan species, gorillas and the New World atelines may have each evolved suspensory behavior independently in response to local competition from an expanding population of monkeys. Genetic evidence of rapid evolution among chimpanzees suggests that adaptations to suspensory behavior, vertical climbing, knuckle-walking, consumption of terrestrial piths and intercommunity violence had not yet evolved or were still being refined when panins (chimpanzees and bonobos) and hominins diverged.
... observation). Like most Colobus angolensis subspecies and other Colobus spp., Colobus angolensis palliatus are highly arboreal, spend much of their time feeding and resting in the main canopy, and are renowned for their spectacular leaping ability (Dunham and McGraw 2014;Dunham 2015). Research has shown that Colobus angolensis are largely folivorous throughout their ranges but may also rely heavily on seeds and/or lichens (Bocian 1997;Maisels et al. 1994;Lowe and Sturrock 1998;Fimbel et al. 2001). ...
Infant adoption has been reported in a variety of primate taxa both in captive and natural settings. Adoption by females may be adaptive by increasing inclusive fitness via shared genes between adoptive mother and adoptee or by providing valuable maternal practice which, in turn, may increase the female's future reproductive success. Others have argued that adoption may be non-adaptive and the result of a general attraction toward infants. Our study examines a unique case of adoption by an adult female Angola black and white colobus monkey (Colobus angolensis palliatus) who adopted an extra-group infant alongside her own biological infant. We compare infant behaviors and mother-infant interactions between biological infant and adoptee and then compare both biological infant and adoptee behavioral profiles to those of infants under normal circumstances. Data were collected from July 2014 to June 2015 on three habituated groups in the Diani Forest of Kenya. Scan sampling and pooled data were used to create daily and monthly behavioral profiles for the biological infant and adoptee, as well as a mean monthly profile of four infants under normal circumstances. Data include time spent (1) clinging to mother/adoptive mother, (2) clinging to another individual, (3) behaving independently, and (4) behaving in close proximity to mother/adoptive mother. Initially, the adoptee struggled to achieve behavioral profiles consistent with those of the biological infant and normal colobus infants of the same age as he spent significantly more time moving independently and significantly less time clinging to the adoptive mother. After the mysterious death of the biological infant in mid-January 2015, the adoptee assumed a behavioral profile similar to that of infants under normal conditions. This case does not support adaptive hypotheses for adoption (i.e., inclusive fitness or learning to mother). Instead, because the biological infant died, possibly due to the presence of the adoptee, we argue that this case of infant adoption was non-adaptive. Ultimately, this adoption appears to have been an outcome of the adoptee's persistent desire to be cared for and the female's strong propensity to engage in allomaternal behavior.
