Troop size and human-modified habitat affect the ranging patterns of a chacma baboon population in the cape peninsula, South Africa

Behavioral adjustments of endangered Barbary macaques (Macaca sylvanus) living at the edge of an agricultural landscape in Morocco

Transition zones between natural and human-altered spaces are eroding in most terrestrial ecosystems. The persistence of animals in shared landscapes depends in part on their behavioral flexibility, which may involve being able to exploit human agricultural production. As a forest-dependent species, the Barbary macaque (Macaca sylvanus) is affected by the progressive conversion of forest-adjacent lands into crops. We explore how Barbary macaque behavior differs between groups living in a forest at the edge of agricultural zones (hereafter "disturbed groups") and groups inhabiting undisturbed forests (hereafter "natural groups"). We compare the diets, activity-budgets, home range sizes, daily path lengths, and sleeping site locations of the groups. We also quantify anthropogenic disturbances (i.e., rates of encounter with humans and dogs) and investigate relationships between such disturbances and the diets and activity budgets of macaques through multiple co-inertia analysis. Disturbed groups included high proportions of cultivated food items in their diet and encountered over 0.5/h anthropogenic disturbances. Activity-budgets differed between disturbed and natural groups and were mostly influenced by diets, not anthropogenic disturbances. Disturbed groups spent more time feeding and less time resting than natural ones. Patterns of space use differed markedly between groups, with disturbed groups displaying smaller home ranges, shorter daily path length, and much higher reutilization of sleeping sites than natural groups. This study highlights the dietary and behavioral flexibility of Barbary macaques living in human-altered environments. Their patterns of space use suggest a reduction in energy expenditure in the disturbed groups due to the inclusion of cultivated food items in their diet possibly leading to increased foraging efficiency. However, the high rates of anthropogenic encounters, including aggressive ones, are likely stressful and may potentially induce extra energy costs and lead to macaque injuries. This could result in demographic costs for crop-foraging groups, threatening the conservation of this endangered species.

Home range, sleeping site use, and band fissioning in hamadryas baboons: Improved estimates using GPS collars

Variation in spatial and temporal distribution of resources drives animal movement patterns. Links between ecology and behavior are particularly salient for the multilevel society of hamadryas baboons, in which social units cleave and coalesce over time in response to ecological factors. Here, we used data from GPS collars to estimate home range size and assess temporal patterns of sleeping site use in a band of hamadryas baboons in Awash National Park, Ethiopia. We used GPS data derived from 2 to 3 collared baboons over three 8-12-month collaring intervals to estimate annual and monthly home ranges using kernel density estimators (KDEs) and minimum convex polygons (MCPs). The 95% KDE home range was 64.11 km2 for Collaring Interval I (July 2015-March 2016), 85.52 km2 for Collaring Interval II (October 2016-October 2017), 76.43 km2 for Collaring Interval III (July 2018-May 2019), and 75.25 km2 across all three collaring intervals. MCP home ranges were 103.46 km2 for Collaring Interval I, 97.90 km2 for Collaring Interval II, 105.22 km2 for Collaring Interval III, and 129.33 km2 overall. Ninety-five percent KDE home range sizes did not differ across months, nor correlate with temperature or precipitation, but monthly MCP home ranges increased with monthly precipitation. Our data also revealed a southward home range shift over time and seven previously unknown sleeping sites, three of which were used more often during the wet season. Band cohesion was highest during dry months and lowest during wet months, with fissioning occurring more frequently at higher temperatures. One pair of collared individuals from Collaring Interval III spent 95% of nights together, suggesting they were members of the same clan. Our results both suggest that previous studies have underestimated the home range size of hamadryas baboons and highlight the benefits of remote data collection.

Roadside monkeys: anthropogenic effects on moor macaque (Macaca maura) ranging behavior in Bantimurung Bulusaraung National Park, Sulawesi, Indonesia

A growing body of research focuses on how anthropogenic factors affect the behavior and ecology of primates and their ecosystems. Infrastructural development, such as roads, is an increasingly pervasive anthropogenic impact that destroys primate habitat, affects the distribution and dispersal of primates, and facilitates human-primate interactions. At our field site in Bantimurung-Bulusaraung National Park, Sulawesi, Indonesia, a major road bisects the habitat of the endangered moor macaque (Macaca maura). Beginning in 2015, we observed a behavioral shift by our main study group: they began spending more time along the road foraging in trash pits and waiting for provisions from vehicles. Our objective in this study was to examine how access to anthropogenic foods has affected the group's ranging behavior by comparing ranging data collected before (2010-2011) and after the shift (2016-2017). In contrast to what we expected, home ranges were significantly larger and daily travel distance was significantly longer after the shift compared to before. As predicted, mean distance to the road decreased after the shift. These results likely reflect the irregular and spatially dispersed nature of provisioning at this site. The macaques appear to be attracted to the road because it presents opportunities to obtain palatable and energy-dense foods. Our results indicate that moor macaques are able to flexibly adjust their ranging behavior in response to anthropogenic impacts. However, given the risks of being in proximity to roads and humans, management of this emerging human-macaque interface is needed.

Behavioral Causes, Ecological Consequences, and Management Challenges Associated with Wildlife Foraging in Human-Modified Landscapes

Humans have altered up to half of the world's land surface. Wildlife living within or close to these human-modified landscapes are presented with opportunities and risks associated with feeding on human-derived foods (e.g., agricultural crops and food waste). Understanding whether and how wildlife adapts to these landscapes is a major challenge, with thousands of studies published on the topic over the past 10 years. In the present article, we build on established theoretical frameworks to understand the behavioral causes of crop and urban foraging by wildlife. We then develop and extend this framework to describe the multifaceted ecological consequences of crop and urban foraging for the individuals and populations in which they arise, with emphasis on social species for which interactions with people are, on balance, negative (commonly referred to as raiding species). Finally, we discuss the management challenges faced by urban and rural land managers, businesses, and government organizations in mitigating human-wildlife conflicts and propose ways to improve the lives of both wildlife and humans living in human-modified landscapes and to promote coexistence.

Energetics at the urban edge: Environmental and individual predictors of urinary C-peptide levels in wild chacma baboons (Papio ursinus)

As human-modified landscapes encroach into natural habitats, wildlife face a reduction in natural food sources but also gain access to calorie-rich, human-derived foods. However, research into the energetics of wildlife living within and adjacent to urban and rural landscapes is lacking. C-peptide - a proxy for insulin production and a diagnostic tool for assessing pancreatic function in humans and domestic animals - can be quantified non-invasively from urine (uCP) and may provide a way to investigate the energetic correlates of living in human-altered landscapes. UCP is increasingly used in studies of primate energetics, and here we examine predictors of variation in uCP levels in n = 17 wild chacma baboons (Papio ursinus) living at the urban edge on the Cape Peninsula, South Africa. We find that uCP was positively associated with food provisioning and negatively with night fasting. UCP levels were comparable between winter and summer but significantly lower during spring, possibly driven by consumption of energy-rich seeds during summer and more human-derived foods during winter. UCP was elevated in pregnant females and similar for lactating and cycling females. We find no effect of dominance rank on uCP. Samples collected with synthetic Salivettes had significantly lower uCP levels than directly pipetted samples. Overall, our results indicate that uCP is a reliable, non-invasive measure of energy balance and intake in baboons, and suggest potential energetic benefits of living at the urban edge. More broadly, studies of uCP may offer unique insight into the environmental control of hormone-behaviour relationships in species crossing natural and urban environments.

Density-dependent space use affects interpretation of camera trap detection rates

Camera traps (CTs) are an increasingly popular tool for wildlife survey and monitoring. Estimating relative abundance in unmarked species is often done using detection rate as an index of relative abundance, which assumes that detection rate has a positive linear relationship with true abundance. This assumption may be violated if movement behavior varies with density, but the degree to which movement behavior is density-dependent across taxa is unclear. The potential confounding of population-level relative abundance indices by movement would depend on how regularly, and by what magnitude, movement rate and home-range size vary with density. We conducted a systematic review and meta-analysis to quantify relationships between movement rate, home-range size, and density, across terrestrial mammalian taxa. We then simulated animal movements and CT sampling to test the effect of contrasting movement scenarios on CT detection rate indices. Overall, movement rate and home-range size were negatively correlated with density and positively correlated with one another. The strength of the relationships varied significantly between taxa and populations. In simulations, detection rates were related to true abundance but underestimated change, particularly for slower moving species with small home ranges. In situations where animal space use changes markedly with density, we estimate that up to thirty percent of a true change in relative abundance may be missed due to the confounding effect of movement, making trend estimation more difficult. The common assumption that movement remains constant across densities is therefore violated across a wide range of mammal species. When studying unmarked species using CT detection rates, researchers and managers should explicitly consider that such indices of relative abundance reflect both density and movement. Practitioners interpreting changes in camera detection rates should be aware that observed differences may be biased low relative to true changes in abundance. Further information on animal movement, or methods that do not depend on assumptions of density-independent movement, may be required to make robust inferences on population trends.

Home range utilization by chacma baboon (Papio ursinus) troops on Suikerbosrand Nature Reserve, South Africa

Rapid urbanization coupled with decreasing areas of natural habitat are causing baboon populations to become scattered and isolated, often resulting in increased levels of human-baboon conflict. To implement baboon-human conflict management strategies, it is essential to formulate realistic conservation policies that deal with all stakeholder concerns and ensure the conservation of viable baboon populations. A study was initiated in response to complaints of perceived excessive baboon numbers and associated lack of food resources on Suikerbosrand Nature Reserve in South Africa. Data obtained from GPS tracking collars fitted to one baboon from each of 10 identified troops were analyzed to determine home range size and utilization. The spatial representation of home ranges generated from this study will allow reserve management to identify areas of potential high and low human-baboon conflict and will contribute to the development of a formal baboon management plan to reduce human-baboon conflict on and around the reserve. Home ranges were unevenly distributed and had a mean size of 26.72 km² ± 13.91 SD in the cold/dry season and 26.54 km² ± 12.76 SD in the warm/wet season. Troop home ranges overlapped to some degree and five troops utilized areas outside the reserve. Although no significant relationship between troop size and home range was found, there was a positive relationship between troop size and daily distance travelled. All troops had significantly longer mean daily distances during the warm/wet season than during the cold/dry season (P ≤ 0.02).

Extreme behavioural shifts by baboons exploiting risky, resource-rich, human-modified environments

A range of species exploit anthropogenic food resources in behaviour known as 'raiding'. Such behavioural flexibility is considered a central component of a species' ability to cope with human-induced environmental changes. Here, we study the behavioural processes by which raiding male chacma baboons (Papio ursinus) exploit the opportunities and mitigate the risks presented by raiding in the suburbs of Cape Town, South Africa. Ecological sampling and interviews conducted with 'rangers' (employed to manage the baboons' space use) revealed that baboons are at risk of being herded out of urban spaces that contain high-energy anthropogenic food sources. Baboon-attached motion/GPS tracking collars showed that raiding male baboons spent almost all of their time at the urban edge, engaging in short, high-activity forays into the urban space. Moreover, activity levels were increased where the likelihood of deterrence by rangers was greater. Overall, these raiding baboons display a time-activity balance that is drastically altered in comparison to individuals living in more remote regions. We suggest our methods can be used to obtain precise estimates of management impact for this and other species in conflict with people.

Isotopic assessment of marine food consumption by natural-foraging chacma baboons on the Cape Peninsula, South Africa

OBJECTIVES

Stable isotope analysis has been used to investigate consumption of marine resources in a variety of terrestrial mammals, including humans, but not yet in extant nonhuman primates. We sought to test the efficacy of stable isotope analysis as a tool for such studies by comparing isotope- and observation-based estimates of marine food consumption by a troop of noncommensal, free-ranging chacma baboons.

MATERIALS AND METHODS

We determined δ¹³ C and δ¹⁵ N values of baboon hair (n = 9) and fecal samples (n = 144), and principal food items (n = 362). These values were used as input for diet models, the outputs of which were compared to observation-based estimates of marine food consumption.

RESULTS

Fecal δ¹³ C values ranged from -29.3‰ to -25.6‰. δ¹⁵ N values ranged from 0.9‰ to 6.3‰ and were positively correlated with a measure of marine foraging during the dietary integration period. Mean (± SD) δ¹³ C values of adult male and female baboon hairs were -21.6‰ (± 0.1) and -21.8‰ (± 0.3) respectively, and corresponding δ¹⁵ N values were 5.0‰ (± 0.3) and 3.9‰ (± 0.2). Models indicated that marine contributions were ≤10% of baboon diet within any season, and contributed ≤17% of dietary protein through the year.

DISCUSSION

Model output and observational data were in agreement, both indicating that despite their abundance in the intertidal region, marine foods comprised only a small proportion of baboon diet. This suggests that stable isotope analysis is a viable tool for investigating marine food consumption by natural-foraging primates in temperate regions.

Estimation of baboon daily travel distances by means of point sampling - the magnitude of underestimation

Daily travel distance (DTD), the distance an animal moves over the course of the day, is an important metric in movement ecology. It provides data with which to test hypotheses related to energetics and behaviour, e.g. impact of group size or food distribution on DTDs. The automated tracking of movements by applying GPS technology has become widely available and easy to implement. However, due to battery duration constraints, it is necessary to select a tracking-time resolution, which inevitably introduces an underestimation of the true underlying path distance. Here we give a quantification of this inherent systematic underestimation of DTDs for a terrestrial primate, the Guinea baboon. We show that sampling protocols with interval lengths from 1 to 120 min underestimate DTDs on average by 7 to 35 %. For longer time intervals (i.e. 60, 90, 120 min), the relative increase of deviation from the “true” trajectory is less pronounced than for shorter intervals. Our study provides first hints on the magnitude of error, which can be applied as a corrective when estimating absolute DTDs in calculations on travelling costs in terrestrial primates.

The ecological determinants of baboon troop movements at local and continental scales

BACKGROUND

How an animal moves through its environment directly impacts its survival, reproduction, and thus biological fitness. A basic measure describing how an individual (or group) travels through its environment is Day Path Length (DPL), i.e., the distance travelled in a 24-hour period. Here, we investigate the ecological determinants of baboon (Papio spp.) troop DPL and movements at local and continental scales.

RESULTS

At the continental scale we explore the ecological determinants of annual mean DPL for 47 baboon troops across 23 different populations, updating a classic study by Dunbar (Behav Ecol Sociobiol 31: 35-49, 1992). We find that variation in baboon DPLs is predicted by ecological dissimilarity across the genus range. Troops that experience higher average monthly rainfall and anthropogenic influences have significantly shorter DPL, whilst troops that live in areas with higher average annual temperatures have significantly longer DPL. We then explore DPLs and movement characteristics (the speed and distribution of turning angles) for yellow baboons (Papio cynocephalus) at a local scale, in the Issa Valley of western Tanzania. We show that our continental-scale model is a good predictor of DPL in Issa baboons, and that troops move significantly slower, and over shorter distances, on warmer days. We do not find any effect of season or the abundance of fruit resources on the movement characteristics or DPL of Issa baboons, but find that baboons moved less during periods of high fruit availability.

CONCLUSION

Overall, this study emphasises the ability of baboons to adapt their ranging behaviour to a range of ecological conditions and highlights how investigations of movement patterns at different spatial scales can provide a more thorough understanding of the ecological determinants of movement.

30 days in the life: daily nutrient balancing in a wild chacma baboon

For most animals, the ability to regulate intake of specific nutrients is vital to fitness. Recent studies have demonstrated nutrient regulation in nonhuman primates over periods of one observation day, though studies of humans indicate that such regulation extends to longer time frames. Little is known about longer-term regulation in nonhuman primates, however, due to the challenges of multiple-day focal follows. Here we present the first detailed study of nutrient intake across multiple days in a wild nonhuman primate. We conducted 30 consecutive all day follows on one female chacma baboon (Papio hamadryas ursinus) in the Cape Peninsula of South Africa. We documented dietary composition, compared the nutritional contribution of natural and human-derived foods to the diet, and quantified nutrient intake using the geometric framework of nutrition. Our focus on a single subject over consecutive days allowed us to examine daily dietary regulation within an individual over time. While the amounts varied daily, our subject maintained a strikingly consistent balance of protein to non-protein (fat and carbohydrate) energy across the month. Human-derived foods, while contributing a minority of the diet, were higher in fat and lower in fiber than naturally-derived foods. Our results demonstrate nutrient regulation on a daily basis in our subject, and demonstrate that she was able to maintain a diet with a constant proportional protein content despite wide variation in the composition of component foods. From a methodological perspective, the results of this study suggest that nutrient intake is best estimated over at least an entire day, with longer-term regulatory patterns (e.g., during development and reproduction) possibly requiring even longer sampling. From a management and conservation perspective, it is notable that nearly half the subject’s daily energy intake derived from exotic foods, including those currently being eradicated from the study area for replacement by indigenous vegetation.