Desert Baboons Research Articles

Paternal effects on access to resources in a promiscuous primate society

The evolution of paternal care is rare in promiscuous mammals, where it is hampered by low paternity confidence. However, recent evidence indicates that juveniles whose fathers are present experience accelerated maturation in promiscuous baboon societies. The mechanisms mediating these paternal effects remain unclear. Here, we investigated whether father–offspring associations might facilitate offspring access to resources in wild desert baboons (Papio ursinus). We combined paternity analyses and behavioral observations of juveniles that had started feeding autonomously to show that (1) offspring associate more often with their genetic father than with any other male, and actively manage such associations, (2) offspring associate more closely with their father when another adult male is in sight, and when their mother is out of sight, (3) father–offspring associations are more frequent when juveniles are feeding (relative to other activities), and these associations enable juveniles to access richer food patches, and (4) father–offspring associations are stronger among subordinate males and their offspring. Taken together, these findings indicate that fathers may buffer the social and ecological environment faced by their offspring. In addition to mitigating risks of attacks by predators or conspecifics, paternal presence improves offspring access to food in wild baboons, highlighting a new mechanism through which fathers may impact offspring fitness in promiscuous primate societies. Key wor ds: baboons, foraging success, paternal care, primates, promiscuity , reproductive strategies, sex roles. [Behav Ecol]

A rule-of-thumb based on social affiliation explains collective movements in desert baboons

Animals living in groups will profit most from sociality if they coordinate the timing and nature of their activities. Self-organizing mechanisms can underlie coordination in large animal groups such as insect colonies or fish schools, but to what degree these mechanisms operate in socially complex species that live in small stable groups is not well known. We therefore examined the collective departure of wild chacma baboons, Papio ursinus, from their sleeping sites. First, in line with previous observations, the departure process appeared to be coordinated through the cue of individuals ‘moving off’, with no role for specific vocal or visual signalling. Second, we employed network analyses to explore how interindividual relationships influenced departure patterns, and found that a local rule, to follow the movements of those baboons with whom they shared a close social affiliation, determined when the baboon group departed. Finally, using an agent-based model, we were able to simulate mathematically the observed patterns of collective movements based upon the emergent rule that we identified. Our study adds weight to the idea that social complexity does not necessitate cognitive complexity in the decision-making process, consistent with heuristic decision-making perspectives studied by cognitive psychologists and researchers studying self-organization in biological systems.

The dining etiquette of desert baboons: the roles of social bonds, kinship, and dominance in co‐feeding networks

To better understand how individual relationships influence patterns of social foraging in primate groups, we explored networks of co-feeding in wild desert baboons (Papio ursinus). To minimize the risk of aggression and injury associated with contest competition, we expected that individual group members would choose to co-feed with those group-mates that are most likely to show tolerance and a willingness to share food patches. We tested two alternative hypotheses about who those group-mates might be: the "social bonds hypothesis" predicts that preferred foraging partners will be those with whom individuals share strong social bonds, indexed by grooming, whereas the "kinship hypothesis" predicts that preferred foraging partners will be relatives. We also investigated and controlled for the effects of dominance rank, given that competitive ability is known to shape foraging patterns. Social network analyses of over 5,000 foraging events for 14 adults in a single troop revealed that baboon co-feeding was significantly correlated with grooming relationships but not genetic relatedness, and this finding was also true of the female-only co-feeding network. Dominant individuals were also found to be central to the co-feeding network, frequently sharing food patches with multiple group-mates. This polyadic analysis of foraging associations between individuals underlines the importance of dominance and affiliation to patterns of primate social foraging.

Foraging opportunities drive interspecific associations between rock kestrels and desert baboons

AbstractInterspecific associations can arise for varied reasons including reduced predation risk and improved foraging success. In the case of bird–primate associations, birds typically appear to follow primate groups to harvest insects flushed by primates' movements. However, while previous studies have linked temporal changes in bird–primate associations to environmental conditions, few have assessed the additional effects of bird activity patterns and primate group behaviour and none have disentangled their potentially interdependent effects. Here, we test the hypothesis that foraging opportunities can drive interspecific associations in a previously undescribed bird–primate association between rock kestrels Falco rupicolus and chacma baboons Papio ursinus in central Namibia. Data were collected from two baboon groups and associated kestrels using instantaneous scan sampling during full‐day follows over a 7‐month field period, and analysed using generalized linear mixed models. We found that kestrel associations with baboons vary with season, show diurnal cycles and are more frequent when the baboons are in open desert habitat, engaged in travel foraging and in a large group. These patterns are statistically independent and consistent with the hypothesis that the kestrel–baboon association is driven by the foraging opportunities acquired by the kestrels. As the baboons do not appear to gain any benefits nor incur any costs from the association, we conclude that the kestrels are likely to be commensal with the baboons.

Ecological and social determinants of spacing behaviour in desert baboon groups

This paper investigates the determinants of individual spacing behaviour in a desert baboon population (Papio cynocephalus ursinus). Patterns of neighbour proximity and neighbour density were examined among adults in four groups under different ecological and social conditions (through instantaneous sampling during focal follows). Initial analysis of these data shows that (1) the use of vertical substrates (refuges such as tall trees and cliff faces) can confound patterns of spacing, and (2) individual differences in spacing can depend on the spatial scale over which it is measured. To minimise these substrate and scale effects, this analysis focuses on animals which are off refuges and examines spacing behaviour through its underlying statistical `dimensions' (identified through factor analysis). Analysis of these dimensions indicates that sex, group size, activity-habitat and female reproductive state can all have independent effects on spacing: (1) males are more dispersed than females in smaller groups, (2) male and female dispersion increases with time spent in foraging habitats, and (3) female dispersion is reduced during lactation. According to the hypotheses tested, these results indicate that feeding competition only affects spacing behaviour during foraging while predation risk plays little or no role in spacing. Most aspects of spacing behaviour are best explained by male reproductive strategies and their social repercussions.

The Role of Vigilance in the Survival and Reproductive Strategies of Desert Baboons

This study investigates the relative importance of vigilance in the survival strategies (detection of predators) and reproductive strategies (detection of mates and competitors) of adult baboons Papio cynocephalus ursinus among four groups in a desert population. The proportion of time spent vigilant under a variety of conditions was quantified through instantaneous sampling of focal individuals. Matched comparisons were then conducted to test six predictions for each functional explanation (survival or reproduction). These relate vigilance to (1) sex, (2) group size, (3) activity, (4) habitat, (5) refuge use and (6) spacing behaviour. Vigilance levels do not differ between sexes or groups. However, females are more vigilant when engaged in high-risk activities, when distant from refuges and when distant from neighbours. Male vigilance similarly covaries with refuge use and spacing behaviour, but males are not always more vigilant in dangerous activities and show greater vigilance in open rather than closed habitats. According to the predictions tested, the results provide partial support for the proposal that vigilance plays a role in predator detection for both sexes, although in males the detection of potential mates and competitors appears to be of greater importance. There was no evidence that males provide a vigilance service for females. Vigilance patterns are complicated by activity constraints and the multifactorial nature of anti-predator strategies.

Refuge use and predation risk in a desert baboon population

Baboons face a serious threat of predation from leopards,Panthera pardusand lions,Panthera leoSince trees and cliff faces provide safety from these predators, baboons might use such refuges in order to reduce predation risk. This hypothesis was explored in a study of four groups of chacma baboons,Papio cynocephalus ursinusin a desert population in Namibia (groups ranged between 22 and 55 individuals with one to six adult males). All baboons spent most of their time close by refuges and little time distant from them. This pattern was most accentuated among females in smaller groups. These females spent more time on refuges primarily as a result of greater refuge use during resting and grooming. This pattern was less clear during feeding and travelling, apparently owing to the constraints on refuge use imposed by the nature of these activities. A comparison of refuge use in high-risk and low-risk habitats (after the confounding effects of habitat-specific refuge availability had been removed) suggests that baboons might adopt one of two strategies in high-risk areas; if refuges are widespread they will use refuges more intensively, but if refuges are scarce they will adopt a time-minimizing strategy to leave the area as rapidly as possible. The baboons also increased their vigilance when refuges were distant. These results are consistent with the hypothesis that baboons use refuges to reduce predation risk.

Alarm Calling and Implications for Risk Perception in a Desert Baboon Population

AbstractPatterns of alarm calling and their implications for perceived predation risk were explored among adult baboons Papio cynocephalus ursinus in four social groups differing in both size and composition (22–55 members with one to six adult males) in a desert population. Data were collected in a field experiment where alarm calls were elicited from baboons under similar conditions of risk in response to the approach of a potential predator, a human observer. The results show that females call more frequently than males in most groups. In addition, the median calling rate of females shows an exponential increase in smaller groups. These patterns suggest that females in small groups may perceive the highest risk in this population. Nevertheless, there was no clear tendency for either sex to be the first to call. The observer approaches were also used to evaluate the influence of group size on the ease of detection of 1. the baboons by the observer; and 2. the observer by the baboons. Group size did not appear to affect detection distances for either subject, although the probability that baboons were more likely to perform alarm calls before the observer had detected them increased in smaller groups.

Trade-offs between foraging and predation risk determine habitat use in a desert baboon population

This study explored how baboons,Papio cynocephalus ursinus, in a desert population trade off foraging and predation risk in patterns of habitat use. Four hypotheses were proposed and tested; that habitats are used on the basis of (1) availability, (2) foraging rewards (following the ideal free distribution), (3) foraging rewards modified by the constraints of nocturnal predation risk (partial trade-off) or (4) foraging rewards modified by the constraints of continuous predation risk (full trade-off). Food availability in each habitat was quantified through quadrat surveys describing stem density, plant part availability and nutrient availability (protein and energy) of key plant foods per unit area. Predation risk in each habitat was evaluated using measures describing the relative threat of attack and capture by both leopards,Panthera pardus, and lions,Panthera leo; attack risk was determined on the basis of habitat visibility and predator ambush distances, while capture risk was calculated using a simple model incorporating predator and prey velocities, habitat visibility and nearest refuge distance. Patterns of baboon behaviour were assessed for adult males and females in four groups through day-follows and instantaneous sampling. The baboons did not use habitats directly in proportion to their availability in the group's ranging area (in contrast to hypothesis 1). Nor did patterns of habitat use match those expected on the basis of the ideal free distribution, either during all activities (hypothesis 2) or during feeding (hypothesis 3). Instead, the baboons spent less time feeding in the high-risk food-rich habitat but more time feeding in the low-risk relatively food-poor habitat. Baboons also preferred low-risk habitats in other activities, where during resting and grooming all habitats were avoided except the safest (where key food species were absent). These results support hypothesis 4. Deviations from these patterns by a unimale group indicate that male reproductive strategies may also play a role in habitat selection.

Deaths in a desert baboon troop

Over a 4-year period, three of 22 infants born in a desert-dwelling chacma baboon troop (Papio ursinus) survived to more than 6 months of age. Tick infestation and infant kidnapping by adult females were the main causes of infant death. The high neonatal mortality resulted in a rapid birth rate through a decrease in duration of interbirth intervals for mature females. There were more adult male deaths in the troop than adult female deaths. Males died from canine inflicted wounds sustained during fights.

Social relationships of mountain baboons: Leadership and affiliation in a non-female-bonded monkey.

Instead of close and differentiated relationships among adult females, the accepted norm for savanna baboons, groups of Drakensberg mountain baboons (Papio ursinus) showed strong affiliation of females towards a single male. The same male was usually the decision-making animal in controlling group movements. Lactating or pregnant females focused their grooming on this "leader" male, producing a radially patterned sociogram, as in the desert baboon (P. hamadryas); the leader male supported young animals in the group against aggression and protected them against external threats. Unlike typical savanna baboons, these mountain baboons rarely displayed approach-retreat or triadic interactions, and entirely lacked coalitions among adult females. Both groups studied were reproductively one-male; male-female relationships in one were like those in a unit of a hamadryas male at his peak, while the other group resembled the unit of an old hamadryas male, who still leads the group, with a male follower starting to build up a new unit and already monopolizing mating. In their mountain environment, where the low population density suggests conditions as harsh for baboons as in deserts, adults in these groups kept unusually large distances apart during ranging; kin tended to range apart, and spacing of adults was greatest at the end of the dry, winter season. These facts support the hypothesis that sparse food is responsible for convergence with hamadryas social organization. It is suggested that all baboons, though matrilocal, are better categorized as "cross-sex-bonded" than "female bonded".

Greeting Behaviour in Male Baboons, I: Communication, Reciprocity and Symmetry

AbstractMatrilineal structures are typical of many species of Old World monkeys including the savanna baboon. Both isosexual dyads of females and heterosexual dyads frequently reach the stage of greatest social compatibility, i.e. grooming. Male dyads, in contrast, very rarely reach such stage, they show instead marked mutual intolerance and overt aggressive competition. Grooming and other forms of physical contact are fairly frequent between adult males in the patrilineal society of chimpanzees. In the hamadryas baboon, also with patrilineal organization, adult males do not groom with each other but they frequently exchange greeting interactions, particularly in contexts of excitement provoked by social tension. Species-specific differences (savanna versus desert baboons) in the morphology of greeting interactions have also been reported. The objective of this study was to examine the nature and function of this category of non-agonistic interactions recorded over a period of 9 years between 20 males members of a well-established colony of baboons, Papio hamadryas, P. cynocephaus and their hybrids, housed in a large, open enclosure in the Madrid Zoo. Greetings were conceptualized as interactions, i.e. in which each participant's action is examined in relation to that of the other interacting partner. A description and qualitative analysis were provided of the morphology (i.e. facial, vocal, manipulatory and contact, postural and orientation, and locomotory patterns) and properties (i.e. reciprocity/non-reciprocity, and symmetry/asymmetry) of greeting interactions. The most significant feature of greeting interactions was the three-stage pattern of performance observed, corresponding with the phases of approximation, proximity, and retreat. In each phase, characteristic behavioural patterns were displayed, some were quite stereotyped but others seemed to be rather influenced by the identity of, and social relationship of, the interacting males, and also by the immediate social context of the interaction. A quantitative analysis of 1583 greeting interactions and 1039 aggressive episodes between the 20 study males was then carried out. Individual males were assigned to one of the following classes of reproductive status: subadult (SA), follower (FW), new leader (NL), prime leader (PL), old leader (OL), and old follower (OFW). It was found a correlation between a male's status class and the frequency with which he played several different roles in greeting and aggressive interactions. Greeting interactions were typical of mature males (FWs, NLs, PLs, OLs, and OFWs), but very especially of reproductive males (NLs, PLs, and OLs). Their rate of participation (both as initiator and recipient) was positively related both to the size of their harem (e.g. prime leaders) and to the potentiality to increase the harem size by taking over new females (e.g. prime and new leaders). Males at its prime reproductive period (i.e. PLs) showed the highest rates of involvement in symmetrical greetings, and the males who were reaching that stage (i.e. NLs) were the ones who most frequently refused to reciprocate a greeting approach. As males approached the stages of higher reproductive potential their rates of symmetrical, i.e. non-contact and notifying, greetings increased. In contrast, the contact patterns observed during asymmetrical greetings were mostly displayed in interactions in which at least one of the participants was either an immature or a young nonreproductive (i.e. follower) male. Reproductive males, i.e. prime and new leaders, were the most frequent initiators and recipients of both greeting and aggression. Examination of the morphology of greeting interactions, particularly of the symmetrical and unreciprocated greetings, i.e. the approach/retreat non-contact pattern, that were typical of prime and new leader males, and of the contexts in which both aggression and many greeting episodes took place, i.e. agonistic conflicts and competition over resources, suggested that these two categories of behaviour might share some causal factors and that they might be regarded as two alternative strategies to deal with a similar problem, namely, the resolution of conflicts. In many cases, greeting may be regarded as a quasi-aggressive behaviour aimed at testing a potential or actual rival's tendencies in a competition situation rather than as a category of affiliative or friendly behaviour. Greeting in baboons is a nice example of a non-stereotyped behaviour in a higher animal, in which relational and interactional properties can be studied, and in which, as discussed in the paper, all the traditional ethological issues of causation, development, function, and evolution can be addressed.

Social relationships of mountain baboons: Leadership and affiliation in a non-female-bonded monkey.

Instead of close and differentiated relationship among adult females, the accepted norm for savanna baboons, groups of Drakensberg mountain baboons (Papio ursinus) showed strong affiliation of females towards a single male. The same male was usually the decision-making animal in controlling group movements. Lactating or pregnant females focused their grooming on this "leader" male, producing a radially patterned sociogram, as in the desert baboon (P. hamadryas); the leader male supported young animals in the group against aggression and protected them against external threats. Unlike typical savanna baboons, these mountain baboons rarely displayed approach-retreat or triadic interactions, and entirely lacked coalitions among adult females. Both groups studied were reproductively one-male; male-female relationships in one were like those in a unit of hamadryas male at his peak, while the other group resembled the unit of an old hamadryas male, who still led the group, with a male follower starting to build up a new unit and already monoplizing mating. In their mountain environment, where the low population density suggests conditions as harsh for baboons as in deserts, adults in these groups kept unusually large distances apart during ranging; kin tended to range apart, and spacing of adults was greatest at the end of the dry, winter season. These facts support the hypothesis that sparse food is responsible for convergence with hamadryas social organization. It is suggested that all baboons, though matrilocal, are better categorized as "cross-sex-bonded" than "female bonded".

One-male groups and intergroup interactions of mountain baboons

The behavioral ecology of mountain baboons, Papio ursinus,cuts across the traditional dichotomy between savannah and desert baboons, providing fresh opportunities to examine socioecological relationships. Mountain baboons were studied at a site where covariation in altitude and group size helps to clarify the influence of ecology on social behavior. One-male groups and lone males were regularly found in the highest-altitude zones. In encounters with multimale groups, a one-male group retreated; the group’s single male attacked his females, herding them far away from the multimale group. The male himself then approached and watched (and often loud-called at) this group. In a two-male group, the younger male herded the females, while the older sometimes defended the group. One-male groups did not show regular, stable aggregations, but two such groups seasonally coordinated their ranging “in tandem.” Ecological explanations for these behaviors and their relationship to the behavior of hamadryas baboons are evaluated, and a new theory of the origin of one-male groups in baboons is developed.