Fission-fusion Social System Research Articles

Chimpanzees employ context-specific behavioral strategies within fission-fusion societies.

Fission-fusion social systems allow individuals to make flexible choices about where, with whom, and in what contexts to spend their time in response to competing social and ecological pressures. The ability for fission-fusion societies to support individual behavioral strategies that vary across contexts has been suggested, but the potential function of such context-specific social choices remains largely understudied. We adopted the concept of social niche construction to explore possible differences in social complexity at the individual and group level across feeding contexts. Specifically, we examined patterns of co-attendance across two common ecological contexts in wild Central African chimpanzees (Pan troglodytes troglodytes) in the Goualougo Triangle, Republic of Congo. From data compiled over 6years, we used multidimensional social network analysis to study the patterns of co-attendance generated from 436 group scans at Ficus and 4527 visits to termite mounds. These two contexts were chosen, because they are both fixed spatial features across the landscape that serve as well-defined points to compare association patterns. We identified context-specific social niche construction in a fission-fusion chimpanzee society that produce different patterns of relationships and social complexity that are consistent in their expression over many years, and offer functional benefits. While enhancing our understanding of chimpanzee behavioral strategies, culture, and conservation, our investigation also indicates that the social niche construction framework aids in elucidating the evolutionary advantages of fission-fusion sociality by accounting for intra- and interindividual variability, cognition, and choice in newfound ways.

Flexible grouping patterns in a western and eastern chimpanzee community.

Primate social organizations, or grouping patterns, vary significantly across species. Behavioral strategies that allow for flexibility in grouping patterns offer a means to reduce the costs of group living. Chimpanzees (Pan troglodytes) have a fission-fusion social system in which temporary subgroups ("parties") change in composition because of local socio-ecological conditions. Notably, western chimpanzees (P. t. verus) are described as showing a higher degree of bisexual bonding and association than eastern chimpanzees, and eastern female chimpanzees (P. t. schweinfurthii) are thought to be more solitary than western female chimpanzees. However, reported comparisons in sociality currently depend on a small number of study groups, particularly in western chimpanzees, and variation in methods. The inclusion of additional communities and direct comparison using the same methods are essential to assess whether reported subspecies differences in sociality hold in this behaviorally heterogeneous species. We explored whether sociality differs between two communities of chimpanzees using the same motion-triggered camera technology and definitions of social measures. We compare party size and composition (party type, sex ratio) between the western Gahtoy community in the Nimba Mountains (Guinea) and the eastern Waibira community in the Budongo Forest (Uganda). Once potential competition for resources such as food and mating opportunities were controlled for, subspecies did not substantially influence the number of individuals in a party. We found a higher sex-ratio, indicating more males in a party, in Waibira; this pattern was driven by a greater likelihood in Gahtoy to be in all-female parties. This finding is the opposite of what was expected for eastern chimpanzees, where female-only parties are predicted to be more common. Our results highlight the flexibility in chimpanzee sociality, and caution against subspecies level generalizations.

How Sanctuary Chimpanzees (Pan troglodytes) Use Space after Being Introduced to a Large Outdoor Habitat.

Wild chimpanzees live in large, mixed-sex groups that display a fission-fusion social organization. To provide a social environment more like that of wild chimpanzees, Chimp Haven integrated smaller groups of 3-4 individuals into one large group of 18 individuals. This large group was introduced to a 20,234.28 m2 forested habitat and associated indoor areas. This space was designed to allow the individual chimpanzees to choose their proximity to social companions and provide the group with a more natural environment in which they could express more species-typical behavior. The study took place over a 7-month period that began two weeks prior to the first groups being integrated and ended 4 months after the chimpanzees were released into the habitat. We collected data on the chimpanzees' arboreal, terrestrial, indoor, and outdoor spatial use. The chimpanzees' proximity to their nearest neighbor was also recorded, noting whether they were touching or within arm's reach. Data were collected during daytime and nighttime hours and were utilized to make management decisions about potential group formations. We examined the data using generalized linear mixed models (GLMMs) with individual subjects as a random factor and months as a repeated measure for location and proximity results. There were significant differences in the use of arboreal and outside space over the 7-month time frame, with females more likely to use the arboreal space than males. The chimpanzees were more likely to utilize the habitat over time and increased their proximity to group mates. The results of this study indicate that the chimpanzees responded positively to living in large groups in a spacious naturalistic environment.

SMO Algorithm to Unravel CEED Problem using Wind and Solar

This research proposes a more advanced way to address Combined Economic Emission Dispatch (CEED) concerns. Economic Load Dispatch (ELD) and Economic Emission Dispatch (EED) have been implemented to reduce generating unit fuel costs and emissions. When both economics and emission targets are taken into account, the dispatch of an aggregate cost-effective emission challenge emerges. This research affords a mathematical modeling-based analytical technique for solving economic, emission, and collaborative economic and emission dispatch problems with only one goal. This study takes into account both the fuel cost target and the environmental impact of emissions. This bi-intention CEED problem is converted to a solitary goal function using a price penalty factor technique. In this case, a metaheuristic and an environment-inspired, intelligent Spider Monkey Optimization technique (SMO) are used to address the CEED dilemma. By following the generator’s scheduling process, the SMO method is used to regulate the output from the power generation system in terms of pollution and fuel cost. The Fission-Fusion social (FFS) structure of spider monkeys promotes them to utilize a global optimization method known as SMO during foraging behaviour. The emphasis is mostly on lowering the cost of generation and pollution in order to improve the efficiency of the power system and handle dispatch problems with constraints. The economic dispatch has been remedied, and the improved result demonstrates that the system’s performance is stable and flexible in real time. Finally, the system’s output demonstrates that the system has improved in resolving CEED difficulties. When compared to earlier investigations, the proposed model’s findings have improved. As the generating units, wind and solar are used to explore the CEED crisis in the IEEE 30 bus system.

Social Structure and Temporal Distribution of Tursiops truncatus in the Gulf of Taranto (Central Mediterranean Sea)

This study aims to provide information on the site fidelity, residency patterns and the social structures of bottlenose dolphins occurring in the Gulf of Taranto in order to supply effective indications supporting the future management and conservation measures of the species. Out of 141 photo-identified individuals about 76% were re-sighted from 2 up to 31 times. The site fidelity analysis of photo-identified individuals highlighted the occurrence of 20 seasonal residents, 62 visitors and 59 transient individuals that were included in a local population in which emigration and reimmigration events occurred, as suggested by the residency-pattern analysis. The association pattern, performed using SOCPROG 2.9, highlighted a relatively low mean value of the overall half-weight association index (0.11 ± 0.04). However, the test for the null hypothesis of ‘random association’ was rejected and the temporal analysis made with SLAR suggested the presence of both extremely fluid and stable associations between individuals, describing a fission fusion social structure with a certain degree of social organization. Moreover, the cluster and social network analysis showed two geographically and socially segregated units. Thus, more investigations are needed and the development of a specific conservation plan for bottlenose dolphins in the whole area is required.

Binary spider monkey algorithm approach for optimal siting of the phasor measurement for power system state estimation

The phasor measurement unit (PMU) is an essential measuring device in current power systems. The advantage seems to be that the measuring system could simultaneously give voltages and currents phasor readings from widely dispersed locations in the electric power grid for state estimation and fault detection. Simulations and field experiences recommend that PMUs can reform the manner power systems are monitored and controlled. However, it is felt that expenses will limit the number of PMUs that will be put into any power system. Here, PMU placement is done using a binary spider monkey optimization (BSMO) technique that uses BSMO by simulating spider monkeys’ foraging behavior. Spider monkeys have been classified as animals with a fission-fusion social structure. Animals that follow fission-fusion social systems divide into big and tiny groups, and vice versa, in response to food shortage or availability. The method under development produced the optimum placement of PMUs while keeping the network fully observable under various contingencies. In the study published in IEEE14, IEEE24, IEEE30, IEEE39, IEEE57, and IEEE118, the proposed technique was found to reduce the number of PMUs needed.

Movement behaviour after birth demonstrates precocial abilities of African savannah elephant, Loxodonta africana, calves

Living in groups has many benefits including predator protection and information sharing that can outweigh the associated costs. African savannah elephants live in a matriarchal fission–fusion social structure where groups merge or split depending on the relative costs of group living. However, elephants are also nonsynchronous breeders which may cause optimal movement patterns to differ between group members, particularly around parturition. Both the mother and the group must assess whether the benefits outweigh the costs of group cohesion. Understanding the impact of gestation, parturition and the presence of a newborn calf on the mother's movement patterns could provide key insights into the drivers of fission–fusion social dynamics. Here, we examined the relationship between reproductive state and movement using GPS tracking data collected during 23 parturitions from multiparous elephants (≥ second calving) and three from primiparous females. We analysed daily mean speed before, during and after parturition, and used a three-state hidden Markov model to determine whether parturition results in a distinctive change in speed. The results show that, although speed decreased on the estimated parturition date, parturition could only be detected in four of 23 multiparous parturition events when placed in the context of speed over a 2-month period. Furthermore, the speed on the day before and the day after parturition (i.e. first complete day of the calf's life) was not significantly different from the yearly mean. By contrast, a speed decrease was detected in the limited sample of primiparous females but was of short duration. Our results indicate that the precocial abilities of calves facilitate the maintenance of group cohesion within the matriarchal fission–fusion social structure of elephants. We speculate that, alongside cognitive development, elephants may have evolved a long gestation period to facilitate an advanced stage of fetal physical development. • We analysed the movement behaviour of parturient African savannah elephants. • Gestation, parturition and neonatal calves had little impact on mothers' movements. • We demonstrate the precocial abilities of elephant calves. • Movement after birth could be a significant advantage for a social species. • Extended gestation of elephants may have evolved for advanced fetal development.

Modified Spider Monkey Optimization Algorithm Based on Self-Adaptive Inertia Weight

Spider monkey optimization (SMO) algorithm is a new swarm intelligence optimization algorithm proposed in recent years. It simulates the foraging behavior of spider monkeys which have fission-fusion social structure (FFSS). In this paper, a modified spider monkey optimization algorithm is proposed. The self-adaptive inertia weight is introduced in the local leader phase to enhance the self-learning ability of the spider monkey. According to the function value of an individual, the distance from the optimal value is determined, so the inertia weight related the individual function value is added to strength the global search ability or local search ability. The proposed algorithm is tested on 20 benchmark problems and compared with the original SMO and the hybrid algorithm SMOGA and GASMO. The numerical results show that the proposed algorithm has a certain degree of improvement in convergence accuracy and convergence speed. The performance of the proposed algorithm is also inspected by two classical engineering design problems.

Social bonds predict dominance trajectories in adult male chimpanzees

In some species, individuals form well-differentiated and affiliative social relationships that facilitate cooperation and confer adaptive benefits, but few studies of males have addressed the benefits of same-sex social bonds. Among mammals, adult male chimpanzees, Pan troglodytes, form some of the strongest and most stable social bonds, and several studies have found that higher-ranking males attain short- and long-term benefits. No study in chimpanzees, however, has demonstrated a link between social bonds and dominance trajectories. To fill this gap, we used 37 years of data from Gombe National Park, Tanzania, to test the hypothesis that social bonds in adult male chimpanzees predict changes in dominance strength, which were measured by annual changes in mean Elo scores. Across 24 adult males, we found that social bonds, which were identified using both association in small groups and grooming activity, showed positive relationships with changes in dominance strength. From previous studies, the most likely mechanism for the observed relationship between adult male bond strength and dominance trajectories is the formation of cooperative coalitions, by which males with stronger bonds leverage established relationships to maintain or increase their position in the dominance hierarchy. Given the fission–fusion social structure of chimpanzees, both party-level associations and grooming relationships are essential components of male social bonding, and these results, in combination with prior studies, suggest that having strong social bonds is a valuable strategy for achieving higher rank.

Intra-Population Variability in Group Size of Indo-Pacific Humpback Dolphins (Sousa chinensis)

Group size is a key social trait influencing population dynamics of group-living animals. The Indo-Pacific humpback dolphins (IPHDs), Sousa chinensis, a shallow water delphinid species, display a fission-fusion social system. Yet little is known about how social organization of this species vary with temporal scales and behavioral state. In this study, we sampled group size estimates from the world’s second largest population of humpback dolphins (Sousa spp.), which inhabit the eastern waters of Zhanjiang, China. IPHD group sizes changed seasonally and inter-annually, but not with tidal phases. Group sizes also changed with behavioral state of IPHD groups and with number of mother-calf pairs present. IPHDs formed larger groups in the autumn than in other seasons, which might be related to seasonal changes in food availability and reproductive cycle. Of the groups observed, we recorded the presence of mother-calf pair in 85 groups (i.e., nursery groups: 47 ones with one pair, 25 ones with two pairs, and others with three pairs). Notably, nursery groups were about 2–4 times larger than non-nursery groups. In addition, group sizes greatly increased with the number of mother-calf pairs. Living in relatively large groups, more protection, food, and resources might be available for IPHD mothers and calves, and such social strategy provide higher reproduction efficiency and survival success for this species. During our observations, feeding (45.5%) and traveling (25.2%) represented the majority of IPHD’s behavioral budget, while socializing (8.4%) and resting/milling (6.8%) were not frequently observed. Resting/milling groups were approximately 50% smaller than feeding, traveling, or socializing groups, while the latter three types had a similar mean group size. Large groups when IPHDs foraged, traveled, or socialized, might provide more added group benefits. For the first time, our findings clearly revealed intra-population variability in IPHD group sizes across different behavioral and temporal variables, and provided a better understanding of IPHDs’ adaptations to various biological processes and ecological constraints.

Evolving fuzzy reasoning approach using a novel nature-inspired optimization tool

In general, fuzzy reasoning tool with Mamdani approach has good readability, but low accuracy; whereas the same with Takagi and Sugeno’s approach ensures high accuracy but at the cost of readability. In the developed combined form of fuzzy reasoning, the merits of both the above two approaches are utilized to obtain both the high accuracy as well as good readability. The above combined form is evolved using a recently-developed nature-inspired technique, namely Bonobo Optimizer (BO). This optimization method mimics the fission-fusion social structure and reproductive schemes adopted by bonobos. In addition, controlling parameters of the BO are designed to be adaptive and self-adjusting to perform efficiently for a variety of problems. The performances of the developed models have been tested and compared with that of the combined fuzzy reasoning tool evolved using Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Grey-Wolf Optimizer (GWO) and Jaya Algorithm for three data sets. The novelty of this study lies with the ability of the recently proposed BO to evolve an efficient fuzzy reasoning approach.

The impact of Masai giraffe nursery groups on the development of social associations among females and young individuals

Fission–fusion social systems involve the splitting and merging of subgroups with frequent changes in membership occurring as a result of a number of ecological and social factors, such as demographic processes including birth, movement, or death. Giraffe reside in fission–fusion social systems, and we studied how reproductive status influence associations among females, as well as how associations differ between calves and juveniles. Data were collected in Katavi National Park, Tanzania, during five study periods. We used social network analysis to identify whether reproductive status and developmental stages predict differences in giraffe social association. We found that females with offspring maintain stronger associations than females without offspring. We also revealed that calves and juveniles had similar network association patterns. Our results suggest that the presence of dependent offspring influences the social associations of females and individuals less than 1.5 years of age are still maintaining strong social associations with nursery group members. We conclude that nursery groups among giraffe are co-operative rearing units that probably reduce the costs of rearing to mothers, and may provide a group structure for animals to begin to develop skills useful for their future life in a fission–fusion social system.

A citizen science approach reveals long-term social network structure in an urban parrot, Cacatua galerita.

Parrots are often referenced in discussions of social and cognitive complexity, yet relatively little is known of their social organization in the wild. In particular, the presence of long-lasting social ties has been highlighted as a hallmark of social complexity; however, the presence of such ties can be masked in fission-fusion systems like that exhibited by most parrot species. Social network analysis has the potential to elucidate such multi-level dynamics. While most parrot species are tropical canopy dwellers, a subset has successfully colonized urban habitats, where they are often the focus of much public interest. Our study takes advantage of this to use citizen science to collect observations of wing-tagged sulphur-crested cockatoos in central Sydney and record their social associations over multiple years. Using a specifically designed mobile phone application 'Wingtags', we collected over >27,000 citizen science reports of wing-tagged cockatoos, and built social networks from spatial-temporal co-occurrences in observations for 130 tagged birds. To validate this novel methodology, we GPS-tagged a subset of wing-tagged birds and compared networks built from both data collection methods. We then examined correlates of social network structure before exploring the temporal dynamics of network structure and social associations. Social networks constructed from GPS data and citizen science data were highly correlated, suggesting that this novel methodology is robust. Network structure exhibited little seasonal variability and was largely driven by roost site choice; however, individuals also showed a surprising degree of mixing between roosts in their foraging associations. Finally, within this larger fission-fusion system, individuals tended to maintain specific social ties for long periods of time. There was an effect of age on these temporal dynamics, with aging individuals increasing both social stability and longevity of associations. Our findings highlight the utility of citizen science to measure social networks in urban species, and add to the evidence that long-lasting social associations can persist in fission-fusion social systems such as those observed in wild sulphur-crested cockatoos.

Collective Computation in Animal Fission-Fusion Dynamics.

Recent work suggests that collective computation of social structure can minimize uncertainty about the social and physical environment, facilitating adaptation. We explore these ideas by studying how fission-fusion social structure arises in spider monkey (Ateles geoffroyi) groups, exploring whether monkeys use social knowledge to collectively compute subgroup size distributions adaptive for foraging in variable environments. We assess whether individual decisions to stay in or leave subgroups are conditioned on strategies based on the presence or absence of others. We search for this evidence in a time series of subgroup membership. We find that individuals have multiple strategies, suggesting that the social knowledge of different individuals is important. These stay-leave strategies provide microscopic inputs to a stochastic model of collective computation encoded in a family of circuits. Each circuit represents an hypothesis for how collectives combine strategies to make decisions, and how these produce various subgroup size distributions. By running these circuits forward in simulation we generate new subgroup size distributions and measure how well they match food abundance in the environment using transfer entropies. We find that spider monkeys decide to stay or go using information from multiple individuals and that they can collectively compute a distribution of subgroup size that makes efficient use of ephemeral sources of nutrition. We are able to artificially tune circuits with subgroup size distributions that are a better fit to the environment than the observed. This suggests that a combination of measurement error, constraint, and adaptive lag are diminishing the power of collective computation in this system. These results are relevant for a more general understanding of the emergence of ordered states in multi-scale social systems with adaptive properties–both natural and engineered.

REM: performance on a high-density fallow deer (Dama dama) population

We present an application of the random encounter model (REM) to estimate population density of a closed population of fallow deer (Dama dama). REM promises to be a powerful tool for providing density estimates for species which are not individually recognisable, but it still requires thorough testing to assess its limits and performance. In our study area, effective fencing prevents animals from migrating in or out of the area thus assuring a closed population; still the application of REM presented several challenges, including a very high density (more than 600 ind/km2) and a constant fission/fusion of groups of the study species. We applied both stratified and unstratified analysis approach, and we estimated density over a range of daily range values. The REM approach underestimates the true density value of about 31% and 28% the CV of the estimates was 0.39 and 0.52, for stratified and unstratified approach, respectively. Still it provides evidence in support of REM as a method for providing density estimates of free-ranging unmarked individuals with a fission–fusion social structure.

Analysis of stereotypic behaviour and enhanced management in captive Northern Giraffe Giraffa camelopardalis housed at Zoological Garden Alipore, Kolkata

In the wild, giraffes live complex social lives exhibiting fission-fusion social systems. They have sophisticated communication which likely forms a crucial component regulating subgroup dynamics. They spend a large part of their day browsing and traveling over large distances. In captivity, lack of continuous browsing opportunities and limited space can lead to various abnormal and stereotypic behaviours. These stereotypic behaviours can have cascading detrimental health consequences. A behavioural analysis of stereotypic behaviours in giraffes under human care was conducted to evaluate sources of variation within a population and provide management recommendations. The aim of this investigation was threefold: 1. to examine current behaviour of giraffes in Zoological Garden Alipore, Kolkata to advise on their enhanced management; 2. to highlight any behavioural abnormalities and recommend enrichment mechanisms; and 3. to compare the observed stereotypic behaviours with behaviour described in other zoological institutions and in the wild to provide a focal trajectory in the development of guidelines. Four individuals (two adult males, one adult female, and one male calf) were observed outdoors for seven days, three times a day for 30 minutes by instantaneous scan sampling method. During the observation period, the giraffe exhibited oral stereotypy more than any other behaviour recorded, though this was recorded disproportionally between individuals. The giraffe spent a larger amount of time exhibiting oral stereotypy compared to feeding/foraging activities. The study suggests incorporating diet and feeding strategies with provision of natural browse as well as offering enrichment methods to increase the foraging time using various time-engaged feeding devices to mitigate the observed abnormal stereotypic behaviour. Additionally, recommendations are made for expanding the size of the open enclosure to meet guidelines by the Central Zoo Authority, as a minimum.

Hyperbolic Spider Monkey Optimization Algorithm

Background: Spider monkey optimization algorithm is recently developed natureinspired algorithm. It is based on fission-fusion social structure of spider monkeys. Perturbation rate is one of the important parameter of spider monkey optimization algorithm, which affects the convergence behavior of spider monkey optimization algorithm. Generally, perturbation rate is a linearly increasing function. However, due to the availability of non-linearity in different applications, a non-linear function may affect the performance of spider monkey optimization algorithm. Objective: This paper provides a detailed study on various perturbation techniques used in spider monkey optimization algorithm and recommends a novel alternative of hyperbolic spider monkey optimization algorithm. The new approach is named as hyperbolic Spider Monkey Optimization algorithm as the perturbation strategy inspired by hyperbolic growth function. Methods: The proposed algorithm is tested over a set of 23 CEC 2005 benchmark problems. Results: The experimental outcomes illustrate that the hyperbolic spider monkey optimization algorithm effectively increase the reliability of spider monkey optimization algorithm in comparison to the considered approaches. Conclusion: The hyperbolic spider monkey optimization algorithm provides improved perturbation rate, desirable convergence precision, rapid convergence rate, and improved global search capability.

Relationships between male giraffes’ colour, age and sociability

In species in which males signal competitive ability through secondary sexual traits, males with different levels of trait expression may adopt different reproductive tactics to maximize their reproductive success. In fission–fusion social systems, the most dominant males often roam widely in search of females in oestrus, and thus exhibit different patterns of sociability from subordinate males that utilize alternative reproductive tactics. Giraffes, Giraffa camelopardalis, are rare among mammals in that they are sexually dimorphic in colour, and colour is hypothesized to function as a signal of males’ social status by displaying their competitive ability. Here we analysed the coat colour and sociability of 66 wild male giraffes over 12 years at Etosha National Park in Namibia to test two premises underlying this hypothesis. First, we found that males did not all darken at the same rate or to the same degree, and colour variation increased with age. This suggests that colour is not solely an age-based trait but could be a secondary sexual trait. We then showed a distinct difference in the sociability of both young and pale males compared to darker males. Both younger and paler old males tended to be more gregarious while darker males were more solitary. This is consistent with a system where darker, more dominant males roam looking for females in oestrus. Younger or subordinate males may delay roaming or use an alternative tactic, such as remaining in groups with females to gain copulations when a more dominant male is not present. Our results are consistent with the hypothesis that male giraffe coat colour functions as a signal of social status through competitive ability, but deeper study into movement patterns and the costs and benefits associated with darker colours is required.

Commensal bacterial sharing does not predict host social associations in kangaroos.

Social network analysis has been postulated as a tool to study potential pathogen transmission in wildlife but is resource-intensive to quantify. Networks based on bacterial genotypes have been proposed as a cost-effective method for estimating social or transmission network based on the assumption that individuals in close contact will share commensal bacteria. However, the use of network analysis to study wild populations requires critical evaluation of the assumptions and parameters these models are founded on. We test (a) whether networks of commensal bacterial sharing are related to hosts' social associations and hence could act as a proxy for estimating transmission networks, (b) how the parameters chosen to define host associations and delineate bacterial genotypes impact inference and (c) whether these relationships change across time. We use stochastic simulations to evaluate how uncertainty in parameter choice affects network structure. We focused on a well-studied population of eastern grey kangaroos (Macropus giganteus), from Sundown National Park, Australia. Using natural markings, each individual was identified and its associations with other kangaroos recorded through direct field observations over 2years to construct social networks. Faecal samples were collected, Escherichia coli was cultured and genotyped using BOX-PCR, and bacterial networks were constructed. Two individuals were connected in the bacterial network if they shared at least one E.coli genotype. We determined the capacity of bacterial networks to predict the observed social network structure in each year. We found little support for a relationship between social association and dyadic commensal bacterial similarity. Thresholds to determine host associations and similarity cut-off values used to define E.coli genotypes had important ramifications for inferring links between individuals. In fact, we found that inferences can show opposite patterns based on the chosen thresholds. Moreover, no similarity in overall bacterial network structure was detected between years. Although empirical disease transmission data are often unavailable in wildlife populations, both bacterial networks and social networks have limitations in representing the mode of transmission of a pathogen. Our results suggest that caution is needed when designing such studies and interpreting results.

Evaluating the social structure of captive Rothschild’s giraffes (Giraffa camelopardalis rothschildi): Relevance to animal management and animal welfare

ABSTRACTSocial network analysis (SNA) is useful for evaluating management zoo regimes to ensure that any fitness benefits of sociality are preserved in captive-housed groups. This paper explores the association patterns of 13 giraffes housed at Longleat Safari Park, UK. Wild giraffes exhibit a fission–fusion social system with preferential bonding. As zoo-housed giraffes are common, they are excellent study subjects for using SNA to investigate key aspects of sociality within a managed social environment. Social bonds were assessed over different seasons and data from two study periods (2011 and 2015) were analyzed to see consistency of “social type” (i.e., more social or more solitary). Associations showed the occurrence of consistent preferential bonds between named individuals but time of year influenced the patterns of social bonds. Female-female bonds and female-offspring bonds appeared to be strongest. For animals present in 2011 and 2015, differences in time spent socializing between years were apparent. Results suggest that giraffes may be flexible in their choice of social partner and zoo-managed herds should include a range of individuals from which each animal can choose a preferred associate.