A social network analysis of social cohesion in a constructed pride: implications for ex situ reintroduction of the African lion (Panthera leo)

Genetic diversity of lion populations in Kenya: Evaluating past management practices and recommendations for future conservation actions

The decline of lions (Panthera leo) in Kenya has raised conservation concerns about their overall population health and long-term survival. This study aimed to assess the genetic structure, differentiation and diversity of lion populations in the country, while considering the influence of past management practices. Using a lion-specific Single Nucleotide Polymorphism (SNP) panel, we genotyped 171 individuals from 12 populations representative of areas with permanent lion presence. Our results revealed a distinct genetic pattern with pronounced population structure, confirmed a north-south split and found no indication of inbreeding in any of the tested populations. Differentiation seems to be primarily driven by geographical barriers, human presence and climatic factors, but management practices may have also affected the observed patterns. Notably, the Tsavo population displayed evidence of admixture, perhaps attributable to its geographic location as a suture zone, vast size or past translocations, while the fenced populations of Lake Nakuru National Park and Solio Ranch exhibited reduced genetic diversity due to restricted natural dispersal. The Amboseli population had a high number of monomorphic loci likely reflecting a historical population decline. This illustrates that patterns of genetic diversity should be seen in the context of population histories and that future management decisions should take these insights into account. To address the conservation implications of our findings, we recommend prioritizing the maintenance of suitable habitats to facilitate population connectivity. Initiation of genetic restoration efforts and separately managing populations with unique evolutionary histories is crucial for preserving genetic diversity and promoting long-term population viability.

Behaviour and welfare of African lion (Panthera leo) cubs used in contact wildlife tourism

Lion (Panthera leo) cubs are used in wildlife interaction tourism but the effects on cub welfare are unknown. We assessed the behaviour of three cohorts of lion cubs, twelve animals in total, at three different interaction facilities, using continuous and scan-sampling methodologies for the entire duration of cub utilisation for human interactions. Cubs spent most time inactive (62%), particularly sleeping (38%), but also spent a substantial amount of time playing (13%) and being alert (12%). A generalised linear mixed model revealed that cub behaviour was similar in two facilities but different from cubs in the third. In these two similar facilities, as human interactions increased, the time spent resting, sleeping and playing with other cubs decreased, and alert behaviour, grooming of humans and flight responses increased. In the third facility, cubs had an abnormal activity budget, with high levels of inactivity (80%) accompanied by a lack of response to human interactions. We conclude that in some facilities normal cub behaviour cannot be achieved and may be compromised by a high frequency of human interactions, which therefore needs to be controlled to limit adverse effects on cub behaviour.

Social responses to the natural loss of individuals in Barbary macaques

In recent years, there has been considerable interest in investigating how animal social structure is affected by the loss of individuals. This is often achieved using simulations that generate predictions regarding how the removal of ‘key’ individuals from a group affects network structure. However, little is known about the effects of such removals in wild and free-ranging populations, particularly the extent to which naturally occurring mortality events and the loss of a large proportion of individuals from a social group affects the overall structure of a social network. Here, we used data from a population of wild Barbary macaques (Macaca sylvanus) that was exposed to an exceptionally harsh winter, culminating in the death of 64% of the adults from two groups. We analysed how social interaction patterns among surviving individuals were affected by the natural loss of group members using social networks based on affiliative (i.e., grooming) and aggressive social interactions. We show that only the structure of the pre-decline grooming networks was conserved in the post-decline networks, suggesting that grooming, but not aggression networks are resilient against the loss of group members. Surviving group members were not significantly different from the non-survivors in terms of their affiliative and agonistic relationships, and did not form assorted communities in the pre-decline networks. Overall, our results suggest that in primates, patterns of affiliative interactions are more resilient to changes in group composition than aggressive interaction patterns, which tend to be used more flexibly in new conditions.

Assessing the Social Cohesion of a Translocated Pride of White Lions Integrated with Wild Tawny Lions in South Africa, Using Social Network Analysis

In South Africa, lions are protected in national parks and smaller fenced reserves. Translocating lions between fenced reserves, whilst necessary to maintain genetic diversity, is disruptive and can impact survivorship and pride cohesion. Critical to translocation success is pride cohesion. White lions are a natural colour variant occurring in the Greater Kruger Park Region, where anthropogenic threats eliminated this population until reintroduction in 2006. Through social network analysis (SNA), the sociality of a released pride of captive-origin white and wild tawny lions was compared to two captive-origin and wild prides of tawny lions. Social interactions and pride dynamics were recorded for each pride. For all prides, cubs and subadults were central to the play network, while adults received the most social interactions. White and wild tawny adult males initiated more social interactions than captive-origin tawny males, whilst a keystone adult female was identified in each pride. For the constructed pride, social interactions were more evenly distributed, suggesting a high level of connectedness and cohesion. This is the first study to demonstrate that captive-origin white and wild tawny lions can form a socially functional pride, suggesting that white lions would survive in the wild in the absence of anthropogenic threats.

Oxytocin promotes social proximity and decreases vigilance in groups of African lions

Oxytocin modulates mammalian social behavior; however, behavioral responses to intranasal oxytocin can vary across species and contexts. The complexity of social interactions increases with group dynamics, and the impacts of oxytocin on both within- and between-group contexts are unknown. We tested the effects of intranasal administration of oxytocin on social and non-social behaviors within in-group and out-group contexts in African lions. We hypothesized that, post intranasal oxytocin administration, lions would be in closer proximity with fellow group members, whereas out-group stimuli could either produce a heightened vigilance response or an attenuated one. Compared to control trials, post oxytocin administration, lions increased their time spent in close proximity (reducing their distance to the nearest neighbor) and decreased vigilance toward out-group intruders (reducing their vocalizations following a roar-playback). These results not only have important implications for understanding the evolution of social circuitry but may also have practical applications for conservation efforts.

•

We administered oxytocin to groups of African lions

•

Relative to control conditions, oxytocin administration enhanced social proximity

•

Oxytocin administration decreased vigilance (roars following roar playback)

Social networks research in ex situ populations: Patterns, trends, and future directions for conservation-focused behavioral research

Social networks research using non-human animals has grown over the past decade, utilizing a wide range of species to answer an array of pure and applied questions. Network approaches have relevance to conservation, evaluating social influences on fecundity, health, fitness and longevity. While the application of network approaches to in situ populations with conservation concern appears in published literature, the degree to which ex situ and zoo-housed populations are the focus of "social networks for conservation research" is limited. Captive environments provide scientists with an ability to understand the social behavior of species that may be hard to observe consistently in the wild. This paper evaluates the scope of network research involving ex situ populations, analyzing output from 2010 to 2019 to determine trends in questions and subjects using ex situ populations. We show that only 8.2% of ex situ social network analysis (SNA) implications are of conservation-focus, apparent in papers relating to birds, carnivores, bats, primates, reptiles, and ungulates. Husbandry and welfare questions predominate in ex situ network research, but over half of these papers have nonpractical application (basic science). The chance of a citation for a basic science paper was 95.4% more than for a conservation-based paper. For taxonomic groups, primate-focused papers had the most citations. The focus of ex situ conservation-based networks research may be driven by the needs of conservation programs (e.g., population recovery outcomes) or by a need to evaluate the efficacy of ex situ conservation goals. We evaluate our findings considering the IUCN's One Plan Approach to conservation to show how in situ and ex situ network research is applicable to global conservation efforts. We have identified that there is a lack of application and evaluation of SNA to wildlife conservation. We highlight future areas of research in zoos and hope to stimulate discussion and collaboration between relevant parties.

Play fighting social networks do not predict injuries from later aggression

Early play fighting mimics later aggression in many species, and may, therefore, be expected to reduce costs from later aggressive interactions. Using social network analysis (SNA) the effect of a central play fighting network position on later skin lesions from aggression was assessed in domestic pigs. Piglets (n = 263) were kept in litter groups or socialised pre-weaning with another litter to enhance play fighting experience. Play fighting was recorded for 1.5 h per day over 6 days pre-weaning. Play fighting network centrality was quantified using measures of individual network position and entire network structure (degree, eigenvector, betweenness, clustering coefficient). Skin lesions from aggression were counted after a dyadic contest and at 24 h and 3 weeks following group mixing. Pigs with play fighting interactions with many partners experienced fewer lesions from the dyadic contest (in-degree, p = 0.01) and tended to received fewer lesions 3 weeks after group mixing (degree, p = 0.088) but no other play fighting centrality measures affected the number of lesions at any point. The benefits of play fighting were therefore limited to specific aggressive social contexts. The tendency of socialised piglets to play fight with non-littermates did not affect subsequent lesions. We advocate the use of SNA over approaches that only consider dyadic interactions to further our understanding of the influence of early social group interactions on later life experience.

A genome-wide data assessment of the African lion (Panthera leo) population genetic structure and diversity in Tanzania

The African lion (Panthera leo), listed as a vulnerable species on the IUCN Red List of Threatened Species (Appendix II of CITES), is mainly impacted by indiscriminate killing and prey base depletion. Additionally, habitat loss by land degradation and conversion has led to the isolation of some subpopulations, potentially decreasing gene flow and increasing inbreeding depression risks. Genetic drift resulting from weakened connectivity between strongholds can affect the genetic health of the species. In the present study, we investigated the evolutionary history of the species at different spatiotemporal scales. Therefore, the mitochondrial cytochrome b gene (N = 128), 11 microsatellites (N = 103) and 9,103 SNPs (N = 66) were investigated in the present study, including a large sampling from Tanzania, which hosts the largest lion population among all African lion range countries. Our results add support that the species is structured into two lineages at the continental scale (West-Central vs East-Southern), underlining the importance of reviewing the taxonomic status of the African lion. Moreover, SNPs led to the identification of three lion clusters in Tanzania, whose geographical distributions are in the northern, southern and western regions. Furthermore, Tanzanian lion populations were shown to display good levels of genetic diversity with limited signs of inbreeding. However, their population sizes seem to have gradually decreased in recent decades. The highlighted Tanzanian African lion population genetic differentiation appears to have resulted from the combined effects of anthropogenic pressure and environmental/climatic factors, as further discussed.

Temporal modification of social interactions in response to changing group demographics and offspring maturation in African lions (Panthera leo)

In group living animals, affiliative social interactions maintain cohesion between individuals. Involvement in these interactions is likely to differ between individuals, depending on their sex, age and life history stages. Here we investigated different social network measures to describe greeting interactions within two prides of captive-origin African lions (Panthera leo). We aimed to determine if the introduction of cubs to these prides altered the strength of greeting networks among female lions. We also tested if the strength of greeting interactions changed between the age classes as younger lions matured. We found that interactions amongst female lions decreased from the period before cubs were born (least square means [95% CIs] 15.3 [7.67-22.93]) compared to after their integration into a pride (5.63 [-1.99-13.26] χ²₁ = 210.03, p < 0.001). In contrast, greeting network strength increased as offspring matured, with adults directing more interactions towards younger lions from 30 months of age (12.89 [1.96-23.82]) compared to when offspring were cubs (-0.69 [-11.63--10.24] χ²₁₀ = 156.03, p < 0.001). We suggest that social interactions between age classes may mediate recruitment and dispersal in lion prides.

An assessment of African lion Panthera leo sociality via social network analysis: prerelease monitoring for an ex situ reintroduction program

The wild population of the African lion Panthera leo continues to decline, requiring alternate conservation programs to be considered. One such program is ex situ reintroduction. Prior to release, long-term monitoring and assessment of behavior is required to determine whether prides and coalitions behave naturally and are sufficiently adapted to a wild environment. Social network analysis (SNA) can be used to provide insight into how the pride as a whole and individuals within it, function. Our study was conducted upon 2 captive-origin prides who are part of an ex situ reintroduction program, and 1 wild pride of African lion. Social interactions were collected at all occurrence for each pride and categorized into greet, social grooming, play, and aggression. Betweenness centrality showed that offspring in each pride were central to the play network, whereas degree indicated that adults received (indegree) the greatest number of overall social interactions, and the adult males of each pride were least likely to initiate (outdegree) any interactions. Through the assessment of individual centrality and degree values, a social keystone adult female was identified for each pride. Social network results indicated that the 2 captive-origin prides had formed cohesive social units and possessed relationships and behaviors comparable with the wild pride for the studied behaviors. This study provided the first SNA comparison between captive-bred origin and a wild pride of lions, providing valuable information on individual and pride sociality, critical for determining the success of prides within an ex situ reintroduction program.

The effect of excluding juveniles on apparent adult olive baboons (Papio anubis) social networks

In recent years there has been much interest in investigating the social structure of group living animals using social network analysis. Many studies so far have focused on the social networks of adults, often excluding younger, immature group members. This potentially may lead to a biased view of group social structure as multiple recent studies have shown that younger group members can significantly contribute to group structure. As proof of the concept, we address this issue by investigating social network structure with and without juveniles in wild olive baboons (Papio anubis) at Gashaka Gumti National Park, Nigeria. Two social networks including all independently moving individuals (i.e., excluding dependent juveniles) were created based on aggressive and grooming behaviour. We used knockout simulations based on the random removal of individuals from the network in order to investigate to what extent the exclusion of juveniles affects the resulting network structure and our interpretation of age-sex specific social roles. We found that juvenile social patterns differed from those of adults and that the exclusion of juveniles from the network significantly altered the resulting overall network structure. Moreover, the removal of juveniles from the network affected individuals in specific age-sex classes differently: for example, including juveniles in the grooming network increased network centrality of adult females while decreasing centrality of adult males. These results suggest that excluding juveniles from the analysis may not only result in a distorted picture of the overall social structure but also may mask some of the social roles of individuals belonging to different age-sex classes.

Behavioral correlates between daily activity and sociality in wild and captive origin African lions

Study of behavioral correlations within and across populations has long been of interest to ethologists. An exploration of behavioral correlations between sociality and behavior of African lions (Panthera leo) was undertaken to examine if this approach is better able to reveal important aspects of lion behavior not easily discernible by looking at these behaviors separately. Resting behavior and received play interactions were correlated in 2 captive-origin prides and one wild pride, attributable to the involvement of cubs and sub-adults. Direct and exploratory movement was negatively correlated with groom centrality in 2 of the 3 prides, due to adults engaging in high levels of both of these activities. Exploration of these behavioral correlations highlighted the differences between age-groups in activity and sociality, facilitating the understanding of the complex behavior and interactions of lions. In addition, the finding of similar behavioral correlations between captive-origin and the wild prides provides confidence in the suitability if captive-origin candidates for ex-situ release. This is imperative to ensure the success of sub-groups and prides under an ex-situ reintroduction program.

Detection of social group instability among captive rhesus macaques using joint network modeling

Social stability in group-living animals is an emergent property which arises from the interaction amongst multiple behavioral networks. However, pinpointing when a social group is at risk of collapse is difficult. We used a joint network modeling approach to examine the interdependencies between two behavioral networks, aggression and status signaling, from four stable and three unstable groups of rhesus macaques in order to identify characteristic patterns of network interdependence in stable groups that are readily distinguishable from unstable groups. Our results showed that the most prominent source of aggression-status network interdependence in stable social groups came from more frequent dyads than expected with opposite direction status-aggression (i.e. A threatens B and B signals acceptance of subordinate status). In contrast, unstable groups showed a decrease in opposite direction aggression-status dyads (but remained higher than expected) as well as more frequent than expected dyads with bidirectional aggression. These results demonstrate that not only was the stable joint relationship between aggression and status networks readily distinguishable from unstable time points, social instability manifested in at least two different ways. In sum, our joint modeling approach may prove useful in quantifying and monitoring the complex social dynamics of any wild or captive social system, as all social systems are composed of multiple interconnected networks.