Bull Elephants Research Articles

Persistence of the African baobab (Adansonia digitata L.) in a system experiencing chronic utilization by elephants

AbstractChronic utilization of woody vegetation by African savanna elephants may transform woodland vegetation to open savanna and threaten the extirpation of targeted species. This situation has arisen in Gonarezhou National Park (GNP), Zimbabwe, where a large elephant population (>2 km−2) threatens the persistence of the long‐lived baobab (Adansonia digitata) tree, through elevated mortality levels. This study investigated whether complete or partial refugia from elephant utilization existed for baobabs, and whether protection of trees by management, using wire netting or log‐ or rock‐packs around a tree base, had been effective. A total of 563 baobabs were sampled across northern GNP. Elephants had debarked 99% of trees to some degree, and gouged holes in the stem of 22% of trees. The probability, and severity, of debarking and gouging decreased with increasing distance to permanent water, increasing slope, and the amount of boulder cover. Slope gradient had the greatest effect on elephant impact, with trees located on steep slopes being less affected by elephants than those on flat ground. Distance to water had an effect despite the farthest tree, at 9 km from water, being within the 15 km foraging range of bull elephants. Large boulders partly protected trees even on gentle terrain. None of these factors provided a complete refuge from elephant impact within GNP, but, individually and collectively, provided a partial refuge at current elephant densities. Protection measures doubled tree survival over approximately 5 years, with fencing wire wrapped around baobab stems proving to be the most effective method. Assessment of the future security of baobabs in GNP requires knowledge of their distribution and that of the refugia provided by distance from permanent water, slope, and boulder cover.

Intervention by an older, dominant bull elephant (Elephas maximus) during an agonistic interaction between adolescents at Denver Zoo

Bull Asian elephant (Elephas maximus) sociality is complex and understudied. Increasingly, researchers recognize the role of mature bull elephants in teaching adolescent bulls appropriate social and reproductive behaviours that enable them to have normal intra-species relationships after the adolescents leave their natal herds. We describe a specific intervention event by a mature, dominant bull in a novel social group with adolescent bull elephants at Denver Zoo, Colorado, USA. The mature bull intervened on behalf of an adolescent elephant, allowing this adolescent to escape from two other adolescents who were repeatedly chasing him, marking boundaries of appropriate behaviour for the adolescent bulls. This example provides evidence for adolescent bull elephants learning appropriate social behaviours from mature conspecifics and suggests that mature bulls play an active role in this relationship. Overall, this intervention behaviour supports the inclusion of mature bulls in social groupings of bull elephants in managed care.

Immunoglobulin A and Physiologic Correlates of Well-Being in Asian Elephants

Zoological institutions aim to continually improve the lives of the animals under their stewardship. To this end, bull elephants are now increasingly maintained in all-male groups to mimic social conditions observed in the wild. While cortisol is the most frequently used “stress” biomarker, secretory immunoglobulin A (sIgA) as a measure of health and positive affect, and the social hormone, oxytocin, are increasingly viewed as additional markers of welfare. The introduction of a pair of bull elephants to an existing group of three bull elephants at Denver Zoo presented an opportunity to assess sIgA, oxytocin and cortisol in response to the socialization process. In this study, sIgA varied greatly between individuals and did not correlate with cortisol but did correlate with salivary oxytocin. sIgA and oxytocin concentrations differed the most between social and solo situations during the introduction period compared to before bulls were introduced, and after a stable group had been formed. In contrast to findings in some species, sIgA and oxytocin were higher when housed alone than socially. Nonetheless, these results suggest that sIgA and oxytocin may be involved in social engagement and establishment of new social dynamics, and thus provide more insight into overall welfare states.

Mapping Floristic Composition Using Sentinel-2A and a Case Study Evaluation of Its Application in Elephant Movement Ecology in Sagalla, Kenya

The quantification of vegetation structure and composition at local and global scales provides valuable information for understanding the balance of the natural and human-made environment, which is crucial for natural resource planning and management, and the sustenance of ecosystem biodiversity. In this study, we proposed using the Sentinel 2A imagery to classify vegetation cover into communities based on the floristic association of individual vegetation species. We apply traditional remote sensing techniques to process the satellite image and identify training regions of interest (ROI) which are thoroughly assessed for spectral uniqueness before using the pixel-based supervised classification algorithms for our classification. Ground truthing assessment and species dominance computations are done to determine the vegetation community composition and naming based on floristic associations. We apply the floristic compositions output in analysing elephant movement tracks in the area, to assess the potential influence the location of specific vegetation species and communities utilized by elephants has on their movement and presence, as well as on elephant bulls and family groupings. The results show that the 10 m spatial resolution Sentinel-2A is suitable for investigating and mapping vegetation species in communities for large-scale mapping operations. We determined Near-Infrared band 8 and shortwave Infrared band 11 as key for identifying and differentiating ROIs at the floristic association community vegetation mapping level. We attained an overall accuracy of 87.395%. The analysis proved the 10 m spatial resolution of Sentinel 2A to be sufficient in distinguishing vegetation communities, including those with similar dominant species but variations in other contributing species. We also found a direct connection between vegetation location and elephant movement based on the summative analysis of utilised vegetation by the different elephant groupings. Bull elephants were predominantly present in areas with Combretum, family groups in areas with Commiphora, and mixed groups with both bulls and families in areas with Commiphora, and Cissus. This study shows the value that remote-sensing scientific support can offer conservationists and governments in objective evidence-based land management, policy making and governance.

Predictors of testosterone in zoo-managed male African elephants (Loxodonta Africana).

Reproductive complications for both male and female zoo-managed African elephants (Loxodonta africana) contribute to the rapidly declining population. In zoo-managed bull elephants, few studies have explored the potential physiological, physical, social, and environmental factors that influence bull fertility, particularly, androgen production. Testosterone is the essential steroid hormone for male sexual maturation and inadequate concentrations can be detrimental for spermatogenesis. Testosterone, fecal glucocorticoid metabolites, leptin, glucose, insulin, and triglycerides were analyzed from weekly fecal and blood serum samples taken over 6 months from six zoo-managed African elephant bulls (10-19 years of age). Testosterone levels were compared to endocrine factors, weekly social and environmental variables, daily musth signs, and body condition scores (BCS). The glucose-to-insulin ratio (G:I) was the only physiological biomarker found to be positively associated with testosterone. Predictive physical variables included Musth Score (+) and Moderate Exercise (+). Bulls with BCSsignifying overweight (BCS 4) had lower testosterone (36.6 ± 1.6 ng/g fecal extraction [FE]) than bulls with healthyBCS 3; 51.2 ± 4.9 ng/g FE). Numerous social variables influenced testosterone concentrations, including Total Contact Day (+), Female Interaction Day (+), Indirect Contact Day (+), Indirect Contact Night (+) and Total No Contact (-). Both percentage of Time Outdoor and Time Mixed positively influenced testosterone, whereas testosterone decreased for percentage of Time Indoors. Each additional daily browse opportunity increased testosterone by approximately 7 ng/g FE. In managed care, the emphasis should be placed on optimizing these predictors of testosterone production to promote bull reproductive health.

The behaviour and fate of translocated bull African savanna elephants (Loxodonta africana) into a novel environment

AbstractTranslocation of elephants is used to mitigate human‐elephant conflict in Asia and Africa. However, few studies investigate how translocations affect the movements and social behaviour of individuals following their release, which may have important implications for whether translocated animals survive and succeed. Using GPS‐tracking data, we explored movements of five translocated bull elephants (Loxodonta africana) moved to Tsavo, Kenya, and compared them with five resident bull elephants. Position data was collected hourly for 1 year (March 2018–March 2019), and analysed to investigate home range, displacement rates, problematic behaviour and group size. Of the five translocated elephants, three were illegally killed and one continued to break fences and raid crops. Only one elephant stayed away from human settlement. We found group size and composition to be significantly different, with translocated elephants observed in smaller groups with no female elephant interactions. All elephants showed variation in home ranges and displacement rates, but differences were not significant between resident and translocated elephant groups. For future translocations, we recommend careful consideration of elephant social systems, elephant age, timing, release site and proximity to human settlements that might create human‐elephant conflict. This will improve chance for success of such high‐stake and expensive translocations.

Serum Insulin-like Growth Factor-1 Is a Biomarker of Testosterone Production and Intact Acrosome in Asian Elephants (Elephas maximus).

Simple SummaryIn Thailand, the low fertility rate of Asian elephants has been identified. Factors contributing to poor semen quality in the elephants are not fully understood. Insulin-like growth factor-1 (IGF-1) is related to male infertility. It plays an essential role in testicular development by stimulating cell proliferation, differentiation, and steroidogenesis. In addition, there is increasing evidence that IGF-1 plays a critical role in spermatogenesis. This may be conducive to finding the causes of poor sperm quality in Asian elephants (Elephas maximus). In the present study, we investigated the relationships among serum IGF-1, serum testosterone level, and semen parameters in seven elephant bulls. The findings suggest that serum IGF-1 concentration is likely to predict sperm quality like acrosome integrity. The further mechanism by which IGF-1 affects sperm quality requires further investigation.The objective of this study was to find relationships among serum IGF-1, serum testosterone, seminal plasma IGF-1 concentrations and semen parameters in Asian elephants (Elephas maximus). A total of 17 ejaculates (one to three ejaculates/bull) were collected from seven captive elephant bulls by performing rectal massage. Before each ejaculation, blood samples were obtained for serum IGF-1 and testosterone assays. Subsequently, the semen characteristics of each ejaculate were evaluated. Mean serum IGF-1 concentration of elephant bulls was estimated as 326.3 ± 114.6 ng/mL (median, 286.2 ng/mL; range, 167.4–542.7 ng/mL). An increase in serum IGF-1 concentration was found to correlate with the percentage of spermatozoa with intact acrosomes. In addition, IGF-1 concentration was positively correlated with testosterone level. However, seminal IGF-1 concentrations could not be detected. In conclusion, our findings suggest that serum IGF-1 concentration is likely a biomarker of normal testicular functions, particularly spermatogenesis in elephants. Moreover, this commercial IGF-1 ELISA is eligible for analyzing serum IGF-1 concentration in Asian elephants.

Characterization of Longitudinal Testosterone, Cortisol, and Musth in Male Asian Elephants (Elephas maximus), Effects of Aging, and Adrenal Responses to Social Changes and Health Events.

Simple SummaryThe conservation of endangered species and sustainability of managed populations requires good health and welfare of individuals. Male elephants experience a biological phenomenon called “musth”, characterized by a suite of physiological and behavioral changes which serve to facilitate copulation between the sexes, but can also pose unique challenges under human care. This study characterized longitudinal patterns of circulating testosterone and cortisol in relation to musth in four adult Asian elephant bulls and assessed age-related effects on musth activity and adrenal responses to social changes and clinical health events. All bulls exhibited regular annual musth cycles, and there was no clear evidence of chronically elevated cortisol secretion outside of musth. Circulating cortisol covaried positively with testosterone and musth, highlighting intrinsic patterns that should be considered when evaluating the impact of changes on adrenal glucocorticoid activity. Testosterone decreased with age in sexually mature bulls, whereas age-related changes in cortisol varied across individuals, with the three older bulls showing the greatest rate of change during musth. Changes in cortisol were associated with treatment for Mycobacterium tuberculosis in two bulls, but not with activation of disease. In contrast to physiological factors, there was no evidence that social changes involving male herdmates impacted adrenal glucocorticoid activity in the short term. This study highlights the importance of longitudinal hormone monitoring to track changes in physiological function and identify factors that may influence welfare, which is important for making more informed decisions on how to manage male elephants under varying degrees of human care.The conservation of endangered species and sustainability of managed populations requires considerations to ensure the health and welfare of individuals. Male elephants experience a biological phenomenon called “musth”, which is characterized by increased testosterone production, temporal gland secretion and urine dribbling, heightened aggression and sexual behavior, and therefore can pose unique challenges for human safety and animal welfare. This study characterized longitudinal (9 to 22 years) patterns of circulating testosterone and cortisol in relation to musth in four adult Asian elephant bulls spanning ages from 12 to 54 years. Age-related effects on musth activity and adrenal responses to social changes and clinical health events were also examined. All bulls exhibited regular annual musth cycles. Circulating cortisol covaried positively with testosterone and musth, highlighting intrinsic patterns that should be considered when evaluating the impact of social, health, and environmental changes on adrenal glucocorticoid activity. Except for an end-of-life cortisol increase in one bull, there was no clear evidence of chronically elevated cortisol secretion outside of musth in any individual. Testosterone decreased with age in sexually mature bulls, whereas age-related changes in cortisol varied across individuals, with the three older bulls showing the greatest rate of change during musth versus inter-musth periods. In contrast to physiological factors, there was no evidence of social factors, such as addition of a new male and death of male herdmates, impacting adrenal glucocorticoid activity in these bulls in the short term. Changes in cortisol were associated with treatment for Mycobacterium tuberculosis (M. tb) in two bulls, increasing after start of treatment and decreasing with cessation of treatment, but were not clearly associated with activation of disease. This study highlights the importance of longitudinal hormone monitoring to track changes in physiological function and responses to social, health, and environmental change in elephant bulls, which is important for making more informed decisions on how to manage male elephants under varying degrees of human care to ensure welfare and safety.

Impacts of Socialization on Bull Asian Elephant (Elephas maximus) Stereotypical Behavior

There is a growing need for animal care institutions to house multiple bull elephants as the population increases due to transfers from private ownership and the births of male offspring in managed care. Elephants in North American, European, and Latin American zoos exhibit stereotypies—repetitive, fixed behaviors. Previous research demonstrated that housing Asian elephants alone increased stereotypic behavior. Therefore, for animals in managed care, social restriction can contribute to stereotypy and, by extension, reduce welfare. In this study, we examine how being alone affects stereotypic behavior by monitoring pacing and head-bobbing in individual bull Asian elephants at Denver Zoo when housed alone as well as with other bulls. Two young males arrived at Denver Zoo in September 2018 and joined an existing all-male group of three elephants that were previously socialized and housed together. From July 2018 to December 2019, we used instantaneous scan sampling to collect data on stereotypic behavior of focal bulls when they were housed alone and socially. The frequency of pacing and head-bobbing significantly decreased when the elephants were housed socially compared to when they were housed alone; these stereotypies were lower when elephants were housed with at least one other bull and were in close proximity to a conspecific. Additionally, pacing decreased as the proportion of affiliative behaviors increased, and the amount of agonistic behavior did not significantly affect stereotypic behavior. When housed alone, bulls in musth engaged in significantly more pacing behavior than when they were out of musth. Our results indicate that housing bull Asian elephants in all-male groups substantially improves their welfare by reducing stereotypies and provides a basis for future evidence-based management.

Cardiopulmonary responses of free-ranging African elephant (Loxodonta africana) bulls immobilized with a thiafentanil–azaperone combination

ObjectiveTo determine the time course and certain cardiopulmonary effects of trunk-breathing elephants immobilized with thiafentanil–azaperone. Study designProspective descriptive study. AnimalsA convenience sample of 10 free-ranging African elephant bulls (estimated weight range: 3000–6000 kg). MethodsElephants were immobilized using thiafentanil (15–18 mg) and azaperone (75–90 mg) administered by dart. Once recumbent, the respiratory rate, minute ventilation (V˙e), end-tidal carbon dioxide (Pe′CO2), arterial blood pressure and heart rate were recorded immediately after instrumentation and at 5 minute intervals until 20 minutes. Arterial blood gases were analysed at the time of initial instrumentation and at 20 minutes. On completion of data collection, thiafentanil was antagonized using naltrexone (10 mg mg–1 thiafentanil; administered intravenously). A stopwatch was used to record time to recumbency (dart placement to recumbency) and time to recovery (administration of antagonist to standing). Data were compared using a one-way anova. Data are presented as mean ± standard deviation. ResultsAll elephants were successfully immobilized, and there were no significant changes in cardiopulmonary variables over the monitoring period. Average time to recumbency was 12.5 (± 3.9) minutes. The measured V˙e was 103 (± 30) L minute–1. The average heart and respiratory rates over the 20 minute immobilization were steady at 49 (± 6) beats minute–1 and 5 (± 1) breaths minute–1, respectively. The mean arterial blood pressure was 153 (± 31) mmHg. The elephants were acidaemic (pH: 7.18 ± 0.06), mildly hypoxaemic (PaO2: 68 ± 15 mmHg; 9.1 ± 2.0 kPa) and hypercapnic (PaCO2: 52 ± 7 mmHg; 6.9 ± 0.9 kPa). Average time to recovery was 2.2 ± 0.5 minutes. Conclusion and clinical relevanceAfrican elephant bulls can be successfully immobilized using thiafentanil–azaperone. Recumbency was rapid, the cardiopulmonary variables were stable over time, and recovery was rapid and complete. Mild hypoxaemia and hypercapnia were evident.

The Melagiri Elephant Fence - A Crucial tool for Human-Elephant Control

Effectively restraining elephants within forests and away from human use areas is critical to solving human-elephant conflict (HEC). Present methods such as solar fences, elephant proof trenches, alarm systems, scaring and driving methods have met with mixed results and not achieved the desired reduction in elephant crop depredation, human and elephant deaths. This case study showcases the successful development of the Melagiri Elephant Fence, using steel wire rope strands and precast steel reinforced concrete posts as the primary elements of the fence. The Melagiri Elephant Fence was field-tested in a high human-elephant conflict area of the Hosur Forest Division and monitored using camera traps. The final design of the fence was successful in containing even the most persistent and largest bull elephants. The Melagiri Elephant Fence is a cost-effective, permanent and maintenancefree elephant proof barrier for landscape-level occupancy planning and mitigation of human-elephant conflict. No injury to elephants, humans or other animals have been reported, and the fence may be considered as safe for use.

Social and Seasonal Factors Contribute to Shifts in Male African Elephant (Loxodonta africana) Foraging and Activity Patterns in Kruger National Park, South Africa.

Simple SummaryAfrican savannah elephants are able to greatly modify the vegetation around them through their foraging activities. Accordingly, studying the factors that affect elephant foraging behaviour during different seasons are important to understand their impact on the environment and will also aid in predicting how elephants might react to potential threats such as climate change and land transformation. This article aimed to reinforce current knowledge regarding elephant foraging behaviour by examining how the behaviour is affected across (a) season (wet versus dry); (b) time of day (before or after noon); (c) presence or absence of other elephants; and (d) reproductive state; for six adult elephant bulls monitored in Kruger National Park. Results indicated that elephant foraging behaviour is indeed affected by seasonal and social factors. This highlights how these animals are able to adjust their foraging behaviour during the day to aid in thermoregulation, or during different seasons to fulfil their nutritional requirements. Furthermore, this study opens the door for further research regarding how reproductive activity affects the foraging behaviour of male elephants.African savannah elephants (Loxodonta africana) are well-known as ecosystem engineers with the ability to modify vegetation structure. The present study aimed to examine how male elephant foraging behaviour is affected across (a) season (wet versus dry); (b) time of day (before or after noon); (c) presence or absence of other elephants; and (d) reproductive state (musth versus no musth). Six radio-collared adult elephant bulls were observed twice per week from June 2007–June 2008 in Kruger National Park (KNP), South Africa. Using generalized linear mixed effect modeling, results indicate that elephant bulls graze more during the wet season and browse more during the dry season. To potentially offset the costs associated with thermoregulation during the heat of the day, KNP elephants spent more time foraging during the morning, and more time resting during the afternoon. Male elephants also foraged significantly less when they were associated with females compared to when they were alone or with other males. This is likely due to male–female associations formed mainly for reproductive purposes, thus impeding on male foraging behaviours. In contrast, the condition of musth, defined by the presence of related physical signs, had no significant effect on foraging behaviour.

The elephant in the farm: long‐term solutions are the key to coexistence

The elephant in the farm: long‐term solutions are the key to coexistence

GEOSPATIAL ASSESSMENT OF HUMAN-WILDLIFE-ENVIRONMENT INTERACTIONS FOR SPATIAL DECISION SUPPORT

Abstract. Human-Elephant Conflict (HEC) is a global concern that requires geospatial data collection, analysis and geovisualization for decision support and mitigation. Bull African elephants, (Loxodonata africana), are often responsible for breaking fences, raiding crops and causing economic hardship in local communities in Botswana, Zimbabwe and Zambia. Methods for monitoring and understanding elephant movements are needed to mitigate conflict, find ways for coexistence and secure the future of Africa’s elephant populations. Researchers from academia and conservation organizations are partnering with decision makers and scientists of the Zimbabwe Department of National Park and Wild Life Management (PWMA) to track the movement of 15 bull elephants in the general area of Victoria Falls to analyse spatio-temporal patterns of elephant behaviour related to climatic factors, habitat conditions and changing land uses. Spatial decision support for local famers, resource managers and planners will assist in avoiding agricultural expansion and urban development that coincides with elephant corridors and access to water resources.

Social Dynamics of a Newly Integrated Bachelor Group of Asian Elephants (Elephas maximus): Welfare implications

ABSTRACT Male associations are a typical component of elephant society, allowing bulls to practice appropriate social behavior. To improve zoo elephant welfare, it is important to provide bulls with social opportunities. In fall 2018, Denver Zoo added two bull Asian elephants to its existing all-male group of three bulls, offering the opportunity to conduct a systematic behavioral study of the integration of the new bulls into the resident group. We recorded aggressive and affiliative behaviors before, during, and after the introduction of the new males. The proportion of aggressive behavior was significantly higher during the five-month introduction period compared to before their introduction. By the end of the study period, the elephants engaged in significantly more affiliative behavior and less aggressive behavior than during the introduction period, suggesting they had formed a new stable social dynamic. These results suggest group compatibility and positive elephant welfare resulting from housing male elephants together and can be used to inform management plans for bull elephants that prioritize their welfare.

Heterogeneity in African savanna elephant distributions and their impacts on trees in Kruger National Park, South Africa.

Though elephants are a major cause of savanna tree mortality and threaten vulnerable tree species, managing their impact remains difficult, in part because relatively little is known about how elephant impacts are distributed throughout space.This is exacerbated by uncertainty about what determines the distribution of elephants themselves, as well as whether the distribution of elephants is even informative for understanding the distribution of their impacts.To better understand the factors that underlie elephant impacts, we modeled elephant distributions and their damage to trees with respect to soil properties, water availability, and vegetation in Kruger National Park, South Africa, using structural equation modeling.We found that bull elephants and mixed herds differed markedly in their distributions, with bull elephants concentrating in sparsely treed basaltic sites close to artificial waterholes and mixed herds aggregating around permanent rivers, particularly in areas with little grass.Surprisingly, we also found that the distribution of elephant impacts, while highly heterogeneous, was largely unrelated to the distribution of elephants themselves, with damage concentrated instead in densely treed areas and particularly on basaltic soils.Results underscore the importance of surface water for elephants but suggest that elephant water dependence operates together with other landscape factors, particularly vegetation community composition and historical management interventions, to influence elephant distributions.

Emergence of the wrapped Cauchy distribution in mixed directional data

Inferring the most appropriate distribution (or distributions) to describe observed directional data is important in many applications of circular statistics. In particular, animal movement paths are typically analysed and modelled by considering the distribution of step lengths and turning (or absolute) angles. Here we demonstrate that a single-wrapped Cauchy distribution can appear to fit directional data mixed from two different underlying wrapped normal distributions. We derive mathematical expressions to calculate the parameter space for which this occurs and illustrate the result by analysing an example data set of the movements of African bull elephants (Loxodonta Africana). We conclude that the presence of a wrapped Cauchy distribution in observed directional data can, in certain cases, be explained by data coming from two distinct underlying distributions. We discuss how this may relate to the presence of multiple movement modes within an observed path when analysing animal movement data.

Sperm motility, kinematics, morphometry and morphology over two seasons in free-ranging African elephants (Loxodonta africana).

This study aimed to address the lack of information on quantitative semen and sperm characteristics of free-ranging African elephants. Nineteen ejaculates were collected from 12 elephant bulls by means of electroejaculation in spring (Season 1, end of dry season, n=7) and in autumn (Season 2, end of rainy season, n=12). While most elephant cows are in oestrus in the rainy season, it is not evident whether sperm quality also improves during this period. Semen samples were assessed using computer-aided sperm analysis (CASA), brightfield microscopy and transmission electron microscopy. Seasonal differences and individual variation in sperm quality of bulls were apparent, with ejaculates collected during Season 2 revealing higher percentages for total motility, progressive motility, rapid-swimming spermatozoa and kinematic parameters compared with Season 1 (P<0.05). Although normal sperm morphology percentage was similar over the two seasons, more sperm tail defects were found in Season 2 (P<0.05). The baseline reference data and multivariate sperm parameter associations reported in this study can be used to predict elephant bull sperm quality and potential to fertilise. It is clear that CASA can detect subtle differences in sperm quality of African elephant ejaculates and should be the approach for future investigations.

Facilitating the social behaviour of bull elephants in zoos

In the wild, bull elephants socialize with conspecifics of all ages and both sexes, and young bulls develop social bonds with other elephants which will be sustained throughout their lives. Significant progress has been made towards providing an environment that facilitates social behaviour and multi‐generational family structure for female elephants in zoos. However, it is more complex and challenging to build facilities and manage groups of elephants in ways that allow fission–fusion herd dynamics and give the elephants choice over their environment. For bulls, this is further complicated by their potential strength and aggressive behaviour. To advance the development of best‐practice management for zoo elephants and achieve high standards of welfare, it is necessary to improve our understanding of the social and behavioural needs of bull elephants, and implement radical and innovative solutions to their care. In this paper we (1) consider how the social behaviour of bull elephants is addressed in zoos, comparing their social management with their behaviour in the wild, (2) contribute novel preliminary data about how these issues are addressed, and (3) propose some new approaches to the management of bull elephants in zoos for the future.

Seroprevalence of Mycobacterium tuberculosis Complex in Free-Ranging African Elephants (Loxodonta africana) in Kruger National Park, South Africa

Tuberculosis (TB) is a pathogenic disease that affects a range of wildlife species, including African elephants (Loxodonta africana). The recent discovery of fatal disease caused by infection with Mycobacterium tuberculosis in a bull elephant in the Kruger National Park (KNP), which is a bovine TB endemic area, emphasizes the importance this disease could have on both wild and captive elephant populations globally. Elephants with culture-confirmed TB have previously been shown to produce strong antibody-responses before the mycobacteria can be isolated. Therefore, we used two serologic assays that detect TB antibodies to retrospectively screen a cohort of 222 free-ranging African elephants sampled between 2004 and 2018 in KNP. The estimated TB seroprevalence for this free-roaming elephant population was between 6% (95% confidence interval [CI], 2-12%) and 9% (95% CI, 6-15%) based on the two tests. Overall, males had a higher TB seroprevalence than females, and adults (≥25 yr) had a higher TB seroprevalence than younger elephants (≤24 yr) on both rapid tests. The relatively high TB seroprevalence that we found highlighted the value of conducting retrospective studies in free-ranging wildlife populations in order to better understand the potential risk of disease.