Male Elephant Research Articles

Reproductive Endocrinology and Musth Indicators in a Captive Asian Elephant (Elephas maximus).

Even in the best situations, the artificial social constructs of captivity alter natural elephant behavior and unfortunately create distress. Asian elephants are powerful and intelligent animals that require consideration for their well-being and prudent management. The males present particular difficulties due to a temporary state of heightened aggressive behavior unique to male elephants called "musth." When he is in this state, the danger the elephant poses to other animals and the people around him is considerable. In addition to antagonistic behavior, musth is also characterized by temporal gland secretion and urine dribbling. In previous studies, musth has been attributed to elevated testosterone levels. This study attempted to enhance the knowledge base concerning these phenomena by examining hormone concentrations (n = 357) in Onyx, a male Asian elephant housed at Dickerson Park Zoo, with intermittent access to females (n = 1-5) over a 12-year period. Behavior and signs of musth also were recorded daily by elephant department staff. Musth indicators (temporal gland secretion, aggression, urine dribbling) increased with musth but not prior to it. We confirmed that temporal gland secretion was a better indicator of behavioral musth than urine dribbling. Hormones concentrations increased as musth approached, and presumably initiated musth indicators, but variability was high. Therefore, these hormones cannot be used to predict the onset of musth in this individual. Rather, the free/total testosterone ratio was a good indication of the 60-day pre-musth period. In addition, testosterone production and musth indicators increased in intensity when a young bull at the zoo started entering musth.

Temporal gland secretion in African elephants (Loxodonta africana)

The underlying causes of temporal gland secretion (TGS) in African elephants are not well understood. In order to better understand TGS predisposing factors, we assessed TGS in relation to a suite of intrinsic and environmental variables in free ranging elephants. TGS monitoring was done in fully protected areas of Lake Manyara National Park (LMNP) and Tarangire National Park (TNP) and Manyara Ranch (MR), a semi-protected multiple use area. Using a hierarchical modeling approach that accounted for the nested data structure, we found that TGS was mainly associated with elephant-specific variables. The likelihood of TGS increased with elephant age. Female elephants were more likely to show TGS than male elephants. In larger groups, females were less likely to have TGS, whereas the likelihood for TGS increased with group size in male elephants. This information enhances our understanding of TGS, and its importance as physiological marker.

Housing and Social Environments of African (Loxodonta africana) and Asian (Elephas maximus) Elephants in North American Zoos.

We evaluated 255 African (Loxodonta africana) and Asian (Elephas maximus) elephants living in 68 North American zoos over one year to quantify housing and social variables. All parameters were quantified for the both the day and the night and comparisons were made across these time periods as well as by species and sex. To assess housing, we evaluated not only total exhibit size, but also individual animals’ experiences based on the time they spent in the unique environments into which the exhibits were subdivided. Variables developed to assess housing included measurements of area as a function of time (Total Space Experience), environment type (Indoor, Outdoor, In/Out Choice) and time spent on hard and soft flooring. Over the year, Total Space Experience values ranged from 1,273 square feet to 169,692 square feet, with Day values significantly greater than Night values (p<0.001). Elephants spent an average of 55.1% of their time outdoors, 28.9% indoors, and 16% in areas with a choice between being in or out. Time spent on hard flooring substrate ranged from 0% to 66.7%, with Night values significantly greater than Day (p<0.001). Social factors included number of animals functionally housed together (Social Experience) and social group characteristics such as time spent with juveniles and in mixed-sex groups. Overall Social Experience scores ranged from 1 to 11.2 and were significantly greater during the Day than at Night (p<0.001). There were few significant social or housing differences between African (N = 138) and Asian (N = 117) species or between males (N = 54) and females (N = 201). The most notable exception was Total Space Experience, with African and male elephants having larger Total Space Experience than Asian and female elephants, respectively (P-value<0.05). The housing and social variables evaluated herein have been used in a series of subsequent epidemiological analyses relating to various elephant welfare outcomes.

Information content and acoustic structure of male African elephant social rumbles.

Until recently, the prevailing theory about male African elephants (Loxodonta africana) was that, once adult and sexually mature, males are solitary and targeted only at finding estrous females. While this is true during the state of ‘musth’ (a condition characterized by aggressive behavior and elevated androgen levels), ‘non-musth’ males exhibit a social system seemingly based on companionship, dominance and established hierarchies. Research on elephant vocal communication has so far focused on females, and very little is known about the acoustic structure and the information content of male vocalizations. Using the source and filter theory approach, we analyzed social rumbles of 10 male African elephants. Our results reveal that male rumbles encode information about individuality and maturity (age and size), with formant frequencies and absolute fundamental frequency values having the most informative power. This first comprehensive study on male elephant vocalizations gives important indications on their potential functional relevance for male-male and male-female communication. Our results suggest that, similar to the highly social females, future research on male elephant vocal behavior will reveal a complex communication system in which social knowledge, companionship, hierarchy, reproductive competition and the need to communicate over long distances play key roles.

Finding approximate solutions of NP-hard optimization and TSP problems using elephant search algorithm

A novel bio-inspired optimization algorithm called elephant search algorithm (ESA) has been applied to solve NP-hard problems including the classical traveling salesman problem (TS) in this paper. ESA emerges from the hybridization of evolutionary mechanism and dual balancing of exploitation and exploration. The design of ESA is inspired by the behavioral characteristics of elephant herds; hence, the name Elephant Search Algorithm which divides the search agents into two groups representing the dual search patterns. The male elephants are search agents that outreach to different dimensions of search space afar; the female elephants form groups of search agents doing local search at certain close proximities. By computer simulation, ESA is shown to outperform other metaheuristic algorithms over the popular benchmarking optimization functions which are NP-hard in nature. In terms of fitness values in optimization, ESA is ranked after Firefly algorithm showing superior performance over the other ones. The performance of ESA is most stable when compared to all other metaheuristic algorithms. When ESA is applied to the traveling salesman problem, different ratios of gender groups yield different results. Overall, ESA is shown to be capable of providing approximate solutions in TSP.

Variation in the diet of killer whales Orcinus orca at Marion Island, Southern Ocean

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 549:263-274 (2016) - DOI: https://doi.org/10.3354/meps11676 Variation in the diet of killer whales Orcinus orca at Marion Island, Southern Ocean Ryan R. Reisinger1,5,*, Darren R. Gröcke2, Nico Lübcker1, Erin L. McClymont3, A. Rus Hoelzel4, P. J. Nico de Bruyn1 1Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, Pretoria, South Africa 2Department of Earth Sciences, Durham University, South Road, Durham DH1 3LE, UK 3Department of Geography, Durham University, South Road, Durham DH1 3LE, UK 4School of Biological and Biomedical Sciences, Durham University, South Road, Durham DH1 3LE, UK 5Present address: Department of Zoology, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031, South Africa *Corresponding author: ryan.r.reisinger@gmail.com ABSTRACT: Diet seems to be a key factor driving diversity and isolation among killer whale populations. Killer whales at Marion Island, Southern Ocean, have been observed preying on seals and penguins but are also know to depredate Patagonian toothfish from longline fishing vessels. However, their diet is poorly known especially when they occur offshore. We analysed carbon and nitrogen stable isotope ratios in 32 skin samples collected from 24 killer whales belonging to 8 social units. Adult males showed higher δ15N values than adult females or subadults, indicating that they occupy a higher relative trophic level. There were no significant differences in δ13C among social units, but δ15N differed significantly and 2 individuals from social units which have been observed depredating Patagonian toothfish had higher δ15N values. The inshore presence of killer whales at Marion Island was a significant predictor of δ13C values, but not of δ15N values. This suggests some foraging north of Marion Island, potentially on lower trophic level prey. We also analysed tissue samples from seal, penguin and Patagonian toothfish prey and used available values for Antarctic fur seals. Results show that killer whales around Marion Island are apex predators, but that they do not feed exclusively on other high trophic level predators such as elephant seals, fur seals, and Patagonian toothfish. Killer whales had δ15N values similar to those of Patagonian toothfish and adult male elephant seals, implying that the diet of killer whales at Marion Island includes some lower trophic level prey such as cephalopods or fishes. KEY WORDS: Predator · Stable isotopes · Carbon · δ13C · Nitrogen · δ15N · Foraging · Trophic level Full text in pdf format Supplementary material PreviousNextCite this article as: Reisinger RR, Gröcke DR, Lübcker N, McClymont EL, Hoelzel AR, de Bruyn PJN (2016) Variation in the diet of killer whales Orcinus orca at Marion Island, Southern Ocean. Mar Ecol Prog Ser 549:263-274. https://doi.org/10.3354/meps11676 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 549. Online publication date: May 10, 2016 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2016 Inter-Research.

The use of audio playback to deter crop-raiding Asian elephants

Human–elephant conflict (HEC) and poaching are the foremost threats to the survival of elephants (African, Loxodonta africana; Asian, Elephas maximus) in their natural environments. Reducing HEC has the potential to save hundreds of elephant and human lives annually across Asia and Africa. Lone adult male elephants are the principal crop raiders; therefore, we investigated the effectiveness of a variety of audio playbacks at deterring 22 wild adult male Asian elephants from food sources in a wildlife reserve in southern Sri Lanka in January, 2011. Food was provided ad libitum, and the reactions of the elephants in response to various stimuli were recorded and analyzed. Vocalizations from a wild Asian elephant matriarchal group resulted in a flight response in 65% of trials conducted, in contrast to a control sound, a chainsaw, which produced no flight responses from any adult male. We demonstrated that audio playbacks could be used as a short-term deterrent to wild adult male Asian elephants from crop raiding; thus, providing a simple, natural, cost-effective, and humane way of mitigating HEC. © 2016 The Wildlife Society.

A new metaheuristic optimisation algorithm motivated by elephant herding behaviour

In this paper, a new swarm-based metaheuristic algorithm, called elephant herding optimisation EHO, is proposed for solving global optimisation tasks, which is inspired by the herding behaviour of the elephant groups. In nature, the elephants belonging to different clans live together under the leadership of a matriarch, and the male elephants will leave their family group when growing up. These two behaviours can be modelled into two following operators: clan updating operator and separating operator. In EHO, the elephants are updated using its current position and matriarch through clan updating operator, and the separating operator is then implemented. Moreover, EHO has been benchmarked by 20 standard benchmarks, and two engineering cases in comparison with BBO, DE and GA. The results clearly establish the supremacy of EHO in finding the better function values on most test problems than those three algorithms. The code can be found in the website: http://www.mathworks.com/matlabcentral/fileexchange/53486.

A new metaheuristic optimisation algorithm motivated by elephant herding behaviour

In this paper, a new swarm-based metaheuristic algorithm, called elephant herding optimisation (EHO), is proposed for solving global optimisation tasks, which is inspired by the herding behaviour of the elephant groups. In nature, the elephants belonging to different clans live together under the leadership of a matriarch, and the male elephants will leave their family group when growing up. These two behaviours can be modelled into two following operators: clan updating operator and separating operator. In EHO, the elephants are updated using its current position and matriarch through clan updating operator, and the separating operator is then implemented. Moreover, EHO has been benchmarked by 20 standard benchmarks, and two engineering cases in comparison with BBO, DE and GA. The results clearly establish the supremacy of EHO in finding the better function values on most test problems than those three algorithms. The code can be found in the website: http://www.mathworks.com/matlabcentral/fileexchange/53486.

Potential of a gonadotropin-releasing hormone vaccine to suppress musth in captive male Asian elephants (Elephas maximus)

Musth in adult bull elephants is a period of increased androgen concentrations ranging from a few weeks to several months. For captive elephant bull management, musth presents a serious challenge because of the aggressive behavior of musth bulls toward people and other elephants. Commercially available GnRH vaccines have been shown to suppress testicular function by interrupting the hypothalamo-pituitary-gonadal (HPG) axis in many species. The aim of this study was to test the efficacy of a GnRH vaccine in elephant bulls for suppressing the HPG axis and mitigating musth-related aggressive behavior. Five adult Asian elephant bulls (22–55 years old) were immunized with a GnRH vaccine starting with an initial injection 2–4 months before the predicted musth period, and followed by three boosters at approximately 4-week intervals. Blood samples were collected twice weekly for hormone and antibody titer analysis. An increase in GnRH antibody titers was observed in all bulls after the second or third booster, and titers remained elevated for 2–3 months after the final booster. Musth was attenuated and shortened in three bulls and postponed completely in two. We conclude that GnRH vaccination is capable of suppressing symptoms of musth in adult bull elephants. With appropriate timing, GnRH vaccination could be used to control or manage musth and aggressive behavior in captive elephant bulls. However, more work is needed to identify an optimal dose, booster interval, and vaccination schedule for complete suppression of testicular steroidogenesis.

Pharmacokinetics of amoxicillin trihydrate in male Asian elephants (Elephas maximus) following intramuscular administration.

The purpose of this study was to investigate the pharmacokinetic characteristics of amoxicillin (AMX) trihydrate in male Asian elephants, Elephas maximus, following intramuscular administration at two dosages of 5.5 and 11 mg/kg body weight (b.w.). Blood samples were collected from 0.5 up to 72 h. The concentration of AMX in elephant plasma was measured using liquid chromatography electrospray ionization mass spectrometry. AMX was measurable up to 24 h after administration at two dosages. Peak plasma concentration (Cmax ) was 1.20 ± 0.39 μg/mL after i.m. administration at a dosage of 5.5 mg/kg b.w., whereas it was 3.40 ± 0.63 μg/mL at a dosage of 11 mg/kg b.w. A noncompartment model was developed to describe the disposition of AMX in Asian elephants. Based on the preliminary findings found in this research, the dosage of 5.5 and 11 mg/kg b.w. produced drug plasma concentrations higher than 0.25 mg/mL for 24 h after i.m. administration. Thereafter, i.m. administration with AMX at a dosage of 5.5 mg/kg b.w. appeared a more suitable dose than 11 mg/kg b.w. However, more studies are needed to determine AMX clinical effectiveness in elephants.

Crush injury by an elephant: life-saving prehospital care resulting in a good recovery.

The 1200 kg male Asian elephant was born in captivity and was well known to the keeper. On the day of the incident, they were involved in a training session when the elephant challenged an instruction. The keeper recognised this change in his behaviour and tried to leave the training area, but the elephant used his trunk to pin her by the chest against a bollard in the barn, resulting in immediate dyspnoea and brief loss of consciousness for 20e30 seconds. Her colleagues arrived and moved her to safety.

Mortality records (1979–2011) shed light on threats to Asian Elephants Elephas maximus Linnaeus, 1758 (Mammalia: Proboscidea: Elephantidae) in Nilgiris, southern India

We compiled records of 291 elephant deaths over a 33-year period (1979–2011) from the Mudumalai Tiger Reserve and the reserved forests of Nilgiri North and South divisions of southern India from the databases of the Tamil Nadu Forest Department, the Wildlife Protection Society of India and the Nilgiri Wildlife and Environment Association. We tested the null hypothesis that the causes of elephant deaths would not differ with time, by gender and with level of protection. We classified records by gender and age: adults (≥15 years), sub adults (5–15 years), juveniles (>1– 1–<5) and 22 calves (≤ 1). MTR had the maximum records (148) followed by NND (138) and NSD (4). The median age of death was 20 years for adult males and 30 years for adult females. Mean survival time for adult males was 22.45 years, and 31.84 for females. Poaching was responsible for the majority of deaths (40%), particularly of male elephants (82%), and unknown causes (31%) for the majority of female deaths (66%). Human-caused deaths, which included poaching and some accidents, averaged 72% between 1979 and 2000 and decreased to 22% during 2001–2011. Deaths due to unknown causes and diseases increased from 28% in 1979-1989 to 69% in 2001–2011. Relative to estimated population size, deaths attributed to poaching was higher in NND (47%) than in MTR (34%). The causes of death differed by region. In conclusion, the elephant population in the Nilgiris is at risk and needs stringent protection; the mortality database should be systematised; forensic capabilities upgraded, and detection of carcasses improved.

Diversity Of Mandibular Morphology In Some Carnivorans

Abstract Comparison of mandibular morphology of some aquatic (seals, walruses, and sea otters) and terrestrial (hyenas and pandas) carnivorans demonstrates a rather general pattern correlating size of condyloid angle, size of gape, and diet. Structural differences of carnivoran jaws reveal morphological and ecological adaptations that are directly correlated with availability of prey, diving depth, feeding competition and specialized feeding methods. Specifically, the inclination of the condyloid process relative to the axis of the alveolar row (= condyloid angle) can be used to determine dietary preferences, including size of prey. Generally, carnivorans with a large condyloid angle feed on larger prey, while a low condyloid angle suggests feeding on small prey or can be an advantageous feeding mechanism. Mirounga angustirostris (Northern elephant seal) displays sex-specific characters in cranial and postcranial elements. Likewise, significant sexually dimorphic differences in the size of condyloid angle imply that deeper-diving male Northern elephant seals have a feeding niche dissimilar to that of females. Morphological assessment of male M. angustirostris suggests they are bottom-feeding seals that utilize a suction-feeding mechanism to capture small prey and crush shells with their teeth, which become weaker as they age.

Tusker's social bonds in Rajaji

Male elephants are known to live solitary life after attaining the pubertal stage which is considered as ±15 years. However, cases of solo movement of young male elephants (±10 years) were also observed in different elephant ranges by several workers. In contrast, few studies have explored that male elephants do have associations; however these associations are occasional and temporary. In Rajaji National Park, north-western Shivalik landscape of India, bull elephants were observed to have a year round association, mainly to perform movements outside the boundaries of protected habitats and to enjoy palatable crops. Such strategies of bull elephants however are temporary and for achieving some particular target, but would affect their social behaviour especially in context of ranging pattern. Observations made in between 2006-2010 exposed that bull groups consists of 2-8 individuals, who were performing movement in parts of Rajaji National Park, Haridwar forest division and agriculture fields. An exceptional example, revealing on their strong social bond and attachment, is illustrated, which was recorded while observing them randomly in between 2006-2010. Since a long continuous chain of forests which exists in between Rajaji–Corbett wildlife corridor has disrupted mainly because of habitat fragmentation and man-elephant conflict is increasing rapidly, regular monitoring of elephant’s habitat and population would be of paramount importance. This is the first time such an unusual interaction among bull elephants has been recorded and possible explanations for the behaviour are discussed. Download the complete issue.

Tuberculosis surveillance of elephants (Elephas maximus) in Nepal at the captive-wild interface

A comprehensive elephant tuberculosis (TB) survey using culture and four serological screening tests was conducted in Nepal in response to concern raised by wildlife officials that TB could threaten wild populations of elephants, rhinos, and other susceptible species. Captive elephants come into close contact with wild animals during conservation and tourism activities inside Nepal’s national parks. Private and government-owned male and female captive Asian elephants (Elephas maximus) were included in the study. The mean reported age was 38 years (range 5–60 years). A total of 289 samples from 120 elephants were collected for mycobacterial culture. Culture samples were processed at the National Tuberculosis Centre (NTC) in Nepal and the National Veterinary Services Laboratories (NVSL) in Ames, IA. Acid-fast organisms were observed in 11 and 21 samples processed at NTC and NVSL, respectively, and nontuberculous mycobacteria (NTMs) were isolated from six elephants. There were no isolations of Mycobacterium tuberculosis or Mycobacterium bovis. Blood samples were also collected from 115 of the elephants for serological testing using the Chembio ElephantTB STAT-PAK®, the Chembio MultiAntigen Print Immunoassay test, a multi-antigen ELISA, and an immunoblot assay. Culture and serological results were variable and required careful interpretation to develop criteria to assess TB risk. Elephants were assigned to one of four disease risk groups (high, moderate, low, and undetermined), and management recommendations for each group were made to government authorities. Serological results were prioritized in developing recommendations because of culture limitations and inconclusive culture results. This strategy was based on evidence for the early predictive value of serological tests and the urgent need expressed by wildlife authorities in Nepal to protect their captive elephants, mitigate TB at the captive-wild interface, and safeguard tourism.

Why males and females look different

Why do males and females look different? In “Odd Couples: Extraordinary Differences Between the Sexes in the Animal Kingdom,” (2013, Princeton University Press, p. 312), Daphne J. Fairbairn provides a scrupulous catalog of possible answers, perhaps the most detailed collection of animal sex differences since Darwin’s 1874 “The Descent of Man and Selection in Relation to Sex.” Sexual dimorphism is the condition in which males and females exhibit distinct phenotypes, beyond physiological traits involved with reproduction. Fairbairn’s volume is supplied with some of the best examples of such differences now known, and the disparate sources of data are pressed into compelling shape by a talented scholar and careful experimentalist. Fairbairn’s manifesto is, “an overtly Darwinian approach to understanding sexual differences” (p. 3). She notes that when selection operates in sex-specific ways, “we expect trait distributions typical for each sex to be adaptive for that sex” (p. 4), and she launches the reader into this view of dimorphism with sweeping taxonomic and gender-modified scope. We learn of lumbering male elephant seals, who in the throes of their ardor may annihilate the offspring of their future mates; of great bustards, giant Eurasian cranes whose males shove rivals and take blows to the face like bear-pit pugilists while females watch nearby; of shellcarrying cichlid fish, whose territorial and satellite males dart and parry for opportunities to ejaculate into snail shells containing females’ unfertilized ova. As vertebrates, we humans are most familiar with mating systems in which males are larger or somehow more elaborate than females. Fairbairn answers this preexisting bias with fascinating contrasts, weaving tales of yellow garden spiders and blanket octopus, whose gigantic females either squat in the center of conspicuous webs, or float huge and enigmatic over tropical reefs, each attended by males of their species as much as 40,000 times smaller in size. We learn of giant seadevil anglerfish, whose enormous, fang-jawed females host tiny males, who cling to female undersides by their own peculiar mouths, absorbing nutrients from a shared bloodstream and dangling close enough to their mate’s genitalia to ensure successful spawning. Fairbairn details the divergent life histories of bizarre, deep-sea bone worms whose females embed their bulbous bodies within decaying skeletons of whales, and maintain hundreds of minute suitors within their translucent skins. Lastly, she describes shell-burrowing barnacles, in which embedded females may (or may not—45% of females fail to mate) host posses of minuscule males with colossal, inflatable penises that may exceed each little fellow’s corporal dimensions by as much as eight times. The density of information and much delightful prose make this a fascinating read for lay and professional readers alike. Footnotes and appendices comprise nearly one-third of the book. One diagram describes the distribution of sexual dimorphism among 73 animal classes, a synthesis across 1.4 million species that is the first I have seen of its kind. Fairbairn glides among the animals with remarkable skill, and does Darwin one better with abundant recent data. In each chapter, she recounts male and female life spans, the fractions of individuals who do and do not mate, and the numbers of offspring that individuals in each sex produce. The raw materials are here to make concise, quantitative statements about how a sex difference in the variance in relative fitness (also known as the opportunity for sexual selection; Wade 1979) can explain the magnitude and direction of sexual dimorphism. But each chapter ends without an attempt. Offspring numbers are what Fairbairn considers “the currency of Darwinian fitness,” yet the trove of such information presented is used mainly for implication. Fairbairn concludes, “the enduring message is that there is no one way of being a male or a female animal . . . there is no “normal” or “typical” pattern of sexual differentiation across the animal kingdom,” and furthermore that the lack of sex differences in externally fertilizing species “remains a mystery” (p. 165). I found such capitulation

Oxidative stress is a potential cost of breeding in male and female northern elephant seals.

The trade-off between current reproductive effort and survival is a key concept of life history theory. A variety of studies support the existence of this trade-off but the underlying physiological mechanisms are not well-understood. Oxidative stress has been proposed as a potential mechanism underlying the observed inverse relationship between reproductive investment and lifespan. Prolonged fasting is associated with oxidative stress including increases in the production of reactive oxygen species, oxidative damage and inflammation.Northern elephant seals (NES) undergo prolonged fasts while maintaining high metabolic rates during breeding. We investigated NES of both sexes to assess oxidative stress associated with extended breeding fasts. We measured changes in the plasma activity or concentrations of markers for oxidative stress in 30 adult male and 33 adult female northern elephant seals across their 1-3 month breeding fasts. Markers assessed included a pro-oxidant enzyme, several antioxidant enzymes, markers for oxidative damage to lipids, proteins and DNA, and markers for systemic inflammation.Plasma xanthine oxidase (XO), a pro-oxidant enzyme that increases production of oxidative radicals, and several protective antioxidant enzymes increased over breeding in both sexes. Males showed increased oxidative damage to lipids and DNA and increased systemic inflammation, while oxidative damage to proteins declined across breeding. In contrast, females showed no oxidative damage to lipids or DNA or changes in inflammation, but showed increases in oxidative damage to proteins. XO activity, antioxidant enzymes, oxidative damage markers, and inflammatory markers were strongly correlated in males but these relationships were weaker or non-existent in females.NES provide evidence for oxidative stress as a physiological cost of reproduction in a capital breeding mammal. Both sexes strongly up-regulated antioxidant defenses during breeding. Despite this response, and in contrast to similar duration non-breeding fasts in previous studies on conspecifics, there was evidence of oxidative damage to tissues. These data demonstrate the utility of using plasma markers to examine oxidative stress but also suggest the necessity of measuring a broad suite of plasma markers to assess systemic oxidative stress.

The impact of male contraception on dominance hierarchy and herd association patterns of African elephants (Loxodonta africana) in a fenced game reserve

Overpopulation of African elephants (Loxodonta africana) in fenced reserves in South Africa is becoming increasingly problematic to wildlife managers. With growing opposition to culling and the high cost of translocation, alternative management strategies focusing on male elephants are being investigated. In this study, hormonal treatment via Gonadotropin Releasing Hormone (GnRH) suppression, and surgical treatment via vasectomy were trialled. Focusing on behavioural responses, we tested the male dominance hierarchy for transitivity, and examined the rank order of individuals in relation to age and contraceptive treatment received. Additionally, we studied association patterns between males within the male population and with the female herds.Findings suggest that the treatment of one individual with GnRH suppressant is affecting the rank order of the dominance hierarchy, though it is still transitive, yet fluid (Landau’s linearity index h=0.7), as expected in a normal elephant population. Between males, association patterns were found to be weak. However, some males had relatively strong associations with the female herds, with association indices between 0.25 and 0.41. This suggests that the reduction on births is resulting in the males spending atypically large amounts of time with the female herds. The future conservation implications of this population control mechanism are discussed.

Controlling for behavioural state reveals social dynamics among male African elephants, Loxodonta africana

The drivers of social affiliation may vary over time as individuals change their goals with respect to changing environments or physical condition. Studies of companion preference rarely consider shifts in motivational state, despite the potential importance of such shifts in structuring association and population processes. Ignoring state dependence in social behaviour may weaken the ability to recognize social properties and identify their underlying drivers. Modifying established approaches, we apply a state-specific analysis to investigate social properties in male African elephants, which are thought to be weakly social. Specifically, we delineate associations during distinct sexually active and inactive periods and quantify common social metrics (network size, density, betweenness and the number and age of preferred companions) to examine how sexual states may relate to male elephant social relationships. We found that state-dependent association index values were higher and quantitative definitions of preferred companions were more conservative than those derived when sexual state was not taken into account. Preferred companions tended to be closer in age among sexually inactive dyads relative to sexually active dyads, indicating that bulls seek out age-mates when sexually inactive. Networks were larger and denser when sexually inactive. By accounting for dynamic behaviour in social systems, this study demonstrates that male African elephants show more social preference than had been previously thought.