Male Elephant Research Articles

Reproductive evaluation of elephants culled in Kruger National Park, South Africa between 1975 and 1995

AbstractTo reduce elephant densities and preserve biological diversity, 14,629 elephants were culled from Kruger National Park, South Africa (1967–1999). Data were catalogued between 1975 and 1996 on 2737 male and female elephants, including pregnancy and lactational status for 1620 females (≥5 years of age) and, uterine and/or ovarian characteristics for 1279. This study used these data to investigate the effects of age and precipitation on reproduction. The youngest age of conception was 8 years (n = 6) and by 12 years of age all females were sexually mature. From the age of 14 years, the percentage of reproductively active females (pregnant and/or lactating) was >90%; however, this percentage declined when females reached 50 years of age. Overall, one‐tenth of females were nonreproductive (not pregnant or lactating) at any given time, mostly in the youngest (<15 years) and oldest (>50 years) age classes. Eighteen (3.3%) of the nonpregnant females had reproductive tract pathologies, including endometrial, uterine or ovarian cysts. There was a seasonal distribution of mating activity that correlated with the rainy season. As has been demonstrated in other populations of free‐ranging African elephants, most of the females in Kruger National Park were reproductively active; however, age and climate affected reproductive activity.

Immobilization of adult male southern elephant seals (Mirounga leonina) during the breeding and molting periods using a tiletamine/zolazepam mixture and ketamine

Seventy-seven immobilizations were carried out on adult male southern elephant seals at Stranger Point, Isla 25 de Mayo (King George Island) using a combination of Zoletil® (tiletamine and zolazepam) and ketamine in order to obtain biological samples. During 2006/2007, 22 males were immobilized at the beginning of their breeding period (EB), 19 of which were recaptured at the end of breeding (LB). Four were given only once at an unknown stage of breeding (USB) and 18 males were immobilized at the beginning of molting (BM). During 2007/2008, 14 adult males were immobilized at an USB. Zoletil® was administered using an automatic discharge device, whereas ketamine was injected directly with a syringe, and was used only when the initial sedation was not enough to carry out the programmed sampling. The initial mean dose of Zoletil® was 1,387 ± 304 mg, which represented 0.60 ± 0.14 mg/kg, range 0.36–1.05, n = 77. In 47 procedures, an average dose of 1.04 ± 0.66 mg/kg of ketamine was added. Mean immobilization time was 34 ± 14 min. In 25 out of the 77 procedures, males showed apnea, which lasted 8 ± 4 min (range 2–15 min). The necessary doses of Zoletil® and ketamine to attain immobilization differed between stages. For animals taken twice, doses (mg/kg) of Zoletil® and ketamine were significantly higher at the beginning than at the end of breeding. During molting, the doses of Zoletil® given were significantly lower than those used during breeding, although the proportion of animals that required ketamine during molting was significantly higher than during breeding. Zoletil® proved to be a safe immobilizing agent for field work on adult males of this species, given the wide range of doses used without any serious consequences. Furthermore, the addition of ketamine was useful when the initial sedation was not satisfactory or for prolonging the immobilization period in a practical and reliable way.

Acquisition of brains from the African elephant ( Loxodonta africana): Perfusion-fixation and dissection

The current correspondence describes the in situ perfusion-fixation of the brain of the African elephant. Due to both the large size of proboscidean brains and the complex behaviour of these species, the acquisition of good quality material for comparative neuroanatomical analysis from these species is important. Three male African elephants (20–30 years) that were to be culled as part of a larger population management strategy were used. The animals were humanely euthanized and the head removed from the body. Large tubes were inserted into to the carotid arteries and the cranial vasculature flushed with a rapid (20 min) rinse of 100 l of cold saline (4 °C). Following the rinse the head was perfusion-fixed with a slower rinse (40 min) of 100 l of cold (4 °C) 4% paraformaldehyde in 0.1 M phosphate buffer. This procedure resulted in well-fixed neural and other tissue. After perfusion the brains were removed from the skull with the aid of power tools, a procedure taking between 2 and 6 h. The brains were immediately post-fixed in the same solution for 72 h at 4 °C. The brains were subsequently placed in a sucrose solution and finally an antifreeze solution and are stored in a −20 °C freezer. The acquisition of high quality neural material from African elephants that can be used for immunohistochemistry and electron microscopy is of importance in understanding the “hardware” underlying the behaviour of this species. This technique can be used on a variety of large mammals to obtain high quality material for comparative neuroanatomical studies.

Spatial behaviour of translocated African elephants (Loxodonta africana) in a novel environment: using behaviour to inform conservation actions

[When animals encounter a novel environment they can either reject it and leave or accept it and explore their new home. It is important to understand what governs animals' response to a novel place because of the fitness consequences and wildlife management implications entailed. Here I examine the spatial behaviour of translocated African elephants (Loxodonta africana) upon arrival at a novel environment. I monitored the movement patterns of 12 radio-collared elephants for a year post-translocation. I documented the first account of both female and male African elephants homing back to their natal habitat. More males than expected left the release site, but female–calf units also homed to their natal habitat, demonstrating that homing is not confined to one sex or age. When examining the spatial behaviour of elephants that remained near the release site I did not find a relationship between habitat exploration and last distance from release site, elephant age, or social association. However, I did find a negative correlation between habitat exploration and distance from human activities. This work provides biological insights regarding individual variation in spatial activity of animals in a novel environment and offers recommendations for future management actions., When animals encounter a novel environment they can either reject it and leave or accept it and explore their new home. It is important to understand what governs animals' response to a novel place because of the fitness consequences and wildlife management implications entailed. Here I examine the spatial behaviour of translocated African elephants (Loxodonta africana) upon arrival at a novel environment. I monitored the movement patterns of 12 radio-collared elephants for a year post-translocation. I documented the first account of both female and male African elephants homing back to their natal habitat. More males than expected left the release site, but female–calf units also homed to their natal habitat, demonstrating that homing is not confined to one sex or age. When examining the spatial behaviour of elephants that remained near the release site I did not find a relationship between habitat exploration and last distance from release site, elephant age, or social association. However, I did find a negative correlation between habitat exploration and distance from human activities. This work provides biological insights regarding individual variation in spatial activity of animals in a novel environment and offers recommendations for future management actions.]

Sexual dimorphism in the performance of chemosensory investigatory behaviours by African elephants (Loxodonta africana)

AbstractSexual dimorphism in morphology can be accompanied by behavioural differences between the sexes. We examined if investigatory behaviour involving the trunk of African elephants showed sexual dimorphism. Males compete and search for females, but they have a lengthy period of development before they are socially viable mates. Receptive females are relatively rare. We hypothesized that males would display higher rates of chemosensory behaviour following puberty than females. Because males disperse, they were hypothesized to be more likely to contact elephants outside their kinship group. We observed the trunk tip, chemosensory behaviours of African elephants at Addo Elephant National Park, South Africa. For 208 elephants, we found no significant differences in state behaviours around waterholes by age or sex. Yet, older elephants were more likely to investigate the environment and elephant excrement than younger animals. Males were more likely to investigate urine and faeces than females. Only post-puberty animals contacted non-family with males investigating both sexes, while investigations by and to females only involved post-puberty males. Overall, the probability of performing chemosensory behaviours depended on age and sex. Male elephants appear more reliant than females on signals in urine and faeces with ensuing inspections of individuals through trunk tip contacts.

Adult male southern elephant seals from King George Island utilize the Weddell Sea

AbstractAdult male southern elephant seals instrumented in 2000 on King George Island (n = 13), travelled both to the north (n = 2) and to the east (n = 6) of the Antarctic Peninsula. Five males remained within 500 km of the island focusing movements in the Bransfield Strait and around the Antarctic Peninsula. Sea surface temperatures encountered by these animals showed little variation. While animal trajectories appeared unaffected by sea ice cover, areas of shallow depths were frequented. Three males moved as far as 75°S to the east of the Peninsula with maximum distances of more than 1500 km from King George Island. They travelled into the Weddell Sea along the western continental shelf break until they reached the region of the Filchner Trough outflow. Here the sea floor consists of canyons and ridges that support intensive mixing between the warm saline waters of the Weddell Gyre, the very cold outflow waters and ice shelf water at the Antarctic Slope Front. The need for re-instrumentation of adult males from King George Island is highlighted to investigate whether males continue to travel to similar areas and to obtain higher resolution data.

Do male African elephants, Loxodonta africana, signal musth via urine dribbling?

The phenomenon of musth in male elephants involves increased sexual activity, heightened aggression and nearly continuous dribbling of pungent smelling urine. Urine chemistry during musth is altered, suggesting that urine may signal the musth status of the individual. Signalling musth remotely may benefit individuals if it reduces the likelihood of physical confrontation between males, which can lead to injury and even death. Few studies, however, have asked whether and how male elephants respond to urine of other males. We tested two predictions of the hypothesis that urine signals musth status to male conspecifics: (1) that male African elephants differentiate musth and nonmusth urine, and (2) that males differentiate between urine dribbled during early and late musth. The second prediction stems from the observation that males lose weight and presumably body condition during musth. We conducted two related bioassays with 26 captive nonmusth males ranging from 13 to 52 years of age. In each assay, subjects were simultaneously presented with three urine samples (nonmusth, early musth, late musth), each from a different donor male, and a control. We found that subjects differentiated between musth and nonmusth samples using their vomeronasal organ system, but did not discriminate between the samples using their main olfactory system. Males did not differentiate early from late musth. In addition, we found that subject contextual factors, specifically age, dominance status and social grouping, significantly predicted response. We discuss these results within the framework of male elephant longevity and social relationships and their importance to reproductive success.

Click-evoked potentials in a large marine mammal, the adult male northern elephant seal (Mirounga angustirostris)

Auditory evoked potential (AEP) hearing studies in marine mammals should consider an expected size-dependent reduction in AEP amplitude. This study is the first to measure the click-evoked response in a large marine mammal, the adult male elephant seal (Mirounga angustirostris). Click stimuli were presented at peak-peak equivalent sound pressure levels of 117-118 dB re: 20 microPa. Three positive peaks (P1-P3) and two negative peaks (N4 and N5) were observed in the AEP. Response latencies were longer than previously observed in a 1.8 yr old seal and the maximum peak-peak amplitude was comparatively reduced by more than 60%. The inverse relationship between size and AEP amplitude will likely require increased averaging with larger subjects and possibly modifications to electrode placement and design in order to increase the quality of recorded evoked responses.

Adolescence in male African elephants, Loxodonta africana, and the importance of sociality

The degree of sociality during an animal's life changes as it modulates its behaviour to reflect different life stages. Only a few species of mammal undergo a period of adolescence, but for these species it is probably one of their most important life stages. It is when individuals acquire skills and develop relationships that are of both immediate and long-term benefit to their survival and reproductive success, particularly in polygynous males in which sexual selection favours size and dominance. We collected focal and observational data on male African elephants in the Okavango Delta, Botswana, to assess behaviour and social interactions during adolescence. Adolescent males (10–15 and 16–20 years of age) were the most sociable age group, showing preferences for larger social groupings and being in closer proximity to other elephants; later adolescent males (ages 16–20) showed a tendency for higher social levels. Males of all ages preferred to have males ≥36 years of age as their nearest neighbour. We argue that this proximity to older males provides opportunities for males to learn from more experienced individuals. It has long been recognized that matriarchs are the repositories of social and ecological knowledge within elephant breeding herds: we suggest that mature males are reservoirs for such knowledge within bull society.

Risk and Ethical Concerns of Hunting Male Elephant: Behavioural and Physiological Assays of the Remaining Elephants

BackgroundHunting of male African elephants may pose ethical and risk concerns, particularly given their status as a charismatic species of high touristic value, yet which are capable of both killing people and damaging infrastructure.Methodology/Principal FindingsWe quantified the effect of hunts of male elephants on (1) risk of attack or damage (11 hunts), and (2) behavioural (movement dynamics) and physiological (stress hormone metabolite concentrations) responses (4 hunts) in Pilanesberg National Park. For eleven hunts, there were no subsequent attacks on people or infrastructure, and elephants did not break out of the fenced reserve. For three focal hunts, there was an initial flight response by bulls present at the hunting site, but their movements stabilised the day after the hunt event. Animals not present at the hunt (both bulls and herds) did not show movement responses. Physiologically, hunting elephant bulls increased faecal stress hormone levels (corticosterone metabolites) in both those bulls that were present at the hunts (for up to four days post-hunt) and in the broader bull and breeding herd population (for up to one month post-hunt).Conclusions/SignificanceAs all responses were relatively minor, hunting male elephants is ethically acceptable when considering effects on the remaining elephant population; however bulls should be hunted when alone. Hunting is feasible in relatively small enclosed reserves without major risk of attack, damage, or breakout. Physiological stress assays were more effective than behavioural responses in detecting effects of human intervention. Similar studies should evaluate intervention consequences, inform and improve best practice, and should be widely applied by management agencies.

Endocrine and behavioral changes in male African elephants: Linking hormone changes to sexual state and reproductive tactics

Hormones play a crucial role in mediating genetic and environmental effects into morphological and behavioral phenotypes. In systems with alternative reproductive tactics (ART) shifts between tactics are hypothesized to be under proximate hormonal control. Most studies of the underlying endocrine changes behind ART have focused on fish and amphibians rather than mammals and few have investigated the potential interaction between different endocrine axes in regulating shifts between conditional dependent tactics. Using a combination of endocrine and behavioral data from male African elephants we expand on our previously published analysis and show that the initial increase in androgens predates the behavioral shifts associated with reproductively active periods, supporting the role of androgens in activating sexually active periods in males. A strong interactive effect between androgens and glucocorticoids was found to determine the presence or absence of temporal gland secretion and urine dribbling, signals associated with the competitive reproductive tactic of musth, with elevated glucocorticoids levels suppressing the occurrence of musth signals. In addition external environmental conditions affected hormone levels. The presence of receptive females resulted in elevated androgens in dominant musth males but increased glucocorticoids in subordinate non-musth males. The presented data on hormones, behavior and reproductive tactics strongly support an underlying endocrine mechanism for mediating the translation of intrinsic as well as extrinsic local conditions into the conditional dependent reproductive tactics in male elephants via interactions between the hypothalamic-pituitary-gonadal and -adrenal axes.

Fine‐scale population genetic structure in a fission–fusion society

Nonrandom patterns of mating and dispersal create fine-scale genetic structure in natural populations - especially of social mammals - with important evolutionary and conservation genetic consequences. Such structure is well-characterized for typical mammalian societies; that is, societies where social group composition is stable, dispersal is male-biased, and males form permanent breeding associations in just one or a few social groups over the course of their lives. However, genetic structure is not well understood for social mammals that differ from this pattern, including elephants. In elephant societies, social groups fission and fuse, and males never form permanent breeding associations with female groups. Here, we combine 33 years of behavioural observations with genetic information for 545 African elephants (Loxodonta africana), to investigate how mating and dispersal behaviours structure genetic variation between social groups and across age classes. We found that, like most social mammals, female matrilocality in elephants creates co-ancestry within core social groups and significant genetic differentiation between groups (Phi(ST) = 0.058). However, unlike typical social mammals, male elephants do not bias reproduction towards a limited subset of social groups, and instead breed randomly across the population. As a result, reproductively dominant males mediate gene flow between core groups, which creates cohorts of similar-aged paternal relatives across the population. Because poaching tends to eliminate the oldest elephants from populations, illegal hunting and poaching are likely to erode fine-scale genetic structure. We discuss our results and their evolutionary and conservation genetic implications in the context of other social mammals.

Activity Budgets and Sexual Segregation in African Elephants (Loxodonta africana)

Abstract The activity budget hypothesis is 1 of 4 main hypotheses proposed to explain sexual segregation by large herbivores. Because of their smaller body size, females are predicted to have higher mass-specific energy requirements and lower digestive efficiency than males. As a result, females are expected to forage longer to satisfy their nutritional demands. Maintaining the cohesion of a mixed-sex group with differing activity budgets and asynchronous behavioral patterns is increasingly difficult, ultimately leading to spatial segregation of males and females. We tested this hypothesis using data (2002–2005) from 3 distinct populations of African elephants (Loxodonta africana), a species that exhibits marked sexual segregation. Group and individual behaviors were assessed at discrete points in time throughout the day, with a minimum of 10 min between consecutive records. Focal samples of individual male and female elephants also were recorded, with behavioral data logged every minute for 15 min. Data ...

Development of aggressive vocalizations in male southern elephant seals (Mirounga leonina): maturation or learning?

Summary Vocalizations are an important component of male elephant seal agonistic behaviour. Acoustic and behavioural components of vocalizations emitted during agonistic contests show gross differences between young and old males, but the variation with age depends on the specific feature. Vocalizations become more frequent and effective at later ages. Acoustic features that are constrained by structural phenotype, which changes with age, also should change with age, while acoustic features that are independent from structural phenotype should show no relationship with age. We demonstrate that, in southern elephant seals, formant frequencies, which are constrained by the vocal tract length and, therefore, by body size, show a clear decrease with age, whereas temporal and structural features of sounds, which potentially are unconstrained, show no correlation with age. Formants ontogeny seems, therefore, to be mostly the result of body maturation, and hence formants may be reliable signals of age. In contrast, acoustic features such as temporal features and syllable structure, are free to change, and hence may serve as the raw material for vocal learning and individual recognition.

Purulent Trunk Dermatitis in a Male Ceylon Elephant (Elephas maximus maximus)

The study describes the therapy of purulent trunk dermatitis in an aggressive male Ceylon elephant (Elephas maximus maximus). The elephant was immobilized 4 times with 1.7 ml Large Animal (LA) Immobilon i.m. within 50 days. The anaesthetic action was antagonised with 1.7 ml LA Revivon + 8.0 ml Naloxone i.v. and 0.5 ml LA Revivon + 6.0 ml Naloxone i.m. From skin lesions the following pathogens were isolated: Staphylococcus spp., Streptococcus spp. and Candida tropicalis. Local therapy consisted of the debridement of the affected skin, application of antibiotics and skin antiseptics. Depot penicillin, vitamins, probiotics and autogenous yeast vaccine were administered generally. In haematological indicators the biggest changes were found in the numbers of white blood cells and segmented neutrophils. Markedly low zinc concentrations were found repeatedly. Despite the non-standard steps we took (repeated anaesthesia during a short time, non-compliance with the recommendations for the administration of some drugs, etc.) and difficult handling (aggressive, uncontrollable elephant, no restraint chute), it proved possible to treat such a case in this manner.

The Asian elephants Elephas maximus of Cat Tien National Park, Vietnam: status and conservation of a vanishing population

This study updates the status and conservation of the Endangered Asian elephant Elephas maximus in Cat Tien National Park, Vietnam. Line transect indirect surveys, block surveys for elephant signs, village surveys of elephant-human conflict incidents, guard-post surveys for records of sightings, and surveys of elephant food plants were undertaken during the dry and wet seasons of 2001. A minimum of 11 elephants and a maximum of 15-17 elephants was estimated for c. 500 km2 of the Park and its vicinity. The elephants are largely confined to the southern boundary of the Park and make extensive use of the adjoining La Nga State Forest Enterprises. During the dry season the elephants depend on at least 26 species of wild and cultivated plants, chiefly the fruits of cashew. Most of the villages surveyed reported some elephant-human conflict. Two adult male elephants seem to cover a large area to raid crops, whereas the family groups restrict themselves to a few villages; overall, the conflict is not serious. Since 2001 there have been no reports of any deaths or births of elephants in the Park. We make recommendations for habitat protection and management, increasing the viability of the small population, reducing elephant-human conflicts, and improving the chances of survival of the declining elephants of this Park. The Government has now approved an Action Plan for Urgent Conservation Areas in Vietnam that calls for the establishment of three elephant conservation areas in the country, including Cat Tien National Park.

Age- and tactic-related paternity success in male African elephants

Information on age- and tactic-related paternity success is essential for understanding the lifetime reproductive strategy of males and constitutes an important component of the fitness trade-offs that shape the life-history traits of a species. The degree of reproductive skew impacts the genetic structure of a population and should be considered when developing conservation strategies for threatened species. The behavior and genetic structure of species with large reproductive skew may be disproportionately impacted by anthropogenic actions affecting reproductively dominant individuals. Our results on age- and tactic-specific paternity success in male African elephants are the first from a free-ranging population and demonstrate that paternity success increases dramatically with age, with the small number of older bulls in the competitive state of musth being the most successful sires. However, nonmusth males sired 20% of genotyped calves, and 60% of mature bulls (.20 years old) were estimated to have sired offspring during the 5-year study period. The 3 most successful males sired less than 20% of the genotyped offspring. Hence, contrary to prediction from behavior and life-history traits, reproduction was not heavily skewed compared with many other mammalian systems with a similar breeding system. Nevertheless, these results indicate that trophy hunting and ivory poaching, both of which target older bulls, may have substantial behavioral and genetic effects on elephant populations. In addition, these results are critical to the current debate on methods for managing and controlling increasing populations of this species. Key words: Eelephants, musth, paternity, reproductive strategy, skew, tactic. [Behav Ecol]

A Case Study: Fecal Corticosteroid and Behavior as Indicators of Welfare During Relocation of an Asian Elephant

This study was a preliminary investigation of an enzyme immunoassay for measuring fecal glucocorticoid metabolites in a male Asian elephant (Elephas maximus) by investigating changes in behavior and cortisol metabolite excretion associated with a putative stressful event. The study collected fecal samples for 10 days prior to, and 10 days after, 24-hr transport and relocation of the elephant to a new herd. The study measured cortisol metabolites using 2 enzyme immunoassays indicating a 389% and 340% increase in cortisol metabolite excretion following relocation. Maximal cortisol metabolite excretion occurred 2 days after relocation and remained elevated during establishment of the new herd. Stereotypic behavior increased approximately 400% after relocation. The relocation disturbed sleep patterns, the elephant spent less time sleeping during the night, and the elephant slept standing up. These results provide preliminary evidence that noninvasive monitoring of fecal cortisol metabolites can be used to investigate adrenal activity in Asian elephants and may be a safe, practical, and accurate welfare indicator.

Application of photographic capture–recapture modelling to estimate demographic parameters for male Asian elephants

AbstractIn addition to the threats of habitat loss and degradation, adult males of the Asian elephant Elephas maximus also face greater threats from ivory poaching and conflict with humans. To understand the impact of these threats, conservationists need robust estimates of abundance and vital rates specifically for the adult male segment of elephant populations. By integrating the identification of individual male elephants in a population from distinct morphology and natural markings, with modern capture–recapture (CR) sampling designs, it is possible to estimate various demographic parameters that are otherwise difficult to obtain from this long‐lived and wide‐ranging megaherbivore. In this study, we developed systematic individual identification protocols and integrated them into CR sampling designs to obtain capture histories and thereby estimate the abundance of adult bull elephants in a globally important population in southern India. We validated these estimates against those obtained from an independent method combining line‐transect density estimates with age–sex composition data for elephants. The sampled population was open to gains and losses between sampling occasions. The abundance of adult males in the 176 km2 study area was N̂(SÊN̂) = 134(14.20) and they comprised 14% (±1%) of the total elephant population. Time‐specific abundance estimates for each sampling occasion showed a distinct increase in adult male numbers over the sampling period, explained by seasonal patterns of local migration. CR‐based estimates for adult male abundance closely matched estimates from distance‐based methods. Thus, while providing abundance data of comparable rigour and precision, photographic CR methods permit estimation of demographic parameters for the Asian elephant that are both urgently needed and difficult to obtain.

The cost of success: reproductive effort in male southern elephant seals (Mirounga leonina)

Reproductive effort is a key parameter of life history because it measures the resources allocated to reproduction at the expense of growth and maintenance. Male reproductive effort always had a minor role with respect to female effort both in the development of theories and in field research. Elephant seals are an ideal subject for reproductive effort studies because they fast during the breeding season, splitting the phase of energy acquisition from the phase of energy use for breeding. In this paper, we present results on male reproductive effort (weight loss estimated by photogrammetry) in southern elephant seals (Mirounga leonina), the most dimorphic and polygynous of all mammal species. We show that total reproductive effort increases with age, with no sign of late decrease or senescence. Male reproductive effort in this species depends mostly on behavioral factors, i.e., the success in competition with other males, and the intensity of interaction with females. A large effort results in large gains in both mating success and fertilizations. The large reproductive success that a few males are able to achieve come at a big cost in terms of energy expenditure, but this cost does not seem to affect the likelihood of survival to the following breeding season.