Free-ranging African Elephants Research Articles

Short-read full-length 16S rRNA amplicon sequencing for characterisation of the respiratory bacteriome of captive and free-ranging African elephants (Loxodonta africana)

Hypervariable region sequencing of the 16S ribosomal RNA (rRNA) gene plays a critical role in microbial ecology by offering insights into bacterial communities within specific niches. While providing valuable genus-level information, its reliance on data from targeted genetic regions limits its overall utility. Recent advances in sequencing technologies have enabled characterisation of the full-length 16S rRNA gene, enhancing species-level classification. Although current short-read platforms are cost-effective and precise, they lack full-length 16S rRNA amplicon sequencing capability. This study aimed to evaluate the feasibility of a modified 150 bp paired-end full-length 16S rRNA amplicon short-read sequencing technique on the Illumina iSeq 100 and 16S rRNA amplicon assembly workflow by utilising a standard mock microbial community and subsequently performing exploratory characterisation of captive (zoo) and free-ranging African elephant (Loxodonta africana) respiratory microbiota. Our findings demonstrate that, despite generating assembled amplicons averaging 869 bp in length, this sequencing technique provides taxonomic assignments consistent with the theoretical composition of the mock community and respiratory microbiota of other mammals. Tentative bacterial signatures, potentially representing distinct respiratory tract compartments (trunk and lower respiratory tract) were visually identified, necessitating further investigation to gain deeper insights into their implication for elephant physiology and health.

DETECTION OF ELEPHANT ENDOTHELIOTROPIC HERPESVIRUS (EEHV) IN FREE-RANGING AFRICAN ELEPHANTS (LOXODONTA AFRICANA) IN THE KRUGER NATIONAL PARK, SOUTH AFRICA.

Elephant endotheliotropic herpesvirus (EEHV) infection can cause acute, often fatal, EEHV hemorrhagic disease in free-ranging and human-managed Asian elephants (Elephas maximus) and human-managed African elephants (Loxodonta africana). However, significant knowledge gaps exist pertaining to the presence of EEHV in free-ranging African elephant populations. We retrospectively screened 142 opportunistically collected samples (blood, n=98; bronchoalveolar lavage (BAL) fluid, n=21; trunk wash (TW) fluid, n=23) obtained between 2010 and 2020 from 98 free-ranging African elephants in the Kruger National Park, South Africa, for the presence of different EEHVs, as well as determining the real-time quantitative PCR positivity rate in this population. With the use of validated, previously published DNA extraction and real-time quantitative PCR protocols provided by the National Elephant Herpesvirus Laboratory (Washington, DC, USA), EEHV was detected in nine male African elephants from samples collected in 2011 (n=1), 2013 (n=1), 2018 (n=2), 2019 (n=4), and 2020 (n=1). Viral detection was more common in respiratory compared with blood samples. Six elephants tested positive for EEHV2 subtype (blood, n=2; BAL, n=3; TW, n=2), including one individual that tested positive on matched respiratory samples (BAL and TW). Four elephants tested positive for EEHV3-4-7 (blood, n=1; BAL, n=2; TW, n=1), whereas EEHV6 was not detected in any of the study animals. One elephant tested positive for both EEHV2 and EEHV3-4-7 in the same BAL sample. Even though the levels of viremia varied between 158 and 1,292 viral genome equivalents/mL blood and viral shedding of EEHV2 and EEHV3-4-7 was detected in respiratory samples, no clinical signs were observed in these apparently healthy elephants. These findings are consistent with reports of asymptomatic EEHV infection in human-managed African elephants.

Combining methods for non-invasive fecal DNA enables whole genome and metagenomic analyses in wildlife biology.

Non-invasive biological samples benefit studies that investigate rare, elusive, endangered, or dangerous species. Integrating genomic techniques that use non-invasive biological sampling with advances in computational approaches can benefit and inform wildlife conservation and management. Here, we used non-invasive fecal DNA samples to generate low- to medium-coverage genomes (e.g., >90% of the complete nuclear genome at six X-fold coverage) and metagenomic sequences, combining widely available and accessible DNA collection cards with commonly used DNA extraction and library building approaches. DNA preservation cards are easy to transport and can be stored non-refrigerated, avoiding cumbersome or costly sample methods. The genomic library construction and shotgun sequencing approach did not require enrichment or targeted DNA amplification. The utility and potential of the data generated was demonstrated through genome scale and metagenomic analyses of zoo and free-ranging African savanna elephants (Loxodonta africana). Fecal samples collected from free-ranging individuals contained an average of 12.41% (5.54-21.65%) endogenous elephant DNA. Clustering of these elephants with others from the same geographic region was demonstrated by a principal component analysis of genetic variation using nuclear genome-wide SNPs. Metagenomic analyses identified taxa that included Loxodonta, green plants, fungi, arthropods, bacteria, viruses and archaea, showcasing the utility of this approach for addressing complementary questions based on host-associated DNA, e.g., pathogen and parasite identification. The molecular and bioinformatic analyses presented here contributes towards the expansion and application of genomic techniques to conservation science and practice.

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.

Mycobacterium bovis Infection in Free-Ranging African Elephants.

Mycobacterium bovis infection in wildlife species occurs worldwide. However, few cases of M. bovis infection in captive elephants have been reported. We describe 2 incidental cases of bovine tuberculosis in free-ranging African elephants (Loxodonta africana) from a tuberculosis-endemic national park in South Africa and the epidemiologic implications of these infections.

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.

Normalized difference vegetation index, temperature and age affect faecal thyroid hormone concentrations in free-ranging African elephants.

Conservation biologists can use hormone measurements to assess animals’ welfare, reproductive state, susceptibility to stressors, as well as energy expenditure. Quantifying hormone concentrations from faecal samples is particularly advantageous as samples can be collected without disturbing animals’ behaviour. In order for an endocrine marker to be useful for wildlife managers, we need to understand how extrinsic and intrinsic factors affect hormone concentrations in free-ranging animal populations. Thyroid hormones are linked to basal metabolic rate and energy expenditure. Previous research demonstrated that triiodothyronine (T3) can be measured successfully in faecal matter of African elephants, Loxodonta africana. However, to our knowledge, research into factors affecting changes in elephant T3 levels has only been carried out in captive elephants so far. Thus, we present the first study of faecal T3 metabolite (mT3) concentrations of a large population of free-ranging African elephants. Over 15 months, we collected faecal samples from identified (n = 43 samples) and unidentified (n = 145 samples) individuals in Madikwe Game Reserve, South Africa. We investigated whether vegetative productivity [normalized difference vegetation index (NDVI)] in interaction with mean monthly temperature, age and sex affected mT3 concentrations. We found a significant negative interaction effect of NDVI and temperature. Increasing NDVI was related to higher concentrations of mT3, but increasing temperature was related to a decrease in mT3 concentrations in individually identified and unidentified elephants. In unidentified individuals, juvenile elephants had significantly higher mT3 concentrations compared to adult elephants. Faecal T3 can successfully be quantified in samples from free-ranging elephant populations and thus provides insight into energy expenditure in large herbivores.

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.

Fatal Tuberculosis in a Free-Ranging African Elephant and One Health Implications of Human Pathogens in Wildlife.

Tuberculosis (TB) in humans is a global public health concern and the discovery of animal cases of Mycobacterium tuberculosis (Mtb) infection and disease, especially in multi-host settings, also has significant implications for public health, veterinary disease control, and conservation endeavors. This paper describes a fatal case of Mtb disease in a free-ranging African elephant (Loxodonta africana) in a high human TB burden region. Necropsy revealed extensive granulomatous pneumonia, from which Mtb was isolated and identified as a member of LAM3/F11 lineage; a common lineage found in humans in South Africa. These findings are contextualized within a framework of emerging Mtb disease in wildlife globally and highlights the importance of the One Health paradigm in addressing this anthroponotic threat to wildlife and the zoonotic implications.

African savanna elephants (Loxodonta africana) as an example of a herbivore making movement choices based on nutritional needs.

BackgroundThe increasing human population and global intensification of agriculture have had a major impact on the world’s natural ecosystems and caused devastating effects on populations of mega-herbivores such as the African savanna elephants, through habitat reduction and fragmentation and increased human–animal conflict. Animals with vast home ranges are forced into increasingly smaller geographical areas, often restricted by fencing or encroaching anthropogenic activities, resulting in huge pressures on these areas to meet the animals’ resource needs. This can present a nutritional challenge and cause animals to adapt their movement patterns to meet their dietary needs for specific minerals, potentially causing human–animal conflict. The aim of this review is to consolidate understanding of nutritional drivers for animal movement, especially that of African savanna elephants and focus the direction of future research. Peer reviewed literature available was generally geographically specific and studies conducted on isolated populations of individual species. African savanna elephants have the capacity to extensively alter the landscape and have been more greatly studied than other herbivores, making them a good example species to use for this review. Alongside this, their movement choices, potentially linked with nutritional drivers could be applicable to a range of other species. Relevant case study examples of other herbivores moving based on nutritional needs are discussed.MethodsThree databases were searched in this review: Scopus, Web of Science and Google Scholar, using identified search terms. Inclusion and exclusion criteria were determined and applied as required. Additional grey literature was reviewed as appropriate.ResultsInitial searches yielded 1,870 records prior to application of inclusion and exclusion criteria. A less detailed review of grey literature, and additional peer-reviewed literature which did not meet the inclusion criteria but was deemed relevant by the authors was also conducted to ensure thorough coverage of the subject.DiscussionA review of peer reviewed literature was undertaken to examine nutritional drivers for African elephant movement, exploring documented examples from free-ranging African savanna elephants and, where relevant, other herbivore species. This could help inform prediction or mitigation of human–elephant conflict, potentially when animals move according to nutritional needs, and related drivers for this movement. In addition, appropriate grey literature was included to capture current research.

Beehive fences as a multidimensional conflict-mitigation tool for farmers coexisting with elephants.

Increasing habitat fragmentation and human population growth in Africa has resulted in an escalation in human-elephant conflict between small-scale farmers and free-ranging African elephants (Loxodonta Africana). In 2012 Kenya Wildlife Service (KWS) implemented the national 10-year Conservation and Management Strategy for the Elephant in Kenya, which includes an action aimed at testing whether beehive fences can be used to mitigate human-elephant conflict. From 2012 to 2015, we field-tested the efficacy of beehive fences to protect 10 0.4-ha farms next to Tsavo East National Park from elephants. We hung a series of beehives every 10 m around the boundary of each farm plot. The hives were linked with strong wire. After an initial pilot test with 2 farms, the remaining 8 of 10 beehive fences also contained 2-dimensional dummy hives between real beehives to help reduce the cost of the fence. Each trial plot had a neighboring control plot of the same size within the same farm. Of the 131 beehives deployed 88% were occupied at least once during the 3.5-year trial. Two hundred and fifty-three elephants, predominantly 20-45 years old entered the community farming area, typically during the crop- ripening season. Eighty percent of the elephants that approached the trial farms were kept out of the areas protected by the beehive fences, and elephants that broke a fence were in smaller than average groups. Beehive fences not only kept large groups of elephants from invading the farmland plots but the farmers also benefited socially and financially from the sale of 228 kg of elephant-friendly honey. As news of the success of the trial spread, a further 12 farmers requested to join the project, bringing the number of beehive fence protected farms to 22 and beehives to 297. This demonstrates positive adoption of beehive fences as a community mitigation tool. Understanding the response of elephants to the beehive fences, the seasonality of crop raiding and fence breaking, and the willingness of the community to engage with the mitigation method will help contribute to future management strategies for this high human-elephant conflict hotspot and other similar areas in Kenya.

Finding pathways to human–elephant coexistence: a risky business

AbstractFinding ways for people and wildlife to coexist requires affording both parties access to critical resources and space, but also a behavioural change by both to avoid conflict. We investigated pathway use in a population of free-ranging African elephants Loxodonta africana in the Okavango Panhandle, Botswana that share their range with humans in a multi-use, heterogeneous landscape. We used detailed ground surveys to identify and map elephant movement pathways, and mixed-effect models to explore factors influencing elephant numbers and movement behaviour on and around these pathways. We found deviation in pathway use among the elephant population, suggesting behavioural adaptations to avoid human-associated risk: avoiding pathways near settlements, particularly near larger settlements; avoiding pathways close to cultivated land; and adopting a safety-in-numbers strategy when moving through areas of human use. Our findings suggest there is opportunity to capitalize on risk avoidance by elephant populations, to minimize resource-use overlap and reduce conflict between humans and elephants. We discuss a strategy that involves ensuring appropriate protection of elephant pathways in land-use planning, using development-free buffer zones, combined with mitigation techniques along the interface with agricultural lands to increase risk levels and reinforce human–elephant interface boundaries. We recommend further examination of the use of landscape-level mitigation techniques that encourage elephants to use pathways away from human activity and help define spatial boundaries for management of human–elephant conflict in multi-use landscapes.

Age-group estimation in free-ranging African elephants based on acoustic cues of low-frequency rumbles

Animal vocal signals are increasingly used to monitor wildlife populations and to obtain estimates of species occurrence and abundance. In future, acoustic monitoring should function not only to detect animals, but also to extract detailed information about populations by discriminating sexes, age groups, social or kin groups, and potentially individuals. Here we show that it is possible to estimate age groups of African elephants (Loxodonta africana) based on acoustic parameters extracted from rumbles recorded under field conditions in a National Park in South Africa. Statistical models reached up to 70% correct classification to four age groups (infants, calves, juveniles and adults) and 95% correct classification when categorizing into two groups (infants/calves lumped into one group vs. adults). The models revealed that parameters representing absolute frequency values have the most discriminative power. Comparable classification results were obtained by fully automated classification of rumbles by high-dimensional features that represent the entire spectral envelope, such as Mel-frequency cepstral coefficient (75% correct classification) and Greenwood function cepstral coefficient (74% correct classification). The reported results and methods provide the scientific foundation for a future system that could potentially automatically estimate the demography of an acoustically monitored elephant group or population.

LAPAROSCOPIC VASECTOMY IN AFRICAN SAVANNAH ELEPHANT (LOXODONTA AFRICANA); SURGICAL TECHNIQUE AND RESULTS

Several small, enclosed reserves in southern Africa are experiencing significant elephant population growth, which has resulted in associated environmental damage and changes in biodiversity. Although several techniques exist to control elephant populations, e.g., culling, relocation, and immunocontraception, the technique of laparoscopic vasectomy of free-ranging bull elephants was investigated. Bilateral vasectomies were performed in 45 elephants. Of these elephants, one died within 24 hr of recovery and two had complications during surgery but recovered uneventfully. Histologic examination confirmed the resected tissue as ductus deferens in all the bulls. Most animals recovered uneventfully and showed no abnormal behavior after surgery. Complications recorded included incisional dehiscence, 1 full-thickness and 2 partial-thickness lacerations of the large intestine, and initial sling-associated complications, for example, deep radial nerve paresis. One bull was found dead 6 weeks after surgery without showing any prior abnormal signs. Vasectomy in free-ranging African bull elephants may be effectively performed in their normal environment. The surgical procedure can be used as a realistic population management tool in free-ranging elephants without major anesthetic, surgical, or postoperative complications.

Ovarian cycle activity varies with respect to age and social status in free-ranging elephants in Addo Elephant National Park, South Africa.

Free-ranging African elephants live in a fission-fusion society, at the centre of which is the matriarch. Matriarchs are generally older females that guide their families to resources and co-ordinate group defense. While much is known about elephant society, knowledge is generally lacking about how age affects the physiology of wild elephants. Investigation of the ovarian activity of free-ranging elephants could provide insight into the reproductive ageing process, with implications for population management. Faecal samples were collected from 46 individuals ranging in age from 14 to 60 years for a 2-year period, and progestagen metabolite analyses were used to examine relationships between social status, age, season, and ovarian activity in female elephants in Addo Elephant National Park, South Africa. Social status was the strongest predictor of faecal progestagen metabolite concentrations in non-pregnant elephants, with grand matriarchs (n = 6) having the lowest values compared with matriarchs (n = 21) and non-matriarch females (n = 19). Likewise, social status and age were the strongest predictors of faecal progestagen metabolite concentrations in pregnant elephants (n = 27). The number of years since a non-pregnant female gave birth to her last calf (post-partum duration) was longer for older females with a higher social status, as well as during the dry season. Our results indicate that social standing and age of elephants are related to reproductive function, and that older females exhibit reductions in ovarian capacity. These results expand our understanding of reproduction and fertility throughout an elephant's lifespan, and the factors that impact gonadal function in free-ranging females. Given that possible over-abundance of elephants in areas such as Addo Elephant National Park is fuelling the debate over how best to manage these populations, knowledge about the reproductive potential of high-ranking females can provide managers with biological data to identify the best candidates for controlling growth through translocation or contraception.

Stable isotope turnover and variability in tail hairs of captive and free-ranging African elephants (Loxodonta africana) reveal dietary niche differences within populations

Many herbivore species expand their dietary niche breadths by switching from browse-rich diets in dry seasons to grass-rich diets in rainy seasons, in response to phenological changes in plant availability and quality. We analyzed stable isotope series along tail hairs of captive and free-ranging African elephant (Loxodonta africana (Blumenbach, 1797)) to compare patterns of seasonal dietary variability across individuals. Results from elephants translocated from the wild into captivity, where their diets are semicontrolled, revealed tail hair growth rates of ∼0.34 mm/day, on average, and relatively rapid isotope turnover through the transition from wild into captivity. Sampling hairs at 10 mm increments thus archives dietary chronologies at a resolution suitable for tracking diet switches at seasonal, and even subseasonal, scales. Hairs of free-ranging elephants showed extensive carbon isotopic variability within individuals, consistent with seasonal switches between C3-browsing and C4-grazing. Similarly extensive, but asynchronous, shifts in nitrogen isotope ratios were also observed, suggesting an influence of factors other than seasonality. Across individuals, switching patterns differed across habitats, and across age classes, with older, larger animals including increasing amounts of C3browse into their diets. These results demonstrate how stable isotope approaches characterize complex patterns of resource use in wildlife populations.

Antiphonal vocal bouts associated with departures in free-ranging African elephant family groups (Loxodonta africana)

We describe the interactive nature of vocalizations emitted by African elephant (Loxodonta africana) family groups while visiting waterholes. Despite being in close visual contact with each other, individuals called interactively within a series of overlapping or antiphonal vocal bouts that increased significantly while departing from the waterhole. After initiating departure from the waterhole, elephants in this study increased their calling rate and their production of overlapping vocal bouts. The majority of calls either overlapped or occurred within 1.5 seconds of another call as part of an antiphonal bout, rather than as isolated calls. The departure of larger herds was accompanied by a greater number of calling bouts. The increase in interactive antiphonal bouts during departure might serve to facilitate group coordination and cohesion, as well as possibly reinforce social bonds. The longer repeated bouts could also facilitate eavesdropping by distant elephants by boosting signal detection since the repetition of these longer calls may yield an increase in the signal-to-noise ratio (SNR) that reduces the noise floor for better longer distance communication.

Fecal 20-oxo-pregnane concentrations in free-ranging African elephants (Loxodonta africana) treated with porcine zona pellucida vaccine

Because of overpopulation of African elephants in South Africa and the consequent threat to biodiversity, the need for a method of population control has become evident. In this regard, the potential use of the porcine zona pellucida (pZP) vaccine as an effective means for population control is explored. While potential effects of pZP treatment on social behavior of African elephants have been investigated, no examination of the influence of pZP vaccination on the endocrine correlates in treated females has been undertaken. In this study, ovarian activity of free-ranging, pZP-treated African elephant females was monitored noninvasively for 1 yr at Thornybush Private Nature Reserve, South Africa, by measuring fecal 5α-pregnan-3β-ol-20-on concentrations via enzyme immunoassay. A total of 719 fecal samples from 19 individuals were collected over the study period, averaging 38 samples collected per individual (minimum, maximum: 16, 52). Simultaneously, behavioral observations were made to record the occurrence of estrous behavior for comparison. Each elephant under study showed 5α-pregnan-3β-ol-20-on concentrations rising above baseline at some period during the study indicating luteal activity. Average 5α-pregnan-3β-ol-20-on concentrations were 1.61 ± 0.46 μg/g (mean ± SD). Within sampled females, 42.9% exhibited estrous cycles within the range reported for captive African elephants, 14.3% had irregular cycles, and 42.9% did not appear to be cycling. Average estrous cycle duration was 14.72 ± 0.85 wk. Estrous behavior coincided with the onset of the luteal phase and a subsequent rise in 5α-pregnan-3β-ol-20-on concentrations. Average 5α-pregnan-3β-ol-20-on levels positively correlated with rainfall. No association between average individual 5α-pregnan-3β-ol-20-on concentrations or cyclicity status with age or parity were detected. Earlier determination of efficacy was established via fecal hormone analysis with no pregnancies determined 22 mo post-treatment and onward. Results indicate the presence of ovarian activity amongst pZP-treated female African elephants in 2 yr after initial immunization. Further study should now be aimed toward investigating the long-term effects of pZP vaccination on the reproductive function of female African elephants.

Non-invasive assessment of the reproductive cycle in free-ranging female African elephants (Loxodonta africana) treated with a gonadotropin-releasing hormone (GnRH) vaccine for inducing anoestrus.

BackgroundIn southern Africa, various options to manage elephant populations are being considered. Immunocontraception is considered to be the most ethically acceptable and logistically feasible method for control of smaller and confined populations. In this regard, the use of gonadotropin-releasing hormone (GnRH) vaccine has not been investigated in female elephants, although it has been reported to be safe and effective in several domestic and wildlife species. The aims of this study were to monitor the oestrous cycles of free-ranging African elephant cows using faecal progestagen metabolites and to evaluate the efficacy of a GnRH vaccine to induce anoestrus in treated cows.MethodsBetween May 2009 - June 2010, luteal activity of 12 elephant cows was monitored non-invasively using an enzyme immunoassay detecting faecal 5alpha-reduced pregnanes (faecal progestagen metabolites, FPM) on a private game reserve in South Africa. No bulls of breeding age were present on the reserve prior to and for the duration of the study. After a 3-month control period, 8 randomly-selected females were treated twice with 600 micrograms of GnRH vaccine (Improvac®, Pfizer Animal Health, Sandton, South Africa) 5-7 weeks apart. Four of these females had been treated previously with the porcine zona pellucida (pZP) vaccine for four years (2004-2007).ResultsAll 12 monitored females (8 treated and 4 controls) showed signs of luteal activity as evidenced by FPM concentrations exceeding individual baseline values more than once. A total of 16 oestrous cycles could be identified in 8 cows with four of these within the 13 to 17 weeks range previously reported for captive African elephants. According to the FPM concentrations the GnRH vaccine was unable to induce anoestrus in the treated cows. Overall FPM levels in samples collected during the wet season (mean 4.03 micrograms/gram dry faeces) were significantly higher (P<0.002) than the dry season (mean 2.59 micrograms/gram dry faeces).ConclusionsThe GnRH vaccination protocol failed to induce anoestrus in the treated female elephants. These results indicate that irregular oestrous cycles occur amongst free-ranging elephants and are not restricted to elephants in captivity. The relationship between ecological conditions and endocrine activity were confirmed. Free-ranging female elephants were observed to not cycle continuously throughout the year in the absence of adult bulls.

Age Determination by Back Length for African Savanna Elephants: Extending Age Assessment Techniques for Aerial-Based Surveys

Determining the age of individuals in a population can lead to a better understanding of population dynamics through age structure analysis and estimation of age-specific fecundity and survival rates. Shoulder height has been used to accurately assign age to free-ranging African savanna elephants. However, back length may provide an analog measurable in aerial-based surveys. We assessed the relationship between back length and age for known-age elephants in Amboseli National Park, Kenya, and Addo Elephant National Park, South Africa. We also compared age- and sex-specific back lengths between these populations and compared adult female back lengths across 11 widely dispersed populations in five African countries. Sex-specific Von Bertalanffy growth curves provided a good fit to the back length data of known-age individuals. Based on back length, accurate ages could be assigned relatively precisely for females up to 23 years of age and males up to 17. The female back length curve allowed more precise age assignment to older females than the curve for shoulder height does, probably because of divergence between the respective growth curves. However, this did not appear to be the case for males, but the sample of known-age males was limited to ≤27 years. Age- and sex-specific back lengths were similar in Amboseli National Park and Addo Elephant National Park. Furthermore, while adult female back lengths in the three Zambian populations were generally shorter than in other populations, back lengths in the remaining eight populations did not differ significantly, in support of claims that growth patterns of African savanna elephants are similar over wide geographic regions. Thus, the growth curves presented here should allow researchers to use aerial-based surveys to assign ages to elephants with greater precision than previously possible and, therefore, to estimate population variables.