Adult Female Elephants Research Articles

Twisting collars on male elephants in shrub terrain: animal welfare considerations for researchers, managers and manufacturers

For the purposes of testing the impacts of habitat expansion on elephant movement, six XL LoRa elephant radio collars were fixed on three adult male elephants and three adult female elephants prior to a fence being removed at Kariega Game Reserve, South Africa. While none of the collars on female elephants twisted, within five months, all the male elephant collars had twisted, with some triple and double twisting. Behavioural monitoring revealed indications of irritation that resulted in the removal and/or replacement of all twisted collars. It was discovered that two of the male elephants had developed wounds underneath their twisted collars, therefore, only one elephant was re-collared, with a collar that was modified to minimize further risk of twisting, however it twisted again. To investigate this rare incidence of elevated collar twisting, our study assessed the following: elephant behaviour to guide decision-making around interventions and well-being; when, where and how these incidents occurred to investigate the mechanism of twisting and the likelihood of human error; collar design and refurbishment to develop recommendations to minimize the likelihood of twisting; and data obtained from organizations using elephant collars for comparison. From this, it was theorized that browsing behaviour in bulls in dense vegetation, and inadequate collar design were the likely causes in twisting occurrence. We urge organizations using LoRa elephant collars to emphasize post-application monitoring, and exercise caution, when attaching on bulls in dense vegetation. We encourage collar manufacturers to thoroughly investigate twisting incidents and adjust collar structures accordingly, and inform clients about the possibility of twisting. By addressing these issues, we can better ensure the well-being of elephants, research success, and improved device safety and efficacy.

Distribution and ranging area of elephant in Simpan Panti Forest, Kota Tinggi, Johor, Malaysia

Abstract. Hassan NHN, Abdullah NM, Norazlimi NA, Saaban S, Yazi MFA. 2023. Distribution and ranging area of elephant in Simpan Panti Forest, Kota Tinggi, Johor, Malaysia. Biodiversitas 24: 5731-5738. Home range estimation is one of the most used animal ecology studies using a Geographic Information System (GIS). One adult female Asian elephant (Elephas maximus Linnaeus, 1758) was fitted with a telemetry satellite collar African Wildlife Tracking (AWT) to determine its home range size distribution through its ranging behaviour and to identify the relationship between the GPS collar location record and the area covered. The home range estimation was determined using GPS collar location data from a satellite telemetry system and analyzed by using the Minimum Convex Polygon methods. GPS collar location data were obtained from the Department of Wildlife and National Parks (DWNP). The movement of elephant data was overlayed with the land use data of the Simpan Panti Forest (Hutan Simpan Panti), Kota Tinggi District, Johor, Malaysia before being exported to ArcGIS Pro software. The ArcGIS Pro software can estimate this Asian elephant home range sizes by using the MCP method for twelve months, from 1 June 2019 until 31 May 2020. The total home range size is 447.17 km². Home range size is estimated to be 31.77 to 303.86 km² in one year. The size of this home range has presumably been impacted by extensive human activities such as highways and settlement areas. So, good and strong management is needed to control this conflict for humans to live in harmony in one area and protect the remaining forest reserve area from expanding to agricultural activity and human development areas.

Trans‐oceanic subsurface photovoltaic performance

AbstractUtilization of marine photovoltaic energy is primarily focused on surface harvesting with limited photovoltaic cell implementations in submarine environments. Potential applications include marine wildlife telemetry devices, autonomous underwater vehicles, or remote sensing assets. In these applications, understanding the power at depth is critical, but there has yet to be a long‐term study of cell performance in a realistic marine environment that spans time, geographic location, and depth. In this paper, we present photovoltaic assessments carried out by devices mounted to adult female northern elephant seals (Mirounga angustirostris) during their spring migrations in the Pacific Ocean with deployment times between 76 and 107 days. Encompassing a large geographic area between Santa Cruz, California, and the Aleutian Islands of Alaska during their migrations, elephant seal behavior allows for repeated depth profiles each day, making them an ideal host for subsurface power assessments. This paper presents the first longitudinal study of photovoltaic cell performance in the marine environment that spans location, time, and depth. This work discusses the calibration, data time alignment, and power calculations of these oceanic deployments. Deployment results, including power results and energy predictions from the data record, are presented up to 22 m in depth. We highlight how the recorded power data of these cells compares to previously published results and how depth impacts subsurface power and energy harvesting.

Adrenal response to ACTH challenge alters thyroid and immune function and varies with body reserves in molting adult female northern elephant seals.

Intrinsic stressors associated with life-history stages may alter the responsiveness of the hypothalamic-pituitary-adrenal axis and responses to extrinsic stressors. We administered adrenocorticotropic hormone (ACTH) to 24 free-ranging adult female northern elephant seals (NESs) at two life-history stages: early and late in their molting period and measured a suite of endocrine, immune, and metabolite responses. Our objective was to evaluate the impact of extended, high-energy fasting on adrenal responsiveness. Animals were blood sampled every 30 min for 120 min post-ACTH injection, then blood was sampled 24 h later. In response to ACTH injection, cortisol levels increased 8- to 10-fold and remained highly elevated compared with baseline at 24 h. Aldosterone levels increased 6- to 9-fold before returning to baseline at 24 h. The magnitude of cortisol and aldosterone release were strongly associated, and both were greater after extended fasting. We observed an inverse relationship between fat mass and the magnitude of cortisol and aldosterone responses, suggesting that body reserves influenced adrenal responsiveness. Sustained elevation in cortisol was associated with alterations in thyroid hormones; both tT3 and tT4 concentrations were suppressed at 24 h, while rT3 increased. Immune cytokine IL-1β was also suppressed after 24 h of cortisol elevation, and numerous acute and sustained impacts on substrate metabolism were evident. Our data suggest that female NESs are more sensitive to stress after the molt fast and that acute stress events can have important impacts on metabolism and immune function. These findings highlight the importance of considering life-history context when assessing the impacts of anthropogenic stressors on wildlife.

Mercury Bioaccumulation and Cortisol Interact to Influence Endocrine and Immune Biomarkers in a Free-Ranging Marine Mammal

Mercury bioaccumulation from deep-ocean prey and the extreme life history strategies of adult female northern elephant seals (Mirounga angustirostris) provide a unique system to assess the interactive effects of mercury and stress on animal health by quantifying blood biomarkers in relation to mercury (skeletal muscle and blood mercury) and cortisol concentrations. The thyroid hormone thyroxine (tT4) and the antibody immunoglobulin E (IgE) were associated with mercury and cortisol concentrations interactively, where the magnitude and direction of the association of each biomarker with mercury or cortisol changed depending on the concentration of the other factor. For example, when cortisol concentrations were lowest, tT4 was positively related to muscle mercury, whereas tT4 had a negative relationship with muscle mercury in seals that had the highest cortisol concentrations. Additionally, we observed that two thyroid hormones, triiodothyronine (tT3) and reverse triiodothyronine (rT3), were negatively (tT3) and positively (rT3) associated with mercury concentrations and cortisol in an additive manner. As an example, tT3 concentrations in late breeding seals at the median cortisol concentration decreased by 14% across the range of observed muscle mercury concentrations. We also observed that immunoglobulin M (IgM), the pro-inflammatory cytokine IL-6 (IL-6), and a reproductive hormone, estradiol, were negatively related to muscle mercury concentrations but were not related to cortisol. Specifically, estradiol concentrations in late molting seals decreased by 50% across the range of muscle mercury concentrations. These results indicate important physiological effects of mercury on free-ranging apex marine predators and interactions between mercury bioaccumulation and extrinsic stressors. Deleterious effects on animals' abilities to maintain homeostasis (thyroid hormones), fight off pathogens and disease (innate and adaptive immune system), and successfully reproduce (endocrine system) can have significant individual- and population-level consequences.

Into the large ears: otitis externa associated with nematodes, mites, and bacteria in Asian elephants (Elephas maximus)

BackgroundThe Asian elephant (Elephas maximus), which is an endangered species, harbors several parasites. Among the ectoparasites that it harbors, ear mites of the genus Loxanoetus have the potential to cause external otitis, an inflammation that may also be associated with the presence of other microorganisms. We assessed the relationships between ear mites, nematodes, yeast, bacterial rods, and cocci sampled from the ears of captive Asian elephants in Thailand. In addition, we discuss the possibility that dust-bathing behavior may be triggered by ear mite infestation, and that this in turn may lead to contamination of the ears with soil microorganisms.Methods Legally owned captive Asian elephants (n = 64) were sampled. Ear swabs were individually collected from both ears and microscopically examined for the presence of mites, nematodes, yeast, bacterial rods, cocci, and host cells. Mites and nematodes were identified to species level using morphological and molecular methods.ResultsLoxanoetus lenae mites were present in 43.8% (n = 28/64) of the animals (19 animals with mites in one ear and nine animals with mites in both ears). Nematodes of the genus Panagrolaimus were detected in 23.4% (n = 15/64) of the animals (10 with nematodes in one ear and five with nematodes in both ears). In adult elephants (Fisher’s exact test, P = 0.0278) and female elephants (Fisher’s exact test, P = 0.0107), the presence of nematodes in both ears was significantly associated with the presence of mites. In addition, higher categorical burdens of nematodes were also significantly associated with the presence of mites (Fisher’s exact test, P = 0.0234) and epithelial cells (Fisher’s exact test, P = 0.0108), and marginally significantly associated with bacterial cocci (Fisher’s exact test, P = 0.0499).ConclusionsThe presence of L. lenae mites in the ear canals of the Asian elephants was significantly associated with the occurrence of other microorganisms, such as soil nematodes, bacteria and yeasts. The presence of mites in their ears may increase the dust-bathing behavior of elephants which, if confirmed, represents a further paradigmatic example of a parasitic infestation affecting animal behavior.Graphical

Effects of disease on foraging behaviour and success in an individual free-ranging northern elephant seal.

Evaluating consequences of stressors on vital rates in marine mammals is of considerable interest to scientific and regulatory bodies. Many of these species face numerous anthropogenic and environmental disturbances. Despite its importance as a critical form of mortality, little is known about disease progression in air-breathing marine megafauna at sea. We examined the movement, diving, foraging behaviour and physiological state of an adult female northern elephant seal (Mirounga angustirostris) who suffered from an infection while at sea. Comparing her to healthy individuals, we identified abnormal behavioural patterns from high-resolution biologging instruments that are likely indicators of diseased and deteriorating condition. We observed continuous extended (3-30minutes) surface intervals coinciding with almost no foraging attempts (jaw motion) during 2weeks of acute illness early in her post-breeding foraging trip. Elephant seals typically spend ~ 2minutes at the surface. There were less frequent but highly extended (30-200minutes) surface periods across the remainder of the trip. Dive duration declined throughout the trip rather than increasing. This seal returned in the poorest body condition recorded for an adult female elephant seal (18.3% adipose tissue; post-breeding trip average is 30.4%). She was immunocompromised at the end of her foraging trip and has not been seen since that moulting season. The timing and severity of the illness, which began during the end of the energy-intensive lactation fast, forced this animal over a tipping point from which she could not recover. Additional physiological constraints to foraging, including thermoregulation and oxygen consumption, likely exacerbated her already poor condition. These findings improve our understanding of illness in free-ranging air-breathing marine megafauna, demonstrate the vulnerability of individuals at critical points in their life history, highlight the importance of considering individual health when interpreting biologging data and could help differentiate between malnutrition and other causes of at-sea mortality from transmitted data.

Foraging behavior of a mesopelagic predator, the northern elephant seal, in northeastern Pacific eddies

The role of mesoscale features in structuring trophic transfer in the mesopelagic zone is poorly understood. Deploying sensors on marine animals, or “biologging,” is a powerful tool to infer the organism's behavior and simultaneously collect high-resolution oceanographic data to describe physical-biological interactions. We investigated whether mesoscale eddies are used by a mesopelagic predator, the northern elephant seal (Mirounga angustirostris), and if so, what mechanisms might create beneficial foraging conditions in association with eddies. We hypothesized seals would increase their foraging behavior in both cyclonic and anticyclonic eddies due to nutrient enhancement and physical aggregation of prey and that seals would dive deeper in anticyclonic eddies in response to a deeper prey field. We used tracking data and continuous in situ temperature measurements from 221 adult female northern elephant seals collected between 2004 and 2019. These predators primarily targeted myctophid fishes and squid throughout the northeast Pacific mesopelagic zone, foraging between approximately 400–800 m. Eddy encounters were identified using remotely sensed sea level anomaly data and confirmed visually with collocated sea level anomaly, in situ temperature, and in situ temperature anomaly. Over more than 30,000 days of data and >3 million temperature casts collected by seals, we found 129 high confidence encounters with anticyclonic eddies and 83 with cyclonic eddies. Overall, seals traveled more slowly and in a less directed manner while associated with eddies, particularly anticyclonic eddies, suggesting increased foraging behavior, especially in the California Current. Elephant seals spent more time at the edges of cyclonic eddies than their center. In contrast, they utilized both the interior and edge of anticyclonic eddies. This suggests that the aggregation of prey at the frontal region of an eddy is an important mechanism, whereas nutrient upwelling associated with an eddy play a more minor role in enhancing the seals' prey field. Seal foraging behavior was not influenced by eddy age, size, amplitude, or rotational speed. The large sample size in this study showed considerable variation between individual behavioral responses, suggesting caution when extrapolating individual behavior to a population level. Our data show that both cyclonic and anticyclonic eddies can affect the seals' prey field as demonstrated by enhanced foraging behavior. Still, the variation in behavioral responses resulting from individual foraging strategies, eddy histories, and possible spatiotemporal mismatches between eddy physics and biological responses relevant to mesopelagic predators merit further investigation.

Acoustic structure and information content of trumpets in female Asian elephants (Elephas maximus).

Most studies on elephant vocal communication have focused on the low-frequency rumble, with less effort on other vocalization types such as the most characteristic elephant call, the trumpet. Yet, a better and more complete understanding of the elephant vocal system requires investigating other vocalization types and their functioning in more detail as well. We recorded adult female Asian elephants (Elephas maximus) at a private facility in Nepal and analyzed 206 trumpets from six individuals regarding their frequency, temporal and contour shape, and related acoustic parameters of the fundamental frequency. We also tested for information content regarding individuality and context. Finally, we recorded the occurrence of non-linear phenomena such as bifurcation, biphonation, subharmonics and deterministic chaos. We documented a mean fundamental frequency ± SD of 474 ± 70 Hz and a mean duration ± SD of 1.38 ± 1.46 s (Nindiv. = 6, Ncalls = 206). Our study reveals that the contour of the fundamental frequency of trumpets encodes information about individuality, but we found no evidence for trumpet subtypes in greeting versus disturbance contexts. Non-linear phenomena prevailed and varied in abundance among individuals, suggesting that irregularities in trumpets might enhance the potential for individual recognition. We propose that trumpets in adult female Asian elephants serve to convey an individual’s identity as well as to signal arousal and excitement to conspecifics.

Clinical approach to colic and collapse in an Asian elephant (Elephas maximus) withSalmonellasaintpaul septicaemia and subsequent ileus

AbstractAn adult female Asian elephant (Elephas maximus) presented with clinical signs of colic unresponsive to analgesia, which progressed to hypothermia and collapse within 48 hours. Repeated sedations using butorphanol and detomidine were performed for initial diagnostic sampling, first aid and subsequent treatment. Initial haematology showed evidence of septicaemia and disseminated intravascular coagulation; urine analysis was consistent with metabolic acidosis. The initial treatment focused on rectal administration of enrofloxacin, metronidazole and fluids. By Day 7, the immune system was recovering as demonstrated by blood parameters but ileus had developed. Sedation interventions were discontinued and treatment consisted of oral ranitidine, fibre provision and rehydration.Salmonellasaintpaul was cultured from the faeces and a disease risk analysis identified a possible infection route through food contamination. Serial haematology provided direction in clinical decision making throughout this challenging case.

Reproductive tract neoplasia in adult female Asian elephants (Elephas maximus).

Recent reports have highlighted a lower-than-expected prevalence of neoplasia in elephants and suggested mechanisms for cancer resistance. But despite infrequent reports in the literature, uterine neoplasia is common in managed Asian elephants (Elephas maximus). This study is an archival review of reproductive tract neoplasia in 80 adult female Asian elephant mortalities in managed care facilities in the United States from 1988 to 2019. Neoplasms occurred in 64/80 (80%) of cases. Most were in the uterus (63/64; 98%) with only a single case of ovarian neoplasia. Myometrial leiomyomas were present in 57/63 (90%) cases with uterine neoplasia. Uterine adenocarcinoma was present in 8/63 (13%) cases. Remaining cases included endometrial adenoma (2), focal carcinoma in situ in endometrial polyps (1), anaplastic carcinoma (1), endometrial hemangioma (1), primitive neuroectodermal tumor (PNET; 1), and angiosarcoma (1). One case with uterine adenocarcinoma had a separate pelvic mass histologically characterized as an anaplastic sarcoma. Distant metastases were documented in 5/8 (63%) cases of uterine adenocarcinoma, and in the uterine anaplastic carcinoma, PNET, and angiosarcoma. Four uterine adenocarcinomas and one carcinoma in situ were examined immunohistochemically for pan-cytokeratin, vimentin, and estrogen receptor. In all, neoplastic cells were pan-cytokeratin positive and vimentin negative, and in 2 cases were immunoreactive for estrogen receptor. Results show that female reproductive tract neoplasia, particularly of the uterus, is common in Asian elephants and is not limited to leiomyomas. Importantly, uterine neoplasms have the potential to impact fecundity and may represent obstacles to conservation in managed care.

Entry and aggregation at a Central African bai reveal social patterns in the elusive forest elephant Loxodonta cyclotis

Social relationships are shaped by ecological conditions, giving rise to diverse societies even among related species. Among elephants, females exhibit close, often familial bonds with some degree of philopatry and fission–fusion dynamics. Forest elephant sociality is the least studied among elephant species, and their ecology differs from that of savannah and Asian elephants. We use over 15 years of data from an individually identified population using the Dzanga Bai forest clearing in Central African Republic to characterize social patterns of adult female elephants in two contexts, when entering the forest clearing and within the clearing. Social properties were nonrandom and highly stable over the study period in both contexts. Composition of aggregations within the clearing indicated considerable mixing among females, while association in groups entering the bai together were limited in composition, likely representing core social units. The co-entry data set exhibited distinct communities that were not apparent in the co-occurrence data set. In contrast to savannah elephants, network centrality and age were negatively correlated, suggesting a muted or absent matriarch social hub role in forest elephants at a broader level than family units. Temporal and community analyses indicated that bai co-entry and co-occurrence contexts may represent distinct processes, with the former social and the latter driven by shared resource use. Our results point to social patterns potentially driven by the need for families to fission into small units because of resource competition and highlight the importance of aggregation context in interpreting association indices. • We examined social patterns of female forest elephants using a bai forest clearing. • Composition of aggregations within the clearing indicated considerable mixing. • Groups that entered the bai together likely represented core social units. • Older females may not function as social hubs, unlike in other elephant species. • Forest resource constraints may shape social patterns of this elusive species.

Fasting affects amino acid nitrogen isotope values: a new tool for identifying nitrogen balance of free-ranging mammals.

Changes in the nutritional status of free-ranging animals have a strong influence on individual fitness, yet it remains challenging to monitor longitudinally. Nitrogen (δ15N) and carbon (δ13C) isotope values measured chronologically along the length of metabolically inert keratinous tissues can be used as a nutritional biomarker to retrospectively reconstruct the foraging ecology and eco-physiology of consumers. We quantitatively describe the physiological effects of fasting on amino acid metabolism using sequentially measured bulk tissue and amino acid δ15N values along the length of whiskers sampled from free-ranging juvenile, subadults, adult female, and male southern elephant seals (SES; Mirounga leonina) on Marion Island in the Southern Ocean. For both juveniles and adult females, whisker segments representing fasting had significantly higher bulk tissue δ15N values of 0.6 ± 0.5‰ and 1.3-1.8‰, respectively, in comparison to segments unaffected by fasting. We also found a large increase (2-6‰) in δ15N values for most glucogenic amino acids and a simultaneous depletion (2-3‰) of alanine in segments reflecting fasting, which enabled us to accurately predict (74%) the nutritional status of our model species. We hypothesize that the glucose-alanine cycle is the mechanism driving the observed depletion of alanine δ15N values during fasting. We demonstrated that keratinaceous tissues can be used as a longitudinal nutritional biomarker to detect changes in the nitrogen balance of an individual. Moreover, it is evident that physiological factors have an important influence on tissue δ15N values and can lead to erroneous bulk tissue or amino acid isotope-based reconstructions of foraging habits.

Expression of obesity-related adipokine genes during fasting in a naturally obese marine mammal.

Northern elephant seals (Mirounga angustirostris) are exceptional among fasting-adapted animals in coupling prolonged fasting with energetically costly activities, relying on oxidation of fat stores accrued during foraging to power metabolic demands of reproduction and molting. We hypothesized that high rates of energy expenditure, insulin resistance, and immune responses to colonial breeding in fasting seals are mediated by adipokines, or signaling molecules secreted by adipose tissue that are associated with obesity and inflammation in humans. We measured mRNA expression of 10 adipokine genes in blubber tissue of adult female elephant seals sampled early and late during their lactation and molting fasts and correlated gene expression with adiposity and circulating levels of corticosteroid and immune markers. Expression of adiponectin (ADIPOQ) and its receptor ADIPOR2, leptin receptor (LEPR), resistin (RETN), retinol binding protein 4 (RBP4), and visfatin/nicotinamide phosphoribosyltransferase (NAMPT) was increased, whereas that of fat mass and obesity-associated protein (FTO) was decreased in late-fasted compared with early-fasted groups. Abundance of adipokine transcripts that increased in late fasting was negatively associated with body mass and positively associated with cortisol, suggesting that they may mediate local metabolic effects of cortisol in blubber during fasting. Expression of several adipokines was correlated with the immune markers IL-6, haptoglobin, IgM, and IgE, suggesting a potential role in modulating immune responses to colonial breeding and molting. Since many of these adipokines have not been measured in other wild animals, this study provides preliminary insights into their local regulation in fat tissue and targeted assays for future studies.

Use of 15N-enriched glycine to estimate vibrissa growth in free-ranging northern elephant seals Mirounga angustirostris

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 614:199-207 (2019) - DOI: https://doi.org/10.3354/meps12913 Use of 15N-enriched glycine to estimate vibrissa growth in free-ranging northern elephant seals Mirounga angustirostris David Aurioles-Gamboa1,*, Seth D. Newsome2, Jason L. Hassrick3, Tatiana Acosta-Pachón4, Félix Aurioles-Rodríguez5, Daniel P. Costa6 1Facultad de Ingeniería Ambiental, Universidad Popular Autónoma del Estado de Puebla, Puebla 72410, México 2Biology Department, University of New Mexico, Albuquerque, New Mexico 87131, USA 3ICF Fish and Aquatic Science, 201 Mission Street, Suite 1500, San Francisco, California 94105, USA 4Departamento Académico de Ciencias Marinas y Costeras. Universidad Autónoma de Baja California Sur, La Paz, Baja California Sur 23080, México 5División de Ciencias Naturales y Exactas, Universidad de Guanajuato, 36050 Guanajuato, México 6Ecology and Evolutionary Biology Department, University of California Santa Cruz, Santa Cruz, California 95064, USA *Corresponding author: daurioles@gmail.com ABSTRACT: The stable isotope composition of continuously growing but metabolically inert tissues remains unaltered after they are synthesized, providing insights on seasonal and inter-annual variation in the ecology of individuals. In pinnipeds, isotope analysis of sub-sampled vibrissae can provide a longitudinal record of movement, diet, and even physiological state at the individual level. To reliably apply this approach, however, taxon-specific vibrissa growth needs to be estimated, especially for species with complicated annual life cycles that undergo periods of active foraging interspersed with reproduction and/or molting associated with fasting. Here, we intravenously injected 15N-enriched glycine to estimate vibrissa growth in 8 free-ranging adult female northern elephant seals during their (shorter) post-breeding and (longer) post-molting foraging trips; all animals were instrumented with satellite tags to track movements and vibrissae were collected when the animals returned to land. We found a significant positive relationship between the maximum δ15N values, representing 15N-glycine injections, and the distance between the origin of the spike and the root of the vibrissa. The δ15N spikes that occurred closest to the root were narrower and had lower δ15N values than those that occurred closer to the tip of the vibrissa, suggesting differential velocities of 15N-glycine absorption and vibrissa growth. A derived von Bertalanffy model yielded mean (±SD) growth of 0.015 ± 0.006 d-1, similar to that previously reported for a single captive northern elephant seal. Vibrissa length is an important consideration for accurately interpreting isotope-based ecological and physiological histories given the non-continuous growth observed in our study. KEY WORDS: Northern elephant seal · Vibrissae growth · 15N-enriched glycine Full text in pdf format PreviousNextCite this article as: Aurioles-Gamboa D, Newsome SD, Hassrick JL, Acosta-Pachón T, Aurioles-Rodríguez F, Costa DP (2019) Use of 15N-enriched glycine to estimate vibrissa growth in free-ranging northern elephant seals Mirounga angustirostris. Mar Ecol Prog Ser 614:199-207. https://doi.org/10.3354/meps12913 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 614. Online publication date: April 04, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Anatomy of the Proboscideal Nerve in the Proboscis of the African Elephant (Loxodonta africana)

The elephant proboscis (i.e., trunk), a unique muscular organ formed by the combined narial and upper lip region, is a complex muscular hydrostat adapted for a multitude of functions, including grasping, holding, and transporting objects, siphoning, holding, and spraying water, and communication. The proboscis has previously been described as containing tens of thousands of muscle fascicles, each working individually to help bend, curve, and curl the trunk in all directions at any point along its length. Although the muscular system of the proboscis has previously been described in some depth, the unique nervous innervation of the proboscis has been given minimal attention. Here, the previously frozen head of an adult female African elephant (Loxodonta africana) is dissected to investigate the anatomy of the neuromuscular anatomy of the proboscis in more depth. In addition to the complexity of interlacing muscle fascicles and the integrated connective tissues, we identified the proboscideal nerve, a large, 2.5 to 3 centimeter thick nerve that is unique to elephants. The proboscideal nerve is made up of the combined distal nerve fibers of the infraorbital branch of the maxillary nerve (CN V3) and zygomatic branch of the facial nerve (CN VII). Specifically, as the infraorbital branch of the maxillary nerve (carrying sensory innervation) exits the cranium through the infraorbital foramen, the zygomatic branch of the facial nerve (carrying motor innervation) runs along the ventral border of the zygomatic arch and joins the maxillary nerve rostrodorsal to the masseter muscle to form the proboscideal nerve. The proboscideal nerve then travels down the length of the proboscis transmitting small sensory and motor nerve fibers to all muscle fascicles and surrounding skin and tissue. Given this anatomy, fine‐tuned neuromuscular control and coordination of the individual nerve fibers are necessary to control the diverse movements that occur throughout the length of the proboscis. This specialized evolutionary adaptation helped shape a functionally innovative organ that grew, modified, and persisted throughout the course of proboscidean evolution.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Influence of the number of calves and lactating adult females in a herd on the adrenocortical activity of free-ranging Asian elephants

Abstract ContextPhysiological stress has the potential to influence animal population persistence. The endangered Asian elephant (Elephas maximus) is involved in intense conflict with humans in many parts of its range, which likely leads to stress for individuals and groups, with consequences for population survival. Thus, it is important to understand how the elephants’ stress levels are influenced by socio-ecological factors when not directly exposed to human-induced threats, and to use this understanding to improve conservation and management strategies. AimsThe present study was designed to provide baseline information on the link between socio-ecological factors and stress levels of undisturbed populations of elephants. The main aim was to determine the influence of a number of factors – herd size, season, number of calves and adult females present in a herd and their lactational status and body condition – on the adrenocortical activity of free-ranging adult female Asian elephants living in protected forests (without any direct exposure to human-induced threats), by measuring their faecal glucocorticoid metabolite (fGCM) levels. MethodsA total of 145 fresh faecal samples were collected from 123 identified adult female elephants inhabiting Bandipur and Nagarahole National Parks of southern India, between the years 2013 and 2015. fGCM levels were measured by employing a group-specific standardised 11-oxoetiocholanolone enzyme immunoassay (EIA). A generalised linear mixed-effects model (GLMM) was used to assess the influence of socio-ecological factors on fGCM levels of adult female elephants. Key resultsWhen fGCM levels were analysed with a GLMM, the following patterns were observed: fGCM levels were negatively correlated with the number of adult females (herd size) and positively correlated with the number of calves in a herd and active lactational status of an adult female. fGCM levels of adult female elephants were higher during the dry season (February to May) than wet season (August to December) and negatively correlated with body condition scores. ConclusionsAdrenocortical activity of female elephants is significantly influenced by the number of calves and adult females present in the herd, seasonality and lactational status. ImplicationsIt is important to consider the influence of multiple ecological and social correlates when assessing and interpreting the adrenocortical activity of Asian elephants. Our findings highlight the importance of maintaining the social structure of elephants in the wild to avoid detrimental effects on their physiological health. Insights from such assessments could be used to evaluate the stress in elephants that are involved in direct conflicts with humans to take appropriate management decisions for mitigating conflicts.

Population characteristics and habitat suitability of Asian elephants (Elephas maximus Linnaeus, 1758) in the Khao Yai National Park, Thailand

Abstract The aim of this study was to investigate the population and habitat of wild elephants in the Khao Yai National Park, to provide elephant population densities using the line transect method. Habitat suitability was also assessed based on the data obtained from the location of the species during monthly ranger patrol across the park area, with the rate of dung decay used for population calculation. The population structure and age class were studied by direct observation to estimate the population trend. On the basis of 116 systematic transect lines that were 2 km in length and separated by 500-m intervals, a total of 1,209 elephant dung piles were found in more than 213.20 km. The analysis of the combined data showed that the dung density was 531.49 dung piles/km2, with a decay rate of 0.0039 dung piles/day based on 56 dung piles checked every 7 days. The annual data showed that the population density was 0.15 individuals/km2. The population structure comprising calf:juvenile:subadult:adult was 1: 1.09:1.14:2.10; the sex ratio of adult male to adult female elephants was 1:1.10; and the ratio of reproductive ability among adult females, juveniles, and calves was 1.00:0.99:0.90. The combined data also showed that the main environmental factor affecting the presence of the animals was salt lick sites. The pooled data analysis found that the habitat most suitable for the elephants covered an area of 220.59 km2. The habitat suitability, based on the dry season appearance data, covered an area of 258.64 km2, whereas during the wet season, it covered an area of 517.45 km2. As the most suitable habitat for elephants appears around the park boundary, habitat improvements for wild elephants should address the central areas of the national park. A greater emphasis should be placed on creating salt licks, being far from human activity sites.

Social Interactions in Two Groups of Zoo-Housed Adult Female Asian Elephants (Elephas maximus) that Differ in Relatedness.

Simple SummaryThe chance to experience positive social interactions is important for captive animals. The amount of positive or negative social interactions that occur within groups of captive animals can be used to evaluate the welfare of the group and determine how compatible the individuals may, or may not, be. In the wild, elephants live in related, multigenerational herds that consist of mainly mothers, daughters, and their offspring. However, in captivity, they are often kept in groups of unrelated individuals, which could reduce the quality of their social interactions, and thus their welfare. Here, we recorded the social interactions between elephants in two groups of four captive female Asian elephants; in one group, all of the individuals were related to one another, whilst in the other, only two out of four individuals were related. We observed more affiliative (friendly) interactions and fewer aggressive interactions in the all-related group. We also observed elephants freely giving way to others more in the related group, with daughters giving way to their mothers and aunts, which is evidence of an established, family-based rank system that allows them to avoid escalation to aggression. These findings support the recommendation that for optimal welfare, elephants should be managed in multigenerational family herds.Opportunities for positive social interaction are important in captive animals, and social interactions can be used as a welfare indicator. Wild elephants live in related multigenerational herds; however, in captivity they are often managed in less related groups, which could impact the quality of their social interactions, and thus their welfare. Here, we used a limited social network analysis to investigate the social interactions in two groups of four female captive Asian elephants, one of which contained individuals that were all related to one another, whilst the other was a mix of related and unrelated individuals. Data on pairwise social interactions was collected from eight days of video footage using an all-occurrence sampling technique. More affiliative, and fewer agonistic interactions were observed in the related elephant group. Additionally, non-contact displacement was observed at a higher frequency in the related elephant group, which we theorise represents an established functioning hierarchy, avoiding the need for overt aggression over resources. Although kinship is not likely to be the only factor affecting captive elephant social behaviour, these findings support the recommendation that for optimal welfare, elephants should be managed in multigenerational family herds. Evaluations of social interactions such as those conducted here would have wider applicability for aiding the management of any captive social species to identify when groups might be incompatible.

Endocrine correlates of puberty in female Asian elephants (Elephas maximus) at the Pinnawala elephant orphanage, Sri Lanka

BackgroundPrevious studies have established ovarian cycle characteristics of adult Asian elephants using progestagen analyses, but little work has been done on young elephants to determine age at puberty. Demographic studies of wild Asian elephants suggest females give birth at about 12–18 years of age (conceiving at 10–16 years of age based on a 2-year gestation). However, there are a few examples of zoo elephants giving birth at only 5–6 years of age, so they would have started cycling much earlier. This study was carried out at the Pinnawela Elephant Orphanage (PEO) in Sri Lanka, where a herd of >80 captive elephants breeds successfully, resulting in a unique opportunity to monitor hormones and document initiation of ovarian cyclicity in young females, thus contributing to the normative reproductive database for this species.ResultsWe measured serum progestagens in samples collected every 10 days for 18 – 24 months from 11 females (3.5–15 years of age), and found six (5.5 – 12 years of age) already were cycling at study onset. Four females started cycling during the study at 4.5, 5.5, 7.5 and 15 years of age. There were no quantitative or qualitative differences between the first pubertal luteal phase and those of subsequent cycles. Of the 46 ovarian cycles observed, 78% were associated with clear behavioral signs of estrus (heightened bull attentiveness, and willingness of females to be mounted) during the late non-luteal period when progestagens were low. The average body weight at puberty was ~48% of that of adult female elephants at PEO.ConclusionsAsian elephants under human care, including under semi-captive conditions, may reach puberty earlier than those in the wild, perhaps due to better nutrition and reaching a body weight capable of supporting reproductive activity at a younger age. Thus, facilities with bulls need to carefully manage elephants to avoid accidental pregnancies in young females that may be too small to safely carry a pregnancy to term.