Publications

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the mummified brain of a pleistocene woolly mammoth (mammuthus primigenius) compared with the brain of the extant african elephant (loxodonta africana).this study presents the results of an examination of the mummified brain of a pleistocene woolly mammoth (mammuthus primigenius) recovered from the yakutian permafrost in siberia, russia. this unique specimen (from 39,440-38,850 years bp) provides the rare opportunity to compare the brain morphology of this extinct species with a related extant species, the african elephant (loxodonta africana). an anatomical description of the preserved brain of the woolly mammoth is provided, along with a seri ...201526011110
a novel objective method of estimating the age of mandibles from african elephants (loxodonta africana africana).the importance of assigning an accurate estimate of age and sex to elephant carcasses found in the wild has increased in recent years with the escalation in levels of poaching throughout africa. irregularities identified in current ageing techniques prompted the development of a new method to describe molar progression throughout life. elephant mandibles (n = 323) were studied and a point near the distal dental alveolus was identified as being most useful in ranking each jaw according to molar p ...201525970428
environmental conditions associated with repetitive behavior in a group of african elephants.repetitive movement patterns are commonly observed in zoo elephants. the extent to which these behaviors constitute a welfare concern varies, as their expression ranges from stereotypies to potentially beneficial anticipatory behaviors. nevertheless, their occurrence in zoo animals is often viewed negatively. to better identify conditions that prompt their performance, observations were conducted on six african elephants (loxodonta africana) at the north carolina zoo. individuals spent most of t ...201525919392
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 the 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 f ...201425821348
all roads lead to rome, even in african savannah elephants--or do they? 201525808893
elucidating the significance of spatial memory on movement decisions by african savannah elephants using state-space models.spatial memory facilitates resource acquisition where resources are patchy, but how it influences movement behaviour of wide-ranging species remains to be resolved. we examined african elephant spatial memory reflected in movement decisions regarding access to perennial waterholes. state-space models of movement data revealed a rapid, highly directional movement behaviour almost exclusively associated with visiting perennial water. behavioural change point (bcp) analyses demonstrated that these ...201525808888
sperm rescue in wild african elephants.this study investigated ways of improving the usefulness of ~1700ml of poor-quality frozen semen collected from wild african elephant (loxodonta africana) bulls. ten semen samples from six bulls, frozen with 5% glycerol in berliner cryomedium, with or without prior removal of the seminal plasma by centrifugation, were tested. all samples were subjected to the following density-gradient centrifugation treatments: no centrifugation (control), sham centrifugation, percoll, optiprep, isolate and pur ...201525763993
exploratory rigid laparoscopy in an african elephant (loxodonta africana).in march 2009, a 25-yr-old captive female african elephant (loxodonta africana) underwent an exploratory laparoscopy after several weeks of diarrhea, submandibular and ventral edema, and swelling on medial and lateral aspects of all feet. although there have been recent advances in laparoscopic vasectomies in free-ranging african elephants in south africa utilizing specially designed rigid laparoscopes and insufflation devices, this was the first attempt at using these same techniques for an exp ...201425632688
ovarian acyclicity in zoo african elephants (loxodonta africana) is associated with high body condition scores and elevated serum insulin and leptin.the purpose of the present study was to determine whether excessive body fat and altered metabolic hormone concentrations in the circulation were associated with ovarian acyclicity in the world's largest land mammal, the african elephant. we compared body condition, glucose, insulin and leptin concentrations and the glucose-to-insulin ratio (g:i) between cycling (n=23; normal 14-16 week cycles based on serum progestagens for at least 2 years) and non-cycling (n=23; consistent baseline progestage ...201625375263
recurrence of hyperprolactinemia and continuation of ovarian acyclicity in captive african elephants (loxodonta africana) treated with cabergoline.hyperprolactinemia is associated with reproductive acyclicity in zoo african elephants (loxodonta africana) and may contribute to the non-self-sustainability of the captive population in north america. it is a common cause of infertility in women and other mammals and can be treated with the dopamine agonist cabergoline. the objectives of this study were to assess prolactin responses to cabergoline treatment in hyperprolactinemic, acyclic african elephants and to determine the subsequent impact ...201425314824
response of african elephants (loxodonta africana) to seasonal changes in rainfall.the factors that trigger sudden, seasonal movements of elephants are uncertain. we hypothesized that savannah elephant movements at the end of the dry season may be a response to their detection of distant thunderstorms. nine elephants carrying global positioning system (gps) receivers were tracked over seven years in the extremely dry and rugged region of northwestern namibia. the transition date from dry to wet season conditions was determined annually from surface- and satellite-derived rainf ...201425299514
data-driven discovery of the spatial scales of habitat choice by elephants.setting conservation goals and management objectives relies on understanding animal habitat preferences. models that predict preferences combine location data from tracked animals with environmental information, usually at a spatial resolution determined by the available data. this resolution may be biologically irrelevant for the species in question. individuals likely integrate environmental characteristics over varying distances when evaluating their surroundings; we call this the scale of se ...201425177532
elevated elephant density does not improve ecotourism opportunities: convergence in social and ecological objectives.in order to sustainably conserve biodiversity, many protected areas, particularly private protected areas, must find means of self-financing. ecotourism is increasingly seen as a mechanism to achieve such financial sustainability. however, there is concern that ecotourism operations are driven to achieve successful game-viewing, influencing the management of charismatic species. an abundance of such species, including the african elephant (loxodonta africana), has been stocked in protected areas ...201425154086
legal ivory trade in a corrupt world and its impact on african elephant populations.illegal hunting of african elephants (loxodonta africana) for ivory is causing rapid declines in their populations. since 2007, illegal ivory trade has more than doubled. african elephants are facing the most serious conservation crisis since 1989, when international trade was banned. one solution proposed is establishment of a controlled legal trade in ivory. high prices for ivory mean that the incentives to obtain large quantities are high, but the quantity of tusks available for trade are bio ...201525103555
african elephants (loxodonta africana) recognize visual attention from face and body orientation.how do animals determine when others are able and disposed to receive their communicative signals? in particular, it is futile to make a silent gesture when the intended audience cannot see it. some non-human primates use the head and body orientation of their audience to infer visual attentiveness when signalling, but whether species relying less on visual information use such cues when producing visual signals is unknown. here, we test whether african elephants (loxodonta africana) are sensiti ...201425013015
bilateral ovarian cystadenoma in a geriatric african elephant (loxodonta africana).a 59-yr-old, captive female african elephant (loxodonta africana) died of a cardiovascular collapse. necropsy revealed bilateral replacement of the ovarian tissue by multiple cystic formations of up to 10 cm in diameter. the cysts were thin walled and filled with clear watery fluid. smaller solid masses with an irregular surface projected from the wall of a few of the cysts. histologically, the cystic structures were characterized by a single layer of well-differentiated cuboidal epithelial cell ...201425000708
development of a body condition scoring index for female african elephants validated by ultrasound measurements of subcutaneous fat.obesity-related health and reproductive problems may be contributing to non-sustainability of zoo african elephant (loxodonta africana) populations. however, a major constraint in screening for obesity in elephants is lack of a practical method to accurately assess body fat. body condition scoring (bcs) is the assessment of subcutaneous fat stores based on visual evaluation and provides an immediate appraisal of the degree of obesity of an individual. the objective of this study was to develop a ...201424718304
laparoscopic vasectomy in african elephants (loxodonta africana).to describe a surgical technique for, and outcome after, laparoscopic vasectomy of free-ranging elephants.201424617837
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 r ...201324437080
characterization of a novel polyomavirus isolated from a fibroma on the trunk of an african elephant (loxodonta africana).viruses of the family polyomaviridae infect a wide variety of avian and mammalian hosts with a broad spectrum of outcomes including asymptomatic infection, acute systemic disease, and tumor induction. in this study a novel polyomavirus, the african elephant polyomavirus 1 (aelpyv-1) found in a protruding hyperplastic fibrous lesion on the trunk of an african elephant (loxodonta africana) was characterized. the aelpyv-1 genome is 5722 bp in size and is one of the largest polyomaviruses characteri ...201324205012
effects of social disruption in elephants persist decades after culling.multi-level fission-fusion societies, characteristic of a number of large brained mammal species including some primates, cetaceans and elephants, are among the most complex and cognitively demanding animal social systems. many free-ranging populations of these highly social mammals already face severe human disturbance, which is set to accelerate with projected anthropogenic environmental change. despite this, our understanding of how such disruption affects core aspects of social functioning i ...201324152378
complex vibratory patterns in an elephant larynx.elephants' low-frequency vocalizations are produced by flow-induced self-sustaining oscillations of laryngeal tissue. to date, little is known in detail about the vibratory phenomena in the elephant larynx. here, we provide a first descriptive report of the complex oscillatory features found in the excised larynx of a 25 year old female african elephant (loxodonta africana), the largest animal sound generator ever studied experimentally. sound production was documented with high-speed video, aco ...201324133151
the progression of small-follicle reserves in the ovaries of wild african elephants (loxodonta africana) from puberty to reproductive senescence.this study aimed to determine whether the follicle reserve in the ovary of the african elephant declines progressively after puberty and whether its depletion constrains the fertility of older females. elephant ovaries were fixed in 4% neutral buffered formalin and small-follicle counts made using stereological protocols. excepting a slight rise in small-follicle numbers between 16 and 25 years of age, there was a trend for follicle numbers to fall from puberty to 70 years. reproductive status d ...201324112390
architectural organization of the african elephant diencephalon and brainstem.the current study examined the organization of the diencephalon and brainstem of the african elephant (loxodonta africana) - a region of the elephant brain that has not been examined for at least 50 years. the current description, employing material amenable for use with modern neuroanatomical methods, shows that, for the most part, the elephant diencephalon and brainstem are what could be considered typically mammalian, with subtle differences in proportions and topology. the variations from th ...201324021932
conservation outside protected areas and the effect of human-dominated landscapes on stress hormones in savannah elephants.biodiversity conservation strategies are increasingly focused on regions outside national protected areas, where animals face numerous anthropogenic threats and must coexist with human settlements, livestock, and agriculture. the effects of these potential threats are not always clear, but they could have profound implications for population viability. we used savannah elephants (loxodonta africana) as a case study to assess the physiological stress associated with living in a human-livestock-do ...201323692020
hyperprolactinemia is not associated with hyperestrogenism in noncycling african elephants (loxodonta africana).african elephants in us zoos are not reproducing at replacement levels. this is in part due to physiological problems, one of which is abnormal ovarian cyclicity that has been linked to increased prolactin secretion (hyperprolactinemia). a relationship between increased estrogen production (hyperestrogenism) and hyperprolactinemia has been found in other species. therefore, the objective of this study was to determine if elevated prolactin was associated with increased estrogen concentrations in ...201323623777
african elephants adjust speed in response to surface-water constraint on foraging during the dry-season.most organisms need to acquire various resources to survive and reproduce. individuals should adjust their behavior to make optimal use of the landscape and limit the costs of trade-offs emerging from the use of these resources. here we study how african elephants loxodonta africana travel to foraging places between regular visits to waterholes. elephant herds were tracked using gps collars during two consecutive dry seasons in hwange national park, zimbabwe. we segmented each individual movemen ...201323554989
enduring consequences of early experiences: 40 year effects on survival and success among african elephants (loxodonta africana).growth from conception to reproductive onset in african elephants (loxodonta africana) provides insights into phenotypic plasticity, individual adaptive plastic responses and facultative maternal investment. using growth for 867 and life histories for 2652 elephants over 40 years, we demonstrate that maternal inexperience plus drought in early life result in reduced growth rates for sons and higher mortality for both sexes. slow growth during early lactation was associated with smaller adult siz ...201323407501
unmanned aerial survey of elephants.the use of a uas (unmanned aircraft system) was tested to survey large mammals in the nazinga game ranch in the south of burkina faso. the gatewing ×100™ equipped with a ricoh gr iii camera was used to test animal reaction as the uas passed, and visibility on the images. no reaction was recorded as the uas passed at a height of 100 m. observations, made on a set of more than 7000 images, revealed that only elephants (loxodonta africana) were easily visible while medium and small sized mammals we ...201323405088
quantifying past and present connectivity illuminates a rapidly changing landscape for the african elephant.there is widespread concern about impacts of land-use change on connectivity among animal and plant populations, but those impacts are difficult to quantify. moreover, lack of knowledge regarding ecosystems before fragmentation may obscure appropriate conservation targets. we use occurrence and population genetic data to contrast connectivity for a long-lived mega-herbivore over historical and contemporary time frames. we test whether (i) historical gene flow is predicted by persistent landscape ...201323398457
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 populati ...201327293609
the release of a captive-raised female african elephant (loxodonta africana) in the okavango delta, botswana.wild female elephants live in close-knit matrilineal groups and housing captive elephants in artificial social groupings can cause significant welfare issues for individuals not accepted by other group members. we document the release of a captive-raised female elephant used in the safari industry because of welfare and management problems. she was fitted with a satellite collar, and spatial and behavioural data were collected over a 17-month period to quantify her interactions with the wild pop ...201326487408
using diel movement behavior to infer foraging strategies related to ecological and social factors in elephants.adaptive movement behaviors allow individuals to respond to fluctuations in resource quality and distribution in order to maintain fitness. classically, studies of the interaction between ecological conditions and movement behavior have focused on such metrics as travel distance, velocity, home range size or patch occupancy time as the salient metrics of behavior. driven by the emergence of very regular high frequency data, more recently the importance of interpreting the autocorrelation structu ...201325709826
social learning in captive african elephants (loxodonta africana africana).social learning is a more efficient method of information acquisition and application than trial and error learning and is prevalent across a variety of animal taxa. social learning is assumed to be important for elephants, but evidence in support of that claim is mostly anecdotal. using a herd of six adult female african bush elephants (loxodonta africana africana) at the san diego zoo's safari park, we evaluated whether viewing a conspecific's interactions facilitated learning of a novel task. ...201323238635
development of the germinal ridge and ovary in the african elephant (loxodonta africana).the follicular reserve and its ontogeny in the elephant are of interest because elephants have the longest reproductive life of all land-based mammals. they also have the longest recorded pregnancy, which allows a protracted view of the series of significant events involved in the development of the embryonic and fetal gonads. the large elephant population of zimbabwe provided the opportunity to collect conceptuses from elephants culled for management reasons and hunted professionally. five embr ...201222991581
wild female african elephants (loxodonta africana) exhibit personality traits of leadership and social integration.animal personalities have been demonstrated for almost 200 species, with stable dimensions of responses (aggressive to fearful; shy to bold) across contexts and with a heritable basis to these traits. as a long-lived and highly social species, elephants (loxodonta africana) were expected to demonstrate complex dimensions to individual characteristics or personalities, which would be obvious to human observers and validated by behavioral observations. we used principal-components analysis of rati ...201222905995
enriching the captive elephant population genetic pool through artificial insemination with frozen-thawed semen collected in the wild.the first successful ai in an elephant was reported in 1998, using fresh semen. since then almost 40 calves have been produced through ai in both asian and african elephants worldwide. following these successes, with the objective of enriching the captive population with genetic material from the wild, we evaluated the possibility of using frozen-thawed semen collected from wild bulls for ai in captivity. semen, collected from a 36-yr-old wild african savanna elephant (loxodonta africana) in sou ...201222898009
growth and development of the ovary and small follicle pool from mid fetal life to pre-puberty in the african elephant (loxodonta africana).follicle numbers and developing ovarian morphology, particularly with reference to the presence of interstitial tissue, are intimately linked within the ovary of the african elephant during the period spanning mid-gestation to puberty. these have not been previously quantified in any studies. the collection of 7 sets of elephant fetal ovaries between 11.2 and 20.2 months of gestation, and 29 pairs of prepubertal calf ovaries between 2 months and 9 years of age during routine management off-takes ...201222824067
effects of daily management changes on behavioral patterns of a solitary female african elephant (loxodonta africana) in a zoo.this study investigated the effects of changes in daily management on behavior of a solitary female elephant in a zoo. the activity budget and space utilization of the subject and the management changes were recorded for 1 year after the conspecific male died. the observation days could be categorized into five clusters (c1-c5) by the characteristic behavioral pattern of each day. c1 had the highest percentage of resting of all clusters, and was observed after the loss of the conspecific and the ...201222776795
genetic identification of five strongyle nematode parasites in wild african elephants (loxodonta africana).african savannah elephants (loxodonta africana) are an ecologically and economically important species in many african habitats. however, despite the importance of elephants, research on their parasites is limited, especially in wild populations. currently, we lack genetic tools to identify elephant parasites. we present genetic markers from ribosomal dna (rdna) and mitochondrial dna (mtdna) to identify five elephant-specific nematode parasites in the family strongylidae: murshidia linstowi, mur ...201222740536
luteal maintenance of pregnancy in the african elephant (loxodonta africana).the ovaries of eight african elephant foetuses and their mothers between 2 and 22 months of gestation, and those of two cycling and two lactating elephants, were examined grossly, histologically and immunocytochemically, with emphasis on the development and regression of accessory corpora lutea (cl) of pregnancy and the steroidogenic capacities of the accessory cl and the foetal ovaries. the results supported recent findings that the accessory cl form as a result of luteinisation, with and witho ...201222457432
dilated ureters, renal dysplasia, and chronic renal failure in an african elephant (loxodonta africana).an ultrasonographic reproductive health examination of a 26-yr-old female african elephant (loxodonta africana) revealed bilateral ureteral wall thickening and dilatation. on ultrasonographic examination, the bladder and both ureters were normal near the trigone; however, the cranial-most aspect of each ureter was dilated and thickened for a length of 30-50 cm. the same month, elevated blood creatinine (3.0 mg/dl), and urine protein-creatinine ratio (4.0) were observed. chronic renal failure was ...201222448523
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 ...201222444560
stable isotope series from elephant ivory reveal lifetime histories of a true dietary generalist.longitudinal studies have revealed how variation in resource use within consumer populations can impact their dynamics and functional significance in communities. here, we investigate multi-decadal diet variations within individuals of a keystone megaherbivore species, the african elephant (loxodonta africana), using serial stable isotope analysis of tusks from the kruger national park, south africa. these records, representing the longest continuous diet histories documented for any extant spec ...201222337695
skeletal development in the african elephant and ossification timing in placental mammals.we provide here unique data on elephant skeletal ontogeny. we focus on the sequence of cranial and post-cranial ossification events during growth in the african elephant (loxodonta africana). previous analyses on ossification sequences in mammals have focused on monotremes, marsupials, boreoeutherian and xenarthran placentals. here, we add data on ossification sequences in an afrotherian. we use two different methods to quantify sequence heterochrony: the sequence method and event-paring/parsimo ...201222298853
quantitative analysis of neocortical gyrencephaly in african elephants (loxodonta africana) and six species of cetaceans: comparison with other mammals.this study provides quantitative data on the extent of gyrencephaly in the large-brained african elephant and several species of cetaceans (from smaller to larger brained) in comparison with other mammals. across three mammalian orders (primates, carnivores, and artiodactyls), the species with the larger brains are more gyrencephalic with each order, exhibiting a specific negative allometry. the african elephant, with a 5-kg brain, has a gyrencephalic index (gi) of 3.89, which, though highly gyr ...201222237903
how immunocontraception can contribute to elephant management in small, enclosed reserves: munyawana population as a case study.immunocontraception has been widely used as a management tool to reduce population growth in captive as well as wild populations of various fauna. we model the use of an individual-based rotational immunocontraception plan on a wild elephant, loxodonta africana, population and quantify the social and reproductive advantages of this method of implementation using adaptive management. the use of immunocontraception on an individual, rotational basis stretches the inter-calving interval for each in ...201122174758
the distribution of small preantral follicles within the ovaries of prepubertal african elephants (loxodonta africana).data on the distribution of primordial (single layer of squamous granulosa cells), early primary (some granulosa cells cuboidal) and primary (all granulosa cells cuboidal) follicles, grouped together as small follicles (sf) within the ovary of the elephant is lacking, yet such information is necessary to be able to estimate accurately the total numbers of small follicles in the ovaries of elephant throughout their lifespan.201122074896
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 add ...201122028925
estimating daily walking distance of captive african elephants using an accelerometer.two central concerns for elephant husbandry and management are whether zoological enclosures are appropriately sized and the degree to which naturalistic exercise and activity are observed in such enclosures. in order to address these issues, accurate data on the daily walking distance of elephants both in situ and ex situ are necessary. we used an accelerometer, a pedometer that measures step count and activity level, to estimate walking distance in african elephants (loxodonta africana) at the ...201121971913
vocal cues indicate level of arousal in infant african elephant roars.arousal-based physiological changes influence acoustic features of vocalizations in mammals. in particular, nonlinear phenomena are thought to convey information about the caller's arousal state. this hypothesis was tested in the infant african elephant (loxodonta africana) roar, a call type produced in situations of arousal and distress. ninety-two percent of roars exhibited nonlinear phenomena, with chaos being the most common type. acoustic irregularities were strongly associated with elevate ...201121895107
the spatial structure of hunter access determines the local abundance of forest elephants (loxodonta africana cyclotis).in many previously remote regions in the world, increasing and often unregulated access is leading to dramatic increases in hunting pressure and declines in the densities of prey species, sometimes to the point of local extinction. not surprisingly, numerous studies have found a correlation between the distance to the closest access point and prey densities. here we hypothesized that, for many wide-ranging species, local abundances are reduced by hunting associated with multiple access points as ...201121774431
reconciling apparent conflicts between mitochondrial and nuclear phylogenies in african elephants.conservation strategies for african elephants would be advanced by resolution of conflicting claims that they comprise one, two, three or four taxonomic groups, and by development of genetic markers that establish more incisively the provenance of confiscated ivory. we addressed these related issues by genotyping 555 elephants from across africa with microsatellite markers, developing a method to identify those loci most effective at geographic assignment of elephants (or their ivory), and condu ...201121701575
landscape nutrition: seeing the forest instead of the trees.recent theories suggest that herbivores forage across many scales and that foraging decisions are driven by the distribution of nitrogen. however, experimental tests of these predictions across large landscapes are rare and difficult. pretorius et al. (2011) present an elegant experimental design to test how patch size, local nutrient density and total nutrient load are detected by foraging african elephants (loxodonta africana) in the colophospermum mopane shrub veld in south africa. this exper ...201121644973
neocortical neuron morphology in afrotheria: comparing the rock hyrax with the african elephant.the mammalian neocortex contains a great variety of neuronal types. in particular, recent studies have shown substantial morphological diversity among spiny projecting neurons in species that diverged close to the base of the mammalian radiation (e.g., monotremes, afrotherians, and xenarthrans). here, we used a golgi technique to examine different neuronal morphologies in an afrotherian species, the rock hyrax (procavia capensis), and provide a comparison with the related african elephant (loxod ...201121534991
organisation and chemical neuroanatomy of the african elephant (loxodonta africana) olfactory bulb.the olfactory system of mammals can be divided into a main and accessory olfactory system with initial processing for each system occurring in the olfactory bulb. the main and accessory olfactory bulbs have similar structural features, even though they appear to be functionally independent. in mammals the main olfactory bulb (mob) is also one of two established sites of lifelong generation of new cells. the present study describes the histological and immunohistochemical neuroanatomy of the olfa ...201121479949
the effects of herbivory by a mega- and mesoherbivore on tree recruitment in sand forest, south africa.herbivory by megaherbivores on woody vegetation in general is well documented; however studies focusing on the individual browsing effects of both mega- and mesoherbivore species on recruitment are scarce. we determined these effects for elephant loxodonta africana and nyala tragelaphus angasii in the critically endangered sand forest, which is restricted to east southern africa, and is conserved mainly in small reserves with high herbivore densities. replicated experimental treatments (400 m(2) ...201121445345
measuring positive and negative affect in the voiced sounds of african elephants (loxodonta africana).as in other mammals, there is evidence that the african elephant voice reflects affect intensity, but it is less clear if positive and negative affective states are differentially reflected in the voice. an acoustic comparison was made between african elephant "rumble" vocalizations produced in negative social contexts (dominance interactions), neutral social contexts (minimal social activity), and positive social contexts (affiliative interactions) by four adult females housed at disney's anima ...201121361461
early primary--rather than primordial follicles constitute the main follicular reserve in the african elephant (loxodonta africana).information on the ovarian follicle reserve in the african elephant (loxodonta africana) is lacking. this study set out to determine the ratios of early preantral follicles and their relative dimensions in the ovaries of 16 african elephant aged 10-34 years. the ovaries were sectioned histologically. follicles were counted and classified according to expansion of the pre-granulosa cells. early primary follicles were the most common (75.8%±11.8%), followed by true primary follicles (23.8%±11.8%), ...201121126835
landscape-scale feeding patterns of african elephant inferred from carbon isotope analysis of feces.the african elephant (loxodonta africana) is a large-bodied, generalist herbivore that eats both browse and grass. the proportions of browse and grass consumed are largely expected to reflect the relative availability of these resources. we investigated variations in browse (c(3) biomass) and grass (c(4)) intake of the african elephant across seasons and habitats by stable carbon isotope analysis of elephant feces collected from kruger national park, south africa. the results reflect a shift in ...201121072541
a surge-like increase in luteinizing hormone preceding musth in a captive bull african elephant (loxodonta africana).this study was conducted to determine the correlation between reproductive hormones and musth in a male african elephant. changes in circulating luteinizing hormone (lh), follicle stimulating hormone (fsh), testosterone and immunoreactive (ir-) inhibin and the degree of musth were evaluated for 4 years. lh increased 4 weeks before musth began. the highest concentrations of testosterone and ir-inhibin were observed from april to october. there were positive correlations among testosterone, ir-inh ...201121041991
lectin histochemistry of the temporal gland of the african elephant (loxodonta africana).the study demonstrates the free sugar spectrum of the secretion of the tubuloaveolar temporal gland of the african elephant (loxodonta africana), using lectin histochemistry. in the elephant, the spectrum contained, besides strongly varying amounts of α-d-mannose, very remarkable reactions for α-d-galactose and to a certain extent also for α-d-n-acetyl-galactosamine or a/ß-d-n-acetylglucosamine. this is in contrast to the free sugar spectrum of the secretion of the mammalian apocrine tubular ski ...201020886437
a framework for understanding the architecture of collective movements using pairwise analyses of animal movement data.the study of collective or group-level movement patterns can provide insight regarding the socio-ecological interface, the evolution of self-organization and mechanisms of inter-individual information exchange. the suite of drivers influencing coordinated movement trajectories occur across scales, resulting from regular annual, seasonal and circadian stimuli and irregular intra- or interspecific interactions and environmental encounters acting on individuals. here, we promote a conceptual framew ...201120826473
vaccination against gnrh may suppress aggressive behaviour and musth in african elephant (loxodonta africana) bulls--a pilot study.aggressive behaviour and musth are constant problems in captive and sometimes in free-ranging african elephant bulls. aggressive bulls are difficult and musth bulls almost impossible to manage without severely restricting their movement either by leg-chaining or using tranquillisers. this study investigated the relationship between faecal androgen metabolites (fam) and faecal cortisol metabolites (fcm) concentrations and aggressive behaviour and tested a gnrh vaccine as a means of down-regulatin ...201020649148
visual acuity and heterogeneities of retinal ganglion cell densities and the tapetum lucidum of the african elephant (loxodonta africana).the eyes of three adult male african elephants were examined, the retinas were whole-mounted, stained and analyzed to determine visual acuity. a range of small to large ganglion cell types were observed across the retinas. we observed three regions of high ganglion cell density, one in the upper temporal quadrant, a visual or horizontal streak and a smaller region at the nasal end of the horizontal streak. the peak density of ganglion cells observed was 5,280/mm(2), and our calculations indicate ...201020587993
why do african elephants (loxodonta africana) simulate oestrus? an analysis of longitudinal data.female african elephants signal oestrus via chemicals in their urine, but they also exhibit characteristic changes to their posture, gait and behaviour when sexually receptive. free-ranging females visually signal receptivity by holding their heads and tails high, walking with an exaggerated gait, and displaying increased tactile behaviour towards males. parous females occasionally exhibit these visual signals at times when they are thought not to be cycling and without attracting interest from ...201020383331
endocrine correlates of musth and the impact of ecological and social factors in free-ranging african elephants (loxodonta africana).sexual activity in mature male african elephants is predominantly associated with the occurrence of musth, a state or condition which refers to a set of physical, physiological and behavioral characteristics, including an elevation in androgen levels. although musth appears to be energetically costly, the degree to which it is associated with changes in adrenal endocrine function (e.g., glucocorticoid output) is still unclear. to investigate the possible effect of musth on adrenocortical functio ...201020188104
density as an explanatory variable of movements and calf survival in savanna elephants across southern africa.1. southern africa's 'elephant problem' is often attributed to an overabundance of elephants (loxodonta africana) in conservation areas. paradoxically, the african elephant is listed as 'vulnerable' (iucn redlist) despite occupying a large geographical range and numbering about 600 000. how densities influence elephant populations is therefore important for conservation management decisions, particularly because a move towards non-equilibrium management of savannas implies a need for elephant po ...201020180876
influence of dominance status on adrenal activity and ovarian cyclicity status in captive african elephants.the north american african (loxodonta africana) elephant population is not self-sustaining, in part because of a high rate of abnormal ovarian activity. about 12% of adult females exhibit irregular cycles and 31% do not cycle at all. our earlier work revealed a relationship between dominance status and ovarian acyclicity, with dominant females being more likely to not cycle normally. one theory is that dominant females may be expending more energy to maintaining peace within the captive herd tha ...201320033989
physical mapping of the elephant x chromosome: conservation of gene order over 105 million years.all therian mammals (eutherians and marsupials) have an xx female/xy male sex chromosome system or some variant of it. the x and y evolved from a homologous pair of autosomes over the 166 million years since therian mammals diverged from monotremes. comparing the sex chromosomes of eutherians and marsupials defined an ancient x conserved region that is shared between species of these mammalian clades. however, the eutherian x (and the y) was augmented by a recent addition (xar) that is autosomal ...200919789986
serum concentrations of calcium, phosphorus, and 25-hydroxyvitamin d in captive african elephants (loxodonta africana).seventy-two serum samples were collected from 14 healthy african elephants (loxodonta africana), including three calves, to test for 25-hydroxyvitamin d [25(oh)d] as well as for performing biochemical panels. samples were collected between july 1997 and january 2008 to establish normal 25(oh)d values for the species and to examine the relationship of season and time on these values. although the number of samples from the calves was small (n = 7), there was no statistically significant differenc ...200919569477
the expression of affect in african elephant (loxodonta africana) rumble vocalizations.affective states are thought to be expressed in the mammalian voice, but such investigations are most common in primates. source and filter features of rumbles were analyzed from 6 adult female african elephants (loxodonta africana) at disney's animal kingdom. rumbles produced during periods of minimal social interaction ("low affect") were compared to those produced during dominance interactions ("high affect"). low-ranking females produced rumbles with increased and more variable fundamental f ...200919450029
vocal communication in african elephants (loxodonta africana).research on vocal communication in african elephants has increased in recent years, both in the wild and in captivity, providing an opportunity to present a comprehensive review of research related to their vocal behavior. current data indicate that the vocal repertoire consists of perhaps nine acoustically distinct call types, "rumbles" being the most common and acoustically variable. large vocal production anatomy is responsible for the low-frequency nature of rumbles, with fundamental frequen ...201119434672
gps assessment of the use of exhibit space and resources by african elephants (loxodonta africana).in public discussions of animal rights and welfare, we as members and proponents of zoological institutions often face significant challenges addressing the concerns of our detractors due to an unfortunate deficiency in systematically collected and published data on the animals in our collections. in the case of elephants, there has been a paucity of information describing their use of space within captive environments. here, using collar-mounted gps recording devices, we documented the use of e ...201119418496
chronology of the extant african elephant species and case study of the species identification of the small african elephant with the molecular phylogenetic method.despite vigorous genetic studies of african elephants (loxodonta africana and l. cyclotis) during the last decade, their evolutionary history is still obscure. phylogenetic studies and coalescence time estimation using longer nucleotide sequence data from denser samplings are necessary to better understand the natural history of african elephants. further, species identification among african elephants is sometimes very difficult using only the external morphological characteristics. this is a s ...200919393173
the pharmacokinetics of orally administered ivermectin in african elephants (loxodonta africana): implications for parasite elimination.loxodonta africana are susceptible to a wide variety of parasites that are often treated with the broad spectrum antiparasitic ivermectin (ivm) based on empirical knowledge. the objectives of this study were to 1) measure plasma ivm levels following administration of 0.1 mg/kg ivm p.o., 2) compare plasma ivm levels following administration with regular versus restricted feed rations, 3) measure ivm excretion in feces, and 4) use these findings to generate dosing recommendations for this species. ...200919368248
plasma preparation and storage for african elephants (loxodonta africana).the use of plasma as a life-saving tool for neonatal african elephants (loxodonta africana) that failed passive transfer of immunoglobulins is proposed. the methodology of blood sampling, plasma extraction, and plasma storage is described. values for cellular component sedimentation and biochemical parameters of extracted plasma that was collected from 2 female elephants is presented. the proposal for a central plasma bank for elephants in european zoos is suggested.200919368242
gps determination of walking rates in captive african elephants (loxodonta africana).the movements of elephants in captivity have been an issue of concern for animal welfare activists and zoological professionals alike in recent years. in order to fully understand how movement rates reflect animal welfare, we must first determine the exact distances these animals move in the captive environment. we outfitted seven adult female african elephants (loxodonta africana) at disney's animal kingdom with collar-mounted global positioning recording systems to document their movement rate ...200919358315
social factors influence ovarian acyclicity in captive african elephants (loxodonta africana).nearly one-third of reproductive age african elephants in north america that are hormonally monitored fail to exhibit estrous cycle activity, which exacerbates the nonsustainability of the captive population. three surveys were distributed to facilities housing female african elephants to determine how social and environmental variables contribute to cyclicity problems. forty-six facilities returned all three surveys providing information on 90% of the ssp population and 106 elephants (64 cyclin ...200919358314
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 ...200919168095
the relationship between social behaviour and habitat familiarity in african elephants (loxodonta africana).social associations with conspecifics can expedite animals' acclimation to novel environments. however, the benefits gained from sociality may change as the habitat becomes familiar. furthermore, the particular individuals with whom animals associate upon arrival at a new place, familiar conspecifics or knowledgeable unfamiliar residents, may influence the type of information they acquire about their new home. to examine animals' social dynamics in novel habitats, we studied the social behaviour ...200919129113
roadless wilderness area determines forest elephant movements in the congo basin.a dramatic expansion of road building is underway in the congo basin fuelled by private enterprise, international aid, and government aspirations. among the great wilderness areas on earth, the congo basin is outstanding for its high biodiversity, particularly mobile megafauna including forest elephants (loxodonta africana cyclotis). the abundance of many mammal species in the basin increases with distance from roads due to hunting pressure, but the impacts of road proliferation on the movements ...200818958284
estimating exposed pulp lengths of tusks in the african elephant (loxodonta africana africana).captive and wild african elephants frequently suffer tusk fractures. several institutions shorten the tusks of captive elephants to reduce fractures and injury as a result of behaviour within enclosures. fracturing or coronal amputations that expose pulp lead to pain for the elephant. estimating coronal pulp lengths may thus help to minimise the risk of pulp exposure during amputations. we aimed to determine the length of the pulp beyond the lip margin from an external tusk characteristic. tusks ...200818678188
cyto-nuclear genomic dissociation and the african elephant species question.studies of skull morphology and of nuclear dna have strongly concluded that african elephants comprise two species. nonetheless, debruyne (2005) has suggested a single-species model for loxodonta based on the polyphyly of a single genetic locus, mitochondrial dna (mtdna). discordant patterns between mitochondrial and nuclear dna markers were subsequently reported in some african savanna elephant populations, further supporting a two-species model, and prompting us to re-examine here the geograph ...200718591997
population genetic structure of savannah elephants in kenya: conservation and management implications.we investigated population genetic structure and regional differentiation among african savannah elephants in kenya using mitochondrial and microsatellite markers. we observed mitochondrial dna (mtdna) nucleotide diversity of 1.68% and microsatellite variation in terms of average number of alleles, expected and observed heterozygosities in the total study population of 10.20, 0.75, and 0.69, respectively. hierarchical analysis of molecular variance of mtdna variation revealed significant differe ...200818477589
african elephants have expectations about the locations of out-of-sight family members.monitoring the location of conspecifics may be important to social mammals. here, we use an expectancy-violation paradigm to test the ability of african elephants (loxodonta africana) to keep track of their social companions from olfactory cues. we presented elephants with samples of earth mixed with urine from female conspecifics that were either kin or unrelated to them, and either unexpected or highly predictable at that location. from behavioural measurements of the elephants' reactions, we ...200818055407
articular cartilage in the knee joint of the african elephant, loxodonta africana, blumenbach 1797.knee joints of one adult and three juvenile african elephants were dissected. the specific features of the articular cartilage with particular reference to matrix components were studied by light and electron microscopy and immunohistochemistry. the elephant knee joint cartilage contains an unusually low concentration of proteoglycans resulting in rather eosinophilic staining properties of the matrix. the very thick collagen fibers of the cartilage possibly represent collagen i. except for the d ...200817972268
tusklessness and tusk fractures in free-ranging african savanna elephants (loxodonta africana).the incidence of tusklessness varies between free-ranging african elephant populations. sex-linked genetic drift predicts 2 outcomes--the condition becomes fixed and sex-specific incidences diverge when populations are small and/or heavily poached. by contrast, for large and intact populations, tusklessness diminishes and there is no variation between sexes. we tested these predictions by comparing sex-specific incidences between 15 populations: a small one with a skewed founder effect towards t ...200717941599
body temperature daily rhythm adaptations in african savanna elephants (loxodonta africana).the savanna elephant is the largest extant mammal and often inhabits hot and arid environments. due to their large size, it might be expected that elephants have particular physiological adaptations, such as adjustments to the rhythms of their core body temperature (t(b)) to deal with environmental challenges. this study describes for the first time the t(b) daily rhythms in savanna elephants. our results showed that elephants had lower mean t(b) values (36.2 +/- 0.49 degrees c) than smaller ung ...200717553537
call repertoire of infant african elephants: first insights into the early vocal ontogeny.african savannah elephants (loxodonta africana) have a complex acoustic communication system, but very little is known about their vocal ontogeny. a first approach in ontogenetic studies is to define the call repertoire of specific age groups. twelve hundred calls of 11 infant elephants from neonatal to 18 months of age recorded at the vienna zoo in austria and at the daphne sheldrick's orphanage at the nairobi national park, kenya were analyzed. six call types were structurally distinguished: t ...200717552738
standing sedation in african elephants (loxodonta africana) using detomidine-butorphanol combinations.standing sedation was provided for 14 clinical procedures in three african elephants (loxodonta africana) managed by combined protected and modified-protected contact and trained through operant conditioning. an initial hand-injection of detomidine hydrochloride and butorphanol tartrate at a ratio of 1:1 on a microg:microg basis was administered intramuscularly, with a dosage range of 50-70 mg (12.9-19.7 microg/kg) for each drug. the initial injection resulted in adequate sedation for initiation ...200517323566
pheochromocytoma in an aged female african elephant (loxodonta africana).a 43 yr-old female african elephant (loxodonta africana) collapsed acutely and died. necropsy revealed an enlarged right adrenal medulla. histologic appearance was typical of pheochromocytoma. special stains and electron microscopy demonstrated chromaffin granules, suggesting that the tumor was derived from catecholamine secreting cells of the adrenal medulla, and may have been functionally secretory. serum levels of both norepinephrine and epinephrine were elevated at time of death, supporting ...200517312735
the role of foraging behaviour in the sexual segregation of the african elephant.elephants (loxodonta africana) exhibit pronounced sexual dimorphism, and in this study we test the prediction that the differences in body size and sociality are significant enough to drive divergent foraging strategies and ultimately sexual segregation. body size influences the foraging behaviour of herbivores through the differential scaling coefficients of metabolism and gut size, with larger bodied individuals being able to tolerate greater quantities of low-quality, fibrous vegetation, whil ...200616927101
ovulation, pregnancy, placentation and husbandry in the african elephant (loxodonta africana).the african elephant reproduces so efficiently in the wild that overpopulation is now a serious problem in some game parks in zimbabwe, botswana and south africa. the female reaches puberty between 10 and 12 years of age in the wild and, when in captivity, shows oestrous cycles of 14-15 weeks duration. she readily conceives a singleton in the wild yet her uterus has the capacity for twins. she shows a gestation length of 22 months and, in the wild, shows a population density and feed dependent i ...200616627297
the ties that bind: genetic relatedness predicts the fission and fusion of social groups in wild african elephants.many social animals live in stable groups. in contrast, african savannah elephants (loxodonta africana) live in unusually fluid, fission-fusion societies. that is, 'core' social groups are composed of predictable sets of individuals; however, over the course of hours or days, these groups may temporarily divide and reunite, or they may fuse with other social groups to form much larger social units. here, we test the hypothesis that genetic relatedness predicts patterns of group fission and fusio ...200616537121
stable isotopes in elephant hair document migration patterns and diet changes.we use chronologies of stable isotopes measured from elephant (loxodonta africana) hair to determine migration patterns and seasonal diet changes in elephants in and near samburu national reserve in northern kenya. stable carbon isotopes record diet changes, principally enabling differentiation between browse and tropical grasses, which use the c3 and c4 photosynthetic pathways, respectively; stable nitrogen isotopes record regional patterns related to aridity, offering insight into localized ra ...200616407164
the fluidity of blood in african elephants (loxodonta africana).the large cellular volume of erythrocytes and the increased plasma concentration of proteins in elephants are factors which potentially affect blood rheology adversely. to verify blood rheology, routine hemorheologic variables were analyzed in four african elephants (loxodonta africana), housed in the zoo of vienna. whole blood viscosity at three different shear rates (wbv at low shear rate: wbv 0.7 s(-1) and wbv 2.4 s(-1); wbv at high shear rate: wbv 94 s(-1) done by ls30, contraves) and erythr ...200516317241
placentation in the african elephant, loxodonta africana. iv. growth and function of the fetal gonads.the gonads, both ovaries and testes, of 44 elephant fetuses weighing 0.09-112 kg (6.1-21.3 months gestation) were examined grossly and histologically. as in equids, elephant fetal gonads undergo a phase of marked growth and enlargement during the second half of gestation, which is more pronounced in ovaries than testes due to growth and antrum formation of numerous follicles in the former. stromal cells undergo hypertrophy and transformation to form zones of interstitial cells that are associate ...200516264100
[contribution of molecular phylogeny and morphometrics to the systematics of african elephants].african elephants are conventionally classified as a single species: loxodonta africana (blumenbach 1797). however, the discovery in 1900 of a smaller form of the african elephant, spread throughout the equatorial belt of this land, has given rise to a debate over the relevance of a second species of elephant in africa. the twentieth century has not provided any definite answer to this question. actually, recent molecular analyses have sustained this issue by advocating either a division of fore ...200415969338
physical, physiological, and behavioral correlates of musth in captive african elephants (loxodonta africana).although musth in male african elephants (loxodonta africana) is known to be associated with increased aggressiveness, urine dribbling (ud), temporal gland secretion (tgs), and elevated androgens, the temporal relationship between these changes has not been examined. here, we describe the pattern of musth-related characteristics in 14 captive elephant bulls by combining long-term observations of physical and behavioral changes with physiological data on testicular and adrenal function. the lengt ...200615957105
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