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African Elephants (african + elephant)

Distribution by Scientific Domains

Life Sciences	88%
Medical Sciences	7%

Distribution within Life Sciences

Ecology & Organismal Biology	38%
Evolution	21%
Conservation Science	12%

Terms modified by African Elephants

african elephant population

Selected Abstracts

Qualitative Comparison of the Cranio-Dental Osteology of the Extant Elephants, Elephas Maximus (Asian Elephant) and Loxodonta africana (African Elephant)

THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 1 2010
Nancy E. Todd
Abstract Few osteological descriptions of the extant elephants and no detailed morphological comparison of the two genera, Elephas and Loxodonta, have been done in recent years. In this study, 786 specimens of extant elephants (crania, mandibles, and molars) were examined for characters unique to each species. Differences between sexes in each species were described, as well as differences between subspecies of each species. Striking differences in morphology were noted between sexes of both elephants and between subspecies, which may complement current genetic studies, the focus of which is to determine division at the subspecies or species level, particularly differences between the savanna elephant (Loxodonta africana africana) and the forest elephant (Loxodonta africana cyclotis). In addition, examination of the two living elephants provides an excellent dataset for identifying phylogenetic characters for use in examining evolutionary relationships within and between fossil lineages of elephantids. Anat Rec, 2010. © 2009 Wiley-Liss, Inc. [source]

Noninvasive Stress and Reproductive Measures of Social and Ecological Pressures in Free-Ranging African Elephants

CONSERVATION BIOLOGY, Issue 4 2001
C. A. H. Foley
This, coupled with political pressures to delist the elephant, has created a need for noninvasive physiological measures that can quantify the long-term effects of past mortality patterns of this long-lived species. We collected fresh fecal samples from 16 female elephants in three different groups over 23 months at Tarangire National Park, Tanzania, and analyzed them for fecal progesterone and cortisol metabolites. Social and ecological measures were collected concurrently. Fecal progesterone metabolite measures corresponded significantly with stage of gestation, and appear to be able to confirm pregnancy in female elephants from as early as 3 months of gestation. We found that progesterone metabolite concentrations were significantly lower during the dry season than during the wet season after controlling for stage of gestation. Fecal cortisol metabolite concentrations showed the opposite seasonal pattern, being significantly higher in the dry season and inversely correlated with rainfall across seasons. Fecal cortisol metabolite concentrations also increased with group size and were correlated positively with dominance rank in the largest group. Our results suggest that measures of progesterone and cortisol metabolites in feces provide indices of reproductive function and physiological stress that can quantify both natural and human disturbances in African elephants. These measures are ideally suited for monitoring the long-term effects of social disruption from poaching and a variety of other management concerns. Resumen: Debido a la cacería furtiva, la población de elefante africano ( Loxodonta africana) declinó en un 60%, principalmente adultos, entre 1979 y 1988. Esto, aunado a presiones políticas para eliminar al elefante de las listas de especies en peligro, ha creado la necesidad de medidas fisiológicas no invasivas que puedan cuantificar efectos a largo plazo de patrones de mortalidad en el pasado de esta especie longeva. Recolectamos muestras fecales de 16 elefantes hembras en tres grupos diferentes en el Parque Nacional Tarangire, Tanzania a lo largo de 23 meses, y las analizamos para detectar metabolitos de progesterona fecal y de cortisol. Al mismo tiempo se recolectaron medidas sociales y ecológicas. Las medidas de metabolitos de progesterona fecal correspondieron significativamente con la etapa de gestación, y parecen permitir la confirmación de preñez en elefantes hembras tan temprano como a los tres meses de gestación. Las concentraciones de metabolitos de progesterona fueron significativamente menores durante la época de sequía que en la de lluvias después de controlar para la etapa de gestación. Las concentraciones de metabolitos de cortisol fecal mostraron un patrón estacional opuesto, siendo significativamente más altas en la época de sequía e inversamente correlacionados con la precipitación en todas las estaciones. Las concentraciones de metabolitos de cortisol fecal también incrementaron con el tamaño del grupo y se correlacionaron positivamente con el rango de dominancia en el grupo más grande. Nuestros resultados sugieren que las medidas de metabolitos de progesterona y cortisol en las heces proporcionan índices de la función reproductiva y del estrés fisiológico que puede cuantificar perturbaciones, tanto naturales como humanas, en elefantes africanos. Estas medidas son idealmente adecuadas para monitorear efectos a largo plazo de la disrupción social por la cacería furtiva y así como una variedad de aspectos del manejo. [source]

The Elephant's Foot: Prevention and Care of Foot Conditions in Captive Asian and African Elephants

AUSTRALIAN VETERINARY JOURNAL, Issue 12 2001
M Lynch
No abstract is available for this article. [source]

Contemporary and historical impacts of megaherbivores on the population structure of tree euphorbias in South African subtropical thicket

AFRICAN JOURNAL OF ECOLOGY, Issue 1 2010
Richard M. Cowling
Abstract African elephant and black rhinoceros , both megaherbivores , impact negatively on the abundance of succulent plants, including tree succulents, in South Africa's subtropical thicket. We sampled 35 sites in subtropical thicket to assess historical and contemporary impacts of African elephant and black rhinoceros on the population structure of three species of succulent tree euphorbia. Population age structures were highly variable and showed no species-specific effects. Almost half the sites had growing populations dominated by young individuals. Sites having contemporary impacts had significantly fewer individuals in the 30,75 years age range, but this effect declined with increasing terrain slope. Eighty-one percent of sites assumed to have been impacted by megaherbivores historically had individuals that predated rhino and elephant extirpation in the region. This and other population age structure data indicate that megaherbivores and tree euphorbias coexisted historically on terrain of low relief. However, in areas not subject to contemporary impacts, euphorbia populations are likely to be much higher now than historically, owing to population relaxation after the extirpation of megaherbivores in the mid 1800s. Given the sensitivity of tree euphorbias to megaherbivore impacts, managers should consider monitoring the population structure of these species in order to identify thresholds of potential concern regarding megaherbivore impacts. Résumé L'éléphant et le rhinocéros africains , deux méga-herbivores , ont un impact négatif sur l'abondance de plantes succulentes, y compris des arbres succulents, dans les fourrés subtropicaux d'Afrique du Sud. Nous avons prélevé des échantillons dans 35 fourrés subtropicaux afin d'évaluer les impacts anciens et actuels des éléphants et des rhinos noirs africains sur la structure de la population de trois espèces d'euphorbes arborescentes succulentes. Les structures d'âges des populations étaient très variables et ne présentaient aucun effet spécifique des espèces. Près de la moitié des sites contenaient des populations en croissance dominées par de jeunes individus. Les sites qui présentaient des impacts actuels comptaient significativement moins d'individus de la classe d'âge comprise entre 30 et 75 ans, mais cet effet diminuait lorsque la pente du terrain s'accentuait. Quatre-vingt-un pour cent des sites supposés avoir subi jadis l'impact des méga-herbivores contenaient des individus qui dataient d'avant l'élimination des rhinos et des éléphants. Ceci, tout comme d'autres données sur la structure d'âge des populations, indique que les méga-herbivores et les euphorbes arborescentes ont longtemps coexisté sur les terrains de faible relief. Cependant, dans les zones qui ne subissent aucun impact actuel, les populations d'euphorbes sont susceptibles d'être beaucoup plus hautes aujourd'hui que jadis, en raison de la libération induite par l'élimination des méga-herbivores au milieu des années 1800. Etant donné la sensibilité des euphorbes arborescentes face aux impacts des méga-herbivores, les gestionnaires devraient envisager le suivi continu de la structure de la population de ces espèces afin de déterminer les seuils d'alerte potentiels en ce qui concerne les impacts des méga-herbivores. [source]

Modelling the effectiveness of contraception for controlling introduced populations of elephant in South Africa

AFRICAN JOURNAL OF ECOLOGY, Issue 4 2009
Robin L. Mackey
Abstract Re-introduced African elephant (Loxodonta africana Blumenbach) populations are growing at very high rates in many of southern Africa's reserves, have attained densities higher than previously thought possible and may be exhibiting irruptive growth. Active management of such populations is necessary to prevent the potentially negative effects on habitat and biodiversity that are associated with elephant overpopulation. One potentially feasible method of elephant management is immunocontraception, but very little is known about the long-term effectiveness of this method. Using demographic data from three South African elephant populations, we made model projections of the effects of contraception on population growth rates to determine whether contraception may be a feasible management tool for elephant. In comparison with noncontracepted populations, realistic reductions in population growth rate after 20 years of contraception were projected to be up to c. 64%, with 50% being a very feasible target. Through its ability to reduce population growth rates, immunocontraception should be an effective tool for preventing or minimizing irruption in elephants and, perhaps, other introduced ungulate species. Résumé Le taux de croissance des populations réintroduites d'éléphants d'Afrique (Loxodonta africana Blumenbach) est très élevé dans les réserves d'Afrique australe; elles ont atteint des densités plus élevées qu'on ne l'avait cru possible et elles pourraient présenter une croissance irruptive. La gestion active de telles populations est nécessaire pour empêcher les effets potentiellement négatifs liés à une surpopulation d'éléphants. Une méthode éventuellement possible pour la gestion des éléphants est l'immuno-contraception, mais on sait très peu de choses sur l'efficacitéà long terme de cette méthode. En utilisant les données démographiques portant sur trois populations d'éléphants d'Afrique du Sud, nous avons modélisé des projections des effets de la contraception sur le taux de croissance des populations pour déterminer si la contraception peut constituer un outil de gestion envisageable pour les éléphants. En comparaison avec les populations sans contraception, des projections réalistes de la réduction du taux de croissance de populations après 20 ans de contraception se chiffraient à environ 64%,50% représentant un objectif tout à fait réaliste. Par sa capacité de réduire le taux de croissance de la population, l'immuno-contraception devrait être un outil efficace pour empêcher ou pour réduire au minimum l'irruption des éléphants et, peut-être, celle d'autres espèces ongulés introduits. [source]

Elephant distribution around a volcanic shield dominated by a mosaic of forest and savanna (Marsabit, Kenya)

AFRICAN JOURNAL OF ECOLOGY, Issue 2 2009
Shadrack M. Ngene
Abstract We investigated the factors that influenced the distribution of the African elephant around a volcanic shield dominated by a mosaic of forest and savanna in northern Kenya. Data on elephant distribution were acquired from four female and five bull elephants, collared with satellite-linked geographical positioning system collars. Based on the eigenvalues (variances) of the correlation matrix, the six factors that contributed significantly to high total variances were distance from drinking water (24%), elevation (15%), shrubland (10%), forest (9%), distance from settlements (8%) and distance from minor roads (7%), contributing to 73% in the observed variation of the elephant distribution. The elephants were found at high forested elevations during the dry season but they moved to the lowlands characterized by shrubland during the wet season. Elevation acts as a proxy for the vegetation structure. The presence of elephants near permanent water points (13%) and seasonal rivers (11%) during the dry and wet seasons, respectively, demonstrates that water is the most important determinant of their distribution throughout the year. We conclude that the distribution of elephants in Marsabit Protected Area and its adjacent areas is influenced mainly by drinking water and vegetation structure. Résumé Nous avons étudié les facteurs qui influencent la distribution de l'éléphant africain autour d'un bouclier volcanique dominé par une mosaïque de forêt et de savane dans le nord du Kenya. Les données sur la distribution des éléphants furent acquises grâce à quatre femelles et cinq mâles équipés de colliers radio avec GPS par satellite. En se basant sur les valeurs propres (variances) de la matrice de corrélation, les six facteurs qui ont contribué significativement à de fortes variances totales étaient la distance par rapport à l'eau (24%), l'élévation (15%), la savane arbustive (10%), la forêt (9%), la distance par rapport à des installations (8%) et celle par rapport à des routes peu importantes (7%), qui contribuent donc ensemble à 73% de la variation observée dans la distribution de l'éléphant. Des éléphants se trouvaient sur de hautes élévations forestières pendant la saison sèche, mais ils se déplaçaient vers les terrains de basse altitude caractérisés par des broussailles pendant la saison des pluies. L'élévation sert de proxy à la structure de la végétation. La présence d'éléphants près des points d'eau permanents (13%) et des rivières saisonnières (11%) pendant la saison sèche et la saison des pluies respectivement montre que l'eau est le déterminant le plus important de leur distribution tout au long de l'année. Nous concluons que la distribution des éléphants dans la Marsabit Protected Area et dans les zones adjacentes est influencée principalement par la disponibilité de l'eau et la structure de la végétation. [source]

Renaut bodies in nerves of the trunk of the African elephant, Loxodonta africana

JOURNAL OF MORPHOLOGY, Issue 5 2007
Kirsti Witter
Abstract Renaut bodies are loosely textured, cell-sparse structures in the subperineurial space of peripheral nerves, frequently found at sites of nerve entrapment. The trunk of the elephant is a mobile, richly innervated organ, which serves for food gathering, object grasping and as a tactile organ. These functions of the trunk lead to distortion and mechanical compression of its nerves, which can therefore be expected to contain numerous Renaut bodies. Samples of the trunk wall of an adult African elephant (Loxodonta africana) were examined histologically using conventional staining methods, immunohistochemistry, and lectin histochemistry. Architecture of nerve plexuses and occurrence of Renaut bodies in the elephant trunk were compared with those in tissues surrounding the nasal vestibule of the pig. Prominent nerve plexuses were found in all layers of the elephant trunk. Almost all (81%) nerve profiles contained Renaut bodies, a basophilic, discrete subperineurial layer resembling cushions around the nerve core. In contrast, Renaut bodies were seen in only 15% of nerve profiles in the porcine nasal vestibule. Within Renaut bodies, fusiform fibroblasts and round, ruff-like cells were placed into a matrix of acidic glycosaminoglycans with delicate collagen and very few reticular fibers. The turgor of this matrix is thought to protect nerves against compression and shearing strain. Renaut bodies are readily stained with alcian blue (pH 2.5) favorably in combination with immunohistochemical markers of nerve fibers. They should be regarded as a physiological response to repeated mechanical insults and are distinct from pathological alterations. alterations. J. Morphol., 2007. © 2007 Wiley-Liss, Inc. [source]

Characterization of tetranucleotide microsatellite loci in the African Savannah Elephant (Loxodonta africana africana)

MOLECULAR ECOLOGY RESOURCES, Issue 2 2003
E. A. Archie
Abstract Most African elephant (Loxodonta africana africana) populations are isolated and thus threatened by a loss of genetic diversity. As a consequence, genetic analysis of African elephant populations will play an increasing role in their conservation, and microsatellite loci will be an important tool in these analyses. Previously published sets of polymorphic microsatellites developed for African elephants are all dinucleotide repeats, which are prone to typing error. Here, we characterize 11 tetranucleotide microsatellite loci in the African elephant. All loci were polymorphic in 32 faecal samples and two tissue samples from 33 individual African savannah elephants. [source]

Brain of the African elephant (Loxodonta africana): Neuroanatomy from magnetic resonance images

THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 1 2005
Atiya Y. Hakeem
Abstract We acquired magnetic resonance images of the brain of an adult African elephant, Loxodonta africana, in the axial and parasagittal planes and produced anatomically labeled images. We quantified the volume of the whole brain (3,886.7 cm3) and of the neocortical and cerebellar gray and white matter. The white matter-to-gray matter ratio in the elephant neocortex and cerebellum is in keeping with that expected for a brain of this size. The ratio of neocortical gray matter volume to corpus callosum cross-sectional area is similar in the elephant and human brains (108 and 93.7, respectively), emphasizing the difference between terrestrial mammals and cetaceans, which have a very small corpus callosum relative to the volume of neocortical gray matter (ratio of 181,287 in our sample). Finally, the elephant has an unusually large and convoluted hippocampus compared to primates and especially to cetaceans. This may be related to the extremely long social and chemical memory of elephants. © 2005 Wiley-Liss, Inc. [source]

Noninvasive Stress and Reproductive Measures of Social and Ecological Pressures in Free-Ranging African Elephants

African elephants: the effect of property rights and political stability

CONTEMPORARY ECONOMIC POLICY, Issue 1 2000
MA. McPherson
African elephant populations have declined by more than 50% over the past 20 years. International outrage over the slaughter led to a worldwide ban on ivory sales beginning in 1989, despite the objections of many economists and scientists, and of several southern African countries that have established systems of property rights over elephants. Far from declining, elephant populations in many of these countries have increased to levels at or above the carrying capacity of the ecosystem. This article estimates the determinants of changes in elephant populations in 35 African countries over several time periods. The authors find that, controlling for other factors, countries with property rights systems of community wildlife programs have more rapid elephant population growth rates than do those countries that do not. Political instability and the absence of representative governments significantly lower elephant growth rates. [source]

How Elephants are Opening Doors: Developmental Neuroethology, Attachment and Social Context

ETHOLOGY, Issue 5 2007
G. A. Bradshaw
Ethology's renewed interest in developmental context coincides with recent insights from neurobiology and psychology on early attachment. Attachment and social learning are understood as fundamental mechanisms in development that shape core processes responsible for informing behaviour throughout a lifetime. Each field uniquely contributes to the creation of an integrated model and encourages dialogue between Tinbergen's four analytical levels: ethology in its underscoring of social systems of behaviour and context, psychology in its emphasis on socio-affective attachment transactions, and neuroscience in its explication of the coupled development of brain and behaviour. We review the relationship between developmental context and behaviour outcome as a topic shared by the three disciplines, with a specific focus on underlying neuroethological mechanisms. This interdisciplinary convergence is illustrated through the example of abnormal behaviour in wild African elephants (Loxodonta africana) that has been systematically observed in human-caused altered social contexts. Such disruptions impair normative socially mediated neuroendocrinological development leading to psychobiological dysregulation that expresses as non-normative behaviour. Aberrant behaviour in wild elephants provides a critical field example of what has been established in ex situ and clinical studies but has been largely absent in wild populations: a concrete link between effects of human disturbance on social context, and short- and long-term neuroethology. By so doing, it brings attention to the significant change in theories of behaviour that has been occurring across disciplines , namely, the merging of psychobiological and ethological perspectives into common, cross-species, human inclusive models. [source]

African elephants Loxodonta africana and human-elephant interactions: implications for conservation

INTERNATIONAL ZOO YEARBOOK, Issue 1 2006
P. C. LEE
African elephants face an uncertain future. Politics, war, sustained media campaigns, corrupt, weak or absent institutions supporting conservation, land-use planning or general governance, and greed are all bringing elephants into direct conflict with humans. Although elephant populations have declined considerably relative to their historical size and range, human populations have expanded to occupy and intensively use remaining elephant areas. Strategies to minimize perceptions of conflict and the implementation of land-use planning with biodiversity protection as its goal could help to sustain at least some populations of elephants. Here, we review threats to elephants, with an emphasis on those resulting from human perceptions of conflict, and suggest some mechanisms for grappling with these threats. [source]

Differences in woody vegetation are unrelated to use by African elephants (Loxodonta africana) in Mkhuze Game Reserve, South Africa

AFRICAN JOURNAL OF ECOLOGY, Issue 1 2010
Angela M. White
Abstract The reintroduction of African elephants into fenced game reserves throughout South Africa has presented managers with several challenges. Although elephants are a natural part of southern African ecosystems, their confinement to fenced protected areas in South Africa has exacerbated their potential to impact their habitats negatively. However, many studies investigating the impact of elephants have failed to control for the effects of other browsers on the vegetative community. In this study, we used location data on an elephant herd to delineate high-use and low-use areas. This paired design allowed us to minimize confounding factors that could explain differences in the structure, diversity and utilization of woody species. We found little evidence to suggest elephant-mediated change in, or selection for, the structure or diversity of woody species; however, our results suggest that elephants may be altering the composition of species by preferentially using areas with higher canopy diversity and by enhancing sapling recruitment. Although stripping of bark was higher in high-use areas, there was no evidence of differential mortality of tree species. Therefore, in our study area, and over the current time scale, elephants are having a negligible impact on the vegetative community. Résumé La réintroduction d'éléphants africains dans des réserves de faune clôturées dans toute l'Afrique du Sud représente plusieurs défis pour les gestionnaires. Bien que les éléphants fassent naturellement partie des écosystèmes d'Afrique australe, leur confinement dans des aires protégées clôturées en Afrique du Sud a exacerbé leur capacité d'avoir des impacts négatifs sur leurs habitats. Pourtant, les nombreuses études qui ont recherché l'impact des éléphants ont omis de contrôler l'effet des autres herbivores sur la communauté végétale. Dans cette étude, nous avons utilisé des données sur la localisation des hardes d'éléphants pour délimiter les zones plus ou moins fréquentées. Cette étude couplée nous a permis de minimiser les facteurs prêtant à confusion qui pouvaient expliquer des différences de structure, de diversité et d'utilisation des espèces ligneuses. Nous avons trouvé peu de preuves qui auraient indiqué que les éléphants changeaient ou sélectionnaient la structure ou la diversité des espèces ligneuses; cependant, nos résultats suggèrent que les éléphants pourraient modifier la composition des espèces en choisissant de préférence les zones où la diversité de la canopée est plus élevée et en stimulant le recrutement de jeunes plants. Même si les arrachages d'écorces étaient plus nombreux dans les zones très fréquentées, il n'y avait aucune preuve d'une mortalité différentielle selon les espèces d'arbres. C'est pourquoi, dans l'aire où nous avons travaillé, et pour le moment, on peut dire que les éléphants n'ont qu'un impact négligeable sur la communauté végétale. [source]

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

AFRICAN JOURNAL OF ECOLOGY, Issue 2 2009
Elizabeth W. Freeman
Abstract To reduce elephant densities and preserve biological diversity, 14,629 elephants were culled from Kruger National Park, South Africa (1967,1999). Data were catalogued between 1975 and 1996 on 2737 male and female elephants, including pregnancy and lactational status for 1620 females (,5 years of age) and, uterine and/or ovarian characteristics for 1279. This study used these data to investigate the effects of age and precipitation on reproduction. The youngest age of conception was 8 years (n = 6) and by 12 years of age all females were sexually mature. From the age of 14 years, the percentage of reproductively active females (pregnant and/or lactating) was >90%; however, this percentage declined when females reached 50 years of age. Overall, one-tenth of females were nonreproductive (not pregnant or lactating) at any given time, mostly in the youngest (<15 years) and oldest (>50 years) age classes. Eighteen (3.3%) of the nonpregnant females had reproductive tract pathologies, including endometrial, uterine or ovarian cysts. There was a seasonal distribution of mating activity that correlated with the rainy season. As has been demonstrated in other populations of free-ranging African elephants, most of the females in Kruger National Park were reproductively active; however, age and climate affected reproductive activity. Résumé Pour réduire la densité des éléphants et préserver la diversité biologique, 14.629 éléphants ont été abattus dans le Parc National Kruger, en Afrique du Sud, entre 1967 et 1999. Des données ont été recueillies entre 1975 et 1999, sur 2 737 éléphants mâles et femelles, y compris le statut de gestation ou de lactation de 1 620 femelles (,5 ans) et les caractéristiques utérines et/ou ovariennes de 1 279 d'entre elles. Cette étude a utilisé ces données pour rechercher les effets de l'âge et des précipitations sur la reproduction. L'âge de conception le plus précoce était de huit ans (n = 6), et à l'âge de 12 ans, toutes les femelles étaient sexuellement mâtures. À partir de l'âge de 14 ans, le pourcentage de femelles en reproduction active (pleines ou allaitantes) était >90%; cependant, ce pourcentage diminuait lorsque les femelles atteignaient l'âge de 50 ans. Globalement, à tout moment, un dixième des femelles n'avaient pas de reproduction active (ni pleines, ni allaitantes) surtout parmi les plus jeunes (<15 ans) et les plus vieilles (>50 ans). Dix-huit (3,3%) des femelles non pleines souffraient de pathologies du système reproducteur, y compris de kystes de l'endomètre, de l'utérus ou des ovaires. Il y avait une distribution saisonnière des accouplements, en corrélation avec la saison des pluies. Comme cela a déjàété montré dans d'autres populations d'éléphants africains vivant en liberté, la plupart des femelles du Parc National Kruger avaient une reproduction active; cependant, l'âge et le climat affectent l'activité reproductrice. [source]

Elephants caught in the middle: impacts of war, fences and people on elephant distribution and abundance in the Caprivi Strip, Namibia

AFRICAN JOURNAL OF ECOLOGY, Issue 2 2009
Michael J. Chase
Abstract We conducted wet [26 March,4 April 2003 (Apr03)] and dry [1,8 November 2005 (Nov05)] season aerial surveys of African elephants (Loxodonta africana Blumenbach) in the Caprivi Strip, Namibia to provide an updated status report on elephant numbers and distribution and assist with a historical analysis of elephant distribution and abundance in the Caprivi Strip. During the wet season when water was available in seasonal pans, elephants were widely distributed throughout the survey area. In contrast, during the dry season, a majority of elephant herds occurred within 30 km of the perennial Kwando, Linyanti and Okavango rivers and few herds occurred within the West Caprivi Game Reserve where water in the seasonal pans was limited. We estimated 5318 elephants for the 7731-km2 survey area (0.71 elephants km,2) for the Apr03 wet season survey and 6474 elephants for the 8597-km2 survey area (0.75 elephants km,2) for the Nov05 dry season survey. Based on our aerial surveys and reports of elephant numbers and distribution from historical aerial surveys and telemetry studies, civil war, veterinary fences and human activities appear to have effected changes in African elephant abundance, distribution and movements in the Caprivi Strip, Namibia since 1988 when the first comprehensive aerial surveys were conducted. Résumé En saison des pluies (avril 2003) et en saison sèche (novembre 2005), nous avons réalisé des contrôles aériens des éléphants africains (Loxodonta africana Blumenbach) dans la Bande de Caprivi, en Namibie, pour pouvoir fournir un rapport actualisé sur le statut du nombre et de la distribution des éléphants, et aider une analyse de longue durée de la distribution et de l'abondance des éléphants dans la Bande de Caprivi. Pendant la saison des pluies, lorsque l'eau était disponible dans les « pans » saisonniers, les éléphants étaient largement distribués dans toute la zone étudiée. Par contre, en saison sèche, la grande majorité des troupeaux d'éléphants se trouvaient dans les 30 km des rivières permanentes Kwando, Linyanti et Okavango, et peu de troupeaux se trouvaient dans la West Caprivi Game Reserve, où l'eau était limitée dans les pans saisonniers. Nous avons estimé le nombre d'éléphants à 5 318 dans les 7 731 km² de la zone étudiée (0,71 éléphant km,²) pour l'étude faite en saison des pluies d'avril 2003, et à 6 474 éléphants dans les 8 597 km²étudiés (0,75 éléphant km,²) pendant la saison sèche de novembre 2005. En se basant sur nos contrôles aériens et sur des rapports concernant le nombre et la distribution des éléphants provenant de contrôles aériens et d'études télémétriques anciens, il s'avère que la guerre civile, les barrières vétérinaires et les activités humaines ont provoqué des changements de l'abondance, de la distribution et des déplacements des éléphants dans la Bande de Caprivi depuis 1988, date où les premiers contrôles aériens complets ont été effectués. [source]

Levels of aloe mortality with and without elephants in the Thicket Biome of South Africa

AFRICAN JOURNAL OF ECOLOGY, Issue 2 2009
D. M. Parker
Abstract Studies concerning the influence of African elephants (Loxodonta africana) on vegetation have produced contradictory results; some show minimal or no effect while others report significant elephant-induced effects. Elephants are generalist megaherbivores but will selectively feed from preferred plant species. We investigated the mortality of aloe plants (highly preferred food items for elephants) at five sites with elephants (treatment) and five paired sites without elephants (control) in the Eastern Cape Province of South Africa. A significantly higher proportion of aloes were dead at treatment sites and significantly more aloes that had lost their crown (headless) were found at treatment sites compared with controls. We conclude that although the proportions of dead aloes at treatment sites were significantly higher, it remains unclear whether there is a need to be concerned with the potential small-scale extinction of aloes from parts of the Eastern Cape Province. The observed mortality may merely be an artefact of the loss of large herbivores through disease (e.g. rinderpest) and hunting in the past. Résumé Des études de l'influence des éléphants africains (Loxodonta africana) sur la végétation ont produit des résultats contradictoires: certaines montrent un effet minimal, voire nul, alors que d'autres signalent des effets significatifs. Les éléphants sont des grands herbivores généralistes, mais ils se nourrissent sélectivement de certaines parties des plantes. Nous avons étudié la mortalité de plants d'aloès (nourriture fortement privilégiée par les éléphants) à cinq sites avec éléphants (traitement) et à cinq autres sites sans éléphant (témoins), dans la Province du Cap oriental, en Afrique du Sud. Il y avait une proportion significativement plus grande d'aloès morts dans les sites du traitement, et ils étaient significativement plus nombreux à avoir perdu leur couronne (étêtés) que dans les sites témoins. Nous concluons que, bien que la proportion d'aloès morts soit significativement plus grande dans les sites du traitement, il n'est pas évident de savoir s'il faut s'inquiéter de cette possible extinction à petite échelle des aloès dans certaines parties de la Province du Cap oriental. La mortalité observée peut bien être simplement un artefact de la perte des grands herbivores en raison de maladies (ex. la peste bovine) et de la chasse dans le passé. [source]

Population pharmacokinetics of isoniazid in the treatment of Mycobacterium tuberculosis among Asian and African elephants (Elephas maximus and Loxodonta africana)

JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 1 2005
J. N. MASLOW
We recently described the clinical presentation and treatment of 18 elephants from six herds infected with TB. Treatment protocols and methods varied between herds to include both oral and rectal dosing using multiple drug doses and formulations. In this paper we present information regarding the pharmacokinetics (PK) of isoniazid (INH) in elephants and provide suggestions regarding initial treatment regimens. Forty-one elephants received INH daily by either oral or rectal administration with different formulations. Population PK analysis was performed using Non-linear Mixed Effect Modeling (NONMEM). Results of oral administration indicated that compared with premixed INH solution, the drug exposure was highest with a suspension prepared freshly with INH powder. When INH was concomitantly given as an admixture over food, Tmax was delayed and variability in drug absorption was significantly increased. Compared with oral administration, similar drug exposures were found when INH was dosed rectally. The data generated suggest that a starting dose of 7.5 mg/kg of INH is appropriate for initial TB treatment in elephants when premixed solution is administered directly into the oropharynx or rectal vault and 4 mg/kg are when INH is administered following immediate suspension from powdered form. [source]

Fine-scale population genetic structure in a fission,fusion society

MOLECULAR ECOLOGY, Issue 11 2008
ELIZABETH A. ARCHIE
Abstract Nonrandom patterns of mating and dispersal create fine-scale genetic structure in natural populations , especially of social mammals , with important evolutionary and conservation genetic consequences. Such structure is well-characterized for typical mammalian societies; that is, societies where social group composition is stable, dispersal is male-biased, and males form permanent breeding associations in just one or a few social groups over the course of their lives. However, genetic structure is not well understood for social mammals that differ from this pattern, including elephants. In elephant societies, social groups fission and fuse, and males never form permanent breeding associations with female groups. Here, we combine 33 years of behavioural observations with genetic information for 545 African elephants (Loxodonta africana), to investigate how mating and dispersal behaviours structure genetic variation between social groups and across age classes. We found that, like most social mammals, female matrilocality in elephants creates co-ancestry within core social groups and significant genetic differentiation between groups (,ST = 0.058). However, unlike typical social mammals, male elephants do not bias reproduction towards a limited subset of social groups, and instead breed randomly across the population. As a result, reproductively dominant males mediate gene flow between core groups, which creates cohorts of similar-aged paternal relatives across the population. Because poaching tends to eliminate the oldest elephants from populations, illegal hunting and poaching are likely to erode fine-scale genetic structure. We discuss our results and their evolutionary and conservation genetic implications in the context of other social mammals. [source]

Phenotype matching and inbreeding avoidance in African elephants

MOLECULAR ECOLOGY, Issue 21 2007
JIM MOORE
Abstract Perhaps the most important ,decision' made by any animal (or plant) is whether to disperse , leave kith and kin, or remain with the familiar and related. The benefits of staying at home are obvious, so dispersal requires an explanation , and the most popular is that dispersal functions to avoid inbreeding depression. Strong support comes from the observation that dispersal is so often sex biased. Simply put, all else being equal members of both sexes should prefer to remain philopatric, but this would lead to inbreeding depression so members of one sex have to disperse. In principle, this link between inbreeding depression and sex-biased dispersal could be broken if individuals recognize close kin and avoid mating with them. Archie et al. (2007) provide one of the most compelling analyses to date of the interaction among inbreeding avoidance, kin recognition and mating strategies in any mammal, clearly showing that elephants recognize even close paternal kin and avoid mating with them. Their important results illuminate the subtleties of elephant inbreeding avoidance as well as illustrate the difficulty of arriving at definitive answers to questions about the evolution of dispersal behaviour. [source]

Characterization of tetranucleotide microsatellite loci in the African Savannah Elephant (Loxodonta africana africana)

The movement of African elephants in a human-dominated land-use mosaic

ANIMAL CONSERVATION, Issue 5 2009
M. D. Graham
Abstract Land outside of gazetted protected areas is increasingly seen as important to the future of elephant persistence in Africa. However, other than inferential studies on crop raiding, very little is understood about how elephants Loxodonta africana use and are affected by human-occupied landscapes. This is largely a result of restrictions in technology, which made detailed assessments of elephant movement outside of protected areas challenging. Recent advances in radio telemetry have changed this, enabling researchers to establish over a 24-h period where tagged animals spend their time. We assessed the movement of 13 elephants outside of gazetted protected areas across a range of land-use types on the Laikipia plateau in north-central Kenya. The elephants monitored spent more time at night than during the day in areas under land use that presented a risk of mortality associated with human occupants. The opposite pattern was found on large-scale ranches where elephants were tolerated. Furthermore, speed of movement was found to be higher where elephants were at risk. These results demonstrate that elephants facultatively alter their behaviour to avoid risk in human-dominated landscapes. This helps them to maintain connectivity between habitat refugia in fragmented land-use mosaics, possibly alleviating some of the potential negative impacts of fragmentation. At the same time, however, it allows elephants to penetrate smallholder farmland to raid crops. The greater the amount of smallholder land within an elephant's range, the more it was utilized, with consequent implications for conflict. These findings underscore the importance of (1) land-use planning to maintain refugia; (2) incentives to prevent further habitat fragmentation; (3) the testing and application of conflict mitigation measures where fragmentation has already taken place. [source]

The influence of increasing population size and vegetation productivity on elephant distribution in the Kruger National Park

AUSTRAL ECOLOGY, Issue 3 2009
KIM D. YOUNG
Abstract Decisions to reduce the impacts of large herbivores on biodiversity in protected areas are often based on controlling their numbers. However, numbers per se may not be the foremost consideration when managing impacts. This is because density-related changes in distribution can also affect habitat utilization and hence, impact. In this study we tested whether changes in the distribution of African elephants are associated with increasing population size. We used spatially explicit count data collected during the dry seasons from 1998 to 2004 in South Africa's Kruger National Park. We did this at five spatial scales and in landscapes defined by vegetation, geology, climate and soils. We then investigated whether observed distributions and grid-cell-specific densities were associated with the remotely sensed Normalized Difference Vegetation Index (NDVI) as a measure of productivity and therefore food resource availability at the landscape scale. Consistent with density mediated changes, we found that elephant grid-cell occupancy increased with population size, while grid-cell-specific density became less variable. In addition, the combined distribution of bull groups and breeding herds became less clumped with increasing population size. We further found that within landscapes elephants were present on grid-cells with higher NDVI values, but that the influence of NDVI during the dry season on densities among landscapes may be weak. These results suggest that NDVI was more indicative of structural habitat choices such as woody vegetation than food availability per se. Our study highlights the need to consider factors other than population size alone when formulating management decisions to reduce large herbivore impacts on biodiversity in protected areas. [source]

Salient features in the locomotion of proboscideans revealed via the differential scaling of limb long bones

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2010
VALERY B. KOKSHENEV
The standard differential scaling of proportions in limb long bones (length against circumference) was applied to a phylogenetically wide sample of the Proboscidea, Elephantidae and the Asian (Elephas maximus) and African (Loxodonta africana) elephants. In order to investigate allometric patterns in proboscideans and terrestrial mammals with parasagittal limb kinematics, the computed slopes between long bone lengths and circumferences (slenderness exponents) were compared with published values for mammals, and studied within a framework of the theoretical models of long bone scaling under gravity and muscle forces. Limb bone allometry in E. maximus and the Elephantidae is congruent with adaptation to bending and/or torsion induced by muscular forces during fast locomotion, as in other mammals, whereas the limb bones in L. africana appear to be adapted for coping with the compressive forces of gravity. Hindlimb bones are therefore more compliant than forelimb bones, and the resultant limb compliance gradient in extinct and extant elephants, contrasting in sign to that of other mammals, is shown to be a new important locomotory constraint preventing elephants from achieving a full-body aerial phase during fast locomotion. Moreover, the limb bone pattern of African elephants, indicating a noncritical bone stress not increasing with increments in body weight, explains why their mean and maximal body masses are usually above those for Asian elephants. Differences in ecology may be responsible for the subtle differences observed in vivo between African and Asian elephants, but they appear to be more pronounced when revealed via mechanical patterns dictated by limb bone allometry. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 16,29. [source]