Forest Elephants (forest + elephant)

Distribution by Scientific Domains


Selected Abstracts


Forest Elephants: Tree Planters of the Congo

BIOTROPICA, Issue 4 2009
Stephen Blake
ABSTRACT The abundance of large vertebrates is rapidly declining, particularly in the tropics where over-hunting has left many forests structurally intact but devoid of large animals. An urgent question then, is whether these ,empty' forests can sustain their biodiversity without large vertebrates. Here we examine the role of forest elephant (Loxodonta africana cyclotis) seed dispersal in maintaining the community structure of trees in the Ndoki Forest, northern Congo. Analysis of 855 elephant dung piles suggested that forest elephants disperse more intact seeds than any other species or genus of large vertebrate in African forests, while GPS telemetry data showed that forest elephants regularly disperse seeds over unprecedented distances compared to other dispersers. Our analysis of the spatial distribution of trees from a sample of 5667 individuals showed that dispersal mechanism was tightly correlated with the scale of spatial aggregation. Increasing amounts of elephant seed dispersal was associated with decreasing aggregation. At distances of<200 m, trees whose seeds are dispersed only by elephants were less aggregated than the random expectation, suggesting Janzen,Connell effects on seed/seedling mortality. At the landscape scale, seed dispersal mode predicted the rate at which local tree community similarity decayed in space. Our results suggest that the loss of forest elephants (and other large-bodied dispersers) may lead to a wave of recruitment failure among animal-dispersed tree species, and favor regeneration of the species-poor abiotically dispersed guild of trees. [source]


Forest elephant (Loxodonta africana cyclotis) stature in the Réserve de Faune du Petit Loango, Gabon

JOURNAL OF ZOOLOGY, Issue 4 2003
Bethan J. Morgan
Abstract The stature of forest elephants Loxodonta africana cyclotis was determined at the Petit Loango Reserve over 14 months from January to December 1998 and May to June 1999 using three measures: shoulder height, hind footprint length and boli diameter. The shoulder height of 53 identified elephants was measured using photogrammetric methods. The minimum estimated shoulder height was 69 cm from a young calf, and the tallest animal was 216 cm. Hind footprint length and boli diameter data were collected from unidentified individuals. The minimum footprint size was 12.5 cm and the largest 35.3 cm. Boli diameter ranged from 4.0 to 16.0 cm. A comparison of the size categories with those of savanna elephants in Amboseli National Park, Kenya, suggested a similar distribution of size, age and population structure, despite a marked difference in overall stature. These are the first data for measures of African forest elephant size compared to African savanna elephant size. Such data may add morphological evidence supporting recent genetic work suggesting that African forest elephants be re-classified as a distinct species from the African savanna elephant. [source]


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]


Forest Elephants: Tree Planters of the Congo

BIOTROPICA, Issue 4 2009
Stephen Blake
ABSTRACT The abundance of large vertebrates is rapidly declining, particularly in the tropics where over-hunting has left many forests structurally intact but devoid of large animals. An urgent question then, is whether these ,empty' forests can sustain their biodiversity without large vertebrates. Here we examine the role of forest elephant (Loxodonta africana cyclotis) seed dispersal in maintaining the community structure of trees in the Ndoki Forest, northern Congo. Analysis of 855 elephant dung piles suggested that forest elephants disperse more intact seeds than any other species or genus of large vertebrate in African forests, while GPS telemetry data showed that forest elephants regularly disperse seeds over unprecedented distances compared to other dispersers. Our analysis of the spatial distribution of trees from a sample of 5667 individuals showed that dispersal mechanism was tightly correlated with the scale of spatial aggregation. Increasing amounts of elephant seed dispersal was associated with decreasing aggregation. At distances of<200 m, trees whose seeds are dispersed only by elephants were less aggregated than the random expectation, suggesting Janzen,Connell effects on seed/seedling mortality. At the landscape scale, seed dispersal mode predicted the rate at which local tree community similarity decayed in space. Our results suggest that the loss of forest elephants (and other large-bodied dispersers) may lead to a wave of recruitment failure among animal-dispersed tree species, and favor regeneration of the species-poor abiotically dispersed guild of trees. [source]


Acoustic estimation of wildlife abundance: methodology for vocal mammals in forested habitats

AFRICAN JOURNAL OF ECOLOGY, Issue 3 2010
Mya E. Thompson
Abstract Habitat loss and hunting pressure threaten mammal populations worldwide, generating critical time constraints on trend assessment. This study introduces a new survey method that samples continuously and non-invasively over long time periods, obtaining estimates of abundance from vocalization rates. We present feasibility assessment methods for acoustic surveys and develop equations for estimating population size. As an illustration, we demonstrate the feasibility of acoustic surveys for African forest elephants (Loxodonta africana cyclotis). Visual surveys and vocalizations from a forest clearing in the Central African Republic were used to establish that low-frequency elephant calling rate is a useful index of elephant numbers (linear regression P < 0.001, radj.2 = 0.58). The effective sampling area was 3.22 km2 per acoustic sensor, a dramatic increase in coverage over dung survey transects. These results support the use of acoustic surveys for estimating elephant abundance over large remote areas and in diverse habitats, using a distributed network of acoustic sensors. The abundance estimation methods presented can be applied in surveys of any species for which an acoustic abundance index and detection function have been established. This acoustic survey technique provides an opportunity to improve management and conservation of many acoustically-active taxa whose populations are currently under-monitored. Résumé La perte d'habitat et la pression de la chasse menacent des populations de mammifères dans le monde entier, ce qui entraîne des contraintes de temps critiques pour l'évaluation des tendances. Cette étude présente une nouvelle méthode de recherche qui échantillonne sur de longues périodes de façon constante et non intrusive et qui permet d'obtenir des estimations d'abondance à partir des taux de vocalisation. Nous présentons les méthodes d'évaluation de la faisabilité d'études acoustiques et nous développons des équations pour estimer la taille des populations. Pour illustrer ceci, nous montrons la faisabilité d'études acoustiques chez les éléphants de forêts africains Loxodonta africana cyclotis. Nous avons utilisé des études visuelles et des vocalisations d'une clairière forestière de République Centrafricaine pour établir que le taux d'appel à basse fréquence des éléphants est un indice intéressant du nombre d'éléphants (régression linéaire P < 0,001, radj² = 0,58). La superficie d'échantillonnage effective était de 3,22 km² par senseur acoustique, ce qui est une augmentation spectaculaire par rapport à la couverture des transects d'études par comptage des crottes. Ces résultats appuient le recours aux études acoustiques pour estimer l'abondance des éléphants dans de vastes zones retirées et dans des habitats variés, en utilisant un réseau de senseurs acoustiques bien répartis. Les méthodes d'estimation de l'abondance présentées peuvent être appliquées à toute espèce pour laquelle on a établi un indice d'abondance acoustique et une fonction de détection. Cette technique d'étude acoustique donne la possibilité d'améliorer la gestion et la conservation de nombreux taxons actifs au point de vue acoustique et dont les populations sont actuellement trop peu suivies. [source]


Heard but not seen: an acoustic survey of the African forest elephant population at Kakum Conservation Area, Ghana

AFRICAN JOURNAL OF ECOLOGY, Issue 1 2010
Mya E. Thompson
Abstract This study, designed to survey forest elephants (Loxodonta africana cyclotis) at Kakum Conservation Area, Ghana, is the first to apply acoustic methods to elephant abundance estimation and to compare results with independent survey estimates. Nine acoustic sensors gathered sound continuously for 38 days. Low-frequency calling rates have been established as useful elephant abundance indices at a Namibian watering hole and a central African forest clearing. In this study, we estimated elephant population size by applying an abundance index model and detection function developed in central Africa to data from simultaneous sampling periods on Kakum sensors. The sensor array recorded an average of 1.81 calls per 20-min sampling period from an effective detection area averaging 10.27 km2. The resulting estimate of 294 elephants (95% CI: 259,329) falls within confidence bounds of recent dung-based surveys. An extended acoustic model, estimating the frequency with which elephants are silent when present, yields an estimate of 350 elephants (95% CI: 315,384). Acoustic survey confidence intervals are at least half as wide as those from dung-based surveys. This study demonstrates that acoustic surveying is a valuable tool for estimating elephant abundance, as well as for detecting other vocal species and anthropogenic noises that may be associated with poaching. Résumé Cette étude, conçue pour étudier les éléphants de forêt (Loxodonta africana cyclotis) de l'Aire de conservation de Kakum, au Ghana, est la première qui applique des méthodes acoustiques pour l'estimation de l'abondance des éléphants et qui compare les résultats avec des estimations indépendantes. Pendant 38 jours, neuf senseurs acoustiques ont récolté les sons en continu. Le rythme des appels à basse fréquence est un indice utile de l'abondance des éléphants que l'on a pu établir à un point d'eau en Namibie et dans une clairière d'une forêt d'Afrique centrale. Ici, nous estimons la taille d'une population d'éléphants en appliquant un modèle d'indice d'abondance et une fonction de détection mis au point en Afrique centrale à des données provenant des senseurs de Kakum pour des périodes d'échantillonnage simultanées. La batterie de senseurs a enregistré une moyenne de 1.81 appel par 20 min, pour une superficie de détection réelle de 10.27 km² en moyenne. L'estimation qui en résulte, qui est de 294 éléphants (95% IC 259,329), tombe dans les limites de confiance de récentes études basées sur les crottes. Un modèle acoustique étendu, qui estime aussi la fréquence à laquelle les éléphants sont silencieux pendant leur présence, donne une estimation de 350 éléphants (95% IC 315,384). Les intervalles de confiance d'une étude acoustique sont au moins la moitié de ceux des études par les crottes. Cette étude montre que l'étude acoustique est un outil intéressant pour estimer l'abondance des éléphants et aussi pour détecter d'autres espèces bruyantes et les bruits d'origine anthropique qui pourraient être associés au braconnage. [source]


Sacoglottis gabonensis, a keystone fruit for forest elephants in the Réserve de Faune du Petit Loango, Gabon

AFRICAN JOURNAL OF ECOLOGY, Issue 2 2009
Bethan J. Morgan
Abstract This study suggests that the fruits of Sacoglottis gabonensis (Baill.) Urb. (Humiriaceae) are a keystone resource for forest elephants (Loxodonta cyclotis Matschie) in a coastal rain forest, the Réserve de Faune du Petit Loango, Gabon (now part of Loango National Park). Faecal counts demonstrated that forest elephants used Sacoglottis -dominated forest more when Sacoglottis was abundant and electivity indices suggest that Sacoglottis is a preferred food. The flora of Petit Loango is characterized by the absence of herbaceous vegetation such as Marantaceae and Zingiberaceae, and during the prolonged dry season few fleshy fruits are present other than Sacoglottis fruits, which are produced in a glut during this time. While inter-annual fruiting reliability remains to be confirmed, fruit production in 1998 and high stem density relative to other study sites provide indirect evidence that Sacoglottis fruits are a reliable inter-annual resource at Petit Loango. It is thus proposed that Sacoglottis gabonensis fruits fulfil an important role as a keystone ,fallback' resource for forest elephants during the dry season at Petit Loango. Résumé Cet article suggère que les fruits de Sacoglottis gabonensis (Baill.) Urb. (Humiriaceae) sont une ressource primordiale pour l'éléphant de forêt (Loxodonta cyclotis Matschie) dans une forêt pluviale côtière, la Réserve de Faune du Petit Loango, au Gabon, qui fait partie du Parc National de Loango. Le comptage des excréments a montré que les éléphants de forêt fréquentent les forêts dominées par Sacoglottis davantage lorsque les Sacoglottis sont abondants, et les indices d'électivité suggèrent que c'est leur nourriture préférée. La flore de Petit Loango se caractérise par l'absence de végétation herbacée comme les Marantaceae et les Zingiberaceae, et pendant la longue saison sèche, il y a peu d'autres fruits pulpeux que les Sacoglottis qui sont produits en abondance à cette saison. Même s'il faut encore confirmer que les fruits sont produits en continu d'une année à l'autre, la production des fruits en 1998 et la densité de hautes pousses, comparées aux autres sites étudiés, montrent indirectement que les fruits de Sacoglottis sont une ressource fiable tout au long de l'année à Petit Loango. On pose donc l'hypothèse que les fruits de Sacoglottis gabonensis jouent un rôle important comme aliment ressource pour les éléphants de forêt de Petit Loango pendant la saison sèche. [source]


Forest elephant (Loxodonta africana cyclotis) stature in the Réserve de Faune du Petit Loango, Gabon

JOURNAL OF ZOOLOGY, Issue 4 2003
Bethan J. Morgan
Abstract The stature of forest elephants Loxodonta africana cyclotis was determined at the Petit Loango Reserve over 14 months from January to December 1998 and May to June 1999 using three measures: shoulder height, hind footprint length and boli diameter. The shoulder height of 53 identified elephants was measured using photogrammetric methods. The minimum estimated shoulder height was 69 cm from a young calf, and the tallest animal was 216 cm. Hind footprint length and boli diameter data were collected from unidentified individuals. The minimum footprint size was 12.5 cm and the largest 35.3 cm. Boli diameter ranged from 4.0 to 16.0 cm. A comparison of the size categories with those of savanna elephants in Amboseli National Park, Kenya, suggested a similar distribution of size, age and population structure, despite a marked difference in overall stature. These are the first data for measures of African forest elephant size compared to African savanna elephant size. Such data may add morphological evidence supporting recent genetic work suggesting that African forest elephants be re-classified as a distinct species from the African savanna elephant. [source]


Forest Elephants: Tree Planters of the Congo

BIOTROPICA, Issue 4 2009
Stephen Blake
ABSTRACT The abundance of large vertebrates is rapidly declining, particularly in the tropics where over-hunting has left many forests structurally intact but devoid of large animals. An urgent question then, is whether these ,empty' forests can sustain their biodiversity without large vertebrates. Here we examine the role of forest elephant (Loxodonta africana cyclotis) seed dispersal in maintaining the community structure of trees in the Ndoki Forest, northern Congo. Analysis of 855 elephant dung piles suggested that forest elephants disperse more intact seeds than any other species or genus of large vertebrate in African forests, while GPS telemetry data showed that forest elephants regularly disperse seeds over unprecedented distances compared to other dispersers. Our analysis of the spatial distribution of trees from a sample of 5667 individuals showed that dispersal mechanism was tightly correlated with the scale of spatial aggregation. Increasing amounts of elephant seed dispersal was associated with decreasing aggregation. At distances of<200 m, trees whose seeds are dispersed only by elephants were less aggregated than the random expectation, suggesting Janzen,Connell effects on seed/seedling mortality. At the landscape scale, seed dispersal mode predicted the rate at which local tree community similarity decayed in space. Our results suggest that the loss of forest elephants (and other large-bodied dispersers) may lead to a wave of recruitment failure among animal-dispersed tree species, and favor regeneration of the species-poor abiotically dispersed guild of trees. [source]


Fruit, Minerals, and Forest Elephant Trails: Do All Roads Lead to Rome?

BIOTROPICA, Issue 3 2004
Stephen Blake
ABSTRACT Tropical forests are among the most heterogeneous environments on earth, and food resources for many animals are patchy both in time and space. In Africa's equatorial forest, permanent trails created and maintained by forest elephants are conspicuous features. Trails may be several meters wide and continue for tens of kilometers. Speculation on which resources determine the distribution of trails has identified fruit, browse, and mineral deposits as candidates. In this study, the relationships between these habitat variables and elephant trails were investigated. The size of individual trails and the density of the trail system increased dramatically with proximity to mineral deposits. Fruit tree basal area decreased with perpendicular distance from trails, while that of non-fruit trees did not. Fruit tree abundance and basal area were significantly higher on trail intersections than random sites and increased with intersection size. No relationship was found between monocotyledon browse abundance and elephant trail system characteristics. Clumped resources, which are at least partially reliable, provide a high nutritional payback, and are not rapidly depleted and can thus be visited repeatedly, appear to influence permanent trail formation by forest elephants. Permanent trails may allow naive individuals or those with imperfect knowledge to locate and acquire important resources. [source]