Showing papers in "African Journal of Ecology in 2007"

The Indian Ocean dipole - the unsung driver of climatic variability in East Africa

Abstract: A growing body of evidence suggests that an independent ocean circulation system in the Indian Ocean, the Indian Ocean dipole (IOD), is partly responsible for driving climate variability of the surrounding landmasses. The IOD had traditionally been viewed as an artefact of the El Nino - Southern Oscillation (ENSO) system although increasingly the evidence is amassing that it is separate and distinct phenomenon. We review the causes of the IOD, how it develops within the Indian Ocean, the relationships with ENSO, and the consequences for East African climate dynamics and associated impacts on ecosystems, in par- ticular along the Eastern Arc Mountains of Kenya and Tanzania. We evaluate current research initiatives focussed on characterizing and constraining the IOD and examine how effective these will be in determining climate change impacts on East African ecosystems and how such predictive capacity can be used in developing policy.

Changes in large herbivore populations across large areas of Tanzania

Abstract: We collated aerial census data collected during the late 1980s to early 2000s for large herbivore populations in eight large census zones in Tanzania. Of the ungulate populations that showed significant changes in densities at the start versus end of this decade, most declined; very few populations increased significantly. Thomson's gazelle, Grant's gazelle, hartebeest, reedbuck, roan antelope, sable antelope, warthog and zebra, for example, declined in over 50% of the zones where they were surveyed. Interestingly, small-bodied species fared particularly poorly in many census zones, whereas elephant and giraffe generally fared well across the country. Most populations of all herbivores declined in some portions of the country (e.g. Burigi-Biharamulo, Katavi, Greater Ruaha and Tarangire census zones). These surveys suggest that, even in a country renowned for its protected areas and conservation commitment, some large herbivore populations need more conservation attention in order to remain stable. Resume Nous avons rassemble les donnees recoltees entre la fin des annees 1980 et le debut des annees 2000 lors de recensements des populations de grands herbivores dans huit vastes zones de Tanzanie. La plupart des populations d'ongules qui presentaient des changements de densite significatifs entre le debut et la fin de ces recensements avaient diminue; tres peu avaient augmente significativement. La gazelle de Thomson, la gazelle de Grant, le bubale, le cobe des roseaux, l'antilope rouanne, l'antilope sable, le phacochere et le zebre, par exemple, avaient decline dans plusieurs zones. Il est interessant de remarquer que les especes de petite taille avaient des resultats plutot mediocres dans de nombreuses zones de recensement alors que les elephants et les girafes s'en sortaient bien dans tout le pays. La plupart des populations de tous les herbivores ont baisse dans certaines parties du pays (ex. les zones de recensement de Burigi-Biharamulo, Katavi, le Grand Ruaha et Tarangire). Ces etudes montrent que, meme dans un pays renomme pour son engagement envers ses aires protegees et la conservation, certaines populations de grands herbivores ont besoin d'une attention de conservation plus grande pour rester stables.

Land use affects rodent communities in Kalahari savannah rangelands

Abstract: Shrub encroachment caused by overgrazing has led to dramatic changes of savannah landscapes and is considered one of the most threatening forms of rangeland degradation leading to habitat fragmentation. Although changes to plant assemblages are becoming better known, however, our understanding of how shrub encroachment affects rodent communities is low. In this study, we investigated relative abundance of five rodent species in sixteen southern Kalahari rangelands where shrub cover ranged from low ( 25%). Rodent abundance was determined on three trapping grids (40 × 100 m) for each site. Our results show that increasing shrub cover affected rodent species differently. The relative abundance of hairy-footed gerbil, short-tailed gerbil and bushveld gerbil declined with increasing shrub cover, whereas highveld gerbil and striped mouse exhibited hump-shaped relationships with shrub cover. Overall, species richness decreased with increasing shrub cover and a negative impact of high shrub cover above 15% on rodent abundance was congruent for all species. We conclude that our results support the hypothesis that long-term heavy grazing that results in area wide shrub encroachment, threatens the diversity of arid environments.

Activity patterns of reintroduced lion Panthera leo and spotted hyaena Crocuta crocuta in the Addo Elephant National Park, South Africa

Abstract: Africa’s large predator guild competes for a limited food resource base. To minimize the degree of competition, we hypothesized that the two largest members of this guild and its fiercest competitors, the lion and the spotted hyaena, would partition their activity patterns to avoid interacting. We used 96-h continuous follows of focal animal(s) to determine when the six radio-collared lions and eight radio-collared spotted hyaenas, reintroduced into Addo Elephant National Park in 2003/2004, were active using a binomial measure of activity which was defined as movements >100 m during each hourly period. Contrary to our predictions, lions and hyaenas did not partition their activity times, probably because of their current low population densities. Both species exhibited a crepuscular activity pattern although hyaenas were far less active during daylight. A sub-adult lioness minimized competitive interactions by becoming diurnal. This is likely to be a common strategy for lions that have been expelled from their natal pride to become nomadic, as it allows them to minimize kleptoparasitic and agonistic interactions from competitively dominant conspecifics and competitors. The increase in testosterone that occurs in males upon reaching sexual maturity, darkens their pelage and causes them to be more directly impacted by the heat, and thereby affords females an opportunity to escape from males during hot temperatures. Similarly, the longer pelage of young hyaenas restricts their activity to the cooler night-time.

Ecological, environmental and socioeconomic aspects of the Lake Victoria's introduced Nile perch fishery in relation to the native fisheries and the species culture potential: lessons to learn

Abstract: Inland fishery ecosystems in Africa are characterized by patterns of overexploitation, environmental degradation and exotic species introductions. Ecological complexity and diversity of aquatic habitats dictate that fishes in general are not evenly distributed in a water body. However, fisheries management regimes tend to ignore this basic principle, assume generalized conditions in a water body, and focus more on ‘desired’ objectives such as maximizing catch. The result is to disregard fish habitat boundaries and anthropogenic influences from the catchment that influence fish production. Overexploitation and environmental degradation disrupt sustainable socioeconomic benefits from the fisheries, create uncertainty among investors, but leave some managers calling for more information with the expectation that the fisheries will recover with time. Open access to the fisheries and full control of fishing effort remain challenges for managers. Exotic species introductions and fish farming can increase production, but such interventions require firm commitment to sound ecological principles and strict enforcement of recommended conservation and co-management measures in capture fisheries. The general tendency to downplay fishing effort issues, other ecosystem values and functions or rely on temperate fisheries models until a new cycle of overexploitation emerges, characterizes many management patterns in inland fisheries. Aquaculture is not an option to challenges in capture fisheries management. Aquaculture should be developed to increase fish production but even this practice may have negative environmental impacts depending on practice and scale. Decades of information on Lake Victoria fisheries trends and aquaculture development did not stop the collapse of native fisheries. The successfully introduced Nile perch (Lates niloticus) has shown signs of overexploitation and aquaculture has again been considered as the option. By reviewing significant trends associated with Nile perch and its feasibility in aquaculture this paper uses Lake Victoria to illustrate ‘special interest management’ targeting selected species of fish rather than the fisheries. Resume Les ecosystemes africains ou se pratique la peche interieure se caracterisent par des schemas de surexploitation, de degradation environnementale et d'introductions d'especes exotiques. La complexite et la diversite des habitats aquatiques impliquent que les poissons ne sont, en general, pas distribues de facon uniforme dans une entite aquatique. Pourtant, les divers regimes de gestion des pecheries tendent a ignorer ce principe elementaire, presument de conditions uniformes dans une entite aquatique et visent plus les objectifs « souhaites », comme des prises maximales. Le resultat, c'est que l'on ne tient pas compte des limites de l'habitat des poissons et des impacts anthropiques du bassin versant qui influencent la production de poisson. La surexploitation et la degradation de l'environnement compromettent les benefices socio-economiques durables de la peche, engendrent l'incertitude parmi les investisseurs et font que certains gestionnaires sollicitent plus d'informations dans l'attente que la peche se redresse avec le temps. L'acces libre a la peche et le controle total des efforts de peche restent de vrais defis pour les gestionnaires. Les introductions d'especes exotiques et les fermes piscicoles peuvent augmenter la production, mais ces interventions exigent un engagement solide vis-a-vis des principes ecologiques responsables et l'application stricte des mesures de conservation et de co-gestion recommandees pour la peche. La tendance generale a minimiser les problemes des efforts de peche et les autres valeurs et fonctions de l’ecosysteme, ou a se baser sur des modeles de peche temperes jusqu’a ce qu'un nouveau cycle de surexploitation emerge, caracterise de nombreux schemas de gestion de peche interieure. L'aquaculture n'est pas une option pour les defis auxquels fait face la gestion de la peche. L'aquaculture devrait etre developpee pour augmenter la production de poisson, mais meme cette pratique peut avoir des impacts environnementaux negatifs dus a l’echelle et a la facon dont on la pratique. Des decennies d'informations sur les tendances de la peche et le developpement de l'aquaculture dans le lac Victoria n'ont pas empeche l'effondrement de la peche originale. La perche du Nil (Lates niloticus), introduite avec succes montre des signes de surexploitation et l'aquaculture a de nouveau ete envisagee. En passant en revue les tendances significatives liees a la perche du Nil et la faisabilite de son aquaculture, cet article se sert du lac Victoria pour illustrer la « gestion d'interet special » qui vise des especes de poissons selectionnees plutot que la peche.

Medicinal plants used by communities of Ngai Subcounty, Apac District, northern Uganda

Abstract: An ethnobotanical survey was carried out in Ngai subcounty in Apac District. Three parishes of Ajerijeri, Abok A and Omach were taken as stratified sample areas in which both male and female traditional healers of different ages were interviewed. Information about the medicinal plants and traditional healing was gathered using questionnaires, semi-structured interviews, informal discussion and field excursion which yielded lists of local plant names, names of diseases treated, mode of administration and parts used. To enhance their effectiveness, medicinal plants are used in combinations to treat various ailments and the extent of knowledge of medicinal plant mixing determines the success of a traditional healer. Roots were the most commonly harvested part and this has greatly affected the regeneration of medicinal plants. It was believed that only plants collected from the wild were effective. Though not intentional, plant parts not used for medicinal purposes are sometimes destroyed in the process of harvesting. This practice, coupled with over harvesting, threatens the continued existence of these plants.

Patterns of scavenger arrival at cheetah kills in Serengeti National Park Tanzania

Abstract: Scavenging by large-bodied vertebrates is observed in many ecosystems but has rarely been quantified. Here we document the timing and order of scavenger arrival at 639 cheetah kills in Serengeti National Park, Tanzania, focusing on ecological and heterospecific factors that may impact detectability of carcasses. We found that small-, medium- and large-sized vultures, jackals, spotted hyaenas and lions were more likely to be present at the carcasses of large-bodied than small-bodied prey. Lions and spotted hyaenas were less likely to locate kills in tall grass; medium-sized vultures were likely to arrive before both large- and small-sized vultures. Spotted hyaenas and vultures were likely to be present at kills simultaneously. Despite numerous anecdotal accounts, we did not find that hyaenas use alighting vultures as a means of locating food. Our findings show that environmental variables and other scavenger species strongly influence scavenger arrival at carcasses in this ecosystem. Resume Le pillage des carcasses par des vertebres de grande taille s'observe dans de nombreux ecosystemes, mais on l'a rarement quantifie. Nous documentons ici les delais et l'ordre d'arrivee des charognards sur 639 proies tuees par des guepards dans le Parc National de Serengeti, en Tanzanie, en nous focalisant sur les facteurs ecologiques et heterospecifiques qui peuvent influencer la detectabilite des carcasses. Nous avons decouvert que les petits, moyens et grands vautours, les chacals, les hyenes tachetees et les lions etaient plus susceptibles de se retrouver pres de carcasses de grande taille que sur des petites proies. Les lions et les hyenes tachetees etaient moins susceptibles de localiser les proies dans les hautes herbes; les vautours de taille moyenne avaient tendance a arriver avant les grands et les petits vautours. Les hyenes tachetees et les vautours etaient susceptibles d'arriver pres des proies en meme temps. Malgre de nombreuses anecdotes allant dans ce sens, nous n'avons pas trouve que les hyenes utilisaient l'envol des vautours comme moyen de localiser la nourriture. Nos decouvertes montrent que des variables environnementales et les autres especes de charognards influencent fortement l'arrivee des charognards pres des carcasses dans cet ecosysteme.

Reduced emissions from deforestation and degradation

Abstract: Reduced emissions from deforestation and degradation Eliakimu Zahabu, Margaret M. Skutsch, Hussein Sosovele and Rogers E. Malimbwi Department of Forest Mensuration and Management, Sokoine University of Agriculture, PO Box 3013, Morogoro, Tanzania, Technology and Sustainable Development Group, Centre for Clean Technology and Environmental Policy, University of Twente, PO Box 217, 7500AE Enschede, The Netherlands and Institute of Resource Assessment, University of Dar es Salaam, Tanzania

Population biology of African buffalo (Syncerus caffer) at Hluhluwe‐iMfolozi Park, South Africa

Abstract: This study examines the population biology of African buffalo (Syncerus caffer Sparrman) at Hluhluwe-iMfolozi Park (HiP), South Africa. An analysis of buffalo census data covering the period from 1956 to 2006 shows that the population has a moderate intrinsic growth rate at around 12% per annum, which is similar to growth rates of buffalo populations measured elsewhere. The population is subject to density dependence when the number of buffalo in the park exceeds approximately 3500 animals. In most years over the past 25 years, the population has exceeded this threshold, and net annual population growth has averaged around 5%. Periods of buffalo population decline always coincided with heavy buffalo removals, suggesting limited resilience of the population to such disturbances. Demographic data from 826 buffalo in 12 herds, captured in 2001–2002, were used to parameterize an age-structured buffalo population model. The model yields an annual population growth rate of 4.05%, similar to recent growth estimates from buffalo censuses at HiP. The predicted stable age distribution is very similar to the age distribution observed in the captured population sample. Elasticity analysis of the model indicates that population growth in buffalo is most sensitive to adult and juvenile survival, and less sensitive to recruitment parameters and survival of old animals. Buffalo populations might therefore be expected to be more vulnerable to mortality factors affecting prime-aged adults than those affecting juveniles or senescent individuals.

East African medicinal plants as a source of lead compounds for the development of new antimalarial drugs

Abstract: Four traditional medicinal plants of east and central Africa, Emilia discifolia (Oliv.) C. Jeffrey, Senecio stuhlmannii, Indigofera emarginella A. Rich. and Aspilia africana (Pers) C.D. Adams, were screened for in vitro antimalarial activity using the nitro-tetrazolium blue-based parasite lactate dehydrogenase assay. The plant parts were collected in two batches: one in the wet season and the other in the dry season. The ethyl acetate extract of A. africana had the highest antiplasmodial activity against both the chloroquine-sensitive D10 [inhibitory concentration (IC)50 = 9.3; 7.7–10.9 μg ml−1] and the chloroquine-resistant K1 (IC50 = 11.5; 8.7–14.3 μg ml−1) strains of P. falciparum. There was a positive correlation between the antiplasmodial activity of the extracts against the D10 and K1 strains of P. falciparum (Pearsons’ coefficient, r = 0.9691, P =0.05). Yields of extracts and their antiplasmodial activity varied with season in some plant species. This study shows that some East African medicinal plants can serve as a source of lead compounds for the development of new drugs against the chloroquine-sensitive and chloroquine-resistant strains of P. falciparum. The need for optimization of the conditions of harvest to maximize yields is also highlighted.

Evidence for the local depletion of bay duiker Cephalophus dorsalis, within the Ipassa Man and Biosphere Reserve, north-east Gabon

Abstract: Malgre son statut de protection, la Reserve d'Ipassa, au nord-est du Gabon, a subi d'intenses activites de braconnage. Des etudes recentes des mammiferes ont montre que la reserve en abrite encore une grande diversite mais que leur densite a decline de facon dramatique au cours des deux dernieres decennies. Nous avons evalue les changements de la diversite des especes de cephalophes dans la reserve en comparant les donnees recoltees il y a 20 ans et celles de 2005-2006 dans la meme region. Les deux seules especes presentes aujourd'hui sont le cephalophe bleu et le cephalophe de Peters. La densite des cephalophes bais etait de 7,1 individus/km2 dans les annees 1980 mais il semble qu'il n'y en ait plus a cet endroit. Comme la chasse pour l'approvisionnement fut la seule activite pratiquee dans la reserve au cours des 20 dernieres annees et que le cephalophe bai est une espece particulierement prisee par les chasseurs de la region, il est tres probable que la chasse soit la raison de cette disparition locale. (Resume d'auteur)

Herbal medicine acceptance, sources and utilization for diarrhoea management in a cosmopolitan urban area (Thika, Kenya)

Abstract: The use of herbal remedies is usually perceived as a rural phenomenon, hence it is usually not clear whether they are an accepted mode of healthcare system in urban areas. This study aimed at investigating the role of herbal medicines in managing diarrhoea in an urban centre, document important plants utilized and their conservation status. The results indicate that diarrhoea is a serious problem in Thika urban slums. Ninety-eight per cent in the study area had suffered had suffered diarrhoea in the recent past (during the last 1 year). In regard to the mode of treatment sought for this condition, 97.45% had used herbal preparations. The majority (52.5%) first seek treatment for diarrhoea from herbalists before going to the hospital. More people (23.7%) in the study area seek herbal preparations for diarrhoea management because they consider them more effective than biomedicines, compared with 13.2% who opt for the herbal concoctions because they are cheap. A large diversity of species (41 species in 25 families) is used in diarrhoea management. The most common plants include Senna didymobotrya (Fresen.) Irwin & Barney, Physalis Peruvian L., and Cucurbita maxima Lam. Most of these are obtained from wild habitats, hence their conservation status needs to be addressed.

The successful reintroduction of leopard Panthera pardus to the Addo Elephant National Park

Abstract: The successful reintroduction of leopard Panthera pardus to the Addo Elephant National Park Matt W. Hayward*, John Adendorff, Lucius Moolman, Gina J. Hayward and Graham I. H. Kerley Department of Zoology, Centre for African Conservation Ecology, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031, Eastern Cape, South Africa and Addo Elephant National Park, PO Box 52, Addo 6105, Eastern Cape, South Africa

The impact of elephants on plants and their community variables in South Africa's Maputaland

Abstract: Elephants confined to protected areas could affect co-occurring species. We expected measurable deviations in the density, species number, turnover and composition, abundance-incidence and rank-abundance patterns of woody plant communities where elephants browse. We examined these variables in the presence (inside South Africa’s Tembe Elephant Park) and absence (uninhabited communal land adjacent to the park) of elephants for sand forests, closed and open woodlands. Woodland type influenced the apparent effect of elephants on tree densities and number of species. In sand forests, the presence of elephants was not associated with lowered tree densities but this did not hold for mixed woodlands. The rates of species turnover in the park were consistently higher than on communal land for all three woodland types. Species composition also differed significantly between these areas, as did the number of favoured food trees of elephants. Elephants had a clear influence on vegetation at the species level. However, at the community level they had no apparent affect on woodlandspecific abundance-incidences and rank-abundance relationships. Elephants were confined to Tembe for only some 20 years before this study and still occur at relatively low densities. This may explain why we could not detect an impact on the bivariate relationships.

Antibacterial activity of Mangifera indica (L.)

Abstract: Leaf extracts of Mangifera indica (L.), a medicinal and horticultural plant were investigated for antibacterial activity against Staphylococcus aureus, Esherichia coli and Pseudomonas aeruginosa. Using the agar-well diffusion and the gradient serial dilution methods the extracts showed weak antibacterial activity against the study organisms compared with the positive control (gentamycin). The ethanolic extract was most active with minimum inhibitory concentration ranging from 5481.0 to 43750.0 l gm l )1 . Chemical tests showed the presence of saponins, steroids and triterpenoids in the ether fraction, alkaloids, anthracenocides, coumarins, flavonones, reducing sugars, catechol and gallic tannins, saponins, steroids and triterpenoids in the ethanolic portion and anthracenocides, flavonones, reducing sugars in the aqueous fraction of the plant extract. These results shows that leaf extracts of M. indica possess some antibacterial activity that could be the basis for their medicinal use in Uganda.

Fire‐tolerance mechanisms of common woody plant species in a semiarid savanna in south‐western Zimbabwe

Abstract: The frequency of fire has increased in savannas yet few studies have assessed how plants persist when subjected to long-term disturbance by fire. We investigated the contributions of bark thickness and resprouting to the persistence of woody plants in two fire trials that were started in 1948 and 1949. The number of resprouts per individual, bark thickness, basal diameter and height of woody plants were measured in unburnt plots and those burnt annually, triennially and quinquennially during the late dry season. Changes in tree density, number of resprouts and individuals in different height classes between 1963 and 2002 were assessed. Bark thickness varied among species and also increased with increases in basal diameter. Generally, plants with thick bark survived fire more than those with thin bark. Resprouting was the major fire survival strategy for most species. The number of resprouts produced per plant ranged from 4 ± 3 (Acacia rehmanniana) to 14 ± 9 (Pseudolachnostylis maprouneifolia). Fire reduced species richness in plots burnt annually and triennially by 47% and 6% respectively. Species richness increased in unburnt plots (5%) and those burnt quinquennially (16%). Most woody species survived fire through a combination of traits.

Breeding seasonality and population dynamics of three rodent species in the Magamba Forest Reserve, Western Usambara Mountains, north‐east Tanzania

Abstract: We investigated breeding seasonality and population dynamics of three rodent species, Lophuromys flavopuncatus, Grammomys dolichurus and Praomys delectorum, in the Magamba Forest, Western Usambara Mountains, north-east Tanzania. Capture–mark–recapture studies were conducted in 2002–2004. Reproductive conditions of males and females showed temporal variations, an indication of breeding seasonality. Animals were reproductively active between February and May. Rainfall in November–January was instrumental for the onset of breeding and continued throughout the wet season. The recruitment of new individuals born during the season led to highest population densities between end of May and August. Populations declined progressively towards the end of the dry season (September–October). Only P. delectorum showed a marked density increase during January–February, indicating greater survival and/or recruitment during the November–January rains. The study shows that despite a relatively stable environment of the forest reserve, rainfall has strong influence on reproduction and population dynamics, probably because of its effect on primary food resources. Resume Nous avons etudie la chronologie saisonniere de la reproduction et la dynamique de la population de trois especes de rongeurs, Lophuromys flavopunctatus, Grammomys dolichurus et Praomys delectorum, dans la foret de Magamba, dans la partie ouest des monts Usambara, au nord-est de la Tanzanie. Des etudes par capture – marquage – re-capture ont ete realisees en 2002 – 2004. La condition reproductrice des mâles et des femelles presentait des variations saisonnieres, un indice de saisonnalite de la reproduction. Les animaux etaient en etat de reproduction active entre fevrier et mai. Les chutes de pluie de novembre a janvier etaient tres importantes pour le declenchement de la reproduction et continuaient pendant toute la saison des pluies. Le recrutement de nouveaux individus nes durant cette saison conduisait a une densite de population qui culminait entre fin mai et aout. Les populations declinaient progressivement jusque vers la fin de la saison seche (septembre – octobre). Seul P. delectorum montrait un taux de recrutement et/ou de survie plus eleve pendant les pluies de novembre a janvier. Cette etude montre que malgre l'environnement relativement stable de la reserve forestiere, les chutes de pluie ont une forte influence sur la reproduction et la dynamique des populations, probablement a cause de leur effet sur les ressources primaires en nourriture.

Factors affecting livestock predation by lions in Cameroon

Abstract: Interviews were carried out in six villages south-west of Waza National Park, Cameroon, to investigate the impact of factors related to the occurrence of livestock raiding by lions. Data were analysed at the village and individual level. Livestock losses (cattle, sheep and/or goats) caused by lions differed between villages, ranging from eight to 232 animals per village per year, or 37 to 1115 US$ per livestock owner. At the village and individual level, season and distance to the park boundary were important factors determining the occurrence of livestock losses (R2 > 0.81). In villages close to the park attacks occurred irrespective of season and predation was high, and in villages farther from the park attacks mainly occurred during the rainy season and predation was low. Owning a large number of animals and attempting to chase away lions during an attack also increased predation on both village and individual level. At individual level, predation increased with the combined ownership of cattle and sheep and/or goats. Herding methods could be changed to decrease livestock predation, for example herding livestock with more than one herder, or building bomas for cattle at night.

Population responses to natural and human‐mediated disturbances: assessing the vulnerability of the common hippopotamus (Hippopotamus amphibius)

Abstract: Vulnerable wildlife populations can face a suite of anthropogenic activities that may threaten their persistence. However, human-mediated disturbances are likely to be coincident with natural disturbances that also influence a population. This synergism is often neglected in population projection models. Here I evaluate the effects of natural (rainfall fluctuation) and human disturbances (habitat loss and unregulated hunting) using a multi-matrix environmental state population model for the common hippopotamus (Hippopotamus amphibius). By evaluating each disturbance type (natural and human) alone and then together, I explicitly consider the importance of incorporating realistic environmental variability into population projection models. The model population was most strongly affected by moderate habitat loss, which yielded the highest probability of crossing the risk thresholds over the 60 year time period, although these probabilities were relatively low (£0.31). However, the likelihood of crossing the risk thresholds were two to five times as high when humanmediated and natural disturbances were considered together. When these probabilities were calculated per year of the simulation, the results suggested that even relatively mild human disturbances, when considered in conjunction with realistic natural disturbance, resulted in a high probability (>0.50) of substantial declines within decades. The model highlights the importance of integrating realistic natural disturbances into population models, and suggests that, despite locally abundant populations, protected hippopotamus populations may decline over the next 60 years in response to a combination of environmental fluctuations and human-mediated threats.

Traditional treatment of malaria in Mbarara District, western Uganda

Abstract: An ethnobotanical survey on traditional treatment of malaria was carried out in Mbarara District, western Uganda, a malaria-endemic area. From this study, traditional healers understood malaria symptoms. Malaria was reported to be the most common condition treated by traditional healers in this area. Plants were the single most important source of natural products used for malaria treatment. Most of the plants used in malaria treatment belong to the family Asteraceae. The most commonly used plant parts were the leaves. Water was the most common solvent and the oral route was the most commonly used. From this study there are a number of plants in Mbarara district that can be used as sources of herbal remedies for malaria. A number of these plants can be incorporated in the national primary healthcare package after scientific studies on safety and efficacy are done.

A presence-only habitat suitability model for large grazing African ungulates and its utility for wildlife management

Abstract: A Geographic Information System (GIS)-based model, using presence-only data, was used to predict suitability of habitat for large grazing ungulates on a Zimbabwean wildlife reserve. The management-driven study focused on rare and economically valuable herbivores during the resource-limited hot-dry season. The modelling software Biomapper was used to quantify species-habitat association and derive habitat suitability (HS) maps. Herbivore distribution was primarily determined by distance to surface water, time since last burn and herbaceous layer composition. Findings are discussed within the context of tools available to management and are used to address concerns about the potential for interspecific competition at the habitat level, stocking rate estimation and proposed infrastructure development. Biomapper allowed for the derivation of HS maps here despite the authors' little modelling experience, and appears well suited to management-driven research of African fauna where access to GIS software is available.

Population trends of antelopes in Waza National Park (Cameroon) from 1960 to 2001: The interacting effects of rainfall, flooding and human interventions

Abstract: Antelopes are prominent wildlife in Waza National Park, situated in Sahelo-Sudanian Cameroon, which has witnessed dramatic changes in rainfall and flooding. To assess their impacts, we reviewed 26 aerial and terrestrial surveys, comprising total, transect and localized counts. Estimated numbers of kob using the floodplain throughout the dry season, dropped from 20,000 in the 1960s and 1970s to 2000 in the mid-1980s. They recovered to 5000 in the mid-1990s but not further despite increased flooding. Estimated numbers of korrigum and roan using the floodplain later in the dry season, dropped in the early 1970s and only slightly recovered in the 1990s. The diversity of counting methods notwithstanding, the drop in kob numbers and the disappearance of waterbuck can be attributed to the construction of the Maga dam upstream in 1979 and subsequent low rainfall. The kob population structure suggests that its reproduction capacity was, however, not hit. Antelope?livestock contacts, provoking the transmission of diseases such rinderpest during droughts, explain better the dramatic drops in population numbers than poaching, which is likely to have remained rather constant. The effects of rainfall, flooding and human interventions on antelope populations increasingly appear to be interacting.

Forest elephant group composition, frugivory and coastal use in the Réserve de Faune du Petit Loango, Gabon

Abstract: Results of a 16-month study of forest elephant (Loxodontaafricana cyclotis Matschie) group size and composition,coastal use and frugivory are presented from the Re´servede Faune du Petit Loango, Gabon (now the Parc Nationalde Loango). Mean forest elephant group size was 2.2 (n ¼140) including solitary animals, and 3.1 excluding solit-aries. Elephants consumed fruits of at least 49 species, andof the 220 elephant dungpiles examined, 185 (84.1%)contained seeds and 203 (92.3%) contained the remains offruits (seeds and/or pulp). The mean number of seed spe-cies per dungpile (±SD) was 2.01 ± 1.49, and the meannumber of fruit species was 2.28 ± 1.43. Elephants usedthe coastal habitat more during warmer months, andduring the afternoon than the morning. It is hypothesizedthat coastal habitat use is related to sodium intake throughconsumption of salt-coated vegetation.Key words: elephant, forest, frugivory, Gabon, Loango, rainforest Re´sume´ Cet article pre´sente les re´sultats d’une e´tude de 16 moisportant sur la taille et la composition des groupes d’e´le´-phant de foreˆt(Loxodonta africana cyclotis Matschie), surleur fre´quentation de la coˆte et leur consommation defruits dans la Re´serve de Faune du Petit Loango(aujourd’hui Parc National de Loango) au Gabon. La taillemoyenne du groupe d’e´le´phants de foreˆte´tait de 2.2individus (n ¼ 140), y compris les animaux solitaires,et de 3.1, solitaires non compris. Les e´le´phants consom-maient des fruits d’au moins 49 espe`ces diffe´rentes et, surles 220 tas de crottes d’e´le´phant examine´s, 185 (84.1%)contenaient des graines et 203 (92.3%) contenaient desrestes de fruits (semences et/ou pulpe). Le nombre moyend’espe`ces de graines par tas de crottes (±SD) e´tait de2.01 ± 1.49, et le nombre moyen d’espe`ces de fruits e´taitde 2.28 ± 1.43. Les e´le´phants fre´quentaient plus leshabitats coˆtiers pendant les mois plus chauds, et plus l’apre`s-midi que le matin. On e´met l’hypothe`se que la fre´quentationde l’habitat coˆtier est lie´ea` l’absorption de sodium, par laconsommation de la ve´ge´tation couverte de sel.

The feeding ecology of Eidolon dupreanum (Pteropodidae) in eastern Madagascar

Abstract: We investigated the diet of the endemic fruit bat Eidolon dupreanum (Chiroptera: Pteropodidae) in eastern Madagascar. We collected faecal and ejecta samples under day roosts and at nocturnal feeding trees. Eidolon dupreanum ate mainly fruit, although Eucalyptus spp. flowers were also consumed. In total, 30 plant species (fourteen identified and sixteen unidentified) were recorded in the diet, including six introduced taxa. Polyscias spp. trees, which occurred in humid forest at least 5 km from the roost, were the most frequently recorded plant in the diet. Fruits of Psidium spp. were abundant near to the roost but relatively uncommon in the faeces. Passage through the alimentary canal was limited to seeds <7 mm and there was some evidence for a positive effect on germination after passage through bats' stomachs. The role of fruit bats as seed dispersers in forest ecosystems in Madagascar should be used as an additional leverage for their conservation.

Diets of Kenyan elephants from stable isotopes and the origin of confiscated ivory in Kenya

Abstract: Stable isotopes provide information on the history of individual animals, which can include spatial information. We analysed over 300 ivory and bioapatite samples from elephants and hippopotamus for d 13 C and d 18 O in the context of spatial variability. Elephant and hippopotamus could be distinguished on the basis of d 13 C because elephants are predominantly browsers while hippopotamus are primarily grazers. Comparison of different elephant populations in Kenya shows that d 13 C and d 18 O are different in different regions because of different diet preferences and different sources of water. The Amboseli elephants have the highest percentage of grass in the diets of extant African elephants. Ivory from Central African elephants is significantly depleted in 13 C because of photosynthesis under closedcanopy conditions, and this distinction is used to show that much of the confiscated ivory carvings in Kenya are compatible with a Central African source.

Anthrax outbreak among Grevy's zebra (Equus grevyi) in Samburu, Kenya

Abstract: An anthrax outbreak occurred in the Wamba area of southern Samburu, Kenya, between December 2005 and March 2006. The outbreak affected equids including the endangered Grevy's zebras (Equus grevyi), plain zebras (Equis Burchelli) and donkeys (Equus asinus). Most of the deaths were localized in Nkaroni area just west of Wamba town. The diagnosis of anthrax was rapidly confirmed by bacteriological methods. The relevant government departments, including the Kenya Wildlife Service and Veterinary Department, and other stakeholders were promptly informed. Fifty-three Grevy's zebra and 26 plains zebras died from anthrax. An equal number (eighteen) of adult male and female Grevy's zebras succumbed to the disease. The outbreak affected immature and mature individuals equally. The dead plain zebras included fifteen adult females, two adult males and nine immature individuals. The Veterinary Department responded by vaccinating livestock while Kenya Wildlife Service vaccinated 620 Grevy's zebras within southern Samburu. Examination of sites at which carcasses of animals which succumbed to the disease were burnt, revealed that unsupervised burning did not eliminate anthrax spores in 42% of the cases (n = 14). There is an urgent need to incorporate strategic wildlife disease monitoring in the struggle to save Grevy's zebras and other endangered species. Resume Une epidemie d'anthrax a touche la region de Wamba, dans le sud du pays samburu, au Kenya, entre decembre 2005 et mars 2006. La maladie a touche les equides, y compris les zebres de Grevy (Equus grevyi) qui sont en danger, les zebres de Burchell (Equus burchelli) et les ânes (Equus asinus). La plupart des morts ont ete rapportees du cote de Nkaroni, juste a l'ouest de la ville de Wamba. Le diagnostic fut rapidement confirme par des analyses bacteriologiques. Les departements gouvernementaux concernes, y compris le Kenya Wildlife Service et le Service veterinaire, et les autres partenaires ont vite ete informes. Cinquante-trois (53) zebres de Grevy et 26 zebres de Burchell sont morts de cette maladie. Le meme nombre de mâles et de femelles adultes (18) sont morts chez les zebres de Grevy. L’epidemie a touche de la meme facon les jeunes et les adultes. Chez les zebres de Burchell, on compte 15 femelles adultes, deux mâles adultes et neuf jeunes. Le Service veterinaire a reagi en vaccinant le betail tandis que le Kenya Wildlife Service vaccinait 620 zebres de Grevy dans le sud-Samburu. L'examen des sites ou l'on avait brule les carcasses des animaux infectes a montre que l'incineration non controlee n'avait pas elimine les spores d'anthrax dans 42% des cas (n = 14). Il faut d'urgence integrer un monitoring strategique des maladies de la faune sauvage dans la lutte pour sauver le zebre de Grevy et les autres especes menacees.