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The hydrological regime of the Okavango River Basin is the main driver of ecological change in the delta. The delta supports a small-scale fishery which is a source of livelihood for communities within its fringes. The fish resource is particularly important to subsistence fishers, who have limited access to socio-economic opportunities. However, fish availability is subject to ‘concentration and dilution’ effects because of the hydrological regime. As a copying strategy, fishers use a variety of fishing methods to effectively harvest the delta’s fish community across all its trophic levels. This exploitation regime helps to maintain the delta’s species diversity and only reduces fish biomass proportionally across the different trophical levels. Furthermore, fishers have developed different fish-processing techniques to preserve their harvest for low fishing season periods to cope with low food availability. The aim of this paper therefore, was to explore spatio-temporal variations in fish availability and to show how the delta’s subsistence fishers cope with this dynamicity. [ABSTRACT FROM AUTHOR]

Copyright of African Journal of Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of African Journal of Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Despite rapid socio-economic development in Kalahari drylands, contemporary research suggests that biodiversity remains important as a component of the complex portfolio of livelihood strategies, as a real and perceived safety net in times of stress, and a key factor of cultural identity. The degree to which the spatially and temporally dynamic nature of biodiversity in drylands influences livelihoods is, however, little studied, particularly in socially complex contemporary rural settlements. Greater understanding in this area is required to allow better-informed design and implementation of rural development, poverty alleviation and conservation initiatives. This is particularly true in the light of predicted increases in environmental dynamism with climate change. An interdisciplinary approach was used in two environmentally and socially distinct dryland settlements in Botswana, to investigate the extent to which the dynamic biodiverse setting influences contemporary rural livelihoods. Results illustrate that biodiversity, particularly its dynamics, is of critical contemporary importance to rural settlement livelihoods, particularly in times of inner settlement scarcity. Entitlements to biodiversity dynamics were, however, bound up by complex settlement-specific social, economic and political factors. Unless such contextual within-settlement dynamics are understood, the relative importance of biodiversity in rural development and poverty alleviation strategies in contemporary Kalahari drylands may be undermined. [ABSTRACT FROM AUTHOR]

This study assesses land-use conflicts in the Okavango wetland ecosystem. A survey of the livelihood activities of a sample of four villages has been carried out and a stakeholder approach used to identify and analyse the key actors involved in resource competition and conflicts in the area. Traditional and emerging stakeholders were identified and found to be in conflict not only with each other but within themselves. Institutional policies on land use in the area are not properly harmonized, and there has been a top-down approach to development planning and implementation of development programmes. As a result, land-use conflicts have escalated in the area. The Okavango Delta Management Plan adopted in 2007 should integrate and harmonize all the land-use policies, and land management in the area. [ABSTRACT FROM AUTHOR]

We used body weight ratio to determine the degree of species-packing of the Okavango Delta (22,000 km2) grazers and compared it to that of four conservation areas of similar sizes but varying in the diversity of habitat types. They are Etosha National Park (23,175 km2) in Namibia, Hwange National Park (14,621 km2) in Zimbabwe, Kafue National Park (24,000 km2) in Zambia and Kruger National Park (19,633 km2) in South Africa. We considered possible ecological explanations for existing gaps within the assemblage. The weight ratio (measure of the degree of species-packing) of the grazers of the Okavango Delta was 1.25, with a total of 27 species which was far less than the theoretically expected 2.0. One-way analysis of covariance (ANCOVA) showed that there were significant differences in the degree of species-packing between the Okavango Delta and other conservation areas of similar size in southern Africa ( F1,5 = 166, P < 0.001). Regressing habitat heterogeneity (expressed as number of different habitat types) on species-packing of the five conservation areas yielded a positive linear relationship with R2 = 0.76 implying that 76% of the variation in the degree of species-packing in the five conservation areas is explained by variation in habitat heterogeneity. We conclude that size ratios are useful descriptors of animal communities and it is a useful measure of species diversity, which can be used for monitoring purposes. Imbalances in weight ratios provide a measure of identifying perturbations due to species loss or arrival of new species within a natural ecosystem. Résumé Nous avons employé le rapport du poids corporel pour déterminer le degré de ‘‘ richesse spécifiqueg’’ ( species-packing) des herbivores du delta de l'Okavango (22.000 km2) et nous l'avons comparéà celui de quatre aires de conservation de taille similaire mais qui varient par la diversité de leurs types d'habitats. C’étaient le Parc National d'Etosha (23.175 km2) en Namibie, le Parc National de Hwange (14.621 km2) au Zimbabwe, le Parc National de Kafue (24.000 km2) en Zambie et le Parc National Kruger (19.633 km2) en Afrique du Sud. Nous avons envisagé des raisons écologiques possibles pour expliquer les manques dans les assemblages. Le rapport de poids (mesure du degré de species-packing) des herbivores du delta de l'Okavango était de 1,25, avec un total de 27 espèces, ce qui est beaucoup moins que la valeur théorique attendue de 2,0. L'analyse à une voie de la covariance (ANCOVA) montrait qu'il y avait des différences significatives du degré de species-packing entre le delta de l'Okavango et les autres aires de conservation de taille semblable en Afrique du Sud ( F1,5 = 166 ; P < 0,001). En faisant la régression de l'hétérogénéité de l'habitat (exprimée comme le nombre de types d'habitats différents) sur le species-packing des cinq aires de conservation, on a obtenu une relation linéaire positive avec R2 = 0,76, ce qui implique que 76% de la variation du degré de species-packing dans les cinq aires de conservation s'expliquent par la variation de l'hétérogénéité des habitats. Nous concluons que les rapports de taille sont des indicateurs utiles des communautés animales et que c'est une mesure utile de la diversité des espèces qui peut servir à des fins de monitoring. Des déséquilibres de rapports de poids fournissent une mesure pour identifier les perturbations dues à la perte ou à l'arrivée de nouvelles espèces dans un écosystème naturel. [ABSTRACT FROM AUTHOR]

Copyright of African Journal of Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Determines the influence of large herbivores, rainfall and fire on the growth and survival of established Acacia erioloba seedlings from 1975 to 1997 in the Savuti area of Chobe National Park, Botswana. Pattern of mortality of established seedlings; Changes in seedling height distribution; Availability of alternative food resources; Installation of artificial water points during dry season.

Copyright of African Journal of Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Presents evidence of seasonal movement patterns of some ungulates in the Kalahari ecosystem of Botswana between 1990 and 1995. Overlap between the seasonal ranges of the populations of some species; Eland movements; Wildebeest movements; Hartebeest movements; Springbook movements.

Discusses the use of satellite tracking in northern Botswana. Home range estimation; Relationship with water distribution and habitat selection; System performance of satellite collars; Home ranges and movements.

The article discusses the study on the hunting behavior of lions on elephants in the Chobe National Park in Botswana. The observations were made on at the waterhole in the Savute region of the park. All hunts of the lions were recorded in a total of 7,904 observation time for about four years as either unsuccessful attempts or successful kills. The study showed that a total of 74 elephants were killed in four years by the lion pride that composed of two adult males, eight females and 15 cubs. It was recorded that in all cases, the lions used a rear attack rather than frontal attack.

Abstract We report on a study conducted on free-ranging African elephants in the woodlands of northern Botswana. We compared bull groups and family units with regard to (1) their patterns of habitat use and (2) their ranging distances from perennial water sources. During the dry season, adult males frequented more habitat types than family units, whereas family units used a wider diversity of habitats than bulls during the wet season. Bulls roamed widely (>10 km) from perennial drinking water in the dry season, when family units congregated within 3.5 km of the rivers. During the wet season, when ephemeral pans were abundant, all elephant groups were found at intermediate distances (5 km) from the rivers. The spacing of elephants in the dry season is consistent with sexual segregation but we reject the hypothesis that this is an outcome of indirect competition for food, because our concurrent studies on elephant feeding ecology found no evidence for intraspecific competition. Instead, we propose that most adult male elephants space themselves to avoid conflict with musth bulls and roam widely in the dry season between discretely distributed feeding ‘hotspots’. The small proportion of males that are in musth remain close to family units to maximize mating opportunities, and family units are unable to range far from water in the dry season. This is due to (1) comparatively high rates of water turn-over among juveniles and lactating cows and (2) the reduced mobility of neonates. [ABSTRACT FROM AUTHOR]

Copyright of African Journal of Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)