Makgadikgadi Research Articles

Population Declines, Viable Breeding Areas, and Management Options for Flamingos in Southern Africa

Habitat rehabilitation or intervention to prevent species declines are rarely employed in Africa. I argue that despite protection in national parks, active intervention is necessary to halt declines in southern Africa’s Greater (Phoenicopterus ruber) and Lesser (Phoeniconaias minor) Flamingo populations. Flamingos are long‐lived species that breed sporadically at only two localities in southern Africa: the Makgadikgadi Pans in Botswana and Etosha National Park in Namibia. Despite well‐publicized breeding on Etosha Pan, flamingos have experienced only three major breeding events in 40 years. Breeding failure occurs when high evaporation rates rapidly dry the pan, and up to 100,000 flightless chicks may starve. Consequently, pairs breeding in Etosha exhibit extraordinarily low recruitment (0.040 young pair/year) and extrapolations indicate that adults can replace themselves only if they breed for 38 to 50 years and all offspring survive. Because survival of offspring from fledging to adulthood (5 years) is about 46%, this breeding lifespan rises to an unrealistic 83 years, making Etosha a nonviable breeding site. Alternative, suitable flamingo habitats in Africa are being mined for soda‐ash, are damaged by pollution, or are unprotected. Accordingly, continent‐wide estimates and those from southern Africa alone suggest a population decline of about 40% in both species over the last 15 years. Because Namibia regularly supports 84% of the Greater and 93% of the Lesser Flamingos in southern Africa, conservation strategies are best focused there. Simple but effective management methods, based on those employed in western Europe, could reverse these downward trends. In Etosha a small island surrounded by a water‐filled depression would allow up to 4000 pairs to breed annually. The benefits of enhancing the breeding of flamingos in Etosha include research opportunities, tourism revenue, and a safe haven for two Red Data species.

Seasonal distribution of zebra and wildebeest in Makgadikgadi Pans Game Reserve, Botswana

SummaryThe movement and distribution patterns of zebra and wildebeest, with relation to the salt pans area and the Boteti river in Makgadikgadi Pans Game Reserve, were monitored over consecutive dry and wet seasons between 1989 to 1991.Two methods, the aerial survey and the road survey, were used to assess abundance. The aerial survey suggested that zebra and wildebeest concentrate along the river during the dry seasons, then at the pans in the wet seasons.Road surveys showed, that when analysed year by year, the aforesaid seasonal movements between the river and the pans may not be strictly adhered to. Providing borehole water along the river to augment water supply during drought years is recommended. Areas outside the reserve where the animals may spend the entire year should be zoned as wildlife management areas.RésuméOn a observé le schéma des déplacements et de la distribution des zébres et des gnous en relation avec l'emplacement des salines et la rivière Boteti, dans la Réserve de Faune des Salines de Makgadikgadi, au long des saisons sèches et des saisons des pluies qui se sont succédé entre 1989 et 1991.On a utilisé deux méthodes, la recherche par avion et par route pour évaluer leur nombre. La recherche aérienne suggérait que gnous et zèbres se concentrent le long de la rivière en saison sèche et aux salines en saisons des pluies. Les recherches par la route montraient que, analysés année par année, les mouvements entre la rivière et les salines doivent être plus nuancés. On recommande de creuser un puits de long de la rivière pour augmenter l'apport d'eau lors des années sèchez. II faudrait délimiter comme zones de gestion de la faune les endroits situés en dehors de la réserve où les animaux peuvent passer l'année entière.

Inland salt waters of southern Africa

Inland salt lakes are widely distributed in southern Africa: they are particularly common in South Africa, but many occur in Namibia and Botswana. All are shallow, and most are ephemeral with salinities that are not very high (mostly < 50 g l−1). Fringing zones of halophytes or submerged macrophytes are neither well-developed nor taxonomically diverse. The Cyanobacteria, especially Nodularia spumigena, often dominate the phytoplankton. The fauna of the Makgadikgadi area (northeast Botswana) is diverse and is similar to that of East African salt lakes. The aquatic fauna of salt water south of the Makgadikgadi Basin, on the other hand, is extremely depauperate, has no well-defined assemblage confined to saline waters, and appears mostly to comprise tolerant freshwater forms. Lovenula falcifera and Metadiaptomus transvaalensis (diaptomid copepods), Moina micrura (Cladocera) and Brachionus plicatilis (Rotifera) are frequently encountered zooplankton species, a few species of insects (Anisops sp., beetles, chironomids and ephydrids) are the principal non-planktonic macroinvertebrates. Artemia ‘salina’ is occasionally present, but may be an introduced form. The avifauna, in contrast to the aquatic macroinvertebrate fauna, is rich, with the greater and lesser flamingo often common.

The landforms of the western Makgadikgadi basin in northern Botswana, with a consideration of the chronology of the evolution of Lake Palaeo-Makgadikgadi

The landforms of the western Makgadikgadi basin in northern Botswana, with a consideration of the chronology of the evolution of Lake Palaeo-Makgadikgadi

Historical Geomorphology and Geoarchaeology in the Southwestern Makgadikgadi Basin, Botswana

Abstract Arid landscapes of the southwestern Makgadikgadi, Botswana, are dominated by sandy lacustrine plains, which are veneered by grassy stabilized dunes and small evaporite basins (pans). In addition, the exotic Boteti River delivers a nearly permanent supply of water to the region from the Angolan highlands via the Okavango marshes. The history of this unusually intricate landscape was investigated through regional geomorphological and geoarchaeological studies focused at two archaeological sites. The first site, Toromoja I, preserves residues of Later Stone Age settlement along the shore of a now-dry lake; a mid-Holocene age is suggested. At the second site, Gwi Pan West, a Later Stone Age burial was excavated. This burial appears to be only several hundred years old, and can be referred to a landscape much like the present. The spatial and environmental contexts of these archaeological residues can best be understood in terms of a dynamic historical geomorphology shaped by past climatic, tectonic, ...

N. Lancaster: Formation of the holocene Lake Chilwa sand bar: A discussion

The Holocene African Humid Period (c 14.8–5.5 ka) is now recognised in high-resolution records from western Africa as well as in tropical Africa north of the equator. Establishing a clear picture of Late Quaternary, including Holocene, environmental changes in central southern Africa is proving both difficult and contentious. This is because in dryland systems in particular it can be difficult to distinguish the effects of sub-millennial scale regional climatic variability from those of major externally-forced global climate changes, and because it is essential to distinguish records of environmental drivers from those of environmental responses. We analyse and review existing records for central southern Africa, and neighbouring areas affected by the same climate systems, to understand the primary controls of regional hydrological systems during the Holocene. We then present new data from Makgadikgadi basin barchan dunes that indicate mid-late Holocene aridity following a period of marked hydrological dynamism extending from the early Holocene. We suggest that present-day conditions in central southern Africa are relatively stable compared to the early and mid-Holocene and infer that this period of relative stability in the landscape has occurred since ca 2 ka. We explain Holocene hydrological changes through analysis of changing zonal climatic influences linked to Congo Air Boundary (CAB) and Intertropical Convergence Zone (ITCZ) dynamics, the effects of which filter into the region via complex drainage basin dynamics. It is proposed that, sensu stricto, the AHP was not a spatially uniform feature of early Holocene central southern Africa.

Landform Evolution in the Context of Climatic Change and Neo-Tectonism in the Middle Kalahari of North-Central Botswana

The Middle Kalahari of north-central Botswana is dominated by a huge basin of inland drainage partly filled with the geological formation known as the Kalahari beds, of late Tertiary to Recent age and of aeolian, lacustrine, and fluviatile origin. The landforms appear to have evolved in a climatic environment oscillating between wetter and drier episodes leaving a legacy of humid and arid landform relics in close juxtaposition with active contemporary forms, while downwarping and faulting appear to have greatly influenced their development. What appear to be structural troughs are occupied by the huge active terrestrial delta of the Okavango, and the vast playa-like complex of the Makgadikgadi pans, tenuously linked by the Boteti river. A large lake and a number of smaller lakes, all of fluctuating extent, seem to have occupied much of the area in the past. The mapping and study of the former shorelines of these lakes, and radio-carbon dating of the deposits associated with them may help to establish a chronological framework for the geomorphological evolution of the area, which should in turn aid the stratigraphical ordering and understanding of the succession of the Kalahari beds. Considerable light may also be thrown on the evolution of the Zambezi and Limpopo drainages from the late Tertiary to the mid-Pleistocene. Orange river in the south, into the Zaire basin in the north, and which is probably, according to Wellington, the largest continuous expanse of sand-covered surface in the world. The area comprises the end drainage basin of the Okavango river together with that of the Chobe, and the upper Zambezi which impinges in the extreme north, together with the whole of the depression occupied by the Makgadikgadi pans. The sand surface is continuous except for scattered outcrops of Pre-Cambrian and Karroo rocks, and the relief is slight, the range lying between 00ooo m which is the approximate bounding contour of the area, and a low point of 890 m in the north of Sua pan. The total area is about i6o ooo km2. It is a zone which is remarkable for the close juxtaposition of landforms which are primarily due to the action of water, and others which are entirely the result of arid climate processes, and both groups show examples which are in active process of development or are in a relict state. The whole area comprises a vast basin of internal drainage into which aeolian, fluviatile, and lacustrine sediments have been accumulating probably since late Cretaceous times. Four major rivers, the Cubango and Cuito (which unite into the Okavango), the Cuando (known in Botswana as the Chobe or Linyanti), and the upper Zambezi flow in parallel courses southwards from the Angolan highlands towards this basin. In the latitude i7 50o'S to I8'S these rivers turn eastwards, but then the Okavango and Cuando turn south again into Botswana, leaving only the

Makgadikgadi Pans Complex of Central Botswana

The Makgadikgadi Pans Complex forms a large and unusual surface feature in the central part of the Republic of Botswana (Figs. 1, 2). The two major pans of the complex, Sua and Ntwetwe, comprise an area in excess of 8,400 km 2 (Fig. 3). The pans occupy a basin that is the lowest point in a drainage system extending into Rhodesia Angola, and South West Africa (Namibia). The history of the pans, is complex and, is closely tied to the great climatic changes and tectonic activity that have affected this area since late Tertiary time and which continues today. Continuing seismic, activity in Botswana has been linked to the East, African Rift System/ Considerable work has been undertaken to trace the rift zone beneath the OKavango Swamps, scene of the most intense earthquake activity. Little published information exists, however, on the adjacent Makgadikgadi Pans and their relation to this same rifting process. This paper provides a review of current knowledge about the pans and correlates investigations of nearby, areas with some new data.

Some problems in the quaternary evolution of the landforms of northern Botswana

Northern Botswana is notable for the remarkable juxta-position of the wetland landscapes of the Okavango Delta, and the semi-arid landforms of the closely adjacent Makgadikgadi basin. There is much evidence to suggest that a great pluvial lake occupied the latter at various times in the Pleistocene and Holocene, and may on one or more occasions have formed a very large and continuous body of water with the Okavango - Mababe - Ngami depression. Changing climate and neotectonism have both clearly played a part in the evolution of a very complex assemblage of landforms. The study of these landforms may throw much light on the nature of geomorphic processes under differing climates; on the pattern and chronology of climatic change; on the incidence of neotectonism within the area; and on the history of the movement and settlement of Stone Age man, whose artefacts are found in abundance throughout the region. A very tentative chronology of events is put forward. Nordbotswana ist bekannt für das bemerkenswerte Nebeneinander der Feuchtgebiete des Okavango Deltas und der semiariden Oberflächenformen des dicht benachbarten Makgadikgadi-Beckens. Höchstwahrscheinlich bestand zu verschiedenen Zeiten des Pleistozäns und Holozäns im Makgadikgadi-Becken ein großer pluvialzeitlicher See, der zeitweilig eine zusammenhängende Wasserfläche mit der Okavango - Mababe - Ngami Depression gebildet haben könnte. Sowohl Klimawechsel als auch Neotektonik haben eine Rolle bei der Entwicklung dieses Landschaftskomplexes gespielt. Die Untersuchung dieser Oberflächenformen ergibt Hinweise auf die Art der Geomorphodynamik unter verschiedenen Klimaten, auf Verbreitung und Chronologie der Klimawechsel, auf das Vorkommen von Neotektonik, auf Entwicklungsgeschichte, Wanderungsbewegungen und Siedlungen des steinzeitlichen Menschen, dessen Werkzeuge in diesem Gebiet reichlich zu finden sind. Es wird eine vorläufige chronologische Einordnung dieser Ereignisse vorgelegt.