Zambezian flooded grasslands
Located within the miombo and mopane woodlands of the Central African Plateau, Zambezian flooded grasslands are an anomaly of productivity and abundance in a landscape characterized by nutrient deficient soil and associated vegetation. Unlike the surrounding woodlands that generally support animals only in rather low densities, the wetlands and floodplains of this ecoregion provide habitats to sizable faunal populations, since food and water are abundant throughout the majority of the year. Large populations of waterbirds gather during the rainy season, and numerous herd animals and carnivores frequent the landscape. However, in a climate of rapid population growth and increasing need for land and natural resources, this fragile ecoregion may face increasing threat. Several conservation measures are urgently required for the ongoing survival of these wetland ecosystems and their biota.
Location and general description
Embedded predominantly within miombo and mopane woodlands, the Zambezian flooded grasslands ecosystem forms a discontinuous ecoregion distributed between northern Botswana in the south, to northern Tanzania. The Kilombero Valley, Moyowosi/ Malagarasi system and the Ugalla River in Tanzania; the Okavango River Alluvial Fan in Botswana; Lake Chilwa in Malawi; the Barotse Floodplain, the Kafue Flats, Busanga and Lukanga Swamps, Lake Mweru, Mweru Marsh and Bangwuelu/Luapala/Chambezi system in Zambia and a number of smaller floodplains and wetlands comprise this ecoregion.
Mostly scattered across the Central African Plateau between 1000 and 1200 millimetres (mm) above sea level, the underlying geology of this ecoregion consists largely of Precambrian volcanics, granite, serpentine and sandstone rocks. The gentle warping of the plateau surface is largely responsible for the seasonal flooding of the region that has given rise to the wetlands that make up this ecoregion. Alluvial soils are the predominent underlying wetland substrate, and often consist of heavy clays. These soils are generally waterlogged for part of the season, with a pH ranging from weakly alkaline to weakly acidic. Several of the wetlands are known to have a peaty organic horizon that has a pH as low as 3.5.
This ecoregion experiences a seasonal tropical and hurricanes climate, with most of its rainfall concentrated in the hot summer months between November and March, to the south, and November to the end of May in the north. Harsh droughts lasting up to seven months mark the cooler season. Mean maximum temperatures range anywhere between 18o and 27oC, depending on altitude, while mean minimum temperatures are typically between 9o and 18oC. The variation in rainfall across the ecoregion is significant, with Lake Bangweulu experiencing annual rainfall in excess of 1400 mm, while rainfall as low as 450 to 600 mm per annum is characteristic in the Okavango of Botswana, and along the Ugalla River and Moyowosi system in Tanzania. Inundation of these wetlands is, however, contingent not only on localized rainfall, but on the climatic conditions occurring in the upper sections of the catchments.
This ecoregion falls within the Zambezian Phytochorion, the largest of the centers of plant endemism within Africa. Although mostly characterized by a mosaic of edaphic grassland and semi-aquatic vegetation, local variation in flora between wetlands is notable due to the wide distribution of the flooded areas that constitute this ecoregion. In addition, the seasonal fluctuations in water levels and ranges in tolerance of different plants and plant communities to water-logging result in a complex, constantly changing mosaic of edaphic grasslands interspersed with permanent swamp vegetation as well as grassland and thicket communities found only on better-drained substrates. Grasses belonging to the genera Acrocera, Echinochloa, Leersia, Oryza, Phragmites, Typha and Vossia, together with Cyperus papyrus dominate most of these wetlands Herbaceous freshwater swamps and aquatic vegetation are also common. In some swamps, it appears as if growth of swamp vegetation itself has caused sufficient obstruction to retain the water. In some of the wetlands in this ecoregion, halophytic vegetation is also found.
Elevated areas within these wetlands support different types of vegetation. These include pervasive termite mounds with distinctive patches of grassland and thicket, Zanzibar-Inhambane lowland rainforest in the Kilombero valley, and woodland vegetation in Ugalla. Miombo or mopane woodlands often surround these wetlands, although dry forest, secondary grasslands and Itigi thicket also occur locally.
The more extensive floodplains of this ecoregion have historically provided important habitat for humans. For example, the Lozi people have traditionally occupied the Barotse floodplains. Their livelihoods have been closely linked to the seasonal flooding of the area. The Kafue Flats have been used by the Tonga people for cattle rearing and limited cultivation. However, much of the area comprising this ecoregion falls into areas affected by tsetse flies, vectors of sleeping sickness or trypanosomiasis, which affects both livestock and humans. This factor, in combination with the fact that many of the wetlands are at least afforded partial protection, may explain the relatively low overall human populations in many of these floodplain regions. However, human populations do tend to concentrate on the edges of floodplains. For example, just under half the population of the Barotse plain districts occurs in close proximity to the floodplain. Reliable data on actual human population densities for this ecoregion are, however, difficult to find.
In general, there are rather few endemic species in this ecoregion, but there are high levels of species richness. For example, there are no endemic mammals in the ecoregion. However, it supports high mammal species richness, including huge herds of large mammals that still undertake some seasonal migrations. Red lechwe (Kobus leche) populations are known to exceed 20,000 in Moremi Game Reserve, while more than 35,000 individuals of the endemic subspecies, the Kafue lechwe (Kobus leche kafuensis) have been recorded in Lochinvar National Park. Moreover, the largest remaining population of Puku (Kobus vardoni) is found in the Kilombero Valley and more than 20,000 Cape buffalo (Syncerus caffer) occur in the Moyowosi delta of northwestern Tanzania. Many of the ungulates that inhabit this ecoregion move seasonally through the floodplain in response to the fluctuating water levels. Tsessebe (Damaliscus lunatus), which are mostly restricted to seasonally flooded grasslands, are known to follow the receding waters in the dry season and to retreat to higher ground when the waters rise. Wildebeest (Connochaetes taurinus) and Oribi (Ourebia ourebi) also frequent extensive floodplains and grasslands, although the latter favor less waterlogged areas such as termitaries, where herbs and woody growth provide food and cover. Waterbuck (Kobus ellipsiprymnus), puku (Kobus vardoni), Southern reedbuck (Redunca arundinum), and Sitatunga (Tragelaphus spekei) are also common inhabitants of the floodplains, although these species tend to prefer the reed beds or more wooded vegetation on the margins of the floodplains. Greater kudu (T. strepsiceros), Hartebeest (Alcelaphus buselaphus), Steenbok (Aepyceros melampus), Sable (Hippotragus niger) and Roan antelope (H. equinus) are found in fewer numbers, generally preferring the woodland margins of inundated grasslands. Other herbivores attracted to these verdant pastures include elephant (Loxodonta africana), Burchell's zebra (Equus burchelli) and Eland (Taurotragus oryx). Hippopotamus (Hippopotamus amphibius) is found in almost all of the ecoregion’s prominent floodplains, with a population numbering between 2000 and 3000 individuals in Mweru Marsh.
Although many mammals are common to the entire ecoregion, the disjunct nature of the Zambezian flooded grasslands has resulted in fairly distinct species compositions. For example, black lechwe (Kobus leche smithermani), tsessebe, and sitatunga dominate the Bangweulu basin, while the Kafue lechwe and Burchell's zebra are amongst the most prominent herbivores in Kafue Flats. Similar patterns are evident with the top predators, where different species tend to predominate in different areas. These large carnivores include Lion (Panthera leo), Leopard (P. pardus), Ccheetah (Acinonyx jubatus), Spotted hyaena (Crocuta crocuta) and Painted hunting dog (Lycaon pictus). Smaller predators characteristic of this inundated ecoregion include the water mongoose (Atilax paludinosus), the Cape clawless otter (Aonyx capensis) – common at Lake Chilwa – and the Spotted-necked otter (Hydrictis maculicollis), an animal that requires clear waters and shows preference for rocky undisturbed areas without turbid inflow.
This ecoregion supports a high avifaunal diversity, and provides important habitat to a range of wetland birds. The ecoregion also provides habitat for endemic and near- endemic bird species, as well as five others that are considered globally rare. The only strict endemic is the Kilombero weaver (Ploceus burnieri, VU)). It is known from one locality along the Kilombero River, where it is seasonally common in the riverside swamps that are fringed with tall Phragmites mauritianus reed beds. Two other birds are nearly endemic to the ecoregion. Chaplin's barbet (Lybius chaplini) is endemic to south central Zambia, concentrated in the Kafue basin between Kafue National Park and Lusaka. Reliant on miombo woodland or open country bearing fruiting trees, this species is mostly found on the woody margins of flooded grassland areas. The Tanzania masked weaver (Ploceus reichardi) occurs only in a few swamps in western Tanzania, northern Zambia, and adjacent areas of the Democratic Republic of Congo (DRC). Two further restricted range birds, the Katanga masked weaver (Ploceus katangae) and the grey-crested helmet-shrike (Prionops poliolophus) occur in this ecoregion. In addition, this ecoregion falls within the center of distribution of the globally threatened slaty egret (Egretta vinaceigula, VU). Largely restricted to this ecoregion, this species is an uncommon resident of the marshes and floodplains of the Okavango, Chobe, and the Caprivi Strip as well as from the Zambezi Valley northwards to the Bangweulu swamps. Other globally threatened species recorded in this ecoregion include wattled crane (Bugeranus carunculatus,VU), which has its main breeding populations in the wetlands of Zambia, including the Kafue Flats and the Bangweulu and Busanga swamps, corncrake (Crex crex, VU), lesser kestrel (Falco naumanni, VU), great snipe (Gallinago media) and shoebill stork (Balaeniceps rex). Other rare birds found in these wetlands include the long-toed flufftail (Sarothrura lugens) and the white-headed plover (Vanellus albiceps).
Amphibian and reptile species richness and endemism are not high, with only two strictly endemic species. The merera toad (Bufo reesi) is known only from the Kihanzi-Kilombero floodplain of the Mahenge District of southern Tanzania. A number of amphibian associates are found within the ecoregion,including the Beira Toad (P. beiranus), African clawed toad (Xenopus laevis), African ornate frog (Hildebrandtia ornata), Boettger’s metal frog (Cacosternum boettgeri), Common reed frog (Hyperolius viridiflavus), and the Lukula grass frog (Ptychodena taenioscellus).
Other The Barotse water snake (Crotaphpeltis barotseensis) only occurs on the Kalabo Floodplain of Barotseland. The Nile crocodile (Crocodylus niloticus) and the slender-snouted crocodile (Mecistops cataphractus) are also common in certain floodplains of the ecoregion.
Six of the wetlands comprising this ecoregion are designated as protected areas according to IUCN criteria, and three floodplains (Okavango, Bangweulu Swamps, Lake Chilwa) are designated as Ramsar sites. Other portions of the ecoregion are contained within Game Controlled Areas or similar designations that allow controlled hunting. There are a number of additional proposed Ramsar sites.
The most prominent wetland in this ecoregion is the Okavango Delta. Mainly protected within the Moremi Game Reserve and two adjacent wildlife management areas, the delta remains relatively unspoiled and contains a unique array of fauna and flora. This inland delta covers approximately 68,640 square kilometers (km2) of northern Botswana and consists of stretches of pristine clear waters, wooded islands, inundated grasslands and extensive reed and papyrus beds. It is home to approximately 1060 plant species; the animal diversity of the area is relatively high with roughly 32 large mammals recorded. Designated as a Ramsar site of international importance, the most outstanding feature of this vast area is its prolific birdlife, with more than 650 species recorded.
Zambia contains several wetland protected areas belonging to the ecoregion. Lochinvar and Blue Lagoon National Parks and the Bangweulu-Kafinda Game Management Areas are considered key locations for threatened antelopes in sub-Saharan Africa. In addition, Bangweulu is also designated as a Ramsar site, with more than 400 bird species inhabiting its roughly 2500 km2 area. This game management area contains 17 rivers that flow into the Bangweulu River Basin, where the waters spread out to form expansive floodplains and marshes. Bangweulu, meaning "where the water meets the sky", this is one of the few remaining true wilderness areas in this ecoregion.
In Tanzania, there are three important wetlands in the ecoregion. The Moyowosi and Ugalla systems are particularly worthy of mention. During the peak flood season these wetlands cover roughly 10,000 km2, stretching for about 300 km from north to south and 70 km east to west. These floodplains include large areas of miombo woodlands, with permanent swamps being restricted to the margins of major rivers and their associated lakes. Both these rivers with their associated game reserves are proposed as Ramsar sites in Tanzania. The Kilombero Valley system is also mainly contained within a Game Management Area and is a proposed Ramsar site; its wetlands cover up to 3,000 km2.
Types and Severity of Threats
The combination of historically low human population densities, largely due to water-borne diseases, and the presence of tsetse flies – in and around the wetlands of this ecoregion, and the more recent establishment of parks and reserves centered on several of these floodplains, has ensured that many natural habitats remain. Even in areas that have been home to significant numbers of people, the disturbances and impacts of human activity needs to be seen in the context that wetlands and their surrounding landscapes are inherently unstable and are constantly evolving and changing. Wetland organisms and communities have evolved and adapted to thrive in an environment that is in continual flux.
However, with rapidly expanding populations and increasing use and manipulation of natural resources, this ecoregion is facing increasing threat from a variety of sources. These include: increased land clearance and deforestation of swamp forests and surrounding woodlands, poaching, pollution and eutrophication, and the modification of natural flow regimes.
While several of the wetlands such as the Barotse Floodplain and the Kafue flats have been occupied for centuries, large changes are becoming evident in many of the areas as human activities and land-use intensifies. These changes are largely a result of increased human populations, increased levels of technology available, increased government and donor inputs and better control of tsetse fly. Many of the seasonally flooded grasslands have historically been used for grazing during the dry season. However, several areas that only used to be seasonally grazed are now permanently occupied and cultivated. Although large-scale cultivation is relatively uncommon, subsistence agriculture is practiced by as much as 75 percent of the population of certain areas. Growing staple and cash crops such as maize, cassava, millet, sugarcane and tobacco, therefore, pose significant threats to areas of the ecoregion. Increased wealth and government/aid inputs, as well as extensive tsetse fly control have contributed to a large increase in cattle numbers over the past few decades; as many as 250,000 head of cattle are said to graze only in the Kafue Flats. Not only does overgrazing eliminate the herbaceous components of the vegetation, high numbers of cattle generally displace game, as there is less suitable habitat available.
Fire has always played a role in the ecology of grasslands and woodlands. However it has most probably never been as frequent as it is now, due to the increase of fire setting by humans. The increased incidence of repetitive fires may eliminate fire-sensitive species thereby reducing species diversity and can also result in over-utilization of recovering areas, such as on the Barotse Floodplain.
While most of the ecoregion consists of open grasslands, deforestation of swamp forest patches and surrounding woodlands still has a considerable impact on the healthy function of this ecoregion. Opening up the tree canopy increases the risk of fires. In addition, it reduces the habitat for many mammals such as greater kudu, hartebeest, sable and roan antelope, as well as birds that rely on the woodland-grassland interface for food or shelter.
Poaching and illegal hunting for bushmeat are continuing and increasing problems in several areas of the ecoregion. Hunting of large animals and their gradual replacement by domestic cattle, goats and sheep threaten many mammal populations in the wetlands. This is a problem in all of the wetland areas, but especially in those with higher population densities where there is little effective protection. In the Kafue Flats in Zambia, for example, large mammals are now confined almost exclusively to two national parks (Blue Lagoon and Lochinvar National Parks, a combined area of only 860 km2). In other areas, the local human populations have removed these species for food or to reduce crop-raiding problems. Furthermore, although many of these floodplains are officially protected, ineffective management and lack of funds has resulted in uncontrolled poaching of animals such as hippo, elephant, and rhino. In addition, overfishing is also becoming an issue of increasing concern. For example, over 50 percent of the fish production for Zambia comes from the Bangweulu basin and Kafue Flats.
The biodiversity and integrity of many of the wetlands of the ecoregion are further threatened by pollution, especially close to urban centers, where industrial, domestic wastes and agricultural runoff flow unchecked into the water catchments. It is estimated that these land-based activities contribute as much as 80 percent of the aquatic pollution in Tanzania and pose a major threat to biodiversity. In some of these wetlands and floodplains, eutrophication of waters has led to serious infestations of aquatic weeds such as Salvinia molesta, Eichornia crassipes and Pistia stratiodes, which has resulted in decreased fish production, displacement in natural fauna and flora, and overall loss of biodiversity. Pollution from pesticides such as DDT (dichloro-diphenyl-tricholoroethane) and chemical sprays used in tsetse fly control may also be severely affecting the biota of this ecoregion. Floodplains occurring in the vicinity of mines face serious problems relating to water pollution both in terms of chemical wastes and accumulation of heavy metals. Reports from the Copperbelt have shown that the copper content in rivers found in affected areas was up to 80 times higher than the acceptable level. The Kafue River is known to be contaminated with heavy metals and agricultural run-off. There is therefore considerable concern regarding the effects that bioaccumulation of these contaminants may have on animals that depend on the Kafue Flats for their sustenance.
Changes in the frequency, magnitude and variability of rainfall due to climate change as well as the anthropogenically induced modification of natural flow regimes through water abstraction and dam construction are of considerable threat to this ecoregion. Water diversion for irrigation and hydroelectric dams has already affected some floodplain systems. For example, the Itezhitezhi Dam on the Kafue River has changed the flood regime such that unseasonal flooding occurs on the flats, threatening the breeding sites of the wattled (Grus carunculatus) and grey crowned (Balearica regulorum) cranes. The area of land available for wildlife and for human uses such as fishing and recession farming has been further reduced by dam operations. Prior to the dam, about 6,000 km2 of land flooded in wet years. Now the flooding generally covers 2,000 km2 in normal years and 5,000 km2 in wet years. Weeds have invaded grazing areas and cattle herders must travel much further to water their flocks because of the altered flood regime. The population of Kafue lechwe that numbered about 100,000 in 1971 before construction of hydroelectric dams dropped to nearly half that number in 1987 after dam construction due to the altered flood regime.
A similar fate could await the Okavango Delta. Botswana, Namibia, Angola and Zambia would like to extract large quantities of water from the Okavango and Kwando rivers and their tributaries for irrigation and urban water use. Namibia is currently negotiating drawing an estimated 20 million cubic meters of water annually from the Okavango River system via the Eastern National Water Carrier project. Although this is less than 10% of the yearly flow, it is a very significant amount during the dry season. Excess abstraction from the Okavango River could have deleterious effects on functioning of the delta ecosystem, as well as other effects such as the transfer of fishes from the Okavango to more southerly drainage systems.
More recent damming of rivers, and conversion to agricultural systems is resulting in loss of habitat in parts of the ecoregion. In the Okavango Delta, concern was raised that the erection of a fence to control the movement of buffaloes, which carry disease, would fragment the migrations of large mammals in the area. However, the fence apparently has prevented the movement of cattle into the region and, thus, has benefited local wildlife populations.
Justification of Ecoregion Delineation
All the seasonally flooded areas within the Zambeziean Phytochorion area were mapped within this ecoregion. The borders of each area roughly follow the standards for a ‘herbaceous swamp and aquatic vegetation’ unit.
This ecoregion forms part of larger complex of Caesalpinoid woodland ecoregions that support wet and dry miombo, mopane, thicket, dry forests, Baikiaea woodland, and flooded grassland habitats, among others. The dominance of Caesalpinoid trees is a defining feature of this bioregion (i.e., a complex of biogeographically related ecoregions). Major habitat types (e.g., mopane and miombo) and the geographic separation of populations of large mammals are used to discriminate ecoregions within this larger region. All of these ecoregions contain habitats that differ from their assigned biome or defining habitat type. For example, patches of dry forest occur within larger landscapes of miombo woodlands in several areas. More detailed biogeographic analyses should map the less dominant habitat types that occur within the larger ecoregions.
Additional Information on this Ecoregion
- To see the species that live in this ecoregion, including images and threat levels, see the WWF Wildfinder description of this ecoregion.
- American Museum of Natural History 1999. The Amphibian Species of the World Database. Retrieved 2001.
- Baker, N.E. 1996. Tanzania Waterbird Count. The First Coordinated Count on the Major Wetlands of Tanzania – January 1995. BirdLife International, Tanzania
- Broadley, D.G. 1971. The reptiles and amphibians of Zambia. The Puku 6: 1 - 143.
- Brown, L., E.K. Urban and K. Newman. 1982. The Birds of Africa. Vol I. Academic Press, London. ISBN: 0121373010
- Chabwela, H.N. 1992. The ecology and resource use of the Bangweulu Basin and the Kafue Flats. Pages 11-25 in R. C. V. Jeffrey, H.N. Chabwela, G. Howard, and P.J. Dugan, editors. Managing the wetlands of Kafue Flats and Bangweulu Basin. Kafue National Park, Zambia. IUCN, Gland, Switzerland. ISBN: 2831701023
- Chabwela, H.N. and W. Mumba. 1998. Integrating Water Conservation and Population Strategies on the Kafue Flats. A. de Sherbinin and V. Dompka, editors. Water and Population Dynamics: Case Studies and Policy Implications. Zambia. American Association for the Advancement of Science (AAAS).
- Clemments, J.F. 1991. Birds of the World. A Check List. Ibis Publishing Company, Vista, California. ISBN: 0846701235
- Collar, N.J., M.J. Crosby and A.J. Stattersfield. 1994. Birds to Watch 2. The World List of Threatened Birds. BirdLife International, Cambridge. ISBN 1560985283
- Dodman, T., B. Kamweneshe, D. Kamweneshe, V. Katanekwa, and L. Thole. 1996. Zambia crane and wetland action plan. R. D. Beilfuss, W.R. Tarboton, W. R. and N.N. Gichuki, editors. Proceedings of the African crane and wetland training workshop. Wildlife Training Institute, Botswana. International Crane Foundation, Baraboo, WI.
- East, R. 1999. African Antelope Database 1998. IUCN/SSC Antelope Specialist Group. IUCN, Gland, Switzerland and Cambridge, UK. ISBN: 2831704774
- Estes, R.D. 1991. The behavior guide to African mammals. University of California Press, Berkeley, CA. ISBN: 0520080858
- Frazier, S., editor. 1999. A Directory of Wetlands of International Importance. Wetlands International and Ramsar Convention Bureau. Compact Disc. Metatec, Netherlands.
- Frost. P. 1996. The ecology of Miombo woodlands. B. Campbell,.editor. The Miombo in Transition: Woodlands and Welfare in Africa. CFIOR, Bogor. ISBN: 9798764072
- Fry, C.H., S. Keith, and E.K. Urban. 1988. The Birds of Africa. Vol III. Harcourt Brace Jovanovich Publishers. London.
- Hill, J. and C. Jones. 1994. The Shoebill Stork (Balaeniceps rex), a Status Report. Internal report for the Frankfurt Zoological Society.
- Hilton-Taylor, C. 2000. The IUCN 2000 red list of threatened species. IUCN, ,Gland, Switzerland and Cambridge, United Kingdom. ISBN: 2831705657
- IUCN 1987. IUCN Directory of Afrotropical Protected Areas. IUCN Gland, Switzerland and Cambridge. ISBN: 2880328047
- Kalapula, E.S. 1992. Settlement patterns and resource utilization in the Bangweulu Basin and Kafue Flats. Pages 25-33 in R. C. V. Jeffrey, H.N. Chabwela, G. Howard, and P.J. Dugan, editors. Managing the wetlands of Kafue Flats and Bangweulu Basin. Kafue National Park, Zambia. IUCN, Gland, Switzerland. ISBN: 2831701023
- Kindgon, J. 1997. The Kingdon Field Guide to African Mammals. Academic Press, San Diego. ISBN: 0713665130
- Moyo, S., P. O’Keefe and M. Sill. 1993. The Southern African Environment. The ETC Foundation Earthscan Publication Limited. London. ISBN: 1853831719
- Pennington, K.M. 1978. Pennington’s Butterflies of Southern Africa. Ad donker, Johannesburg, South Africa. 670 pp. ISBN: 0947430466
- Poynton, J. C., & Broadley D. G. (1985). Amphibia Zambesiaca 2: Ranidae. Ann. Natal Mus. 27, 115-181
- Ramsar Convention on Wetlands. 2001. The Annotated Ramsar List. Botswana. Retrieved 2001.
- Ramsar Convention on Wetlands. 2000. The List of Wetlands of International Importance. Retrieved 2001.
- Stuart, S.N. and R.J. Adams. 1990. Biodiversity in Sub-Saharan Africa and its islands: conservation, management and sustainable use. Occasional Papers of the IUCN Species Survival Commission No. 6. IUCN, Gland, Switzerland. ISBN: 2831700213
- Stuart, C. and T. Stuart. 1992. Guide to Southern African Game and Nature Reserves. Struik, Cape Town. ISBN: 0844289663
- Timberlake, J. 1998. Biodiversity of the Zambezi Basin Wetlands. Phase 1: Review and Preliminary Assessment of Available Information. Volume 1: Main Report. Consultancy report for IUCN- Regional Office for Southern Africa, Harare, Zimbabwe.
- Turpie, J., B. Smith, L. Everton and J. Barnes. 1999. Economic Value of the Zambezi Basin Wetlands. IUCN Regional Office for Southern Africa, University of Cape Town, South Africa.
- Uetz, P. 2001. The EMBL Reptile Database. Retrieved 2001.
- UNEP/GEF/NORAD. 1998. Tanzania. Country Study on Biological Diversity. Government of the United Republic of Tanzania Vice-President's Office, Tanzania.
- White, F. 1983. The vegetation of Africa, a descriptive memoir to accompany the UNESCO/AETFAT/UNSO Vegetation Map of Africa (3 Plates, Northwestern Africa, Northeastern Africa, and Southern Africa, 1:5,000,000. UNESCO, Paris. ISBN: 9231019554
- World Conservation Monitoring Centre (WCMC). 2000. Threatened Animals of the World. Retrieved 2001.
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