|Location||Botswana, South East|
|Central coordinates||25o 57.60' East 24o 37.20' South|
|Year of IBA assessment||2001|
Site description Four large sewage-treatment lagoons, operational since late 1990, surrounded by grassland and Acacia-dominated savanna, c.15 km north of Gaborone, close to the dormitory village of Phakalane. The lagoons are roughly rectangular (totalling 70 ha of water), generally steep-sided, and edged by high bunds. There are some exposed muddy edges, small areas of sand and gravel, several very small islands and remnants of dead and dying trees in one lagoon. There is marginal vegetation of Typha, Phragmites and scattered small trees and bushes.The site lies adjacent to the Ngotwane river, a small tributary of the Limpopo, into which the final effluent discharges. Riparian vegetation along this section of the Ngotwane is dominated by Combretum and there are some open areas of wet grassland and Juncus. Upriver in and south of Gaborone (outside the IBA) there are a series of artificial wetlands along the Ngotwane river. These are interlinked in that all are used by waterfowl which frequently move from one dam or sewage pond to another. These wetlands include Mogobane Dam, Ngotwane Dam, the large Gaborone Dam completed in 1964/65 and covering 19 km², various sewage ponds in Gaborone, notably Ngotwane, Maru-a-Pula and Tsholofelo, and associated wetlands such as the Typha swamp in Gaborone Game Reserve. Although all these at times hold a diversity of waterfowl, none support large numbers nor any species in numbers that exceed the 0.5% threshold. Phakalane sewage ponds are undoubtedly the most important in this chain of wetlands.
Key Biodiversity See Box for key species. Phakalane lagoons support a wide diversity of visiting waders, wildfowl and other waterbirds, including both species of Phoenicopterus. Although the total numbers are not exceptionally high, July 1994 saw nearly 1,600 waterbirds of 35 species and January 1995 over 3,000 birds of 36 species. Of particular note are the high numbers of Oxyura maccoa, particularly in the winter (usually 100–200, but with a maximum of 440 recorded in July 1993). There are also regularly high numbers of Netta erythrophthalma.Small numbers of some duck breed by the lagoons whilst waterbirds, notably Threskiornis aethiopicus and Bubulcus ibis, roost on dead trees. In the early years herons and egrets bred in the dead trees in the lagoons but the heronries have largely disappeared as these trees have died and fallen. The Typha stands support large numbers of Acrocephalus warblers. A roost of more than 50,000 Hirundo rustica occurs at Gaborone Dam, some birds also roosting at Phakalane.
Non-bird biodiversity: None known to BirdLife International.
|Species||Season||Period||Population estimate||Quality of estimate||IBA Criteria||IUCN Category|
|Maccoa Duck Oxyura maccoa||winter||1993-1995||100-440 individuals||good||A4i||Near Threatened|
|Southern Pochard Netta erythrophthalma||winter||1993-1995||605 individuals||good||A4i||Least Concern|
|2013||very high||not assessed||negligible|
|Biological resource use||hunting & collecting terrestrial animals - intentional use (species being assessed is the target)||happening now||majority/most of area/population (50-90%)||moderate to rapid deterioration||high|
|Human intrusions and disturbance||work and other activities||happening now||whole area/population (>90%)||very rapid to severe deterioration||very high|
|Invasive & other problematic species, genes & diseases||problematic native species/diseases - unspecified species||happening now||whole area/population (>90%)||very rapid to severe deterioration||very high|
|Pollution||domestic & urban waste water - type unknown/unrecorded||happening now||whole area/population (>90%)||moderate to rapid deterioration||very high|
|Little/none of site covered (<10%)||No management planning has taken place||Very little or no conservation action taking place||negligible|
|IUCN habitat||Habitat detail||Extent (% of site)|
|Artificial - aquatic||major|
|Land-use||Extent (% of site)|
References Bishop (1994), Bishop (1995), Bishop and Tyler (1998), Tyler (2001).
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Recommended citation BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Phakalane sewage lagoons, near Gaborone. Downloaded from http://www.birdlife.org on 25/10/2016
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