|Location||South Africa, Western Cape|
|Central coordinates||18o 12.00' East 31o 42.00' South|
|IBA criteria||A3, A4i|
|Altitude||0 - 30m|
|Year of IBA assessment||1998|
Summary The Olifants River Estuary lies approximately 250 km northwest of Cape Town; it is one of only four perennial estuaries on the west coast of southern Africa. The catchment lies within a winter rainfall area and during winter freshwater flow is strong. Approximately 125 bird species have been recorded at the estuary and its environs; at least 60 of these are waterbirds. The Olifants River Estuary regularly supports over 15 000 waterbirds.
Site description The Olifants river estuary lies c.250 km north-west of Cape Town. The nearest towns are Lutzville and Vredendal, 23.5 km and 42 km east of the estuary respectively. The Olifants river rises in the Agterwitzenberg, a plateau lying between the Winterhoek and the Skurweberg mountains. The flanks of the estuary hold extensive saltmarsh; on both sides of the mouth, a steep rocky shoreline rises to form a gravel terrace.Marine algae grow on rocks near the river mouth, to the west of the island, and in the marshes, both at the mouth and farther upstream. The saltmarsh vegetation is well stratified. The flood-plain also holds numerous plant species with more terrestrial affinities. Reedbeds of Scirpus and Phragmites line the banks of the river upstream from Olifantsdrif. The terrestrial vegetation on higher ground is of considerable interest, as it is one of the few areas where karroid vegetation reaches the west coast. After spring rains the veld breaks out in mass flowering displays.
Key Biodiversity See Box and Table 3 for key species. Approximately 125 bird species have been recorded at the estuary and its environs, with at least 60 of these being waterbirds. The Olifants river estuary regularly supports over 15,000 waterbirds. Pelecanus onocrotalus, which breed at the nearby Dassen Island (IBA ZA088), use the estuary as a primary foraging and roosting area during the non-breeding season. Sterna balaenarum occasionally forage in the estuary. Large numbers of Tadorna cana, Calidris ferruginea and Larus hartlaubii use the estuary when conditions are suitable. Although waterbird numbers are not exceptional, this estuary acts as a vital staging point for both Palearctic migrants and flamingos between the Orange river mouth (IBA ZA023), and the important wetlands to the south and east, such as the Berg river wetlands (IBA ZA083), Langebaan Lagoon (IBA ZA084), Rietvlei (IBA ZA090) and the Wilderness-Sedgefield Lakes complex (IBA ZA093). The vegetation surrounding the estuary is suitable for many of the species restricted to the Namib–Karoo biome and for other arid-zone birds, including Eupodotis vigorsii, Parus afer, the recently recognized Certhilauda albescens, Cercomela tractrac, C. schlegelii, C. sinuata and Serinus alario. Phragmacia substriata occur in the Acacia thickets and reedbeds along the river margin. The recently described Certhilauda curvirostris, a restricted-range species (see account for IBA ZA023), also occurs here.
Non-bird biodiversity: The IBA lies in the centre of the ranges of many Namaqualand-endemic reptiles; most of them have been recorded in the vicinity and are probably present in the terrestrial succulent Karoo vegetation matrix surrounding the wetland, including Homopus signatus, Bitis schneideri (VU), B. cornuta, Acontias litoralis, Typhlosaurus caecus, Scelotes sexlineatus, Meroles knoxii, Cordylus macropholis, Gerrhosaurus typicus (LR/nt), Bradypodion occidentale and Pachydactylus austeni.
|Species||Season||Period||Population estimate||Quality of estimate||IBA Criteria||IUCN Category|
|Ludwig's Bustard Neotis ludwigii||resident||1998||present||-||A3||Endangered|
|Karoo Bustard Heterotetrax vigorsii||resident||1998||present||-||A3||Least Concern|
|Curlew Sandpiper Calidris ferruginea||winter||-||2,131-5,362 individuals||-||A4i||Near Threatened|
|Karoo Lark Certhilauda albescens||resident||1998||present||-||A3||Least Concern|
|Namaqua Warbler Phragmacia substriata||resident||1998||present||-||A3||Least Concern|
|Layard's Warbler Sylvia layardi||resident||1998||present||-||A3||Least Concern|
|Sicklewing Chat Cercomela sinuata||resident||1998||present||-||A3||Least Concern|
|Karoo Chat Cercomela schlegelii||resident||1998||present||-||A3||Least Concern|
|Tractrac Chat Cercomela tractrac||resident||1998||present||-||A3||Least Concern|
|Black-headed Canary Serinus alario||resident||1998||present||-||A3||Least Concern|
|Medium - based upon reliable but incomplete / partially representative data|
|Agriculture and aquaculture||annual & perennial non-timber crops - agro-industry farming||happening now||small area/few individuals (<10%)||no or imperceptible deterioration||low|
|Agriculture and aquaculture||livestock farming and ranching (includes forest grazing) - small-holder grazing, ranching or farming||happening now||some of area/population (10-49%)||slow but significant deterioration||medium|
|Biological resource use||fishing & harvesting aquatic resources - unintentional effects: large scale||happening now||small area/few individuals (<10%)||no or imperceptible deterioration||low|
|Climate change and severe weather||drought||likely in long term (beyond 4 years)||some of area/population (10-49%)||slow but significant deterioration||medium|
|Energy production and mining||mining and quarrying||happening now||some of area/population (10-49%)||moderate to rapid deterioration||high|
|Energy production and mining||renewable energy||likely in short term (within 4 years)||small area/few individuals (<10%)||slow but significant deterioration||low|
|Human intrusions and disturbance||recreational activities||happening now||some of area/population (10-49%)||slow but significant deterioration||medium|
|Natural system modifications||dams & water management/use - large dams||happening now||some of area/population (10-49%)||slow but significant deterioration||medium|
|Pollution||agricultural & forestry effluents - herbicides and pesticides||happening now||some of area/population (10-49%)||slow but significant deterioration||medium|
|Pollution||domestic & urban waste water - sewage||happening now||some of area/population (10-49%)||slow but significant deterioration||medium|
|Residential and commercial development||commercial and industrial development||likely in short term (within 4 years)||some of area/population (10-49%)||slow but significant deterioration||medium|
|Residential and commercial development||housing and urban areas||happening now||some of area/population (10-49%)||slow but significant deterioration||medium|
|Residential and commercial development||tourism and recreation areas||happening now||some of area/population (10-49%)||moderate to rapid deterioration||high|
|Transportation and service corridors||roads and railroads||happening now||some of area/population (10-49%)||slow but significant deterioration||medium|
|Wetlands (inland)||Estuarine waters||0||0||good (> 90%)||moderate (70-90%)||near favourable|
|Little/none of site covered (<10%)||A comprehensive and appropriate management plan exists that aims to maintain or improve the populations of qualifying bird species||Some limited conservation initiatives are in place||low|
|IUCN habitat||Habitat detail||Extent (% of site)|
|Shrubland||Shrubland - Cape (fynbos)||-|
|Wetlands (inland)||Estuarine waters||-|
|Land-use||Extent (% of site)|
|nature conservation and research||60%|
References Cooper et al. (1976), Day (1981), Morant (1984), Ryan et al. (1988), Summers et al. (1977), Turpie (1995).
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Recommended citation BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Olifants river estuary. Downloaded from http://www.birdlife.org on 25/10/2016
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