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Location South Africa, Western Cape
Central coordinates 18o 12.00' East  31o 42.00' South
IBA criteria A3, A4i
Area 2,000 ha
Altitude 0 - 30m
Year of IBA assessment 2001

BirdLife South Africa



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.

Populations of IBA trigger species

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  Least Concern 
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 

IBA Monitoring

2014 high near favourable low
Habitat
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 

Habitats

IUCN habitat Habitat detail Extent (% of site)
Shrubland Shrubland - Cape (fynbos)  -
Wetlands (inland) Estuarine waters  -
Grassland   100%

Land use

Land-use Extent (% of site)
urban/industrial/transport -
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 (2015) Important Bird Areas factsheet: Olifants river estuary. Downloaded from http://www.birdlife.org on 28/05/2015

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