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Location South Africa, Western Cape
Central coordinates 20o 0.00' East  34o 43.00' South
IBA criteria A1, A4i
Area 9,000 ha
Altitude 0 - 20m
Year of IBA assessment 2001

BirdLife South Africa



Summary This complex wetland system is located at the southern tip of the African continent 25 km south of Bredasdorp and consists of the Nuwejaarsrivier and its associated marshes, Soetendalsvlei and the Heuningnes River and its estuary, the latter is located in De Mond Nature Reserve.

Site description This complex wetland system, located at the southern tip of the African continent, 25 km south of Bredasdorp, consists of the Nuwejaarsrivier and its associated marshes, Soetendalsvlei and the Heuningnes river and its estuary (the southernmost estuary in Africa). The area of interest extends from 5 km upstream of the Nuwejaarsrivier–Soetendalsvlei confluence to the mouth of the Heuningnes river. The vlei acts as a reservoir, and when it overflows, the run-off spills over into the Heuningnes river, which feeds the estuary. The primary wetland area is found between Heuningrug and Wiesdrif. Vegetation includes mixed and monospecific stands of tall to short sedges, reeds and grasses (Eleocharis, Cyperus, Scirpus, Typha, Phragmites), open mud patches, shallow water, Isolepis mats, deep pools and shallow pan-like pools. A second wetland area is the 5 km stretch of the Nuwejaarsrivier close to Moddervlei. The Wiesdrif pan on the farm is a shallow flooded depression in grassland, with much emergent vegetation. Many of the river channels are poorly defined and drainage into the estuary occurs via vleis and marshes, which constitute large areas of wetland.The estuary mouth comprises an extensive bay with sand, mudflats and tidal saltmarsh, dominated by Limonium, Salicornia and Sarcocornia. Heavily grazed and degraded flood-plain vegetation is found between the saltmarsh and the sandbanks. Patches of reed Phragmites occur at places along the riverbanks. The terrestrial vegetation adjacent to the estuary consists of dune scrub (coastal fynbos). The estuary is important as a nursery ground for marine fish.

Key Biodiversity See Box for key species. Larus dominicanus regularly nests in the dunes a few kilometres to the north-east of Heuningnes mouth. The pebble slacks behind the beach are one of only two protected, confirmed breeding sites for Sterna balaenarum in South Africa, holding 15% of the national breeding population, and Sterna caspia, Haematopus moquini, Charadrius pecuarius and Plectropterus gambensis all breed regularly. Rostratula benghalensis, of the isolated and declining Western Cape breeding population, is also present in good numbers. Grus paradisea occasionally roosts and feeds at open pools in the middle of the wetland. Circus maurus and C. ranivorus have been recorded at the site. Pelecanus onocrotalus occasionally occurs in large numbers.The Nuwejaarsrivier marshes are excellent for secretive rails and crakes. Porzana pusilla is numerous and probably breeds, Sarothrura rufa has been recorded at a density of one pair/0.25 ha in excellent habitat, and Rallus caeruleus and Amaurornis flavirostris are widespread and abundant. Small numbers of migrant Palearctic and resident waders regularly use the site, including Charadrius hiaticula, C. pecuarius, Calidris ferruginea and C. minuata.

Non-bird biodiversity: The reptile Bradypodion pumilum (CR) is thought to occur in the area.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Kelp Gull Larus dominicanus breeding  300-450 breeding pairs  A4i  Least Concern 
Kelp Gull Larus dominicanus winter  700-1,000 individuals  A4i  Least Concern 
Damara Tern Sternula balaenarum breeding  common  A1  Near Threatened 

IBA Monitoring

2013 high not assessed medium
unset
Medium - based upon reliable but incomplete / partially representative data

Agriculture and aquaculture annual & perennial non-timber crops - shifting agriculture happening now some of area/population (10-49%) slow but significant deterioration medium
Agriculture and aquaculture annual & perennial non-timber crops - small-holder farming happening now some of area/population (10-49%) slow but significant deterioration medium
Agriculture and aquaculture livestock farming and ranching (includes forest grazing) - agro-industry grazing, ranching or farmin happening now some of area/population (10-49%) moderate to rapid deterioration high
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: subsistence/small scale happening now some of area/population (10-49%) slow but significant deterioration medium
Biological resource use hunting & collecting terrestrial animals - persecution/control happening now some of area/population (10-49%) slow but significant deterioration medium
Biological resource use hunting & collecting terrestrial animals - unintentional effects (species is not the target) happening now some of area/population (10-49%) no or imperceptible deterioration low
Climate change and severe weather storms and floods happening now some of area/population (10-49%) no or imperceptible deterioration low
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
Invasive & other problematic species, genes & diseases invasive non-native/alien species/diseases - unspecified species happening now some of area/population (10-49%) slow but significant deterioration medium
Natural system modifications dams & water management/use - abstraction of surface water (unknown use) happening now some of area/population (10-49%) slow but significant deterioration medium
Natural system modifications other ecosystem modifications happening now some of area/population (10-49%) moderate to rapid deterioration high
Pollution agricultural & forestry effluents - herbicides and pesticides happening now some of area/population (10-49%) slow but significant deterioration medium
Pollution agricultural & forestry effluents - nutrient loads happening now some of area/population (10-49%) no or imperceptible deterioration low
Residential and commercial development commercial and industrial development likely in short term (within 4 years) small area/few individuals (<10%) no or imperceptible deterioration low
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%) slow but significant deterioration medium
Transportation and service corridors roads and railroads happening now some of area/population (10-49%) no or imperceptible deterioration low
Transportation and service corridors utility & service lines happening now some of area/population (10-49%) slow but significant deterioration medium

Shrubland   0 0 poor (40-69%) poor (40-69%) very unfavourable
Wetlands (inland) Intertidal mud, sand or salt flats  0 0 moderate (70-90%) moderate (70-90%) unfavourable

Haematopus moquini African Oystercatcher 25 25 individuals 100 favourable
Larus dominicanus Kelp Gull 1000 119 individuals 12 not assessed
Sternula balaenarum Damara Tern 30 10 individuals 34 very unfavourable

Most of site (50-90%) covered (including the most critical parts for important bird species)  A management plan exists but it is out of date or not comprehensive  Substantive conservation measures are being implemented but these are not comprehensive and are limited by resources and capacity  medium 

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
De Mond Provincial Nature Reserve 927 protected area contained by site 1,580  
De Mond (Heuningnes estuary) Wetlands of International Importance (Ramsar) 918 protected area contained by site 918  

Habitats

IUCN habitat Habitat detail Extent (% of site)
Wetlands (inland) Intertidal mud, sand or salt flats; Salt marshes; Sand dunes and beaches - riverine  -
Artificial - terrestrial   12%
Shrubland   62%
Forest   25%

Land use

Land-use Extent (% of site)
other -
nature conservation and research 100%

References Bickerton (1984), Burger et al. (1980), Cowan (1995), Cowan and Marneweck (1996), Crawford et al. (1982a), Summers et al. (1976), Taylor (1997a,b), Underhill and Cooper (1984).

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Recommended citation  BirdLife International (2015) Important Bird Areas factsheet: Agulhas Plain - Heuningnes Estuary. Downloaded from http://www.birdlife.org on 22/05/2015

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