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Location South Africa, Northern Province
Central coordinates 28o 42.00' East  24o 39.00' South
IBA criteria A1, A4i, A4iii
Area 16,000 ha
Altitude 1,050 - 1,140m
Year of IBA assessment 2001

BirdLife South Africa



Summary The Nyl River forms a 70 km long, 16 000 ha grass floodplain, one of the largest in South Africa. It runs from 10 km south of Mookgopong north to Mokopane. This is the largest wetland of its kind in South Africa and it is basically a grass-dominated, seasonally inundated floodplain which can hold thousands of waterbirds.

Site description The Nyl river forms a 70-km-long grassland flood-plain, one of the largest in South Africa. It runs from 10 km south of Naboomspruit north to Potgietersrus. The area, known as Nylsvley, is located in extensive undulating to flat terrain between 1,050 and 1,080 m. The flood-plain starts to widen at the western edge of Nylsvley Nature Reserve and it attains its greatest width, of five to six kilometres, on the farms downstream from there: Vogelfontein, Weltevreden, Zyferkraal, Du Toits Kraal (the last three embraced by the Mosdene Private Nature Reserve), Groenvaley and Zandpan. At its northern end, on the farm Vaalkop, it narrows and assumes the character of a normal river. The only prominent hills occur at Maroelakop (1,140 m) and Stemmerskop (1,090 m), both are on Nylsvley Nature Reserve and are in close proximity to each other. The system derives its floodwaters from rain that falls in the nearby foothills of the Waterberg range (IBA ZA006).This is the largest wetland of its kind in South Africa and it is basically a grass-dominated, seasonally inundated flood-plain, which in years of poor rainfall may not be flooded at all. It requires rainfall of at least 10% above the annual mean to produce significant inundation. The dominant grass in flooded areas is Oryza longistaminata, which may grow up to 2 m tall and provides cover, food and nesting material for many wetland birds. Many other grass species occur. Dominant sedges include Cyperus, Schoenoplectus and Eleocharis. Large stands of reed Phragmites are also found.Bushes and trees, many of Acacia, are scattered throughout the flood-plain and provide nesting sites for herons, bitterns and egrets. On some of the high-lying areas the vegetation comprises broadleaved savanna and grassland, with trees (up to 9 m tall) of Acacia, Burkea, Terminalia and Combretum. The well-drained low termitaria support Acacia thickets.

Key Biodiversity See Box for key species. The area has a list of 426 bird species, about 46% of the species found in southern Africa. The flood-plain occasionally erupts with activity, holding up to 80,000 birds during high rainfall years. Egretta vinaceigula, Ardeola rufiventris, Sarothrura boehmi and Porzana pusilla breed erratically, whenever conditions are suitable. A relatively large Crex crex population occurs here in the austral summer. The wetland also occasionally supports extremely large numbers of Casmerodius albus, Ardeola ralloides, Nycticorax nycticorax, Platalea alba and Netta erythrophthalma. Tyto capensis is fairly common in the flooded grasslands and Glareola nordmanni occasionally occur in large numbers in the drier grassland surrounding the flood-plain. Almost every species of South African duck is found here from time to time, some in very large numbers. The surrounding woodland holds several restricted-range and biome-restricted species.

Non-bird biodiversity: The reserve holds the mammal Hyaena brunnea (LR/nt).

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
White-backed Duck Thalassornis leuconotus winter  120-220 individuals  A4i  Least Concern 
Southern Pochard Netta erythrophthalma winter  1,000-2,000 individuals  A4i  Least Concern 
Southern Pochard Netta erythrophthalma breeding  400-600 breeding pairs  A4i  Least Concern 
African Spoonbill Platalea alba winter  350-600 individuals  A4i  Least Concern 
African Spoonbill Platalea alba breeding  100-120 breeding pairs  A4i  Least Concern 
Dwarf Bittern Ixobrychus sturmii winter  500-800 individuals  A4i  Least Concern 
Dwarf Bittern Ixobrychus sturmii breeding  200-300 breeding pairs  A4i  Least Concern 
Black-crowned Night-heron Nycticorax nycticorax breeding  500-700 breeding pairs  A4i  Least Concern 
Squacco Heron Ardeola ralloides winter  600-1,300 individuals  A4i  Least Concern 
Squacco Heron Ardeola ralloides breeding  300-550 breeding pairs  A4i  Least Concern 
Great White Egret Ardea alba winter  400-600 individuals  A4i  Least Concern 
Great White Egret Ardea alba breeding  200-500 breeding pairs  A4i  Least Concern 
African Snipe Gallinago nigripennis winter  500-1,000 individuals  A4i  Least Concern 
African Snipe Gallinago nigripennis breeding  250-400 breeding pairs  A4i  Least Concern 
Black-winged Pratincole Glareola nordmanni winter  180-500 individuals  A1, A4i  Near Threatened 
A4iii Species group - waterbirds unknown  20,000 individuals  unknown  A4iii   

IBA Monitoring

2011 very high very unfavourable medium
Habitat
Medium - based upon reliable but incomplete / partially representative data

Agriculture and aquaculture livestock farming and ranching (includes forest grazing) - nomadic grazing happening now whole area/population (>90%) moderate to rapid deterioration very high
Biological resource use hunting & collecting terrestrial animals - unintentional effects (species is not the target) 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 likely in short term (within 4 years) whole area/population (>90%) very rapid to severe deterioration very high
Invasive & other problematic species, genes & diseases invasive non-native/alien species/diseases - named species happening now some of area/population (10-49%) slow but significant deterioration medium
Natural system modifications dams & water management/use - dams (size unknown) happening now some of area/population (10-49%) slow but significant deterioration medium
Natural system modifications fire & fire suppression - suppression in fire frequency/intensity happening now majority/most of area/population (50-90%) moderate to rapid deterioration high
Pollution domestic & urban waste water - sewage likely in short term (within 4 years) majority/most of area/population (50-90%) moderate to rapid deterioration high
Pollution garbage & solid waste happening now whole area/population (>90%) slow but significant deterioration high
Residential and commercial development housing and urban areas happening now whole area/population (>90%) very rapid to severe deterioration very high

Wetlands (inland)   0 0 moderate (70-90%) poor (40-69%) very unfavourable

Some of site covered (10-49%)  A comprehensive and appropriate management plan exists that aims to maintain or improve the populations of qualifying bird species  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)  
Nylsvley Nature Reserve 3,101 protected area contained by site 3,985  
Nylsvley Nature Reserve Wetlands of International Importance (Ramsar) 3,970 protected area contained by site 3,970  

Habitats

IUCN habitat Habitat detail Extent (% of site)
Shrubland Scrub - woodland  -
Grassland Grassland - edaphic, wet  -
Wetlands (inland) Ephemeral pools and wetlands  -

Land use

Land-use Extent (% of site)
agriculture -
water management 15%
nature conservation and research 30%

References Coetzee et al. (1977), Harmse (1977), Tarboton (1979, 1987a,b, 1996), Tarboton et al. (1987).

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Recommended citation  BirdLife International (2015) Important Bird Areas factsheet: Nyl River Floodplain. Downloaded from http://www.birdlife.org on 24/05/2015

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