Onrus River Estuary (34241910) | |
|---|---|
Western Cape | |
| CWAC status | REGISTERED-COUNTED REGULARLY |
| Authority | |
| Management status | Coastal Public Property (CPP) |
| Conservation status | Unprotected |
| IBA information | Cape Whale Coast IBA |
| Ramsar information | |
| Heritage information | |
| View Cards | Click here |
Information |
|---|
| Date_registered |
| 2026-02-12 |
| Brief_description |
| The Onrus River Estuary, near Hermanus on the southern coast of the Western Cape, is a small estuarine system where the Onrus River meets the sea, historically forming a shallow lagoon with open water, reed beds, and wetland fringes that support diverse birdlife and aquatic habitats. The Onrus River Estuary forms part of the Cape Whale Coast IBA. The system has been severely disturbed by upstream water abstraction, reduced freshwater inflows, nutrient enrichment, bacterial contamination from aged and damaged sewage infrastructure, and extensive growth of common reed (Phragmites australis), which has reduced open-water areas and biodiversity. Urban development around the estuary and related recreational pressures further alter habitat and contribute to water-quality issues, underscoring the importance of integrated management and restoration for the estuary’s ecological health and recreational value. |
| Hydrological_features |
| • Estuarine waters – permanent water of estuarine systems (90%) • Intertidal mud, sand, or salt flats (10%) |
| Ecological_features |
| WETLAND COMPOSITION: • Emergent vegetation (60%) – Common reed • Open water (35%) • Sand/ mudbanks (5%) • Surrounding vegetation: Fynbos, Strandveld, IAP cover, Trees, Shrubs, Grasses • Dominant substrate type: mud • Acidity: unknown • Salinity: Brak – Saline (dependent on mouth conditions) • Approximate size: 11 ha • Approximate maximum depth: 1-2m (dependent on timing of dredging) • Site/ wetland context: Single, discrete wetland |
| Spp | Common name | Taxonomic name | Min | Avg | Max | IBA | Subregional IBA | RAMSAR |
|---|---|---|---|---|---|---|---|---|
| 67 | Bittern, Little | Ixobrychus minutus | 1 | 1.00 | 1 | |||
| 212 | Coot, Red-knobbed | Fulica cristata | 1 | 3.27 | 7 | |||
| 50 | Cormorant, Reed | Microcarbo africanus | 1 | 3.50 | 8 | |||
| 47 | Cormorant, White-breasted | Phalacrocorax lucidus | 1 | 2.73 | 5 | |||
| 203 | Crake, Black | Zaporina flavirostra | 1 | 2.50 | 4 | |||
| 52 | Darter, African | Anhinga rufa | 1 | 2.44 | 6 | |||
| 96 | Duck, Yellow-billed | Anas undulata | 2 | 5.80 | 9 | |||
| 59 | Egret, Little | Egretta garzetta | 1 | 3.78 | 9 | |||
| 61 | Egret, Western Cattle | Bubulcus ibis | 4 | 12.65 | 21 | |||
| 89 | Goose, Egyptian | Alopochen aegyptiaca | 1 | 5.57 | 22 | |||
| 6 | Grebe, Little | Tachybaptus ruficollis | 2 | 3.00 | 5 | |||
| 288 | Gull, Grey-headed | Chroicocephalus cirrocephalus | 1 | 1.00 | 1 | |||
| 289 | Gull, Hartlaub's | Chroicocephalus hartlaubii | 2 | 10.83 | 24 | |||
| 287 | Gull, Kelp | Larus dominicanus | 1 | 4.62 | 25 | |||
| 55 | Heron, Black-headed | Ardea melanocephala | 1 | 1.89 | 3 | |||
| 54 | Heron, Grey | Ardea cinerea | 1 | 2.22 | 8 | |||
| 57 | Heron, Purple | Ardea purpurea | 1 | 1.00 | 1 | |||
| 62 | Heron, Squacco | Ardeola ralloides | 1 | 1.00 | 1 | |||
| 81 | Ibis, African Sacred | Threskiornis aethiopicus | 4 | 17.05 | 54 | |||
| 84 | Ibis, Hadada | Bostrychia hagedash | 2 | 5.14 | 12 | |||
| 397 | Kingfisher, Malachite | Corythornis cristatus | 1 | 1.00 | 1 | |||
| 394 | Kingfisher, Pied | Ceryle rudis | 1 | 1.90 | 2 | |||
| 245 | Lapwing, Blacksmith | Vanellus armatus | 1 | 4.08 | 9 | |||
| 210 | Moorhen, Common | Gallinula chloropus | 1 | 3.00 | 5 | |||
| 69 | Night Heron, Black-crowned | Nycticorax nycticorax | 1 | 5.25 | 11 | |||
| 231 | Oystercatcher, African | Haematopus moquini | 2 | 2.00 | 2 | |||
| 238 | Plover, Three-banded | Charadrius tricollaris | 3 | 7.00 | 11 | |||
| 235 | Plover, White-fronted | Charadrius marginatus | 2 | 5.14 | 17 | |||
| 94 | Shoveler, Cape | Anas smithii | 2 | 4.11 | 11 | |||
| 270 | Stilt, Black-winged | Himantopus himantopus | 3 | 3.00 | 3 | |||
| 208 | Swamphen, African | Porphyrio madagascariensis | 1 | 1.00 | 1 | |||
| 98 | Teal, Cape | Anas capensis | 2 | 3.50 | 6 | |||
| 97 | Teal, Red-billed | Anas erythrorhyncha | 2 | 2.00 | 2 | |||
| 290 | Tern, Caspian | Hydroprogne caspia | 2 | 2.00 | 2 | |||
| 274 | Thick-knee, Water | Burhinus vermiculatus | 1 | 2.22 | 6 | |||
| 686 | Wagtail, Cape | Motacilla capensis | 1 | 2.89 | 6 |
Wednesday 20 May 2026 02:08
FitzPatrick Institute of African Ornithology
Department
of Biological Sciences - University of Cape Town
This work is licensed under a
Creative
Commons Attribution-Noncommercial-Share Alike 3.0 Unported License