Sites - Important Bird and Biodiversity Areas (IBAs)
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14o 30.00' East 23o 20.00' South
A1, A4i, A4iii
Year of IBA assessment
Site description Sandwich Harbour is a natural lagoon which lies on the Namib desert coast, c.55 km south of Walvis Bay. One of Namibia’s four Ramsar Sites, and the country’s only marine reserve, Sandwich was once a natural harbour for whalers and fish processors who could gain access to fresh water here. Owing to dynamic geomorphological change, its sandbars and lagoons shift constantly with winter storms and longshore currents.
Two main sections of this wetland are recognized: the northern freshwater wetland, much reduced in size since the early 1970s when it covered c.2 km², and the southern mudflats, a 20 km² area of sand and mudflats inundated daily by the tides. The northern wetland is now a thin sliver, mainly of reedbed Phragmites, fed by a massive freshwater aquifer beneath the high dunes of the Namib sand-sea. This potable water slowly seeps through the wetland and there supports lush but dwindling stands of emergent and marginal vegetation. The wetland is protected from the Atlantic Ocean swells by a barrier beach which has moved from 1 km to within 100 m of the dunes. The southern lagoon, which leads into mudflats, is a relatively shallow water-body some 5 km long by 3 km wide. It is protected from the ocean by a western sand-spit that once reached the northern wetland but now joins the mainland some 3 km south of it.Sandwich Harbour is one of the most geomorphologically active areas along the entire Namib coast. In the late 1800s there was no barrier beach and therefore no protected wetland and an otherwise open harbour. The system continues to evolve rapidly and contrary to popular belief it is far from dead.
Key Biodiversity See Box for key species. This is the most important wetland for waterbirds in southern Africa, with counts exceeding 300,000 birds in some years. Sandwich Harbour regularly supports over 50,000 birds in summer and over 20,000 in winter. Traditionally, the northern wetland holds the highest species diversity (up to 51 species of wetland bird), while the southern mudflats hold by far the largest number of birds, dominated by terns, sandpipers, flamingos and cormorants. Shorebirds occur here at densities exceeding 7,000 birds/km², amongst the highest recorded in the world. The largest total counts at Sandwich Harbour have been 238,000 birds in January 1998 and 316,000 in January 2001.
The area is vitally important for Palearctic waders and flamingos, which comprise the majority of the numbers. The area supports massive numbers of several species, including Phalacrocorax capensis, Phoenicopterus ruber and P. minor, Sterna hirundo, up to 40% of the world population of Charadrius pallidus, and tens of thousands of Calidris ferruginea and C. minuta. At times, the combined total of birds in Sandwich Harbour and Walvis Bay is so large that it constitutes half of all birds counted in southern Africa during African waterfowl counts.
Non-bird biodiversity: The dolphin Tursiops truncatus (DD) is seen in the lagoons, with pods of 10–20 animals not uncommon, while a non-breeding colony of c.10,000 Arctocephalus pusillus occupies the beach west of the mudflats. Hyaena brunnea (LR/nt) is a frequent visitor to the wetland.