De Hoop Nature Reserve is situated near the southern tip of Africa, c. 56 km east of Bredasdorp. It comprises a unique diversity of natural habitats situated in a mosaic of grain fields and wheat pastures, and includes a marine protected area that extends c. 5 km offshore and 50 km along the length of the reserve. Also included in the reserve is De Hoop Vlei, a landlocked, brackish expanse of water that formed when the mouth of the Sout River was blocked by the emergence of estuarine sandbars.
The vlei, which is fed by several underground springs and the Sout and Potteberg rivers, is separated from the ocean by 2.5 km of mobile sand dunes. It is c. 15 x 0.5 km in extent and its depth varies considerably, reaching a maximum of 8 m during periods of flooding, which may persist for several years. During floods, large areas of adjacent land, mainly to the south-west, are inundated. On the other hand, the vlei has dried up completely in times of drought. Salinity can also vary considerably; fluctuations of between three and 49 parts per thousand have been recorded over a three-year period. The area is fairly arid and receives an average rainfall of 400 mm p.a. The maritime influence on the climate is obvious, with little temperature variation: the annual average minimum temperature is 13.3 °C and the maximum is 19.4 °C.
Coastal fynbos growing on limestone or karst hills takes up the major part of the reserve. The limestone was deposited over less soluble sandstone during the late Tertiary, and limestone outcrops support an extremely rare fynbos type that is rich in endemic flora, containing distinctive plants that grow only in alkaline soil. The Potberg, an inselberg of sandstone and quartzites holding acidic and nutrient-poor soil, rises abruptly in the north-east. The isolated and unique nature of this mountain has resulted in the evolution of an unusually dry mesic heath that includes many species endemic to the mountain.
The reserve's astonishing terrestrial diversity is coupled with a rugged coastline, which is gently concave and faces the broadest part of the Agulhas Bank. Along the coast, the limestone and sandstone cliffs have been worn into fantastic shapes by wind and waves, which have also eroded reefs and gullies and scoured out rocky pools that are backed by long pristine beaches. The meeting of the icy Benguela and warm, subtropical Agulhas currents contributes to the reserve's diversity of habitats, both terrestrial and marine. A system of shifting dunes – some up to 100 m high – at Koppie Alleen covers c. 1 000 ha. The dunes hold few plant species, but the unique dune fynbos is adapted to this unstable environment.
At least 260 species have been recorded at the reserve, 97 of which are waterbirds and dependent primarily on the Ramsar-designated De Hoop Vlei. The vlei supports on average more than 8 000 birds, although the system is highly variable and numbers of waterbirds visiting and breeding fluctuate considerably, depending on water levels and salinity. In good years the vlei has supported more than 30 000 birds, but during drought years the numbers are severely depleted.
This is the only locality in South Africa where Greater Flamingo Phoenicopterus roseus has bred successfully (in 1960 and 1963), and it still occurs regularly at the vlei. The site is also occasionally used by important numbers of Lesser Flamingo Phoeniconaias minor. Other non-breeding threatened and near-threatened species that occur here include Caspian Tern Sterna caspia, Chestnut-banded Plover Charadrius pallidus and Great White Pelican Pelecanus onocrotalus. The vlei also sometimes has extremely large numbers of Yellow-billed Duck Anas undulata, Cape Shoveler A. smithii, Red-knobbed Coot Fulica cristata and Egyptian Goose Alopochen aegyptiacus. The surrounding marsh and reedbeds hold African Marsh Harrier Circus ranivorus. Damara Tern Sterna balaenarum, which breeds at the nearby Heuningnes Estuary, is occasionally seen along the De Hoop coastline.
A cliff on Potberg has the only remaining colony of breeding Cape Vultures Gyps coprotheres in the Western Cape. At one point the population fell to below 50 individuals, but since the late 1980s the decline has been reversed and numbers have recovered substantially. The improvement can be attributed to a change to more vulture-friendly agricultural practices in the foraging range of the species. The short restioid fynbos on the slopes of Potberg is known to hold Striped Flufftail Sarothrura affinis and Hottentot Buttonquail Turnix hottentottus.
There are significant populations of Blue Crane Anthropoides paradiseus, Denham’s Bustard Neotis denhami, Southern Black Korhaan Afrotis afra and Black Harrier Circus maurus on the open plains of the reserve, as well as in the modified agricultural matrix of the surrounding Overberg Wheatbelt IBA (SA115). De Hoop also has several Cape Fynbos EBA restricted-range species: Orange-breasted Sunbird Anthobaphes violacea occurs in the ericas, while Cape Sugarbird Promerops cafer is almost restricted to the proteoid elements. Cape Spurfowl Pternistis capensis, Cape Bulbul Pycnonotus capensis and Cape Siskin Crithagra totta are widespread in the fynbos. Some typically karroid birds are also found here, including Karoo Korhaan Eupodotis vigorsii and Grey Tit Parus afer, and the localised Agulhas Long-billed Lark Certhilauda brevirostris also occurs. Knysna Woodpecker Campethera notata is a scarce inhabitant of the forested gorges. The beaches hold breeding pairs of African Black Oystercatcher Haematopus moquini.
Globally threatened species are Cape Vulture (242 individuals and 69 breeding pairs), Lesser Flamingo (average 95, maximum 1 700 individuals), Secretarybird Sagittarius serpentarius, Blue Crane, Denham’s Bustard, Southern Black Korhaan, African Black Oystercatcher, Black Harrier, Knysna Woodpecker, Bank Cormorant Phalacrocorax neglectus, Crowned Cormorant P. coronatus, Cape Cormorant P. capensis, Chestnut-banded Plover and Maccoa Duck Oxyura maccoa. Regionally threatened species are Karoo Korhaan, Caspian Tern (average 10, maximum 65 individuals), Greater Flamingo (average 330, maximum 2 000 individuals), Great White Pelican (average 30, maximum 250 individuals), Verreauxs’ Eagle Aquila verreauxii, African Marsh Harrier, Lanner Falcon Falco biarmicus, Black Stork Ciconia nigra, Striped Flufftail and Agulhas Long-billed Lark.
Restricted-range and biome-restricted species that are common in the IBA include Cape Spurfowl, Cape Bulbul, Cape Sugarbird, Orange-breasted Sunbird, Cape Siskin, Southern Black Korhaan, Agulhas Long-billed Lark and Knysna Woodpecker.
Congregatory species meeting the 1% or more population threshold are Cape Shoveler (average 650, maximum 3 050 individuals), Great Crested Grebe Podiceps cristatus (average 70, maximum 530 individuals), Red-knobbed Coot (average 4 460, maximum 20 800 individuals), Egyptian Goose (average 550, maximum 3 200 individuals), White-breasted Cormorant Phalacrocorax lucidus (average 70, maximum 730 individuals), Black-winged Stilt Himantopus himantopus (average 90, maximum 530 individuals), Black-necked Grebe Podiceps nigricollis (average 30, maximum 420 individuals), Maccoa Duck (average 20, maximum 890 individuals), Pied Avocet Recurvirostra avosetta (average 20, maximum 40 individuals), South African Shelduck Tadorna cana (average 50, maximum 900 individuals), Spur-winged Goose Plectropterus gambensis (average 50, maximum 950 individuals), Greater Flamingo, Lesser Flamingo and Caspian Tern. Marsh Sandpiper Tringa stagnatilis (average five, maximum 370 individuals), Swift Tern Thalasseus bergii (average one, maximum 160 individuals) and Great White Pelican (average 27, maximum 435 individuals) meet the 0.5% or more population threshold.
The reserve is thought to contain more than 1 500 plant species, of which 108 fynbos species are threatened and/or endemic to De Hoop and its immediate vicinity. There are at least 50 endemic species: 12 occur only on Potberg and the rest grow on the limestone outcrops. Fourteen species have been discovered recently and are not yet described; eight of these are not known to occur outside De Hoop Nature Reserve.
The reserve holds a healthy population of the South African endemic Cape mountain zebra Equus zebra zebra and the world’s largest population of bontebok Damaliscus dorcas dorcas, which is endemic to the Cape Floral Kingdom. The South African endemic sand toad Bufo angusticeps, sand rain frog Breviceps rosei, Cape sand frog Tomopterna delalandii, silvery dwarf burrowing skink Scelotes bipes, Cape grysbok Raphicerus melanotis, grey rhebok Pelea capreolus and the highly localised southern adder Bitis armata occur in this IBA. The marine reserve off the coast protects a wide diversity of organisms, especially the southern right whale Eubalaena australis, which mates and calves here annually between June and December.
The formal proclamation and wise management of the reserve have minimised the number of threats facing the area and its biodiversity. The major threat comes from invasive alien vegetation such as Port Jackson Acacia saligna, rooikrans A. cyclops, black wattle A. mearnsii and blue gum Eucalyptus species. Encroachment by alien vegetation leads to transformation and loss of habitat for the key trigger bird species and other biodiversity, as well as the loss of threatened vegetation types that occur in this IBA. The 1 500 plant species found in this small reserve, many of which are threatened and/or endemic, represent one of the highest diversities in the Cape Floral Kingdom. In the past, patches of veld were burned in order to improve grazing, often at an undesirable frequency, intensity and season. This resulted in many members of the Proteaceae being destroyed before they had time to produce seeds. The Bredasdorp coastal strip supports a large variety of natural floral communities, with many endemics occurring in small localised populations. These plants are extremely vulnerable to extinction as a result of habitat loss and physical disturbance to their environment. Renosterveld vegetation occurring farther inland is Critically Endangered and more than 90% of it has been ploughed up for agriculture.
Armscor’s development of the Overberg test range next to De Hoop in 1983 resulted in increased activity, vehicular use, construction, noise pollution and the burning of vegetation, all of which have had an impact on the neighbouring land. It is possible that this missile-testing facility will cause additional disturbance, particularly to the Cape Vulture colony.
Cape Vultures forage widely outside the reserve and are vulnerable to the indiscriminate use of poison by small-stock farmers targeting mammalian predators such as jackals, caracals and dogs. Although the farmers around De Hoop are highly responsible and very eager to contribute to conservation programmes, it must be emphasised that a single poisoned carcass could decimate the entire colony. Concerned farmers on property near Potberg and adjacent to De Hoop have set up a vulture restaurant of their own accord, and the increase in vulture numbers in the district can be attributed to the active cooperation of enlightened farmers in the area.
Additional threats include disturbance due to recreational developments and the footprint of the infrastructure associated with these developments, as well as fires that may go out of control because of the age of the natural vegetation. Wind-energy facilities are planned for the Overberg region outside the boundaries of this IBA. Some of the trigger species, such as Cape Vulture and Verreauxs’ Eagle, forage outside the IBA and risk collision with these facilities, as do Blue Crane, Denham’s Bustard, Great White Pelican and Secretarybird. The area immediately to the north (within 20 km) of the IBA forms part of a potential Renewable Energy Development Zone (currently a ‘focal area’), as identified in the national Strategic Environmental Assessment for Renewable Energy.
De Hoop Nature Reserve was established in 1956 for the purpose of breeding game and several farms have subsequently been bought and incorporated into it. The reserve is currently administered and managed by CapeNature. De Hoop Vlei was designated a Ramsar site in 1975 and expanded in 1986 to include the section between the causeway at Apolsfontein in the north and De Mond in the south. The marine reserve, which extends 3 nmi off the coast, was also included in 1986. The reserve is formally protected as a provincial nature reserve, gazetted through NEM:PAA. The offshore section is a marine protected area, which was originally proclaimed under the Marine Living Resources Act but now falls under NEM:PAA. The reserve also forms part of a World Heritage Site.
Comprehensive management plans are required by law for all formally protected areas in South Africa. CapeNature is in the process of drafting Protected Area Management Plans for all its proclaimed nature reserves, and the plan for De Hoop will be finalised and submitted to the Minister of Environmental Affairs in 2015. In the meantime, an annual plan of operations guides all management actions in the reserve. CapeNature staff oversee all aspects of management with respect to conservation, such as alien plant eradication, law enforcement and regular bird monitoring counts at De Hoop Vlei and the Potberg vulture colony, as well as infrastructure maintenance. A private partner has developed certain tourism facilities and activities within the reserve and is responsible for managing them. The Potberg Environmental Education Centre in the reserve is used by schools as part of their curriculum for environmental education.
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