The Swartberg range runs parallel to the Outeniqua Mountains IBA in the east of the Western Cape and these two ranges dominate the landscape at the junction of the Western Cape and Eastern Cape provinces. The Seweweekspoort splits the Swartberg into Klein Swartberg to the west and Groot Swartberg to the east. Klein Swartberg runs some 40 km from the Seweweekspoort to south of Laingsburg. It is dominated by Table Mountain Sandstone and includes peaks such as Toringberg (2 127 m a.s.l.), Towerkop (2 189 m a.s.l.) and, in the Western Cape, Seweweekspoort Peak (2 325 m a.s.l.). Groot Swartberg runs some 170 km from the Seweweekspoort to c. 20 km south-west of Willowmore. The Kangoberg (2 022 m a.s.l.), Kariegasberg (2 053 m a.s.l.), Waboomsberg (2 003 m a.s.l.), Tierberg (2 132 m a.s.l.), Tierhoek (2 130 m a.s.l.) and Blesberg (2 084 m a.s.l.) peaks run from west to east, dominating this section of the range. East of Blesberg, the range recedes, forming the Great Karoo plateau to the north and Little Karoo to the south.
The Swartberg slopes are drained by numerous catchments that supply water to the arid Karoo and are the life-blood of many major river systems. The range is deeply incised by the Buffels, Gamka, Seweweeks and Meiringspoort rivers, which cut deep and precipitous gorges through its western section, creating large cliffs. Water from these rivers runs into the Olifants River and in turn into the Touws, Groot and ultimately the Gourits River. The climate is extreme, with temperatures ranging from -4 °C on some high-altitude peaks in winter to over 44 °C on the plains in summer. Rain falls year-round and is mostly cyclonic and orographic, with occasional thunderstorms. Total annual rainfall varies from 750 mm on the high peaks to about 200 mm on the plains.
Two major plant communities are present in the Swartberg: montane fynbos at higher altitudes; and karroid and renosterveld shrubland on the lower slopes, where rainfall is low enough for non-fynbos shrublands to grow on the Table Mountain Quartzites. The stark variation in altitude yields a wide diversity of micro-habitats, resulting in a distinct contrast between the moist Mediterranean fynbos vegetation of the mountains and the dwarf scrub and thornveld of the lower plains. Restioid, ericoid and proteoid elements dominate the fynbos. Deep, secluded mesic gorges on the southern slopes hold very small pockets of Afro-temperate forest, while the base of the southern slopes is covered mostly with renosterveld. The scrub vegetation that grows on much of the Little Karoo plains and on the lower escarpment south of the Swartberg is dominated by low shrubs, in particular the Mesembryanthemaceae, which can be very local in their distribution. The riverine vegetation that lines the mostly dry riverbeds is dominated by Vachellia (formerly Acacia) karroo.
The IBA is extremely rich in both fynbos and karroid endemic species, supporting several restricted-range and biome-restricted assemblage species. At high altitudes the sclerophyllous fynbos is home to Cape Bulbul Pycnonotus capensis, Orange-breasted Sunbird Nectarinia violacea, Cape Siskin Crithagra totta, Cape Sugarbird Promerops cafer and Protea Seedeater Crithagra leucoptera near protea thickets. Cape Rockjumper Chaetops frenatus is common on exposed rocky slopes above 1 200 m a.s.l. Cape Spurfowl Pternistis capensis is widespread. Habitat suitable for Striped Flufftail Sarothrura affinis and Hottentot Buttonquail Turnix hottentottus occurs, and both species are present.
The cliffs hold Black Stork Ciconia nigra, Peregrine Falcon Falco peregrinus, Cape Eagle-Owl Bubo capensis, Booted Eagle Hieraaetus pennatus and Verreauxs' Eagle Aquila verreauxii. Pale-winged Starling Onychognathus nabouroup, Ground Woodpecker Geocolaptes olivaceus and the secretive and localised African Rock Pipit Anthus crenatus occur in rocky gorges and kloofs.
The lowland karroid plains, particularly to the north of the range and marginally outside the boundary of the IBA, are good for Ludwig's Bustard Neotis ludwigii, Karoo Korhaan Eupodotis vigorsii, Karoo Lark Calendulauda albescens, Spike-heeled Lark Chersomanes albofasciata, Karoo Chat Cercomela schlegelii, Karoo Eremomela Eremomela gregalis and Rufous-eared Warbler Malcorus pectoralis. Martial Eagle Polemaetus bellicosus and Black Harrier Circus maurus are occasionally seen quartering the plains. Black-headed Canary Serinus alario occurs whenever seeding grass and water are available.
The belts of riverine Vachellia karroo woodland support Namaqua Warbler Phragmacia substriata and provide food, shelter and breeding habitat for many species, while the thicket and scrub on the slopes support Layard's Tit-Babbler Sylvia layardi and Grey Tit Parus afer. Other arid-zone species include Pale Chanting Goshawk Melierax canorus, Pririt Batis Batis pririt, Fairy Flycatcher Stenostira scita and White-throated Canary Crithagra albogularis. Occasionally Lesser Kestrel Falco naumanni is seen foraging over the karroid plains. The newly described Karoo Long-billed Lark Certhilauda subcoronata occurs in rocky areas.
Globally threatened species are Martial Eagle, Black Harrier and Hottentot Buttonquail. Regionally threatened species are Verreauxs' Eagle, Karoo Korhaan, Lanner Falcon, Cape Rockjumper and African Rock Pipit.
Common restricted-range and biome-restricted species are Cape Spurfowl and Cape Bulbul, while locally common species are Cape Sugarbird, Orange-breasted Sunbird, Cape Siskin, Karoo Chat, Layard's Tit-Babbler, Black-headed Canary, Pale-winged Starling and Namaqua Warbler. Uncommon biome-restricted species are Victorin's Warbler Cryptillas victorini, Cape Rockjumper, Protea Seedeater, Karoo Lark, Karoo Long-billed Lark, Sickle-winged Chat Cercomela sinuata and Karoo Eremomela.
Being in the centre of the Cape Floral Kingdom, this area is thought to hold c. 2 000 plant species, several of which are endemic and/or threatened. It is not possible to provide a comprehensive list of threatened and/or endemic species, so only the more spectacular and unique flora is included. Thirteen species of high-altitude or alpine endemics are restricted to the Swartberg Mountains: Agathosma purpurea, Protea pruinosa, Restio papyraceus, Leucadendron dregei, Phylica stokoei, P. costata, Pentameris swartbergensis, Thamnochortus papyraceus, Cliffortia setifolia, C. crassinerve, Euryops glutinosus, Erica constatisepala and E. toringbergensis.
The global range of the recently described Swartberg African leaf-toed gecko Afrogecko swartbergensis is restricted to the northern slopes of summits in the Swartberg Mountains. Southern African endemic species of more general occurrence include parrot-beaked tortoise Homopus areolatus, angulate tortoise Chersina angulata, black thread snake Leptotyphlops nigricans, spotted harlequin snake Homoroselaps lacteus, Sundevall's shovel-snout Prosymna sundevallii, cross-marked grass snake Psammophis crucifer, Cape cobra Naja nivea, many-spotted snake Amplorhinus multimaculatus, berg adder Bitis atropos, Cape legless skink Acontias meleagris, red-sided skink Mabuya homalocephala, spotted sand lizard Pedioplanis lineoocellata, common mountain lizard Tropidosaura montana Cape girdled lizard Cordylus cordylus, Cape crag lizard Pseudocordylus microlepidotus, southern rock agama Agama atra, ocellated thick-toed gecko Pachydactylus geitje and Cape grysbok Raphicerus melanotis. Threatened mammals such as leopard Panthera pardus and Cape spiny mouse Acomys subspinosus occur in the mountains. The surrounding karroid plains hold aardwolf Proteles cristatus and aardvark Orycteropus afer.
The high mountains of the Swartberg range make reaching much of this IBA very difficult, so a potential threat is the difficulty of controlling activities along the length of the range and a lack of information about these inaccessible areas. However, very few threats occur within the boundaries of the IBA because of this very inaccessibility, and this and the steep gradients of the landscape mostly preclude development and agricultural activities. There are numerous private landowners along the boundary of the Swartberg IBA, and any threats impacting on the trigger species may arise from the land practices directly adjacent to it.
Alien vegetation, including Acacia, Hakea, Pinus and Eucalyptus species, may invade from adjacent areas. It has become a major threat to fynbos vegetation across the Western Cape, rapidly outcompeting the slower-growing indigenous plants and thus reducing the extent of natural vegetation available for the fynbos-endemic birds. The invasive species significantly modify soil composition, fire regimes and natural plant and animal communities, threatening many indigenous species with extinction. Alien trees are also known to accelerate riverbank erosion and reduce in-stream flow through excessive transpiration. The Working for Water programme physically removes alien plants in water catchment areas, helping to increase water run-off and simultaneously employing people.
Fynbos is a fire-maintained ecosystem, and the use of fire as a control agent is now appropriately incorporated into most management plans. However, human disturbance and high densities of alien vegetation have resulted in increased fire frequency across many of the Western Cape mountains. These frequencies prevent longer-lived fynbos plants such as proteas from establishing seed banks and in the long term reduce the populations of these plants and thereby alter the plant communities. This in turn impacts on the fynbos-endemic birds that rely on these plant species.
Although development and agricultural activities are limited due to formal protection and the rugged nature of the IBA, they can occur in certain sections. The associated transformation of habitat, both on the mountains and in the low-lying areas, will threaten the ecology of the IBA by reducing the extent of natural vegetation and habitat for birds. In the foothills of the mountains, the mismanagement of the agricultural land, such as overgrazing and polluting watercourses, can also have major impacts on the ecosystems. The resulting habitat degradation may affect wide-ranging species such as Ludwig's Bustard, while the use of pesticides and poisons may impact on raptor, crane and bustard populations. Grazing cattle may stray and illegal 4x4 routes or walking trails may lead into the IBA from adjacent farms, resulting in additional habitat disturbance.
There are a number of CapeNature reserves and mountain catchment areas (private and State-owned) along the length of this long IBA. These cover large tracts of the IBA and the most important mountain habitats. Their designation as nature reserves under NEM:PAA ensures this IBA receives the highest level of legislative protection. The reserves and catchment areas are Klein Swartberg Mountain Catchment Area, Groot Swartberg Mountain Catchment Area, Towerkop Nature Reserve, Groot Swartberg Nature Reserve, Gamkaskloof Nature Reserve, Gamkapoort Nature Reserve, Swartberg East Nature Reserve and Swartberg-Oos Mountain Catchment Area.
The provincial CapeNature reserves have complex management plans and the resources to implement them. However, it is uncertain who is responsible for managing the mountain catchment areas and currently no direct management occurs. Land swaps between government departments and the declaration of reserves in the mountain catchment sites is being investigated. The conservation actions on the private land vary widely from landowner to landowner, depending on their attitude to nature conservation and to what extent they need income from the land.
CapeNature undertakes comprehensive conservation actions in all their proclaimed nature reserves, according to their gazetted management plans and available resources. These actions include law enforcement through regular patrols, maintaining infrastructure (including trails, roads and accommodation), monitoring the environment, carrying out controlled burns where necessary, fire-fighting, and controlling invasive alien vegetation and soil erosion.
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