This IBA previously encompassed only the Tsitsikamma section of the Garden Route National Park, but the boundary has been extended further west to incorporate important habitats and species' populations in and around Plettenberg Bay. Approximately 24 000 ha in extent, the Tsitsikamma section of the Garden Route National Park is situated in the De Vasselot area of the Eastern Cape and Western Cape provinces. It stretches for about 80 km, beginning west of the Sout River near Nature's Valley and continuing eastward to the Groot River, which has its source near Kareedouw. This section extends 3–4 km inland along the gorges of the Brak, Sout, Bobbejaans and Groot rivers, whose cliff faces rise to between 40 and 220 m high. To the east of Nature's Valley the park is restricted to the steeply sloping coastal escarpment.
The IBA's boundary has been extended to align with the marine protected area directly offshore of the national park's Tsitsikamma section. It runs from the south-western edge of the Tsitsikamma MPA c. 20 km across to the north-eastern corner of the Robberg MPA, thereby incorporating the entire Plettenberg Bay coastline and near-shore areas. Following the border of the Robberg MPA, it then aligns with the terrestrial boundary of CapeNature's Robberg Nature Reserve, runs north along Robberg Beach, takes in the estuary of the Piesang River and continues north along Plettenberg Bay's middle beach before moving inland to the western shore of the Keurbooms River estuary. The IBA thus incorporates the Keurbooms estuary spit, an important breeding site for Kelp Gull and other species. It joins the CapeNature Keurbooms River Nature Reserve at the Keurbooms River bridge over the N2 highway and extends inland c. 4.5 km along the Keurbooms River valley. The IBA's border then follows this reserve's boundary south and east, where it joins the Nature's Valley section of the Garden Route National Park and encompasses additional fynbos and forest habitats protected in the national park. The final stretch of the IBA aligns with the northern boundary of the Tsitsikamma section of the Garden Route National Park.
The IBA has been enlarged to include the bird breeding colonies on the Keurbooms estuary spit and important fynbos and forest habitats. Much of this expansion aligns with existing protected area boundaries, thus ensuring the sustainable protection of the IBA. At no extra cost, it helps to gain greater protection for these areas by encouraging active support and can play a vital role in increasing avitourism in the region and enhancing public awareness of the area's biodiversity value.
The major geological formations of the area are of Table Mountain Sandstone and Bokkeveld Shale. The Tsitsikamma section of the Garden Route National Park lies on a plateau that falls abruptly to the rocky shoreline 120 m below. The coastal plain, the sheer cliffs dropping into the ocean and the deep, narrow valleys cut by rivers flowing down from the Tsitsikamma Mountains are the dominant topographical features. The interior is hilly, rugged and deeply incised by narrow valleys. The IBA is dissected by the impressive gorges of the Storms, Groot, Elands, Elandsbos, Lottering, Bloukrans and Keurbooms rivers. The Nature's Valley section and Keurbooms River Nature Reserve are characterised by densely forested hills, from which rivers meander into more open estuarine habitats as they near the sea. Robberg Nature Reserve resembles parts of the Tsitsikamma section, with fynbos elements on top of steep cliffs that drop into the ocean below. The area experiences annual average minimum and maximum temperatures of 11 °C and 19 °C respectively and rain falls throughout the year, averaging 1 000 mm p.a.
The Tsitsikamma section of the Garden Route National Park comprises two primary vegetation types: Tsitsikamma Sandstone Fynbos and Southern Afro-temperate Forest. The vegetation of the coastal belt is dominated by typical Afro-temperate forest species that form part of the large Knysna Afro-temperate Forest Complex. Thorny shrubs and very dry scrub-forest grow on slopes with shallow soil and a hot, dry aspect, whereas dry high-forest is found on steep, well-drained slopes with shallow soil and a warm aspect. Moist, tall forest develops in valleys and on deeper soil. Towards the coast, true forest trees become scarce and dune forest elements begin to dominate. Forest patches often lie adjacent to the fynbos and the boundaries between the two are usually fairly abrupt, due to fires that burn right up to the forest edge. There are two primary fynbos communities: mesic mountain fynbos, which grows on the steep coastal escarpment; and, on the inland escarpment, a community that varies from tall closed shrubland to low, open restioid cover. The IBA also includes a number of coastal cliffs, offshore stacks and small islands.
At least 300 species have been recorded in the IBA. The offshore stacks and islands hold breeding White-breasted Cormorant Phalacrocorax lucidus and Cape Cormorant P. capensis, which are now being recorded in very high numbers and have also begun breeding at Robberg Nature Reserve. Kelp Gull Larus dominicanus breeds in very high numbers on the Keurbooms River estuary spit. African Black Oystercatcher Haematopus moquini, Caspian Tern Sterna caspia and White-fronted Plover Charadrius marginatus breed along the beaches of the IBA.
African Finfoot Podica senegalensis and Half-collared Kingfisher Alcedo semitorquata have been recorded, and breed, in the rivers near Nature's Valley and along the Keurbooms River valley. White-backed Night Heron Gorsachius leuconotus has been recorded near Plettenberg Bay and there is a good chance that it occurs in the IBA.
The indigenous forest and fynbos hold many restricted-range and biome-restricted assemblage species. Striped Flufftail Sarothrura affinis has been recorded in low fynbos scrub and almost certainly occurs here. Orange-breasted Sunbird Anthobaphes violacea is widespread among ericas, while Cape Sugarbird Promerops cafer is almost restricted to the proteoid elements, but has infiltrated urban areas too. Cape Spurfowl Pternistis capensis, Cape Bulbul Pycnonotus capensis and Cape Siskin Crithagra totta are widespread in fynbos. Large numbers of Victorin's Warbler Cryptillas victorini are found in moist seeps in hilly areas.
The isolated forest patches hold several forest endemics, including Forest Buzzard Buteo trizonatus, Knysna Turaco Tauraco corythaix, Knysna Woodpecker Campethera notata, Chorister Robin-Chat Cossypha dichroa and Forest Canary Crithagra scotops. The area also holds a substantial proportion of the global Knysna Warbler Bradypterus sylvaticus population. Other forest species include Olive Bush-Shrike Chlorophoneus olivaceus, Narina Trogon Apaloderma narina and Crowned Eagle Stephanoaetus coronatus. The grassland patches potentially support Denham's Bustard Neotis denhami, Black Harrier Circus maurus and Secretarybird Sagittarius serpentarius.
Globally threatened species are Cape Gannet Morus capensis, Cape Cormorant, African Black Oystercatcher, Crowned Eagle, Denham's Bustard, Knysna Woodpecker and Knysna Warbler. Regionally threatened species are African Marsh Harrier Circus ranivorus, African Finfoot, Caspian Tern and Half-collared Kingfisher. Restricted-range and biome-restricted species include the locally common Forest Buzzard, Knysna Turaco, Knysna Woodpecker, Grey Cuckooshrike Coracina caesia, Chorister Robin-Chat, Yellow-throated Woodland Warbler Phylloscopus ruficapilla, Olive Bush-Shrike, Swee Waxbill Coccopygia melanotis, Forest Canary, White-starred Robin Pogonocichla stellata, Cape Spurfowl, Cape Siskin, Orange-breasted Sunbird, Cape Bulbul, Cape Sugarbird and Victorin's Warbler. Knysna Warbler is uncommon.
Species that have met the 1% or more congregatory population threshold are Kelp Gull (1 900 breeding pairs), Cape Cormorant (>7 000 individuals; 1.9%) and African Black Oystercatcher (an estimated 50 pairs of a global population of 3 300–4 000 mature individuals; 2.5%).
The endangered Leucospermum glabrum occurs in the Tsitsikamma section of the Garden Route National Park and a small population of this species has been found in Keurbooms Nature Reserve. Disa hallackii, also endangered, is being monitored in Robberg Nature Reserve.
The IBA is important for a number of species with global ranges restricted to South Africa's southern coastal strip. They include long-tailed forest shrew Myosorex longicaudatus, Duthie's golden mole Chlorotalpa duthieae, Knysna dwarf chameleon Bradypodion damaranum, blue-spotted girdled lizard Cordylus coeruleopunctatus, plain rain frog Breviceps fuscus and southern ghost frog Heleophryne regis. Other South African endemics include forest shrew Myosorex varius, Zulu golden mole Amblysomus iris, Cape grysbok Raphicerus melanotis in fynbos, and Cape sand frog Tomopterna delalandii, striped stream frog Strongylopus fasciatus, bronze caco Cacosternum nanum, rattling frog Semnodactylus wealii, Knysna leaf-folding frog Afrixalus knysnae, arum lily frog Hyperolius horstockii, marbled leaf-toed gecko Afrogecko porphyreus, Cape girdled lizard Cordylus cordylus, black thread snake Leptotyphlops nigricans, Cape legless skink Acontias meleagris and short-legged seps Tetradactylus seps.
Threatened reptiles such as green turtle Chelonia mydas, loggerhead turtle Caretta caretta, hawksbill turtle Eretmochelys imbricata and leatherback turtle Dermochelys coracea occur irregularly in the waters of the Eastern Cape. Threatened mammals include leopard Panthera pardus in the montane fynbos and blue duiker Philantomba monticola in the forests. Many marine fish species found in the IBA's bays and estuaries are endemic to South Africa. Knysna seahorse Hippocampus capensis has been recorded in the Keurbooms River system and a genetic study is under way to compare this population to the ones in the Knysna and Swartvlei estuaries.
The IBA is surrounded by timber plantations and invasive alien vegetation is thus a major threat to its indigenous habitat. More than ten alien plant species affect the IBA, including Hakea sericea, Acacia saligna, A. cyclops, A. longifolia, A. mearnsii, A. melanoxylon, Pinus radiata, P. pinaster and Eucalyptus species. The invasion and subsequent transformation of indigenous habitat types will reduce the habitat available for IBA trigger species. This threat is most relevant to the fynbos that occurs on ridges in the IBA, which is more easily invaded than the Afro-temperate forest.
The rivers that enter the IBA are affected by a number of threats upstream of the protected areas, including pollution, water abstraction and in-stream impoundments. Pollutants from the neighbouring dairy industry and pine plantations wash off the land surface, accumulate in the rivers and may then build up in the different trophic levels of the riverine ecosystems, thus impacting on other aspects of the IBA ecosystem. The danger to the health of these river systems was noted as the greatest threat to the ecosystem integrity in the Tsitsikamma section of the Garden Route National Park.
Changes in fire frequency impact on both fynbos and forest. Increasing fire frequency prevents certain long-lived fynbos elements from re-sprouting or re-seeding as they burn too early in their growth cycles and cannot set enough seed in the seedbed or create enough rootstock for re-sprouting. The loss of these plant types may affect certain IBA trigger species. Regular fires also create disturbance at the forest–fynbos margin which can lead to root damage in larger, older trees and cause them to fall. The frequency of these events could then result in a decrease in the extent of the forest. However, suppressing fires may lead to fynbos habitat becoming moribund and a reduction in the numbers of fynbos-endemic birds. A balanced fire regime, mimicking natural frequencies, is therefore essential to the ecological health of the IBA.
In the past, African Black Oystercatcher showed a high rate of nest desertion, presumably due to disturbance. This was remedied to a large extent by the ban on off-road driving along the coast. However, the Keurbooms River estuary spit, with its associated Kelp Gull colony, and Keurbooms beach, Nature's Valley beach and Lookout beach are subject to high levels of disturbance, particularly during the December holiday season. This can lead some species (Kelp Gull, African Black Oystercatcher and White-fronted Plover) to abandon their nests or can result in some species' nests (Caspian Tern, African Black Oystercatcher and White-fronted Plover) being preyed upon when the birds are disturbed from them. The protection of nest sites from humans during the breeding season has been suggested as a conservation measure. CapeNature field rangers and Nature's Valley Trust staff monitor the active nests of vulnerable species and during their regular patrols they ask members of the public to keep their distance so as not to disturb breeding birds.
The IBA falls within the Tsitsikamma and Nature's Valley sections of the Garden Route National Park, administered by SANParks, and the Robberg and Keurbooms River nature reserves, administered by CapeNature. The Tsitsikamma National Park was originally proclaimed in December 1964. In 1987, the De Vasselot Nature Reserve, which was originally established in 1974, was transferred from the Forestry Department to the stewardship of the National Parks Board (now SANParks). The Garden Route National Park, with additional protected areas around Wilderness and Knysna, was subsequently proclaimed. It has a strong scientific services division, which carries out regular monitoring duties, and has developed comprehensive management plans, as required by South African legislation for all formally protected areas. CapeNature ecological staff also provide support to the managers of the reserves under their jurisdiction to ensure that management strategies area based on sound evidence.
Much of the Tsitsikamma and Nature's Valley sections of the Garden Route National Park are not accessible to members of the public, so the impact of recreational activities is limited. Although the Storms River Mouth rest camp is well developed, the footprint of its accommodation is insignificant and restricted to the site; the same is true of the Nature's Valley rest camp and the small accommodation units in the Robberg and Keurbooms River nature reserves. The maintenance of footpaths, in particular along the Otter Trail and in Robberg Nature Reserve, is ongoing so that soil erosion and other negative impacts are reduced.
In consultation with biologists, management has determined that no prescribed burning is required in the national park and that the burning regime should allow natural fires to take their course. The Working for Water project has been active throughout the area since the late 1990s and many alien vegetation species have been removed through a multi-phase approach that includes the necessary follow-ups.
Active management on the part of CapeNature and SANParks in different sections of the IBA ensures their protection. In addition, NGOs such as Nature's Valley Trust conduct research and monitoring exercises that focus particularly on the coastal and fynbos sections of the IBA, as well as public awareness activities during the December holiday season. BirdLife South Africa has formed the Bitou Valley Local Conservation Group with members of the local bird club (BirdLife Plettenberg Bay), the Bitou Valley Trust and Nature's Valley Trust. This dynamic group undertakes regular monitoring activities, environmental education and public awareness events in the IBA. Members of the group are also working closely with the local municipality to enhance the area as a destination for avitourism, thereby providing additional stimulus to the local economy.
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