Sites - Important Bird Areas (IBAs)

Ornithological information See Box and Tables 2 and 3 for key species. The Overberg holds the largest population of Grus paradisea in the world. Numbers increase during the winter months when many pairs, which have completed breeding activities, join large loose flocks that congregate in this area. At times this IBA can hold nearly 20% of this species’s global population, as well as holding large numbers of Neotis denhami. Gyps coprotheres, which breed at Potberg in the De Hoop Nature Reserve (IBA ZA098), occasionally forage over the agricultural matrix, where Circus maurus is also found frequently. The site also covers a large proportion of the global range of the recently described Certhilauda brevirostris. Within this area, it is almost confined to stony wheatfields and pastureland. Despite its limited range, the species appears to be secure, provided that current land-use patterns persist. Some typically karroid birds are also found within the wheat matrix and the occasional renosterveld patches, including Eupodotis vigorsii, Parus afer and Cercomela sinuata.

Site description Located at the southern tip of the African continent, this large agricultural district stretches from Caledon to Riversdale and encompasses the area south of these two towns, running between the coastal towns of Hermanus and Stilbaai. De Hoop Nature Reserve, which abuts this area, is considered a separate IBA (IBA ZA098). The topography consists of low-lying rolling coastal plains. The landscape consists primarily of cereal croplands and cultivated wheat pastures and crop fields, although a fair amount of natural vegetation still remains along the coast, especially on the Soetanysberg and Agulhas Plain, which hold at least 1,700 plant species. The coast holds thicket, which is dominated by forest patches of milkwood Sideroxylon. Localized, fragmented patches of renosterveld are found throughout the area.

Populations of IBA trigger species

Species	Season	Period	Population estimate	Quality of estimate	IBA Criteria	IUCN Category
Cape Francolin Francolinus capensis	resident	1998	present [units unknown]	-	A3	Least Concern
Black Harrier Circus maurus	resident	-	present [units unknown]	-	A1	Vulnerable
Karoo Bustard Eupodotis vigorsii	resident	1998	-	-		Least Concern
Blue Crane Anthropoides paradiseus	winter	-	2,914-3,484 individuals	-	A1, A4i	Vulnerable
Knysna Woodpecker Campethera notata	resident	1998	-	-		Near Threatened
Cape Long-billed Lark Certhilauda curvirostris	resident	1998	present [units unknown]	-	A3	Least Concern
Cape Bulbul Pycnonotus capensis	resident	1998	present [units unknown]	-	A3	Least Concern
Sicklewing Chat Cercomela sinuata	resident	1998	-	-		Least Concern
Orange-breasted Sunbird Nectarinia violacea	resident	1998	present [units unknown]	-	A2, A3	Least Concern
Cape Sugarbird Promerops cafer	resident	1998	present [units unknown]	-	A2, A3	Least Concern
Cape Siskin Serinus totta	resident	1998	present [units unknown]	-	A2, A3	Least Concern

Habitats

IUCN habitat	Habitat detail	Extent (% of site)
Grassland		-
Shrubland	Shrubland - Cape (fynbos)	-

Land use

Land-use	Extent (% of site)
agriculture	-
nature conservation and research	2%
nature conservation and research	20%
tourism/recreation	-

Other biodiversity The area is extremely rich in highly threatened endemic flora, including the spectacular Leucadendron elimense, L. modestum and L. laxum. The discovery of a new species of Proteaceae, Serruria nova, in 1998, suggests that complete surveys of the area will yield many new endemic species. Among frogs, the spectacular Hyperolius horstockii occurs and Heleophryne purcelli may occur in montane rivers in the wheatbelt matrix.

Management considerations The Bredasdorp coastal strip once supported significant areas of a large variety of natural habitats; the area has been extensively transformed through the establishment of a wheatbelt, which now occupies over 85% of the IBA. Very small, isolated, local patches of natural habitat now remain, and these are brimming with critically threatened populations of a range of endemic plant species that were once more common throughout this landscape. These plants are extremely vulnerable to extinction as a result of habitat destruction and physical disturbance to their environment. The small remnant populations are constantly being encroached upon or mismanaged as their significance is not fully appreciated. Renosterbosveld occurring farther inland is even more threatened because more than 90% has been ploughed up for agriculture.

Although Grus paradisea seem to have benefited from the agricultural changes that have occurred within the region over the past 30 years, the remaining patches of indigenous lowland fynbos in the IBA are unique and intensely threatened by the wheatbelt. It is imperative that the remaining lowland fynbos in this area be conserved at all costs. Under no circumstances should this IBA description be used as motivation to increase the area under wheat.Grus paradisea has recently expanded its range into, and become remarkably common in, the agricultural sectors of the fynbos biome, having originally been absent from this area. Flocks of Grus paradisea are attracted to agricultural fields where they may feed on fallen grain and recently germinated crops. They also gather to feed on supplementary food put out for small stock, especially during times of drought. This has earned them the enmity of some farmers, and occasionally a few have spread poisoned grain on their fields and around feedlots to kill cranes. Most of South Africa’s cranes and crane habitats, particularly in the Overberg, are on privately owned farmland; their future lies firmly in the hands of private land-owners. Poisonings in the Overberg are now very scarce, thanks to an effective awareness campaign by the Overberg Crane Working Group and Cape Nature Conservation, and a very responsive farming community in the area. This project should act as a model for farmer awareness schemes in other parts of South Africa.

Additional threats to Grus paradisea include overhead power cables and electricity structures, which they occasionally strike during flyovers. Eskom (Electricity Supply Commission) and the Endangered Wildlife Trust are attempting to implement a strategy to reduce bird strikes on electricity structures, including marking them with various devices to make them more visible to birds at sites where strike rates are highest. Birds in this area breed in agricultural fields and cultivated pastures. The wheatlands can be managed to benefit the cranes and bustards in this altered landscape. In the Overberg, cranes avoid natural fynbos vegetation and inhabit cereal croplands and cultivated pastures. By contrast, they inhabit natural vegetation in the Karoo and grassland biomes, but also feed in crop fields.

Gyps coprotheres, from the breeding colony at De Hoop Nature Reserve (IBA ZA098), forage outside the reserve structure and are vulnerable to indiscriminate use of poison by small-stock farmers in the area, who may use poison to combat mammalian predators such as jackals and dogs. Although farmers in this region are eager to contribute to conservation schemes, it should be emphasized that a single poisoned carcass could decimate the entire colony. In the nearby Albertina District, farmers have activated a vulture restaurant of their own accord, and the increase in vulture numbers has been ascribed to the active cooperation of enlightened farmers in the area.

References Allan (1989, 1992, 1993a, 1994a,c, 1995a,b, 1996b), Allan and Young (1998), Anderson (1990), Cowling et al. (1988), Hitchcock (1996), Scott (1992), Siegfried (1985), Tarboton (1992), van Ee (1981).

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Recommended citation  BirdLife International (2013) Important Bird Areas factsheet: Overberg wheatbelt. Downloaded from http://www.birdlife.org on 21/05/2013

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