The Platberg–Karoo Conservancy IBA covers the entire districts of De Aar, Philipstown and Hanover, including suburban towns. The landscape consists of extensive flat to gently undulating plains that are broken by dolerite hills and flat-topped inselbergs. The ephemeral Brak River flows in an arc from south-east to north-west, eventually feeding into the Orange River basin. Other ephemeral rivers include the Hondeblaf, Seekoei, Elandsfontein and Ongers rivers with a network of tributaries. Vanderkloof Dam is on the north-eastern boundary.
This IBA is in the Nama Karoo and Grassland Biomes. The eastern Nama Karoo has the highest rainfall of all the Nama Karoo vegetation types and is thus ecotonal to grassland, with a complex mix of grass- and shrub-dominated vegetation types. Eight broad vegetation types are present; seven are Least Threatened and the Upper Gariep Alluvial Vegetation type is classified as Vulnerable.
The land is used primarily for grazing and agriculture. Commercial livestock farming is mostly extensive wool and mutton production, with some cattle and game farming. Less than 5% of this IBA is cultivated under dry-land or irrigated conditions, and includes lucerne and prickly pear Opuntia ficus-indica orchards.
This IBA contributes significantly to the conservation of large terrestrial birds and raptors. These include Blue Crane Anthropoides paradiseus, Ludwig's Bustard Neotis ludwigii, Kori Bustard Ardeotis kori, Blue Korhaan Eupodotis caerulescens, Black Stork Ciconia nigra, Secretarybird Sagittarius serpentarius, Martial Eagle Polemaetus bellicosus, Verreauxs' Eagle Aquila verreauxii and Tawny Eagle A. rapax.
A total of 289 bird species are known to occur here. At the time of the IBA's assessment, its 214 pentads had been poorly atlased for SABAP2.
Blue Crane numbers appear to be stable (R Visagie pers. comm., Camina 2014). The population size of Ludwig's Bustard in the eastern Karoo appears to be slightly higher than the first estimates (Jenkins et al. 2011, Shaw 2013). There is some evidence for a decrease in the populations of Blue Korhaan and Karoo Korhaan Eupodotis vigorsii.
In summer, close to 10% of the global population of Lesser Kestrels Falco naumanni roost in this IBA. Amur Falcons F. amurensis are also abundant and forage and roost with Lesser Kestrels. This IBA is seasonally important for White Stork Ciconia ciconia, and CARs indicate high numbers of this species during outbreaks of brown locusts Locustana pardalina and armoured ground crickets Acanthoplus discoidalis.
Globally threatened species are Blue Crane (c. 1000; R Visagie pers. comm., Camina 2014), Ludwig's Bustard, Kori Bustard, Secretarybird, Martial Eagle, Blue Korhaan, Black Harrier Circus maurus and Denham's Bustard Neotis denhami. Regionally threatened species are Black Stork, Lanner Falcon Falco biarmicus, Tawny Eagle, Karoo Korhaan and Verreauxs' Eagle (30; R Visagie pers. comm., Camina 2014).
Biome-restricted species include Karoo Lark Calendulauda albescens, Karoo Long-billed Lark Certhilauda subcoronata, Karoo Chat Cercomela schlegelii, Tractrac Chat C. tractrac, Sickle-winged Chat C. sinuata, Namaqua Warbler Phragmacia substriata, Layard's Tit-Babbler Sylvia layardi, Pale-winged Starling Onychognathus nabouroup and Black-headed Canary Serinus alario. Congregatory species include Lesser Kestrel (13 200; R Visagie pers. comm., Camina 2014) and Amur Falcon.
Aardwolf Proteles cristatus, aardvark Orycteropus afer, bat-eared fox Otocyon megalotis and black-footed cat Felis nigripes (Vulnerable) are present.
Threats in the area include overgrazing, which results in a depletion of palatable plant species, erosion, and encroachment by Karoo shrubs. The result is loss of suitable habitat and a decrease in the availability of food for large terrestrial birds. Centre-pivot irrigated croplands using underground water are increasing and agriculture is intensifying.
Strychnine poison was used extensively in the past to control damage-causing predators, such as black-backed jackal Canis mesomelas and caracal Caracal caracal, and reduced scavenging raptor populations. The use of poison may be continuing, and the potential impacts on threatened raptor species has not been confirmed or quantified. Outbreaks of brown locust are controlled by means of spraying to prevent damage to crops, resulting in the poisoning of birds that eat the dead locusts. The impact that these pesticides are having on Blue Cranes and Lesser Kestrels is currently unknown. Many landowners still hunt black-backed jackal with dogs or hire predator-control groups, and bat-eared foxes and aardwolves are inadvertently killed. Road-kills of Lesser Kestrels are common during insect outbreaks.
Renewable energy developments are a new threat. Thirteen wind and solar developments have been approved for development within this IBA. All the large trigger species are highly susceptible to collisions with wind turbines, as are large flocks of Lesser Kestrels and Amur Falcons. All the trigger species are predicted to be moderately susceptible to the various impacts of solar-energy facilities.
Numerous existing and new power lines are significant threats to trigger species. Power lines kill substantial numbers of all large terrestrial bird species in the Karoo, including threatened species (Jenkins et al. 2011, Shaw 2013). The planned Eskom central corridor for future power-line developments includes the northern half of this IBA. There is currently no completely effective mitigation method to prevent collisions.
Climate change scenarios for the region predict slightly higher summer rainfall by 2050, and increased rainfall variability. Droughts are expected to become more severe. The Blue Crane's diet depends largely on the timing and amount of rainfall, and climate change is predicted to have both positive and negative consequences for its populations. Increased summer rainfall could improve survival, and conversely drought years can lower long-term average survival. Large, mainly resident species dependent on rainfall are also more vulnerable to climate change. This would include the slow-breeding Verreauxs' Eagle, Tawny Eagle and Martial Eagle, which also exhibit extended parental care. Severe hailstorms kill hundreds of roosting Lesser Kestrels and Amur Falcons and could become more frequent.
There is a potential threat of shale gas fracking in and around this IBA. Populations of bird species may be locally reduced through disturbance caused by lights, vibration, vehicles and dust, and may be affected by pollutants in ponds containing contaminated water produced by returned fracking fluids (Dean 2011).
This IBA is not formally protected. The Platberg–Karoo Conservancy was established in July 1990. In collaboration with MD Anderson of DENC, various research and environmental awareness projects were initiated, including the Karoo Large Terrestrial Bird Survey, the Blue Crane Awareness Project and 11 years of colour-ringing Blue Crane chicks. The major threat of power-line collisions was initially investigated by the Eskom/EWT partnership and MD Anderson. This covered the impact of power lines on populations of large terrestrial bird species and evaluated the effectiveness of earth-wire marking devices. Further studies were subsequently completed (Jenkins et al. 2011, Shaw 2013).
The drowning of raptors in farm water reservoirs was reduced by fitting poles or ladders into the reservoirs to enable raptors to climb out. Hopefully this practice is being maintained and expanding.
Ronelle Visagie has taken over from Francois Taljaard as the first co-ordinator of the Platberg–Karoo Raptor Project funded by the EWT's Birds of Prey Programme. Thanks to this project, awareness has been raised among landowners and raptor breeding and threats to the birds are being monitored.
It is likely that the chemicals used in locust-control operations had a major impact on the region's populations of large terrestrial birds. There are landowners in this IBA who no longer report brown locust outbreaks and don't allow locust control on their farms.
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