Dronfield Nature Reserve is situated on the central plateau of South Africa along the N12, c. 5 km north of Kimberley. The annual average rainfall in this semi-arid region is 400 mm.
The reserve falls within the Savanna Biome and is close to the western edge of the Grassland Biome. One vegetation type, Kimberley Thornveld, is present. This ecosystem is not threatened, but is listed as Least Threatened, poorly protected and 82.3% intact. The thornveld is partly open savanna, comprising camel thorn Vachellia (formerly Acacia) erioloba trees in tall, tufted grasses, and semi-open to closed mixed-acacia woodland. The flora is generally species rich, with forbs and annuals being seasonally dominant. There are four major habitats within this IBA – thornveld, grassland, pan slope and koppieveld – and eight habitat units within these.
Most of the terrestrial habitat remains in a natural state, with less than 5% of the area transformed by the development of utility lines, homesteads, pump houses, cattle posts, farm dams, mining floors, dumps and quarries.
At least 221 species have been recorded during SABAP2 in the six pentads incorporating Dronfield. About 181 of these species have been confirmed in this IBA.
Dronfield supports large numbers of breeding White-backed Vulture Gyps africanus. The Dronfield breeding colony comprises 41% of the breeding pairs in the Kimberley region. The numbers of this species and its breeding success have largely remained stable over the past 20 years. However, the past five years have shown a slight decline in breeding success, which was at its lowest in 2012. In contrast, the 2014 breeding season produced a record 68 chicks out of the 99 breeding attempts, a 69% success rate that is significantly higher than the 22-year average of 59%(Anthony 2014)
Lesser Flamingo Phoeniconaias minor occurs on the pan when it is seasonally inundated.European Roller Coracias garrulus is occasionally seen.
Several acacia thornveld savanna species such as Kalahari Scrub Robin Erythropygia paena, Marico Flycatcher Bradornis mariquensis, Crimson-breasted Shrike Laniarius atrococcineus, Scaly-feathered Finch Sporopipes squamifrons and Violet-eared Waxbill Uraeginthus granatinus are present.
Globally threatened species are White-backed Vulture (200–300 birds, 99 breeding pairs; Anthony 2012), Lappet-faced Vulture Torgos tracheliotos (four birds; Anthony pers. comm.), Secretarybird Sagittarius serpentarius (two breeding pairs; Anthony pers. comm.), Kori Bustard Ardeotis kori, Martial Eagle Polemaetus bellicosus (2–3 breeding pairs; Anthony pers. comm.) and Lesser Flamingo. The only regionally threatened bird species is Tawny Eagle Aquila rapax (two residents; Anthony pers. comm.). Biome-restricted birds include Kalahari Scrub Robin, Sociable Weaver Philetairus socius, Stark’s Lark Spizocorys starki and White-bellied Sunbird Cinnyris talatala.
Populations of black-footed cat Felis nigripes (Vulnerable), aardwolf Proteles cristatus and aardvark Orycteropus afer occur on the farm. The bushveld rain frog Breviceps adspersusis locally common.
There are presently few significant threats to Dronfield as it is being well managed. One of the most important trigger species at this IBA is the White-backed Vulture. In order to conserve this species, it is necessary to protect its breeding colonies, such as the one at Dronfield. Six breeding colonies were located in the greater Kimberley area, with an estimated 240 breeding pairs and 650 individual birds. As these birds forage over wide areas, farmer extension is important to address threats such as food shortage, poisoning, and drowning in farm reservoirs. The use of poisons in farming areas to combat mammalian predators still poses a threat to scavenging raptors, which are attracted to the baited carcasses and consume them. Hundreds of vultures can be killed in a single poisoning incident.
The breeding success of White-backed Vultures at Dronfield has shown a slight decline and was at its lowest in 2012 (at only 33%; Anthony 2012). There are a number of possible causes for the decline, which include lack of food; poisoned carcasses, causing the death of one or both adults; food with a low level of poison, which may only affect the chicks; egg-shell thinning due to pesticide contamination; and an increase in the numbers of potential predators. Pied Crow Corvus albus and vervet monkey Chlorocebus pygerythrus numbers have risen at Dronfield. Pied Crows are possible predators of vulture eggs and chicks. They have been recorded killing a Verreaux's Eagle-Owl Bubo lacteus fledgling and harassing vultures at carcasses, and anecdotal evidence suggests that they eat vulture eggs. Vervet monkeys eat birds' eggs and chicks and potentially vulture chicks.
Collisions with transmission power lines and electrocutions on reticulation and distribution power lines pose an ongoing threat to vultures and other trigger species. Three separate power lines have been modified at Dronfield by DBCM and Eskom to reduce electrocutions. However, collisions are still reported with the earth wire (and possibly the conductors) of the transmission lines that traverse this property.
It is predicted that climate change will cause habitat alteration and shifts, with bush thickening already evident in the region. Strong winds and hailstorms can cause White-backed Vulture chick mortality due to the exposed position of nests on top of camel thorn trees.
High levels of lead have been found in some White-backed Vulture blood samples, probably from ingesting bullet shrapnel in carcasses found in surrounding areas or provided at the vulture restaurant.
Anglo American has recently bought DBCM and this change of ownership may lead to a change in land use or the sale of the property.
Originally purchased by DBCM in 1888, Dronfield featured prominently in the South African War. Game was introduced 75 years later and Dronfield was the first game farm in the Northern Cape to re-introduce white rhino Ceratotherium simum. In 1994, the land use of Dronfield changed to cattle farming, which continued for ten years. The farm was established as a nature reserve in 2004, when many game species, including white rhino, sable antelope Hippotragus niger and roan antelope H. equinus were introduced. Breeding populations of corridor disease-free African buffalo Syncerus caffer and tsessebe Damaliscus lunatus were also eventually established. DBCM is currently practising up-to-date management at this IBA and has protocols regarding the breeding and distribution of savanna species to other conservation areas.
Research on the White-backed Vulture has been undertaken sporadically over four decades since the species was first recorded breeding on Dronfield in 1967. The colony has been monitored for the past 22 years and during this period 50 to 99 breeding pairs have been recorded, using up to 350 nesting trees in this IBA.
A vulture restaurant with a viewing hide was established in 2006. Vulture species observations are recorded by visitors in a logbook in the hide. Cape, Lappet-faced and White-backed Vultures utilise the restaurant when carcasses are available. The number of Pied Crows that feed at the vulture restaurant increased initially, but then decreased when offal was no longer provided.
Action and awareness campaigns to reduce or prevent raptor and vulture poisoning incidents have been developed by the Northern Cape Raptor Conservation Forum and have been implemented with some success. Simple solutions to prevent raptor drownings in farm reservoirs have also been developed and are being applied by some landowners.
This IBA is part of the Diamond Route, a set of ten sites across South Africa that conserve biodiversity and provide education and sustainability opportunities through the De Beers Group of Companies, E. Oppenheimer and Son and Ponahalo Investments. It is not formally protected. DBCM is willing to enter into a Biodiversity Stewardship agreement to secure this IBA as a formally protected area under NEM:PAA. However, Anglo American first has to make a decision on the future land use of this IBA.
Anderson MD. 1994. Mass Whitebacked Vulture poisoning in the Northern Cape. Vulture News 29: 31–32.
Anderson MD. 2000a. Raptor conservation in the Northern Cape Province, South Africa. Ostrich 71: 25–32.
Anderson MD. 2001. Vultures nesting on electricity pylons. African Wildlife 55(5): 10.
Anderson MD. 2003. Kimberley’s vultures. Not just here for De Beers… Africa – Birds & Birding 8(1): 22.
Anderson MD. 2005. Dronfield – four decades of vulture research. Endangered Wildlife 64: 50–52.
Anderson MD, Hohne P. 2007. African White-backed Vultures nesting on electricity pylons in the Kimberley area, Northern Cape and Free State province, South Africa. Vulture News 57: 44–50.
Anderson MD, Kruger R. 1995. Powerline electrocution of eighteen African White-backed Vultures. Vulture News 32: 16–18.
Anderson MD, Kruger R. 2004. Raptor conservation in the Northern Cape Province (3rd edn). Kimberley: Northern Cape Department of Tourism, Environment & Conservation and Eskom.
Anderson MD, Maritz AWA. 1997. The status and distribution of vultures in the Northern Cape Province, South Africa. In: Boshoff AF, Anderson MD, Borello WD (eds), Vultures in the 21st Century: Proceedings of a workshop on vulture research and conservation in southern Africa. Johannesburg: Vulture Study Group. pp 37–45.
Anderson PC. 2008. The description and mapping of the vegetation of Dronfield Nature Reserve, Kimberley, Northern Cape Province, South Africa. Unpublished report. De Beers Consolidated Mines.
Anthony A. 2012. Twenty years of African White-backed Vulture ringing on Dronfield and Inglewood farms, Kimberley. Unpublished report. De Beers Consolidated Mines.
Anthony A. 2014. Dronfield White-backed Vulture breeding summary for 2014. Unpublished report.
Barnes K (ed.). 1998. The Important Bird Areas of southern Africa. Johannesburg: BirdLife South Africa.
Midgley G, Rutherford M, Bond W. 2001. The heat is on… Impacts of climate change on plant diversity in South Africa. Cape Town: National Botanical Institute.
Mucina L, Rutherford M. 2006. The vegetation of South Africa, Lesotho and Swaziland. Strelitzia 19. Pretoria: South African National Biodiversity Institute.
Murn C, Anderson MD, Anthony A. 2002. Aerial survey of African white-backed vulture colonies around Kimberley, Northern Cape and Free State provinces, South Africa. South African Journal of Wildlife Research 32(2): 145–152.
Simmons R, Barnard P. 2011. Pied pirates: Crow threat to raptors? Africa – Birds & Birding 16 (5): 50–54.