Rationale
Listed as Least Concern as Gemsbok are numerous and widespread across the arid and semi-arid regions within the assessment region, and population numbers have increased over three generations (1992â2015) on formally protected areas, often by over 100%. The future of this species in South Africa is regarded as secure, as they continue to occur in large numbers, are resilient to aridity, and survive successfully without permanent sources of drinking water when free-ranging. The Kgalagadi Transfrontier Park contains the largest subpopulation of Gemsbok, with an estimated size of between 6,615 and 14,606 individuals (2012â2013 counts), depending on season. Overall, approximately 9,570 individuals currently exist on other formally protected areas and, due to their high economic value (particularly within the hunting industry), there are around 37,610 individuals present on private land. Thus, overall, there are at least 55,376 individuals in South Africa. No direct conservation interventions are currently required and this species should continue to be a key component in the wildlife economy. The development of a translocation and metapopulation strategy is encouraged to sustain the genetic resilience of the population and to prevent extensive introduction outside its natural range.
Regional population effects: Within the assessment region, migration does take place within the Kgalagadi Transfrontier Park, which is only fenced along its western and southern boundaries, allowing the unrestricted movement of animals between South Africa and southern and central Botswana. Variability in the localised environmental conditions experienced in these areas largely determines the nature and direction of movement across these international borders. Although the Gemsbok subpopulation in Mapungubwe National Park is small, there may be some movement into and out of Botswana. The remaining population is, however, typically restricted to private ranches and reserves, provincial and national protected areas. A degree of genetic dispersal occurs through the translocation of individuals between these protected areas via game sales. No rescue effects are necessary.
Distribution
Historically, Gemsbok occurred extensively in the arid and semi-arid savannah territories of the Kalahari and Karoo regions of southern Africa. They ranged expansively in Namibia aside from the Zambezi Region (previously known as the Caprivi Strip) and surroundings, throughout the arid and semi-arid regions of Botswana, extending marginally into western Zimbabwe and southwest Angola (East 1999). During the 19th and 20th centuries, anthropogenic modification and fragmentation of their habitat resulted in a significant reduction in their range. More recently, however, widespread reintroductions have occurred onto both private and formally protected reserves. Currently, their distribution is widespread, although patchy, across the southwest of southern Africa. A healthy population occurs in the Iona National Park of Angola (B.A. Bennett. pers. comm. 2015), a traditional stronghold for the species (East 1999). Gemsbok have also been introduced onto private game ranches in Zimbabwe (East 1999).
Within the assessment region, Gemsbok historically ranged across the arid regions of the Northern Cape, through Namaqualand, and extended partially into the Karoo (Western Cape), Eastern Cape and Free State; the most eastern limit of their range being the confluence of the Orange and Vaal Rivers and small areas of the North West Province. There may be free-roaming herds in North West (outside fenced areas) but they may also be escapees (Power 2014). Gemsbok were historically permitted in Gauteng and are now mainly held on exemption farms, but no further imports are allowed (C.Whittington-Jones pers. comm. 2016). Their populations have recently increased within their historic range as a result of reintroductions onto many formally protected and private properties (Skinner & Chimimba 2005; Power 2014). Additionally, as a consequence of their commercial value, they have now been introduced onto a number of privately owned game ranches situated outside of their natural distribution, such as the eastern parts of Limpopo Province (Knight 1999).
Population trend
Trend
Gemsbok are widespread and common across the dry regions of southern Africa. Naturally, Gemsbok population distribution and birth rates are known to vary with annual rainfall (Mills & Retief 1984). In 2008, the IUCN Antelope Specialist Group estimated the total Gemsbok population to be 373,000 individuals in southern Africa. The generation length of Gemsbok has been estimated as 7.8 years (Pacifici et al. 2013), which yields a 23.6 year three- generation window. Within the assessment region, the population is thriving and subpopulations are stable or increasing on protected areas, conservancies and private game ranches. For example, over three generations on Camdeboo National Park, Eastern Cape Province (1992â2015), the subpopulation has increased from 15 to 92 individuals; from 180 to 1,855 individuals (930% overall growth) in Karoo National Park; and from 15 (in 2003) to 240 (2015) individuals in Mountain Zebra National Park (A. Gaylard unpubl. data). Similar increases on protected areas have occurred in the Northern Cape over three generations (M. Smit unpubl. data): at Rolfontein Nature Reserve the subpopulation has increased by 363% (from 87 to 403 individuals); by 40% (119 to 167 individuals) in Goegap Nature Reserve; and from 19 individuals in 2002 to 97 in 2013 at Doornkloof Nature Reserve. The subpopulations on both Augrabies Falls National Park (336 individuals; 2012 count) and Mokala National Park (1,544 individuals; 2016 count) are also stable or increasing (C. Bissett unpubl. data). The largest subpopulation exists in Kgalagadi Transfrontier Park, where the subpopulation is estimated to be between 6,615â9,777 individuals (2013 count) in the dry season, and 10,044â14,606 individuals (2012 count) in the wet season (Ferreira et al. 2013). Thus, on formally protected areas alone, there are well over 10,000 mature individuals in the assessment region. We assume trends are similar on private lands. For example, in the North West Province, while there are an estimated 2,121 individuals on formally protected areas, there are c. 17,440 on private lands (2013 estimates). Overall, we estimate a total population size of at least 55,376 individuals across the country. There are no major threats to this species and its numbers on private lands are increasing. Most of the national population is fragmented except the largest subpopulation in the Kgalagadi Transfrontier Park.
Threats
Currently, there are no major threats to the survival of this species within the assessment region. During the 19th and 20th centuries, the population declined significantly as a direct result of habitat loss due to the expansion of urban and agricultural practices in southern Africa. Since then large scale reintroductions and introductions of Gemsbok have occurred both onto private game ranches, and protected areas. Namibia for example, holds the majority of its Gemsbok on private game ranches, and East (1999) noted that the population increased from approximately 55,000 in 1972 to over 164,000 in 1992. By 2006, the Gemsbok population in Namibia was estimated at more than 388,000 (Mendelsohn 2006). Gemsbok have a number of physiological and behavioural adaptations which allow for its successful survival in fragmented, arid environments, even during harsh drought conditions. Their independence from permanent sources of drinking water, are facilitated through their utilisation of water-rich fruit, and underground roots and tubers, microclimate selection, seasonal changes in activity patterns and selective brain cooling. Livestock farming, particularly in the Kalahari, is a minor threat to this species, as a result of expanding competition with livestock and the subsequent habitat loss and degradation from overgrazing and bush encroachment (Verlinden & Masogo 1997; Verlinden 1998; Bergström & Skarpe 1999; Wallgren et al. 2009). Research suggests that, in the region of Kgalagadi, the majority of the most suitable grazing environments is utilised for livestock grazing rather than wildlife (Verlinden 1998; Darkoh 2003).
Although some illegal poaching of this species exists, mostly in Botswana, it is not considered to be a threat for Gemsbok within the assessment region.
Finally, arid southern African savannahs are particularly vulnerable to climate change, and are expected to become hotter and drier with increasingly unpredictable rainfall (Hulme et al. 2001; Hannah et al. 2002; Meadows 2006). Amplified temperatures in association with a decline in the frequency of rainfall could radically constrict key habitats, thus threatening the habitat availability and forage resources of this species.
Uses and trade
This is a popular species in the live animal trade industry at game auctions, and has a subsistence value as venison and for national recreational biltong, meat and trophy hunters. The Gemsbok is considered a high value â high return animal in the captive breeding, game ranch and hunting industries of South Africa (Bothma 2005), and has substantial international value as a trophy animal. Hunting and subsistence use does not, however, have a damaging effect on the stability of Gemsbok populations. This is largely a result of its recent large-scale introduction and reintroduction onto private lands.
Patterson and Khosa (2005) reported that Gemsbok generate 8.7% of hunting income for South Africa, and was described as one of the most hunted species in both Namibia (Lindsey et al. 2007) and South Africa (Patterson & Khosa 2005). A minimum ranch size of 1,200 ha is recommended for private Gemsbok owners, and the smallest viable population should include at least three males and seven females (Osmers 2012).
Conservation
This species is economically important to southern Africaâs wildlife industry, is a valuable trophy species on game farms, and a sustainable source of protein for local communities. Because of this, it is in great demand among game ranchers, and has been extensively introduced into areas outside of its natural distribution. Gemsbok subpopulations have increased substantially across northern South Africa, due to translocations of Namibian animals onto private game farms.
Gemsbok also occur within a number of formally protected areas within the assessment region, where they are important to South Africaâs ecotourism industry. These include the Kgalagadi Transfrontier Park (which contains South Africaâs largest subpopulation), Karoo National Park, Mokala National Park, Augrabies Falls National Park, Molopo Nature Reserve and Madikwe Game Reserve, among others. Population numbers within these reserves are thought to be stable or increasing, and numbers are additionally increasing within the private sector.
No specific conservation interventions are currently required for this species, and wildlife ranching is considered beneficial for Gemsbok conservation in South Africa, and has effectively increased the extent and abundance of this species. Yet, ranch managers should consider the importance of maintaining genetic diversity in isolated subpopulations of Gemsbok, especially on game farms running breeding programmes selecting for particular traits (Osmers 2012) or colour variants, such as the Golden Gemsbok. Genetic variability plays a vital role in continued reproductive success and fitness, which becomes principally important during adverse environmental conditions. Since arid savannahs are particularly vulnerable to enhanced aridity under current climate change predictions, it is vital that managers prevent genetic degradation of populations by inbreeding (see recommendations for land managers and practitioners). Finally, due to its status in the game industry and attractiveness for trophy and venison hunters, it is important to ensure that habitats and water sources are maintained, particularly on small, private properties, where natural movements are restricted by fences. Population trends and genetic diversity should be monitored to prevent inbreeding and the loss of genetic material.
Recommendations for land managers and practitioners:- Continued development of Gemsbok as a keystone species within the sustainable, wildlife-based rural economy, by incentivising landowners to supply cheap, low-carbon protein to local communities, thus ensuring that the benefits of this species are shared.
- Osmers (2012) suggested private ranch-owners should maintain subpopulation viability and genetic diversity by:
- Knowing the origin of founder population animals, and establishing when and from where additional genetic material should be inserted into the population.
- Starting with a founder population as large as possible to ensure the effective population is sustainable, and threats of inbreeding are kept to a minimum.
- Periodically supplement the population with genetic material from an alternate large source population.
- Add individuals to the population from other large, well-managed source populations every few years in order to enrich genetic diversity, and compensate for alleles lost through mutation or trait selection.
- Monitor phenotypic data such as horn length and carcass weight.
Research priorities:- Assessing the vulnerability of Gemsbok to climate change. Considering that the climate of the Northern Cape Province, a stronghold of the Gemsbok, is predicted to become unlike anything currently experienced in South Africa (hotter and drier with increased variability in rainfall), the arid-adapted Gemsbok is an ideal model animal in which to investigate behavioural plasticity - including conservation physiology â in the face of anthropogenic climate change. Studies over the medium-term (c. 5 years) relating individual variability in physiological parameters to reproductive output and success (fecundity) could provide valuable insights into the extent to which ungulates are able to cope with the effects of anthropogenic climate change.
- Quantifying the contribution of Gemsbok to the wildlife economy and in creating sustainable social-ecological systems in South Africa.
Encouraged citizen actions:- Landowners should create conservancies for this species and engage local stakeholders to create sustainable, wildlife-based rural economies.
- Report sightings on virtual museum platforms (for example, iSpot and MammalMAP), especially outside protected areas.
