Course:CONS200/2019/Southern White Rhinoceros Brought Back from the Brink of Extinction

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Young southern white rhino
Current Conservation Status: Near Threatened
Current amount: Current habitat:

Introduction

The previous near extinction of the Southern White Rhinoceros (SWR) (Ceratotherium simum simum) in the late 19th century, brought awareness to the mass poaching and critical conditions of this endangered species. Protected areas have been established amongst other implementations, as an attempt to increase the population of SWR until they are no longer endangered. As their numbers were scarce, a small population was cultivated and placed under protection. The African Savanna parks have been the only area where SWR populations “persist at high densities for several decades”[1], however, their existence has decreased significantly in Kruger National Park (KNP), South Africa (SA) due to the high levels of illegal hunting[2], corruption, and poaching[3]. There is a high value for the horn and even increased military protection has not had significant influence on the protection of the current population. The climatic influence of global warming has brought increased drought to KNP, reducing the food availability for this grazing mammal, leading to dangerously low birth rates[2]. Scientists are attempting to use assisted reproductive technologies to increase SWR populations by combining eggs and “cryopreserved sperm,” to create embryos [4].


History of the Southern White Rhinos

Historic Populations

Kruger National Park

The SWR first “appeared in the Eocene and flourished in the Oligocene"[3]. The white rhinoceros is one of the five rhinoceros species: Black rhinoceros, Indian rhinoceros, Javan rhinoceros and the Sumatran rhinoceros. They are the "largest surviving extant rhino and thus one of the largest terrestrial mammals" [5]. Although rhinoceros' were on the brink of extinction, they were once “ a familiar sight to ancient Europeans” [5] according to stone-age artifacts. They roamed all over Europe 20,000 years ago, before the climate started to change and before humans began to hunt for rhinoceroses. Not long before the hunting of the rhinoceros began, the “woolly rhinoceros disappeared around 12,000 years ago” [5]. In the 1890s, the population of SWR was inadequate and only “a single population of about 20-50 individuals between the Black and White Umfolozi Rivers” [6] located in KwaZulu-Natal, SA. Since this was the only population left of the endangered species, in 1898 it had become the Umfolozi Game Reserve to protect the remaining rhinoceroses. The population had been increasing steadily all the way until the twentieth century. However, a main problem this species still faces today is the struggle of “females [which] are deceased or beyond their reproductive life span, and the captive-born females have exhibited poor reproductive success” even when in protected areas. The African Savanna parks have been the only area to “persist at high densities for several decades,” for white rhinos[1]. The demand for SWR horns will always stay the same with or “without consumer behaviour modification […] legal trade in rhino horn leads to extinction”[7].

Native Home

KNP is located in the northeastern part of SA, with an area of 19,485 km2 and is home to the SWR. They have been recently introduced to Kenya, Zambia, and Cote d’Ivoire. The SWR are mega-herbivores and are one of the few species which “have been lost from most ecosystems world-wide” [8] . They roam SA as the “key drivers of ecosystem structure and functioning,” [8] therefore, their existence is crucial to the ecosystem food chain. A top-down ecological regulation is a system where the top consumers of the food chain control the primary consumer population, resulting in an increase of diversity in the primary producer population. Since, rhinoceroses have no natural predators; their only worry are humans hunting them for their horns. Occasionally, they may be killed or eaten by packs of big cats, hyenas, crocodiles and African wild dogs. However, “the loss of apex consumers has been recognized as possibly ‘humankind’s most pervasive influence on nature” [8] leading to a decrease in population due to their struggle to survive.

The Impacts Leading to Near Extinction

Poaching of the mother's horns

Anthropocentric Impacts

Poaching and Illegal Hunting

The SWR populations have fluctuated historically due to the increased levels of poaching; in the turn of the 19th century, the number of SWR depleted to a single population of 20-50 rhinos[9].  The rhino horn is known as one of the most expensive international goods and is largely desired throughout Asian countries as an ingredient for traditional medicines. Since the creation of the Umfolozi Game Reserve, the population of the SWR had increased to an estimated 20,430 individual rhinos in 2012[6]. Unfortunately, this population rise also exponentially increased the rate of poaching (2007-2014)[10], to over 1000 deaths per year.  If this persists, the death rate will greatly outcompete the number birth rates, and will ultimately lead to the population becoming at risk once again[6]. 

The KNP was created in 1898 under the name “Sambie Game Reserve”, and the name was later changed in 1926 to KNP[11].  The highest levels of poaching have been focused in KNP, lying on the SA side of the SA/Mozambique border[6]. KNP was created on the basis of “fortress conservation”, creating a landscape where there are no human impacts and in doing so, displacing millions of local people and communities[12]. This process lead to high unemployment, creating high levels of local poverty. As a result, many of the poachers hunting in KNP originate from these displaced, demoralized communities, the bounty of a horn far exceeding their past average annual income. The rhinos have been protected at the cost of their land, resources, and livelihood, and they don’t directly benefit from the protected areas.  Wealthy and white men are able to pay the governments money to trophy hunt big mammals such as rhinos, yet the locals are limited and stigmatized when they trespass and hunt on land that was originally theirs[12]. The hierarchal stakeholders use rhino conservation as a business model and directly gain these benefits from tourism and trophy hunting.  Rather than waiting for the “washed down” benefits to eventually reach the local communities down the class scale, they seek immediate financial relief, which poaching offers[12]. Local groups began constructing hunting crews, labeling themselves as “economic freedom fighters, businessmen, or professional hunters"[12] and turned against the conservation efforts of the government and the wild animals they were striving to protect[12]. Because of the low wages earned by the rangers in the park, they were easily swayed to turn a blind eye or even assist in the hunting crews for a fraction of the bounty of the horn[12].  

Militarization of KNP

The levels of corruption of park rangers and officials only worse as a result of the apartheid government in 1948, leaving KNP overtly militarized[13]. The park began to run under a military rule, which initially had the intention of using it’s resources and technology to protect the endangered species, but quickly created many negative impacts. The military established a base, numerous permanent roads, buildings, and accommodation for their operations to run which has had a direct impact on the habitat of the SWR, as well as displacing more human communities[6]. The military also holds sophisticated weapons and specialized insider knowledge of the park, and alike other corrupt armies throughout Africa, began to use the profit from rhino horns to finance their operations. Their weapons and rule threatens biodiversity of the animals in the park as the commercialization of horn trade has increased to a level that’s never been seen before, becoming the largest and most immediate threat to the SWR[6]. The presence of the military in the park is also obstructing the ability for others to manage the park, and conservation sites, putting the biodiversity tourism in jeopardy which is key to sustaining the protected areas[6]. Although SANParks (South Africa National Parks) have attempted new approaches with the military, many are still influenced by the previous regime and ideology and have not been able to prevent transgressions as many members have been arrested for involvement of rhino poaching[6]. Regardless if there were increased levels of military protection, poaching would still occur due to the present corrupted ideology[6].

Environmental Impacts

Rainfall and Drought Patterns of Kruger National Park (1930-2016)

Climatic Influence

"The climate of the KNP is mostly semi-arid with mean annual temperature and precipitation of 22 °C and 550 mm/annum, respectively, and an average potential evaporation of 7 mm/day"[14].  In Africa, there is a high and prominent risk of climate change and the global climate classification has shown that KNP has become drier over the last 100 years.  With this comes longer dry seasons, significantly decreasing trends of total rainfall annually in KNP which can lead to drought or flash flooding[15].

As noted, the majority of SA’s efforts and resources are aimed towards anti-poaching efforts to improve said populations. Without managing land-use or climate variability the future populations are at risk from natural disasters such as intense flooding or drought[10]. The natural processes within KNP are dependent on the amount of rainfall in the area, and the regularity of it; the amount of precipitation directly impacts the amount of vegetation available, fire control, and animal movement.  According to the Department of Environmental Affairs (DEA), “South Africa is projected to become progressively hotter and drier”, which is raising concern regarding the management of local protected areas[15].  Protected areas, are particularly vulnerable to the impacts of climate change, as they are isolated and restricted landscapes where species movements are limited[15].

Drought and Food Availability in Kruger National Park

In 2015/2016, KNP experienced intense drought which became associated with the survival of SWR.  Droughts immediately impact grasses and herbaceous vegetation, decreasing the amount of food available to this grazing mammal increasing mortality. The grass availability fluctuates due to the inconsistent rainfall in KNP[2].  Drought also has negative impacts on the river geomorphology and associated riparian vegetation and species distribution patterns.  As stated above, the SWR population is restricted to KNP as a protected area, and therefore, they do not have an alternative habitat or food source for their populations to survive.  The limited food increases the mortality rate and decreases the birthrate of these mammals, comprising the resilience of the population and it may take much longer these populations to recover[2].  

Rehabilitation

Brought into Captivity to Protect and Maintain Populations

The SWR was brought into captivity, zoos or zoological gardens, to help prevent the further decrease of their population. The SWR has a very low reproductive rate in captivity [16], as the species are found to have little interactions with one another, and the relationships that do start are typically short lived; therefore, they are not able to repopulate in multiple relationships as they would in the wild. Many females that were born and raised in captivity have birth defects, making them infertile. The conservation efforts of breeding the rhino in captivity are questionable, and behavioural observations are being made to see how these efforts can be strengthened [16].

Assisted Reproductive Technologies

The SWR population is anticipated to increase through Assisted Reproductive Technologies (ARTs) by using eggs and “cryopreserved sperm,” to create embryos [4]. Stem cell research is one of the newest technologies used to rehabilitate endangered species, and the SWR is a prime candidate. In the efforts to revitalize the population, specialists from around the world have come together to construct a plan for ideal outcomes to support the future of at risk species. They create an embryo by using live egg cells and fertilizing them with preserved sperm cells, and use invitro fertilization (IVF) to transmit the embryo into the uterus of a female rhino[17]. Unfortunately, there are no cases where there has been any successful embryo transmission to date using in vitro fertilization. The sheer difficulty of obtained sperm and egg samples from rhinos is a challenge as the animals are so large and few in number[4]. Professor Hildebrandt, from the University of Melbourne, has successfully created multiple hybrid embryos of the Northern White Rhino (NWR) and SWR which have now been cryopreserved[17]. Professor Hildebrandt was able to create an ovum pick up device (OPU), that enabled one to collect the eggs from the rhino with ease. Technologies such as OPU will prove the oocytes fundamental to the development of successful in vitro culture systems and protocols[18]. The OPU is now being reviewed to be considered for the future collection of eggs from other species. Since the sperm cells are cryopreserved, it can be problematic as the sperm usually needs stimulation to be properly used. Most of the semen that has been collected is very limited and of poor quality [19]. The concept of this project is now being considered to help other larger endangered animals, including other specific rhino species. Funding for these technologies is limited, and since there is no actual living hybrid of the NWR and SWR to encourage individuals or companies to donate their money, there has been limits to further research and technology.         

Anti-Poaching Patrols

“The Convention on International Trade in Endangered Species CITES (1977) classified trade in rhino horn as illegal,” [20]. Due to the horns of a rhinoceros being so valuable on the black market they are held to be trophies or a symbol of status. To help stop illegal poaching of these endangered species, tourism group near the SWR's natural habitats by groups of people have been able to keep these areas under surveillance [21]. Indigenous populations near the natural habitats are those helping the anti-poaching efforts.

Proposed Solutions to Increase Growth of All Rhinoceros Species

The International Union for Conservation of Nature (IUCN) claims that all rhinoceros species experience some threat to their survival[18]. Proposed solutions for the SWR are also solutions that can be used to help increase the population of other rhino species and potentially even other animal species.

Controlled and Non-Harmful Harvesting of Rhino Horns

SWR horn poaching is one of the leading factors in the species' depreciation rates, “with over 1,200 SWR being poached in SA alone in 2015 and over 1,000 in 2016”[22]. Studies conducted at the University of Helsinki suggest that a controlled and non-harmful method of rhino horn harvesting by local people could be the solution to preventing criminal poaching. Criminal poaching is dangerous for the SWR and most often ends in the rhinoceros’ death. This proposed controlled harvesting would be a relatively painless process for the SWR and “would boost the local economy, increase funds for anti-poaching programs, and decrease the level of illegal hunting”[23]. This method remains very controversial and has not been implemented legally. If this method is proven to be effective for the SWR, this could be implemented for other species as well. However, a rhinoceroses’ horn is their weapon for protection and if removed, they will not strive in the wild. This solution can only be implemented if the species is kept in designated areas, away from threats and predators.

Supplementary Feeding

With the goal to prevent starvation during dry seasons, supplementary feeding is currently being observed to determine its beneficial effects. Researchers at the Palacky University observed two separate groups of SWR in small reserves; one group with supplementary feeding and the other without[24]. They found that the SWRs who were given supplementary feeding changed their distribution in the feeding areas and became more competitive for the food[24]. However, with multiple dispersed feeding locations, supplementary feeding could truly help the SWR[24]. In fact, “conception rates were higher during periods of supplemental feeding"[22]. It was also observed that there is a clear increase in the calving period during the months of December until April[22]. Given that supplementary feeding can be quite expensive, reserves should prioritize supplementary feeding during the calving months to increase the reproduction rate of the SWR. This method has shown some promise for smaller animals but it is yet to be proven efficient for the SWR. If this method were to be implemented, there should be a focus during mating seasons, which could help all the species of rhinos in increasing their populations.

Protection in Captivity

To prevent poaching and to increase the protection of the SWR, many have been placed under protection in captivity, which has lead to problems with fertility[25]. Under the right circumstances, wild-caught SWR will breed in captivity. This requires a specific amount of space, food and breeding aged female rhinos present[22]. Unfortunately, “only 50% of all captive females reproduce successfully, and only 38% of the females born in captivity have produced offspring "[22]. Research has discovered that the sub-fertility of SWR is caused by their diet in captivity. Phytoestrogens, found mostly in legume plants that have undergone stress from extreme temperatures, drought or disease[26], are the cause for this sub-fertility. Prolonged consumption of phytoestrogens can cause many severe medical complications, including permanent infertility"[27]. These effects can also be seen in wild SWR who primarily eat legumes, but it is greatly impacting female SWR raised in captivity since they only have one source of food. Exposing these young SWR to phytoestrogens causes a “manipulation of their estrogen during specific critical windows of development throughout the perinatal period which leads to a myriad of adverse health outcomes including malformations in the ovary, uterus, mammary gland and prostate, early puberty, reduced fertility, disrupted brain organization, and reproductive tract cancers"[26]. Even though protection and breeding in captivity was a huge success for the increasing population of SWR, it is now clear that there are negative effects to the population. Having said this, with the proper nutrition, space and population ratios of females and males, protection in large reserves could truly increase the populations of the rhino species.

The geographical range of the white rhinoceros determined by the International Union for Conservation of Nature (IUCN) in 2011.

Translocation for Conservation

In past attempts, IUCN claims that the lack of monitoring during and after translocation is what caused multiple deaths[28]. However, the SWR that survived translocation did not seem to be bothered by their new home, as long as there was sufficient water, shade and short grass[28]. A recent study determined that "polygamous breeding, where dominant males have access to several adult females seemed to be required"[22] for optimal reproduction rates. A translocation of SWR to a fenced 64 km2 reserve in Uganda is currently being considered to replace the locally extinct NWR[28]. The translocation of a single male into a small population of female SWR would eliminate the competition of subordinate SWR males and would increase breading while decreasing the inbreeding rates of the SWR[29]. "Moreover, translocation of males is a more cost-efficient strategy for introducing new diversity into a population than moving females, because males are likely to have a more substantial genetic contribution"[29]. Some controversy still remains around this proposal considering the removal of competition is removing the natural selection of this species. This aspect should not be of concern if these translocation reserves maintain proper monitoring. Translocation for conservation is a method often implemented and is likely to be used more often in the future for other rhino species if the current translocation studies acquire positive feedback.

Assisted Reproductive Technologies (ARTs)

As medical technology advances, the methods for conservation increase. "The use of ARTs in vivo has been accelerated by the combination of serial ultrasonography, hormone monitoring, ovulation induction, and appropriately timed AI in rhinoceroses"[18]. Much impressive progress has already been made in this field with the goal to increase population numbers, all while insuring genetic diversity within populations and species.

Hybrid Rescue of the North White Rhinoceros

In anticipation of the White Rhinoceros extinction, specialists froze SWR and NWR sperm and eggs[19]. The NWR "is the most endangered mammal in the world with only two females surviving" and unfortunately, both are infertile[19]. There is already research and experiments in place, attempting to create a hybrid of the SWR female and NWR male. This would create a new White Rhinoceros species to replace the NWR. It has been proposed to manipulate and modify the genetics of this new breed to ensure its survival in this new era[18]. There is a lot of controversy about this subject. However, if proven to be efficient and successful, this method of population rehabilitation could be implemented for many different species.

Conclusion

The SWR species has greatly increased their population numbers since their near extinction and continue to increase. This was made possible with the assistance of humans in protected captivity and with anti-poaching patrols. Many more methods are currently being studied to determine their efficiency for the SWR populations and other rhinoceros species. It will be increasingly important to research and monitor genetic diversity for each species to avoid the effects of population bottleneck. Human intervention in the preservation of ecosystem structures and integrity will be a key factor in the long survival of the rhinoceros species.

References

  1. ↑ 1.0 1.1 Waldram, Matthew S. (2008). "Ecological Engineering by a Mega-Grazer: White Rhino Impacts on a South African Savanna".
  2. ↑ 2.0 2.1 2.2 2.3 Ferreira, S. M., Le Roux, N., Greaver, C. (2019). "Species-specific drought impacts on black and white rhinoceroses". PLoS One. 14(1).
  3. ↑ 3.0 3.1 Schellhorn, Rico (2017). "A potential link between lateral semicircular canal orientation, head posture, and dietary habits in extant rhinos (Perissodactyla, Rhinocerotidae)". Journal of Morphology. 279: 50–61 – via Wiley Online Library.
  4. ↑ 4.0 4.1 4.2 Holland, Daryl (2018). "BRINGING BACK THE NORTHERN WHITE RHINO FROM 'EXTINCTION'". Pursuit.
  5. ↑ 5.0 5.1 5.2 Gross, Michael (2018). "Last Call to Save Rhinos". Current Biology. 28: R1–R3 – via Cell Press.
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 Annecke, W., & Masubelele, M. (2016). "A Review of the Impact of Militarisation: The Case of Rhino Poaching in Kruger National Park, South Africa". Conservation and Society. 14(3): 195–204.
  7. ↑ Haas, Timothy C. (2016). "Combating Rhino Horn Trafficking: The Need to Disrupt Criminal Networks".
  8. ↑ 8.0 8.1 8.2 Cromsigt, Joris P.G.M. (2014). "Restoration of a megaherbivore: Landscape-level impacts of white rhinoceros in Kruger National Park, South Africa". Journal of Ecology. 102(3): 566–575 – via British Ecological Society.
  9. ↑ Moodley, Y., Russo,I. M., Robovsky, J., Dalton, D. L., Kotzé, A., Smith, S., Bruford, M. W., Stejskal, J., Ryder, O. A., Hermes, R., Walzer, C. (2018). "Contrasting evolutionary history, anthropogenic declines and genetic contact in the northern and southern white rhinoceros". Proceedings Biological Sciences. 285(1890).
  10. ↑ 10.0 10.1 Ranjan, R. (2019). "Shooting at the poachers while the rhinos drown: Managing short- and long-term threats to endangered wildlife in conservation reserves". Natural Resource Modelling. 32(1).
  11. ↑ Pienaar, U de V (Dr). (1990). "The history on the development of the Sabie and Shingwedzi Reserves and the Kruger National Park, 1898 to 1946- "Nem uit de Verlede"": Chapter 17. Cite journal requires |journal= (help)
  12. ↑ 12.0 12.1 12.2 12.3 12.4 12.5 Hübschle, A. M. (2017). "The social economy of rhino poaching: Of economic freedom fighters, professional hunters and marginalized local people". Current Sociology. 65(3): 427–447.
  13. ↑ Lunstrum, E. (2015). "Conservation Meets Militarisation in Kruger National Park: Historical Encounters and Complex Legacies". Conservation and Society. 13(4): 356–369.
  14. ↑ Mathivha, F. I., Tshipala, N. N., & Nkuna, Z. (2017). "The relationship between drought and tourist arrivals: A case study of Kruger National Park, South Africa". Jamba (Potchefstroom, South Africa). 9(1): 471-e8.
  15. ↑ 15.0 15.1 15.2 MacFayden, S., Zambatis, N., Van Teeffelen, Astrid J. A, & Hui, C. (2018). "Long-term rainfall regression surfaces for the Kruger National Park, South Africa: A spatio-temporal review of patterns from 1981 to 2015". International Journal of Climatology. 38(5): 2506–2519.
  16. ↑ 16.0 16.1 Cinková, Ivana (2013). "Social and reproductive behaviour of critically endangered northern white rhinoceros in a zoological garden". Mammalian Biology – via Elsevier Science Direct.
  17. ↑ 17.0 17.1 Callaway, Ewen (2016). "Stem-cell plan aims to bring rhino back from brink of extinction". Nature. vol. 533, no. 7601 – via Health Reference Center Academic.
  18. ↑ 18.0 18.1 18.2 18.3 Pennington, P.; Durrant, B. (2018). "Assisted reproductive technologies in captive rhinoceroses". Mammal Review. 49(1): 1–15.
  19. ↑ 19.0 19.1 19.2 Hildebrandt, Thomas B.; Hermes, Robert; Colleoni, Silvia; Diecke, Sebastian; Holtze, Susanne; Renfree, Marilyn B.; Stejskal, Jan; Hayashi, Katsuhiko; Drukker, Micha (2018). "Embryos and embryonic stem cells from the white rhinoceros". Nature Communications. 9(1).
  20. ↑ Cheteni, Priviledge (2013). "An analysis of anti-poaching techniques in Africa: A case of rhino poaching". Munich Personal RePEc Archive – via University of Fort Hare.
  21. ↑ Annecke, Wendy (2016). "A Review of the Impact of Militarisation: The Case of Rhino Poaching in Kruger National Park, South Africa". South African National Parks – via Conservation and Society.
  22. ↑ 22.0 22.1 22.2 22.3 22.4 22.5 Ververs, C.; van Zijll Langhout, M.; Hostens, M.; Otto, M.; Govaere, J.; Durrant, B.; Van Soom, A. (2017). "Reproductive performance parameters in a large population of game-ranched white rhinoceroses (Ceratotherium simum simum)". PLOS ONE. 12(12).
  23. ↑ Anonymous (2014). "Horn trade could save rhinos". Nature. 514(7523): 406.
  24. ↑ 24.0 24.1 24.2 Cinková, Ivana; Ganslosser, Udo; Kretzschmar, Petra (2017). "Effect of supplementary feeding on the social behaviour and distribution patterns of free-ranging southern white rhinoceros". Mammalia. 81(5): 433–443.
  25. ↑ Patisaul, H. (2012). "Infertility in the Southern White Rhino: Is Diet the Source of the Problem?". Endocrinology. 153(4): 1568–1571.
  26. ↑ 26.0 26.1 Patisaul, Heather B. (2012). "Infertility in the Southern White Rhino: Is Diet the Source of the Problem?". Endocrinology. 153 (4): 1568–1571.
  27. ↑ Tubbs, C.; Hartig, P.; Cardon, M.; Varga, N.; Milnes, M. (2012). "Activation of Southern White Rhinoceros (Ceratotherium simum simum) Estrogen Receptors by Phytoestrogens: Potential Role in the Reproductive Failure of Captive-Born Females?". Endocrinology. 153(3): 1444–1452.
  28. ↑ 28.0 28.1 28.2 Sheil, D.; Kirkby, A. (2018). "Observations on Southern White Rhinoceros Ceratotherium simum simum Translocated to Uganda". Tropical Conservation Science. 11.
  29. ↑ 29.0 29.1 Purisotayo, T.; Jonsson, N.; Mable, B.; Verreynne, F. (2019). "Combining molecular and incomplete observational data to inform management of southern white rhinoceros (Ceratotherium simum simum)". Conservation Genetics: 1–14.


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