Research Papers

Creating a Conservation Plan for the Black Rhino (Diceros bicornis)

Introduction

The animal chosen to be discussed throughout the course of this paper is the black rhinoceros (Diceros bicornis) or, as other-wise known, the hook-lipped rhinoceros (IUCN, n.d.) because of the hook shaped appearance of its snout. The black rhino (Diceros bicornis) is a member of the Rhinoceros family which has a variety of family members including four species who- just like the black rhino (Diceros bicornis)- are, or were considered endangered at some point in time (Bits & Pieces, 2005). Some of these species include: the white rhino (Cretotherium simum), the Indian rhino (Rhinocerus unicornis), the Javan Rhino (Rhinocerus sondaicus), and the Sumatran rhino (Dicerorhinus Sumatrensis) (Bits & Pieces, 2005).

By means of research it was discovered that each type of rhinoceros is unique in its own way, and some genetic variances can be seen in weight, horn projection, and overall appearance; also habitat distinctions can create different rhino features as well. For example, the white rhino presents a twin horned appearance, and can weigh up to 3600 kg, whereas the Indian rhino presents a single horn appearance and only grows to weigh approximately 2800 kg (Bits & Pieces, 2005). Other species of rhino, such as the Sumatran, presents a hairy appearance (Bits & Pieces, 2005) opposed to the leathery appearance that most Rhinos present.

The black rhino (Diceros bicornis) however has a single horn protrusion, and is rather small in comparison to other species of rhino and only grows to be about 1360 kg in weight (Bits & Pieces, 2005). Approximately eight million years ago the black rhino (Diceros bicornis) began to branch out into different lineages (Coffin, 2013). Not only are there an abundance of different species of rhino but also a variety of subspecies within the black rhino lineage as well (IUCN, n.d.). This includes species such as the western black rhino, etc. (Coffin, 2013).

Some of the other areas covered in this paper fit under the headings: biology, threats, and conservation plan. Throughout the “biology” portion of the paper I will discuss the dietary habits of the black rhino (Diceros bicornis), which species interacts with it in the wild, its habitat preferences, and its range (previous and current). Under the heading of “threats” we will be talking about how the population has declined, factors that lead to this decline, and its current threats. The section labeled “conservation plan” will include a well-supported plan of action in which this species may recover. It will explain why this is the recommended plan and why it is thought to be superior to other plans.

Biology

A lot like many herbivores, rhinos are known to compile diets that consist of many different forms of plants and plant parts (Ganqa & Scogings, 2007). By means of research, it was discovered that a lot of what the black rhinos (Diceros bicornis) decided to eat was relative to food availability and differs depending on where they are located and what season (wet or dry) they are in. For example, Buk and Knight (2010) conducted a study on diet preferences in three national parks and found that Rhinos had been recorded foraging on 127 different plant species; 51 being in Agrabie Falls National Park (AFNP), 53 in Karoo National Park (KRNP), and 41 in Vaalbos National Park (VNP). The top three plants of the plants eaten from each park included: Zygophyllum cf. dregeana, Acacia mellifera, and Euphorbia rectirama in AFNP, A. karroo, Zygophyllum sp., and Lycium cinereum in KRNP, and lastly A. mellifera, Grewia flava, and A. tortilis in VNP (Buk & Knight, 2010). In all three parks the most preferred plants species included Acacia, Zygophyllum, Hermannia, Rhigozum and Sasola (Buk & Knight, 2010). At the Olpejeta Conservancy in Kenya the Acacia drepanolobium made up 75% of the black rhinos diet (Wahungu, Mureu, & Macharia, 2010).

The intake of different plant species varied by season in a sense that the black rhino (Diceros Bicornis) chose to eat evergreen plants during the dry seasons when the deciduous plants didn’t have leaves (Buk & Knight, 2010). Two plants that make up a large portion of rhino diet in the late dry season are Acacia mellifera, and Grewia flava because they get there leaves back early (Buk & Knight, 2010). The most frequently foraged plant in the wet season- making up 68.9% of browsed (eaten) plants- is the Euphorbia bothae.

Because black rhinos (Diceros Bicornis) ingest a lot of their diet by eating twigs as well as leaves, it is important to factor in twig diameter when determining forage efficacy (energy intake, etc.) (Ganqa & Scogings, 2007). Twigs provide a great deal of fibre for the black rhino depending on twig diameter which ultimately effects the plant selection of the black rhinos (Diceros Bicornis) because they prefer diets high in fiber (Ganqa & Scogings, 2007). Rhinos will typically choose to browse (eat) vegetation in which the twig diameter is anywhere between 1-10 mm in diameter (Ganqa and Scogings, 2007).

The black rhino (Diceros Bicornis) interacts with a variety of different animals in its ecosystem. Rhinos can make things fall prey to their habits, can be hunted by predators, and of course they can compete with other animals for resources. Although rhinos are not carnivorous creatures small herbivores can fall prey to the rhino because of how much they can eat at a given time (Ganqa & Scogings, 2007). Also big browsers such as elephants and rhinos forage and knock a variety of trees down (Birkett & Stevens-Woods, 2005) which could ultimately prevent other animals from eating them; thus becoming their prey. This would also fall under the area of “competition”.

However, rhinos do not always out-compete their adversaries and can actually be out contested by other large herbivores such as giraffes and elephants (Birkett & Stevens-Woods, 2005). One of the main food sources at some national parks, the Acacia drepanolobium, has undergone a severe amount of browsing from giraffes, elephants and rhinos (Birkett & Stevens-Woods, 2005). Despite the size and strength of black rhinos (Diceros Bicornis) they can still fall prey to predation and it is speculated that predators such as lions, hyenas, and crocodiles are the only species other than humans to be capable of killing a Rhino (Patton, 2009).

Black rhinos (Diceros Bicornis) can survive in a wide variety of habitats, but the ones that have the highest densities are savannas on nutrient rich soils and succulent valley bushveld areas; they can also be located anywhere from wet forest areas to desert conditions (Namibia) (IUCN, n.d.). Rhino’s seemed to prefer areas of altitude greater than 314 m high, but also prefer flatter landscapes because areas with slopes that angle any more than 30 degrees are considered inaccessible for them (Odendaal-Holmes, Marshal, & Parrini, 2014). Rhinos often choose to avoid human interactions as well, and human disturbance can have a large effect on where the black rhino (Diceros bicornis) populations chose to take refuge.

The black rhino (Diceros bicornis) has existed in western areas of Africa for some time and is native to countries such as Angola, Kenya, Mozambique, Namibia, South Africa, Tanzania, and United Republic of Zimbabwe (IUCN, n.d.). Recently the black rhino (Diceros bicornis) has been reintroduced into areas of Botswana, Malawi, Swaziland and Zambia (IUCN, n.d.). The black rhino is possibly extinct in Ethiopia, but is currently regionally extinct in Cameroon, Chad, and Rwanda (IUCN, n.d.). This should give you an idea on the past and present range sizes.

Threats

Through research it was discovered that there are multiple ways in which rhinos can be killed. Some of these areas (found in a variety of articles) include: competition, predation, habitat loss/environmental factors, other human factors, accidents, density issues, and last but not least poaching/hunting. In the 1960’s the African black rhino (Diceros bicornis) population had already begun to decline to approximately 70 000, which continued to decrease, shrinking to less than 3300 in the 90’s, and in the year 2000 only 2000 African black rhinos (Diceros bicornis) were left in the wild (Rice, & Jones, 2006). These numbers continued to decline until increased conservation efforts in 2007 helped to push this number up to a whopping 4200 Black Rhinos in the wild (Odendaal-Holmes, Marshal, & Parrini, 2014).

One of the contributing factors to this major decline in population was competition and density issues. For example, the Acacia drepnolobium– a plant in Obpejeta conservancy in Kenya- makes up 75% of the black rhino’s (Diceros bicornis) diet at this facility and it is being eaten in abundance by other large herbivores (Wahungu, Mureu & Macharia, 2010). The trio later goes on to report the importance of this plant in regards to black rhino (Diceros bicornis) conservation. Translocations (moving rhinos from one area to another) also create competitive terms in a sense that when males are placed into a new environment’s there is high potential for intra-specific fighting mortality (Gottert, Schone, Zinner, Hodges, & Boer, 2010) that is speculated to be due to mating rituals and aggression. Translocation is also known to produce low reproductive output in black rhinos (Diceros bicornis) as well (Gottert, et al., 2010). However on the flip-side, translocations can also be used to remove Rhino’s from areas of high population concentration, to areas of low population concentration which will increase food availability and reduce population pressures; thus producing a decrease in intra-specific fighting (rhinos fighting other rhinos), (Hearne & Apaloo, 2012).

Predation is not a large cause of mortality in black rhino’s (Diceros bicornis) simply because there are very few animals that can hunt these massive creatures (lion, hyena, and crocodiles) (Patton, 2009). However, though it is not a large cause it does not mean that it doesn’t happen. Lions- apart from humans- are the only other main predator of rhinos and target rhino calves opposed to adults; making it hard to record due to how easily the carcasses can deteriorate (Patton, 2009).

Habitat loss, accidental deaths and other human factors may also cause rhino mortality. According to Coffin (2013) by 1980 one of the big factors leading to rhino death was habitat loss which was due to human activity such as land clearing and agricultural purposes. It also seems likely that ecological processes could have altered this habitat as well given the prevalence of these occurrences in nature. War is another large concern for the environment in some African countries such as Chad, Cameroon, and many others, and has caused government officials to reduce conservation expenditure, and created a lack of will from these officials as well (IUCN, n.d.). Rice and Jones (2006) found a 6% decline between 1989 and 1993 in rhinos due to low breeding, agonistic behaviour and accidental death. Other human factors include stress, which was associated with rhino calf mortality in northwestern Namibia (Odendaal-Holmes, Marshal, & Parrini, 2014).

Finally, hunting/poaching has been a massive problem in the population decline causing more than 95% of the black rhino (Diceros bicornis) deaths since the early 1970’s (Rice, & Jones, 2006). The reason these horns are of high priority to hunters is because it is speculated that there has been an increase in black market prices in recent years (IUCN, n.d.). This price increase is no doubt due to the variety of uses rhino horns can have. Horns have been known to be used for medical purposes in China (creating medicine), and for ornamental use; for example, certain tribes use it for handles of ceremonial daggers (IUCN, n.d.). By means of research, speculation can be made to note that most if not all of these “threats” listed above are no doubt still affecting the black rhino (Diceros Bicornis) population today. It seems likely however that conservation efforts and wildlife management have been limiting these occurrences to bearable amounts allowing reproduction rate to outpace mortality rate in some areas.

Conservation Plan

            Field protection has been a critical factor in increasing black rhino (Diceros bicornis) populations (IUCN, n.d.). A large number of rhino populations are being housed in areas such as: fenced sanctuaries, rhino conservation areas, conservancies and intensive protection zones (areas that provide a great deal of government and legislative protection) (IUCN, n.d.). These areas have proved to be effective in the past, and it seems possible that by creating a sanctuary that encompasses more than one of the methods listed above would be most ideal in creating an effective black rhino (Diceros bicornis) sanctuary.

For instance, it seems very likely that by creating a fenced sanctuary accompanied by the ideology of intensive protection zones, that you could best control black rhino (Diceros bicornis) population. Range size would also be an important idea to factor in when dealing with a fenced sanctuary. If the range size is too small (e.g. >250 km squared) there may be less resource selection, home range establishment and other limiting factors (Odendaal-Holmes, Marshal, & Parrini, 2014). However if the range size is too large there may be complications with mobility and accessibility by individual rhinos; range size will depend on how many rhinos are present (Odendaal-Holmes, Marshal, & Parrini, 2014). By using a medium fenced sanctuary you may be able to monitor environmental factors (predation, competition, etc.), while still providing the rhinos with enough space to maneuver. In Kenya they also use fence ranges to help protect against poaching (Rice & Jones, 2006). Speculation can also be made that by adding the ideas behind intensive protection zones you may further prevent poaching/hunting within this confined area as well.

It was also discovered that rhinos may have avoided areas of higher elevation and tended to prefer maneuvering within relatively flatter spaces (Odendaal-Holmes, Marshal, & Parrini, 2014). Within this domestic sanctuary there could still be risk of over population, which- as listed under the “threats” heading- could potentially lead to high population density, population pressures, and in turn competition over resources. Thus raising the question; is maintaining large populations a good or bad thing?

The idea behind this question has been debated in recent years and can be looked at through two perspectives: the “managers perspective” (keeping high population densities), and the “translocation proponents perspective” (keeping translocations maximal) (Hearne & Apaloo, 2012). The benefits of the Managers Perspective, and having large population in given areas, are as listed: trust within certain conservation sites, high population increases tourist awareness and through that public support, when growth rate is low rhinos are said to be “surviving” and removal would not be ideal, and lastly it provides a sense of ownership over the rhinos (Hearne & Apaloo, 2012).

On the flip-side of this the Translocation Proponents Perspective argues that minimal populations can benefit greatly from small increases in growth rate and that utilising anything that slows increases in growth rate would be best (Hearne & Apaloo, 2012). Therefore, inside this fenced and the legally protected area discussed above, it seems probable that small translocations would prove to be most effective in maintaining a healthy population density within this fabricated sanctuary, in a sense that we could still utilize benefits from both perspectives while attempting to avoid some of the negatives in the process.

For instance, we could keep the population at a level that tourists would still be able to occasionally see them, but not so high that they could be easily hunted without notice. Hearne and Apaloo (2012) in a study concerning translocation strategies for black rhinos (Diceros bicornis), speculate that a good balance between these two perspectives would appear best at a 4% to 5% removal rate. It is also important to note that translocation successes have been proven to be more effective when the rhino is being placed into a vacant reserve opposed to one with a pre-existing rhino population (Odendaal-Holmes, Marshal, & Parrini, 2014).

Dietary patterns are also a large concern when considering black rhino (Diceros bicornis) conservation (Ganqa & Scogings, 2007). Going hand-in-hand with the translocation argument above, Ganqa and Scogings (2007) speculate that rhino populations may need to be monitored in regards to plant-herbivore relationships to validate that they are not eating faster than food is being produced. Listed above under the Biology heading is dietary information concerning the black rhinos (Diceros bicornis) eating preferences which are what we would aim to include inside the contrived sanctuary we have been designing throughout this section.

To reiterate some of these things, we would try to add a variety of evergreen and deciduous species of vegetation- with a higher priority for evergreen- with a twig diameter of approximately 1-10 mm in diameter, which also presents the high amount of fiber preferred by black rhinos (Diceros bicornis), (Ganqa & Scogings, 2007). Some of the vegetation added would include plants such as Acacia drepanolobium which makes up 75% of the black rhinos diet at the Obpejeta conservancy in Kenya (Wahungu, Mureu & Macharia, 2010), and the Acacia mellifera and Grewia flava which make up two of the plants eaten by rhinos in the late dry season (Buk & Knight, 2012). Some more plant species that are thought to be critical for black rhino (Diceros Bicornis) survival are Zygophyllum, Monechma incanum, and Rhigozum trichtomum. Providing rhinos with suitable sources of drinking water for different seasons and times of day would also be ideal in conservation efforts (Odendaal-Holmes, Marshal, & Parrini, 2014).

In another study conducted by Rice and Jones (2006) on bedding sites for black rhinos (Diceros bicornis) they speculate that the shade created by these bedding sites may be critical in rhino habitats and conservation. This means that rhinos would need to be provided with specific plants like Euclea divinorum, which was found to provide 64.3% of the vegetation used in bedding sites, in order to maintain a consistent number of beds for the populations. As a conservation tactic we could potentially create some of these bedding sites for the rhinos (much like the houses created to help house birds) to aid them in finding the refuge and shade they are speculated to need for survival.

In summary, we speculated that by using mixed methods of conservation such as fenced sanctuaries and intensive protection zones that we could best manage/monitor the rhino population and protect them from limiting factors (hunting, etc.). We also discussed that by creating a sanctuary that was neither too big nor too small for the given population of rhinos at a certain sanctuary, that we could also eliminate some major limiting factors from the equation as well. One more aspect to take into consideration in regards to land properties was elevation; which rhinos seemed to prefer flatter areas opposed to steeper ones.

We then moved on to discuss the dangers of over population and over translocation. Through research it was discovered that small amounts of translocation (4 to 5%) would be ideal in maintaining a healthy population size and to avoid density issues (food availability, etc.) and population pressures. Afterwards we talked about the importance of food and water availability and went over a couple of vegetation items that would be preferred by the black rhinos (Diceros bicornis) in our fabricated sanctuary. Lastly, we concluded this section by conversing on the importance of bedding sites in the conservation of black rhinos (Diceros Bicornis) and how we could aid them by creating ones within their sanctuaries.

This plan was recommended for the conservation of black rhinos (Diceros Bicornis) because extensive research has pointed the discussion in this direction, and is thought to be superior because it encompasses the ideas from a variety of sources which act to patch some of the errors that other conservation plans may have had.

References

Anonymous, A. (2005, April 22). Bits & Pieces. Australasian Science26.3, 48.

Buk, K. G., & Knight, M. H. (2010). Seasonal diet preferences of black rhinoceros in three arid South African National Parks. African Journal of Ecology,48(4), 1064-1075.

Birkett, A., & Stevens-Wood, B. (2005). Effect of low rainfall and browsing by large herbivores on an enclosed savannah habitat in Kenya. African Journal of Ecology43(2), 123-130.

Coffin, B. (2013). The Western Black Rhino. National Underwriter Life and Health117(8), 48.

Ganqa, N., & Scogings, P. (2007). Forage quality, twig diameter, and growth habit of woody plants browsed by black rhinoceros in semi-arid subtropical thicket, South Africa. Journal of Arid Environments,70(3), 514-526.

Göttert, T., Schöne, J., Zinner, D., Hodges, J. K., & Böer, M. (2010). Habitat use and spatial organisation of relocated Black Rhinos in Namibia. Mammalia74(1), 35-41.

Hearne, J., & Apaloo, J. (2012, August 12). Dealing with two perspectives concerning the translocation strategy for saving Black Rhino. International Conference on Operations Research and Statistics15, 126-131.

IUCN, S. (n.d.). Diceros bicornis. (Black Rhinoceros, Hook-lipped Rhinoceros). Retrieved October 2, 2014, from http://www.iucnredlist.org/details/6557/0

Odendaal-Holmes, K., Marshal, J. P., & parrini, F. (2014). Disturbance and habitat factors in a small reserve: Space use by establishing Black Rhinoceros (Diceros Bicornis). South African Journal of Wildlife Research44(2), 148-160.

Patton, F. (2009, January 1). Lion Predation on the African Black Rhinoceros and Its Potential Effect on Management.Endangered Species Update26.1, 43-49.

Rice, M. B., & Jones, M. (2006). Characteristics of Black Rhinoceros (Diceros Bicornis) bedding sites. African Journal of Ecology44(4), 452-457.

Wahungu, G. M., Mureu, L. K., & Macharia, P. G. (2010). Variability in survival and mortality of Acacia Drepanolobium Sjostedt following prescribed burning at Olpejeta Conservancy, Kenya. African Journal of Ecology48(3), 744-749.

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