Virunga Volcanoes Range Mountain Gorilla

Transcription

1 2011 Virunga Volcanoes Range Mountain Gorilla Jean Uwilingiyimana Boston University Department of Geography & Environment GE 307: Biogeography

2 1 I. Introduction We are often all too concerned with the consequence of civil war conflicts on human populations so much so that we tend to give little to no attention to the effects that such conflicts have on plant and animal species. The civil war conflicts that have raged the Eastern-African countries of Uganda, Democratic Republic of the Congo, and Rwanda are primarily examples that have an a devastating impact on human populations as well as animal populations. Gorillas in general are listed as one of the top 10 threatened or endangered species, with only 655 species remaining. As far as the mountain gorilla is concerned however, there are approximately 355 in the Volcano and Virunga Mountains of Rwanda and Congo and another separate group of 300 in Uganda s Bwindi Impenetrable Forest. The uniqueness of these three nations is that they re the only places were mountain gorillas reside, no gorillas live outside their native mountain forest homes. It is important to look at all three of these countries in trying to understand the effect of civil conflict on gorillas. Primarily because the civil conflict in each country features its own unique circumstances, characteristics and impact levels. One certain shared characteristic of all three however is the destruction of habitat that only is home to the mountain gorillas but is also a food resource necessarily for the species survival. In many ways, the effects that civil conflicts have had on people in those areas of the world are very similar to the effects on gorillas. Decades of civil conflict in the region have affected the livelihoods of local peoples and in turn have caused significant population displacements and enormous refugee settlements and situations that have all had a large impact on the natural environment and formerly protected area that is home to mountain gorillas. Though there has been great effort put towards restoring their habitats and protecting them from poaching and diseases, mountain gorillas, earth s largest primates are still very much endangered and decades civil conflicts in East Africa have played a great role in doing so, primarily due to habitat destruction. The purpose of this paper and project is to examine the civil conflicts and the level to which they have contributed to the destruction and disturbance of natural habitats and ecosystems that are related to the survival of the gorilla species. Furthermore, to examine

3 2 further the relationship between the decrease in the number of mountain gorillas relative to the escalation of civil conflicts in the region, how small or large of a factor it plays. II. Virunga Volcanoes Range (VVR) Geography The Virunga Volcanoes Range that covers the DRC, Uganda and Rwanda is comprised of three separate parks: The Mikeno Sector of the Virunga National Park (Parc National de Virungas) in the DRC, the Volcanoes National Park (Parc National de Volcans) in Rwanda, and the Mgahinga Gorilla National Park, as shown in Figure 1. The Range is located between 25 o and 35 o latitude south and 29 o and 30 o longitude east. Figure 1. Virunga National Park and Virunga Volcanoes Range (VVR) The VVR covers an area of approximately 450km 2 and ranges in altitudes between 1,850 meters and 4, 507 meters above sea level. The VVR is an area of afromontane forest of high biodiversity importance within the Albertine Rift; this is in part due to the mountain gorilla as well as other endemic flora and fauna found in the volcano range (Plumptre et al., 2003). Virunga Volcanoes Volcano Elevation (ft) Elevation (m) Mikeno 14,557 4,437 Karisimbi 14,787 4,507 Visoke 12,175 3,711 Muside 9,843 3,000 Sabinyo 11,923 3,634 Mgahinga 11,398 3,474 Muhavura 13,540 4,127 Table 1. Volcano names and elevation Approximately, eight different categories of vegetation communities have been identified in

4 3 the VVR according to McNeilage Due to vast range in elevation of the VVR, vegetation zones are distributed according to altitude, ranging from mixed forest at lower altitudes, to bamboo and higher altitude forest types to alpine vegetation and bare rock at the highest altitudes, where you increasingly approach the tops of the volcanoes, as shown in Figure 2. Due to the nature of the volcanoes that are present in the range, there is a battle to access in regards to vegetation and habitats that are suitable for gorillas. Unfortunately, these same places are also the ones that are at accessible and arable altitudes for human populations that fled into the forests during times of conflict. Figure Virunga Landsat TM Classification The bare rock that is observed at the periphery of the VVR is result lava from the volcanoes; it goes without saying of course that the majority of the existing vegetation in the VVR is atop of what used to be lava as well. Also, as supported by the Landsat image in Figure 2, the majority of the mixed forest is at higher altitudes around and rising up the volcanoes. This only leaves the herbaceous, hagenia, and bamboo vegetation available to inhabiting species, particularly gorillas that prefer lower vegetation and rarely frequent

5 4 any areas above 3,3500m [Fossey, 1974; Harcourt & Curry-Lindahl, 1979; Watts, 1984; McNeilage, 2001]. The climate of the VVR is similar to that of any Albertine Rift montane forest, that is to say tropical and subtropical moist broadleaf forests. These forests normally provide trees that are very good for fuel wood, which is very popular in that region of Africa, particularly in refugee settlements. Background and History During the time of the civil conflicts in the East African region, similar conflicts and wars seemed to be increasingly globally as the United Nations identified 28 such complex emergencies ongoing in 1995 alone. One common character of many civil conflicts and wars is that they are fought or tend to occur around border areas. Dating far back in history, international boarders have always been drawn along natural divisions, such as mountain ranges, rivers, and lakes [Lanjouw 2000]. The Virunga Volcanoes Range itself was in such a predicament. A closer look at Figure 3 shows the National Park looked at the intersection of borders of the Democratic Republic of the Congo, Uganda, and Rwanda. Each of these nations has had civil conflicts for at least four decades, internally or externally amongst each Figure 3. Virunga Volcanoes National Park other. Formerly known as Albert National Park, Virunga National Park was created in 1925, making it Africa s first official national park. The United Nations Education, Scientific, and Cultural Organization (UNESCO) declared it a World Heritage Site in Fifteen years later during the ongoing civil and ethnic conflicts in Rwanda and the Congo, UNESCO

6 5 declared the National Park as a World Heritage Site in danger. The park is known for its exceptional diversity, containing more bird, mammal and reptile species than any protected area on the African continent. As the Congo, Rwanda, and Uganda gained independence, they each took on the task of managing the park area within their own territories. This decreased the original cover 8090km 2 of the park by half. The park later became the base for the American naturalist Dian Fossey to carry out her research into the gorillas, where She arrived in 1967 and set up the Karisoke Research Centre between Karisimbi and Visoke. She would go on to spend most of her time in the park, and is widely credited for saving the gorillas from extinction by bringing their plight to the attention of the international community [Briggs and Booth 2001]. While the civil conflicts in all three countries has been ongoing for a breadth of time, the Virunga Volcanoes National Park really saw its worst time beginning in 1992, where it became it a battlefield during the Rwanda Civil War and then later on the war been Rwanda and the Democratic Republic of the Congo. The majority of damage in relation to the Park cover in Uganda can be accredited to the refugee crisis that arose from ethnic conflict in Rwanda in the 1970s during which the Tutsi were expelled from power and from the country all-together. The Tutsi would spend their diaspora primarily in the part of the park held in Uganda, otherwise known as the Mgahinga Gorilla National Park; from here the Tutsi would mount a rebel opposition that would attempt to retake power beginning in III. The Mountain Gorilla Biology Since they were brought to light to the international community by Dian Fossey beginning in 1967, mountain gorillas have received a lot of attention in regards to keeping the species from going extinct. The IUCN Red Data Book places the mountain gorilla, gorilla beringei beringei, as a distinct subspecies of the eastern gorilla species as well as the eastern lowland gorilla, gorilla beringei graueri, found in the Bwindi Impenetrable Forest in Uganda. Figure 4. Male Silverback

7 6 Mountain gorillas are in general much larger physically than other subspecies of the gorilla species and have longer hair. The average adult male weights 350 lbs. while the average female weights 215 lbs. They inhabit montane forests as well as bamboo forests at altitudes ranging between 2,000 and 4, 000 m (8,200 13, 100 ft.). Their diet is composed of leaves, shoots and stems of herbaceous vegetation; nearly 86% of their diet is vegetarian. Mountain gorillas eat 142 different plant species along with three types of fruit. In terms of social structure, mountain gorillas live in stable groups or habituated with a dominant male and several females, though 36% of gorilla groups have more than one adult male. Remaining gorillas are either lone males or exclusively male groups. Emphasis is placed on protecting groups versus territory. Around 12 to 15 years of age, adult males develop a silver spray of hair across their backs, hence the term silverbacks [Fig. 4]. Gorillas live to between 40 and 50 years of age and females generally first give birth amongst the ages of 10 and 12, with a 9 month gestation period as humans do, and inter-birth internals of 3-5 years. Females have a reproductive cycle of approximately 28 days of which they are fertile only 1 to 3 days. Most males and about 60% of females leave their natal group and emigrate to other groups. Males normally leave at 11 years of age and travel alone for 2 to 5 years before they can attract a group of females to form a new habituated group. Whereas females normally leave their natal group around 8 years old and transfer to an already habituated group. Like humans, gorillas are diurnal and mainly terrestrial. The dominant silverback male determines the movements of the group and group cohesion tends to be attributed to the desire of group members to remain close to the silverback male for protection. Population Estimating the mountain gorilla population has presented its challenges particularly because researchers and park authorities were unable to collect population data during the years of serious conflict in the DRC as well as Rwanda. Age Categories Category Age Infant Juvenile Subadult 6-8 Blackback 8-12 Adult female Silverback 8 - death 12 - death Table 2. Age Categories used for classification

8 7 In , researcher George Schaller estimated a population between 400 and 500 individuals in the Virunga Mountains. This estimation however was strictly based on group sin the VVR around Kabara Meadow in Virunga National Park in the DRC and the Ugandan area of the VVR. The next detailed census was carried out between , in which the mountain gorilla population was estimated to be between 260 and 290 individuals [Harcourt & Groom 1972; Groom, 1973]. Three years later, , another census revealed that the gorilla population continued to decrease, now between 253 and 285 individuals [Weber & Vedder, 1983]. Again, in 1981, another census showed a continued gradual decline in absolute population size [Aveling & Harcourt, 1984] estimating the population to now range from 242 and 266 individuals. Vedder and Aveling conducted reported new estimates in 1986, which showed an increase in total population size, 252 and 285 individuals. Another census three years later in 1989 continued to show increasing population, placing the population now at 324 individuals [Sholley, 1991]. Then there was the 2000 census that estimated between 359 and 395 individuals [Kalpers et al, 2003]. This census however was based on knowledge about regularly monitored groups and information gathered during ranger patrols, so it s accuracy was never established. The population size dynamics from 1959 to most recently 2003 are shown in shown below [Fig. 5]. Realistically, it was impossible to undertake a census between 1989 and 2003 due to extreme insecurity in the region and it was generally perceived that gorillas had died amongst the violence. The estimates from 2000 however, which were based decent information and previous knowledge showed otherwise. The most recent census that was carried out in 2003 revealed that there is currently 380 individuals. Further breakdown reveals 16 habituated groups consisting of 269 individuals, 12 unhabituated groups consisting of 80 individuals, and 11 lone silverbacks. The population size reveals a 17% increase since 1989 and annual growth rate of 1.15%. While this growth rate is much less than that seen during the 1980s, it is miraculous that the growth rate managed to remain positive between 1989 and 2003 considering the extremity and longevity of the violence that has taken place in the DRC, Rwanda and Uganda from 1989 to 2003.

9 Gorilla Population Uwilingiyimana / Biogeography (Spring 2011) VVR Population Estimates [ ] Population (Low) Population (High) Years Figure 5. High and Low Population Estimates [Data collected from the ICCN 2003 VVR Census Report] Distribution As mentioned before, mountain gorillas normally prefer altitudes of low vegetation. The 17% increase that was observed in population appears to be concentrated almost entirely in one section of the range, south of Visoke and the flanks of Mount Karisimbi in Rwanda. In the past, the vast majority of groups were found at the heart of the VVR, at Mount Visoke, and the valley between Mount Visoke and Mount Sabyinyo. Gorilla distribution across the VVR varies due to several factors. In the DRC for example, the decline in the Mikeno area population was due to direct poaching during the Zairian civil war in the mi 1960s [Webber & Vedder, 1983] whereas in Rwanda it is attributed to large-scale habitat loss [Harcourt & Fossey, 1981]. Furthermore, it is important to note that the Ugandan area of the VVR has an inadequate supply of food for the mountain gorillas so the population in that region is transient. In some cases also, there will be many groups of gorillas with few individuals in them, or a few groups comprised of a larger number of individuals.

10 9 Figure 6. Gorilla distribution across VVR 2003 Figure 7. Gorilla distribution across VVR 2010

11 10 Distribution shown in Fig. 7 is according to data collected between 2008 and Over the last several years, Rwanda has had the best economic and political climate compared to the DRC and Uganda; consequently the conservation efforts in the Volcanoes National Park of Rwanda have had a much more measurable impact, as seen by the number of habituated gorilla groups in the Rwanda part of the VVR. However, even though the number of groups increased, the size of these groups in general decreased. Even so, the increase is enormous when you compare the gorilla groups census map of 2003 [Fig. 6] versus that of 2010 [Fig. 7]. Even with increased numbers and groups due to conservation however, the distribution in the VVR overall appears to have the same pattern. IV. Threats to the Gorilla Population and Challenges to Conservation Habitat Loss and Destruction The Virunga volcanoes region has high human population densities with an average of 300 people per square kilometer and 820 people per square kilometer in some rural areas [Waller, 1996]. Some 90% of these people rely on subsistence farming for a livelihood and depend on resources such as fuel wood for heating and cooking as well. In addition to the poor communities that were naturally taking advantage of the habitat of the VVR, during the civil war conflicts in the DRC and Rwanda, the VVR was a passing ground as well as hiding and refugee area for people fleeing war. The physical location of the range, amidst the international borders of three countries whose armed conflicts were related in one fashion or another, the mountain gorilla population was not only vulnerable to the direct violence that occurred to its habitat but also now had to deal with increased competition of the same resources and land that the subspecies relies on for survival. Poaching The threat of poaching comes in two varieties, direct and indirect. Direct poaching is the active and intentional capturing and killing of mountain gorillas, as a source of witchcraft in in the early 1970s, then for hands and heads as trophies as well as selling infants to zoos in the mid and late 1970s. The selling of infants to zoos inevitably involves the killing of adult gorillas, particularly males because of their defensive behaviors and protection of their groups, especially their infants. Indirect poaching occurs when gorillas get caught in the cross fire and traps targeted towards other animals in their habitats, such as buffalo,

12 11 bushbuck, and duiker (Plumptre et al., 1997; Mudakikwa et al., 2001). This threat affects the infant and juvenile age-sex categories. Civil Conflict and Decades of War While habitat loss and destruction and poaching can be perceived as issues in their own context, the civil conflict that has taken place in the great lakes region, which contains the DRC, Rwanda, and Uganda, can solely be blamed for all the threats and challenges to preserving the mountain gorilla in the Virunga volcanoes mountain range. During civil and armed conflicts, intentional strategies designed to cause famine and/or disease or divert access to food supplies from one group to another, are often implemented as a tactic of war. This tactic is not only detrimental to the natural environment; it in many cases causes hunger issues which result further destruction of the environment and natural habitats. The civil conflicts along the borders between the DRC, Rwanda, and Uganda that have been ongoing for decades are still unresolved. Militias roam in the Virunga forests of the DRC and other rebel units based in the DRC often attack Rwanda and Uganda. Within the DRC there are clashes amongst different groups that continue to destabilize the country and displace more and more of the DRC population. There also exists a conflict between the Rwandan- and Ugandan-backed rebels in the eastern DRC where the VVR is located. Currently, seven African nations along with a multitude of rebel groups are militarily engaged in the DRC. As one can imagine, all these conflicts have had and still are having a crucial impact on the wildlife, biodiversity and national parks of the involved countries. The threats to the mountain gorilla that is home to this natural habitat and environment include: Destruction of social structures and institutions, as well as a legal framework, which makes it virtually impossible to set any guidelines or laws about anything, including protection of gorillas Increased dependence on natural resources for food, building supplies, firewood, and charcoal; creating competition of resources amongst inhabiting people and gorillas Presence of armed combat, landmines, and booby traps in forests and protected areas home to mountain gorillas.

13 12 Clearing of gorilla habitats by armed factions for security tactics Mass settlements of displaced refugees in natural areas and protected areas which limits space for the gorillas and exposes the mountain gorillas to human diseases Illegal harvest of natural resources and poaching of protected wildlife due to absence of law which lead to the killing of 18 mountain gorillas between 1995 and 1998 These are just some of the threats that the civil conflicts in the DRC, Rwanda, and Uganda has brought about. Going forward, these conflicts must be addressed if the preservation of the mountain gorillas is to be successful. V. Population Viability Analysis The social behavior of the mountain gorilla by nature makes it virtually impossible to have a meaningful population viability analysis even though the Virunga gorillas have been studied for about three generations now. For starters, approximately eight adult females die per year, which is equivalent to 10% of the total number of females in a population. Even though the population is heavily monitored, this number is too close to sampling error especially considering the fact that nearly 60% of all females emigrate and disappearance technically doesn t indicate death. Mace and Lande s (1991) suggested a set of criteria that can be used to determine the imminence of extinction of a species. These are: (1) Population numbers must be less than 250 individuals; (2) the population has suffered a decline in numbers greater than 20% over past two years or 50% over a generation; (3) the population is subject to crashes greater than 50% reduction every five to ten years; (4) the population is fragmented, meaning less than three subpopulations of more than 125 individuals with immigration rates of less than one per generation. For the Virunga gorilla population, which I considered as three separate subpopulations (one in the DRC park, the other in the Rwandan section of the range, and lastly the Ugandan section of the mountain range), the three criteria mentioned above are met but it is virtually impossible to determine the last. For the last criteria, rapid censuses are needed,

14 13 which unfortunately has been impossible due to civil war and conflict in all three countries for nearly the last twenty years and more in some cases. Looking at internal stochastic events, the mountain gorilla population reached its lowest size at 254 individuals, at which point 60% of adults could potentially breed, of which only half of the adult males were in breeding groups. In the long run this produces an effective population of 70 to 100 individuals, which is extremely concerning. However the fact that gorillas tend to live for long years eases the concern. With a generation time of least 20 years, Soule s (1980) estimates about 1000 years until the Virunga gorillas reach an extinction threshold. Similarly, other studies (Durant and Mace 1994; Akcakaya and Ginzburg), point to a 10% probability of the Virunga mountain gorilla going extinct within the next years, assuming no migration and no external deterministic effects such as human interference. External influences on the other hand paint a completely different picture regardless of the lack of data. The mountain gorilla primarily dwells in the forests and the forest loss and destruction rates in Africa strongly correlate to the increasing rates of human population density in and around the natural habitats of mountain gorillas. Forest eradication rates are obtained using rates of population increase and the relation between human density and rate of forest destruction. For example, using the rates of forest eradication at four times the current human population density as measure of intensity of threat as suggested by Harcourt 1995, the Virunga mountain gorilla population goes extinct in under 100 years. This is assuming the forests of the DRC that house the majority of the mountain gorillas completely are destroyed. Aside from the DRC, only three other African countries have forests capable of lasting years, by which point the gorilla population would be either extinct or very close to being extinct. VI. Conclusion It is quite evident that the mountain gorilla (Gorilla beringei beringei) population is currently at low numbers and under many pressures. The population viability analysis clearly shows that with stochastic events alone, the mountain gorilla population can grow to reach a stable population size. It has also shown however, that external deterministic effects on the gorilla population can lead to a very quick extinction of the population.

15 14 In large part, the mountain gorilla population is heavily reliant on its forest dwelling for survival and any compromising and/or destruction of that habitat consequently have a large impact on the viability of the gorilla population. The one critical thing that the population viability analysis shows is the critical important of the mountain gorilla habitat. In addition to the destruction of the forests due to human settlement and civil conflict, increased human population density has caused competition of natural resources and increased gorilla exposure to fatal diseases. If the mountain gorilla preservation is to survive extinction there are two major steps that need to be taken. First and foremost, the civil conflicts that have raged the DRC, Rwanda, and Uganda for decades have to be resolved because for as long as they continue there will be no legal framework for which gorillas can continue to be protected. Fortunately, as of 2005 the region has been getting more and more stable and observed numbers of gorillas continue to increase since Secondly, the national governments of all the DRC, Rwanda, and Uganda have to implement land use policies that direct human settlements away from mountain gorilla habitats. It s goes unsaid that obviously the second step is impossible without rule of law and I fear that as long as the civil conflicts are not fully resolved, the mountain gorilla will always be at risk in the Virunga Volcanoes Range.

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