Summary
New surveys by DFGFI and our Congolese partners, ICCN and UGADEC, throughout the range of Grauer's gorillas in Eastern Democratic Republic of Congo, have revealed the following: 1) the presence of two large local populations of Grauer's gorillas that other scientists believed to be quite small and dwindling before the civil wars; and 2) the continuing presence of gorillas in the Itombwe mountains where they existed before the civil wars.
These findings highlight the need for continuing surveys of Grauer's gorillas to better understand their current numbers and distribution, since earlier surveys appear to have missed or underestimated important local populations. At present, we can only provide a range of estimates for total abundance of Grauer's gorilla of between 5,300 and 28,000 individuals, occupying an area of approximately 21,000 km2. Human threats against these gorillas are intense and continuing, and rapid conservation action is needed. Our recent analyses indicate that at least 24% of the occupancy range of Grauer's gorillas has been lost between 1959 and 2005. Despite these losses, the new DFGFI surveys suggest that Grauer's gorilla populations continue to survive after the civil wars, and there are several centers of important distribution that can be protected with a combination of support for National Parks and community-managed Nature Reserves.
Gorilla Forms and Current Scientific Nomenclature (Taxonomy)
Grauer's gorilla (Gorilla beringei graueri) is sometimes called the “eastern lowland” gorilla, but we refrain from using this common name since it is misleading. Grauer's gorilla is endemic to eastern Democratic Republic of Congo, and is thought to have an unusual evolutionary history.
The Western World “Discovers” Grauer's Gorilla in 1908
The indigenous ba'Twa groups of this region (sometimes referred to as “Pygmies”) have probably been living in these forests and encountering this form of gorilla for at least 10,000 years. Bantu-speaking groups of agriculturalist /hunters are thought to have expanded from Central West Africa at least 1,500 years ago, perhaps even earlier. They too, encountered and “discovered” Grauer's gorilla. By 1908, a westerner, Rudolf Grauer had pushed into the Itombwe mountains (see Figure 2), and shot 12 gorillas to provide specimens for the Vienna Museum. From then until 1959 (when Schaller conducted the first overall survey, below), there were a plethora of western “collectors,” practically providing a new taxonomy each time a new “specimen” was shot or collected from indigenous hunters [3].
The First Scientific Survey of Grauer's Gorillas in 1959
George Schaller and John Emlen conducted the first comprehensive survey of Grauer's gorillas in 1959 [1]. Combining the Graueri, Bwindi and Virunga populations, they suggested a total population size of between 3,000 and 15,000 individuals distributed in a series of isolated and small populations, with a central area of continuous distribution (see Figure 1). Note that even in 1959, many of the populations to the east had been reduced to small, isolated groups surviving in areas that were succumbing to forest degradation through agricultural and pastoral expansion, with the inevitable result that the remaining animals were eventually killed. This first survey provided an understanding of the entire range of this gorilla, from areas in the north, west of Lake Edward to west of the Lindi River (in what is now Maiko National Park) to about 26° 45” E in the west, and then southwards to the Itombwe mountains in the south. Today, based on Schaller's first survey, we divide the distribution into five important areas: 1) the Tayna Sector; 2) Maiko Sector (north and south); 3) the Kasese-Kahuzi-Biega lowland area; 4) the Kahuzi-Biega highland area; and 5) the Itombwe area (Figure 4).
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Figure 1 (click to enlarge).
Distribution of Grauer's gorilla in 1959 and in the early 1990s.
Surveys are Conducted in the 1990s
From 1989 through 1995, before the civil wars began in 1996 in what was then Zaire, there were three large surveys that provided information on distribution, abundance and density for Grauer's gorillas in the Itombwe plateau, in the lowland sector of Kahuzi-Biega National Park and a region northwest of that called “Kasese,” and in Maiko National Park . DFGFI Karisoke staff participated in the Kahuzi-Biega lowland and Kasese survey in 1994-1995. All of these findings from the 1990s were summarized in an article by Hall and colleagues [3] both with a distribution map (Figure 1) and an estimated overall abundance of 17,000 Grauer's gorillas.
New Surveys by DFGFI-Sponsored Community Conservation Programs from 2001-2005
In 2001, during the civil war, DFGFI began a community conservation program in eastern Democratic Republic of Congo. The first and flagship project was the Tayna Gorilla Reserve, now recognized as an official protected area by the DRC national government. By 2002, another seven communities, modeling their conservation efforts after Tayna, joined together to form a federation of community-based conservation projects called UGADEC [4], each wishing to create a protected area, and each using Grauer's gorilla as a flagship species for conservation of all fauna and flora. One of their goals was to establish a biological corridor between Maiko and Kahuzi-Biega National Parks by a series of interconnecting community-managed nature reserves [5].
Tayna staff were trained in census techniques by DFGFI early in the program and through funding by the Louisville Zoo began a series of more complete explorations of their region to determine gorilla distribution. As part of that effort, they also conducted line-transect census techniques to estimate the abundance of Grauer's gorillas in and nearby their reserve (Tayna and south). Their first findings were remarkable [6]. What was thought by Schaller in 1959 to be an area containing only two small populations, and what was discounted by Hall and colleagues [3] as a possible small, but unknown, population of Grauer's gorillas (not displayed in Hall's overall distribution map, see Figure 1) turns out in fact to be an area of continuous distribution that is at least 2500 km2, which contains between 367-1129 Grauer's gorillas (Figure 2).
Figure 2 (click to enlarge).
New DFGFI surveys indicate confirmed presence of Grauer's gorilla in orange quadrats and reported presence in yellow quadrats. These quadrats (125 km2) are one-tenth of a degree latitude and longitude and are used in a cartographic system to indicate gorilla distribution. Note the much wider distribution of Grauer's gorilla in the Tayna sector by 2005 (orange quadrats), as compared to what was reported by Schaller in 1959 (brown polygons) - these surveys were conducted by Tayna and UGADEC staff in conjunction with DFGFI scientists. Also note that in Maiko south, surveys in the mid-1990s indicated one small polygon (black outline) that was reported to contain only 33 gorillas [7], and even Schaller only reported seven isolated, small populations. A recent DFGFI and ICCN survey reveals that gorillas in Maiko south are much more widespread than was previously believed (2125 km2 with confirmed presence, orange quadrats).
During 2002-2005, other UGADEC projects also began to report their findings on gorilla distribution (Figure 3). The ACPN [8], one of the first community groups to join UGADEC, working in Itombwe, has now compiled its findings, and their data confirm that gorilla distribution in Itombwe reported from surveys in the mid-1990s by Omari and colleagues [9] remains very similar to today's Grauer's gorilla distribution (Figure 2). Recently, it appears that another survey in this region has been conducted [10], and although ACPN was not invited to participate or to collaborate, the two data sets are somewhat similar and appear to complement each other (Figure 3).
Figure 3. Click to enlarge
Itombwe surveys by ACPN, a UGADEC project, indicate presence of Grauer's gorilla in 41 four km2 quadrats (164 km2 - red slash quadrats). There are an additional 25 four km2 quadrats recently reported from a WCS survey in the region (100 km2) that also appear to contain gorillas [10]. See Figure 2 for a comparison of gorilla distribution in the mid-1990's and that reported by ACPN by 2005 (Figure 2 displays these as 125 km2 quadrats). Surveys are not complete for this region, but these new findings suggest gorilla presence will be similar to that reported in the mid-1990's. WCS quadrats as displayed in this satellite image are from Gorilla Journal 30, June 2005, figure on page 7.
New Survey by DFGFI and ICCN Maiko National Park Staff [11]
In late 2003, Conservation International (CI) requested that DFGFI take the lead role in a program to rehabilitate Maiko National Park [12]. As part of this effort and to determine current patterns of biodiversity, DFGFI led a large mammal survey that was conducted in the south Maiko sector, which includes areas within and outside the southern sector of Maiko National Park (Figure 2). The findings from the Maiko South survey conducted by DFGFI and ICCN indicate that Grauer's gorillas appear to have at least an occupancy range of approximately 2,125 km2 in this region and that there are between 418 and 1737 individuals for this area of Maiko South, with a central tendency of approximately 600 Grauer's gorillas.
It is clear that this recent DFGFI-ICCN survey has found that gorillas are much more widespread in this region than previously reported . Moreover, we suspect that the entire population of Grauer's gorillas in Maiko National Park form one breeding population and that gene flow is probably maintained between the population in the southern sector with those in the northern sector (Figure 2). DFGFI and UGADEC staff scientists are investigating this working hypothesis, and will also examine the possibility that gorilla populations in the Tayna Sector are connected by gene flow (groups and lone males) with those in Maiko National Park.
Current Threats to Grauer's Gorillas
The most severe threat to Grauer's gorillas is habitat loss and fragmentation through agricultural and pastoral expansion related to the westerly movement of people from high density areas in the east to the forests of the west. Villages in forest zones practice slash and burn (or shifting) agriculture. As fields fatigue and hunting resources are depleted, these settlers move farther (west) into the forest, often selling their previous fields and land to local commercial interests, who then clear-cut large areas for pasturage of dairy and meat cattle, sheep, and goats (a process quite similar to that found in Central and South America). In North Kivu, for example, this process has resulted in the loss of huge expanses of primary forest and the extinction of local fauna through subsistence hunting, including gorilla populations (e.g., Lubero). In Kahuzi-Biega, a similar invasion process has effectively degraded the corridor zone between the highland and lowland sectors [14] and in Itombwe, the process of agricultural/pastoral expansion has been even more intense [15].
Mining activity is also a threat to Grauer's gorillas. The exploitation of coltan (columbite-tantalite used in micro-capacitors for electronic equipment) created a well-publicized late 20th century conservation crisis throughout this area. A boom and bust cycle of pricing lured thousands of people away from agriculture into mining camps where anarchy was common, and has been identified as fueling the civil war in Congo. Recently, however, a fall in coltan prices has caused many coltan miners to turn to the bushmeat and animal trafficking trade or to other mining activities. The newest mining threat is tin mining (cassiterite SnO2), which is now intensifying throughout the range, especially in the area between Maiko and Kahuzi-Biega National Parks. Gold mining is present throughout the Grauer's gorilla range, with a cline of decreasing intensity from north (Maiko - most intense) to south (present in Itombwe). Diamond mining is common in the north, especially within Maiko National Park. Mining techniques for all these ores are nearly identical; miners divert small and medium watercourses through damming (or digging large craters in the streambeds) and then practice sluice and pan techniques, or extract rock from pits and most often use water from nearby diverted streams to separate out the ore. Although these activities can be described as small-scale, their heavy presence throughout these forests has a cumulative large-scale effect. They cause both direct and indirect environmental damage, such as forest clearance, stream pollution, erosion, firewood cutting, tree debarking (panning trays), liana cutting, disturbance to freshwater ecology, and bushmeat hunting [16].
There is a total absence of commercial logging through the range of Grauer's gorilla, and since there are no logging roads, the extraction and commercial transport of bushmeat, while still a persistent threat, exists
at far lower levels than for example, in Cameroon or other areas of Central West Africa [17]. Mining camps (many as large as 1,000 individuals) are probably the most important factor in bushmeat extraction, which is especially intense for example in Maiko and Kahuzi-Biega National Parks. While many of us working in this area believe that this has severely reduced populations of elephant (Bishikwabo, 2001, recent Maiko survey by DFGFI staff ), monkeys and other fauna, the impact on gorilla populations is not so clear, since gorillas do not appear to be targeted for bushmeat per se [18]. Layered onto hunting threats from mining camps is the ongoing and persistent threat of subsistence hunting by agriculturalists expanding throughout the region.
Gorillas (and chimpanzees) are also severely threatened by an illegal animal trafficking for the pet trade, with field prices for young apes varying between $1,000-$5,000. The author is aware of nine gorillas and five chimpanzees confiscated by wildlife authorities in 2004-2005, indicating a brisk trade in the area; this is further complicated by a lack of wildlife sanctuaries, decreasing the motivation of law enforcement officials to engage in confiscation.
A number of socio-economic impediments, common to most developing nations, have been exacerbated in the DRC by the exploitation policies of the Belgian colonials, the Mobutu regime, and finally the recent civil wars of the last decade: poverty, disease, malnutrition, unemployment, lack of education, lack of medical care, and corruption. The regional and civil wars have added genocide, massacres, rape, starvation, child soldiers, destruction of property, and the disintegration of civil society to produce little more than anarchy. This has had profound negative consequences for conservation work throughout the range of Grauer's gorilla. This is changing. There is now a political unification process underway in DRC, with increasing integration of all armed groups into a national army, a reduction in armed conflicts, and improvements in governance and civil security. With these changes, however, new “peace threats” will certainly emerge. As a unified DRC government begins to function and attempts to solve the complex socio-economic needs of the country, it may inevitably turn to the exploitation of natural resources, such as future lumber, mining and petroleum concessions.
The Significance of These New DFGFI-Sponsored Surveys
Schaller's first surveys of Grauer's gorilla in 1959 indicated there may have been as many as 15,000 individuals distributed as several fragmented, local populations. By 2005, various surveys from the 1990s and the new survey information reported herein, reveal that many blocks of the distribution reported by Schaller no longer contain gorillas. Figure 4 displays the Eastern gorilla distributions as Schaller and Emlen reported them for 1959, compared to areas that we believe still contain Grauer's gorillas. It thus provides an indication of which gorilla populations have been extirpated between 1959 and 1996; these are described in Table 1. Thus, depending on the accuracy of Schaller's first surveys, it appears that at least 24% of the occupancy range of Grauer's gorillas has disappeared during the last 36 years, representing approximately 6700 km2.
At present, there are four large populations of Grauer's gorilla, each still probably maintaining internal gene flow, but subject to increasing amounts of fragmentation due to human disturbance: 1) a Tayna population; 2) two Maiko populations, north and south, that are probably connected by gene flow; 3) a Kasese-Kahuzi-Biega lowland population; 4) a Kahuzi-Biega highland population; and 5) an Itombwe population. Gene flow between these populations does not appear possible, with the exception of Maiko and Tayna, which remains to be researched. The Itombwe population appears to be experiencing the most fragmentation. There are also several small, isolated populations with between 18-50 individuals remaining (determined by nest counts): 1) Tshiaberimu (Figure 6, area A); 2) Masisi (area C); and 3) Walikale (area D). The highland sector of Kahuzi-Biega (Figure 6, between area K and Lake Kivu) is also a small isolated population, with only approximately 170 gorillas remaining [19].
Table 1. Click to enlarge
Loss of occupancy range for Grauer's gorilla between 1959 and 1996-2005
Figure 4. Click to enlarge
All major surveys of Grauer's gorillas. New DFGFI-sponsored surveys are indicated by square quadrats in Areas “B, C, D, H”, and between “M” and “N”. DFGFI scientists divide the Grauer's gorilla distribution into five major high-priority populations: 1) Kasese Kahuzi-Biega lowland population; 2) Maiko population (south and north, probably connected by gene flow); 3) Tayna population; 4) Itombwe population; and 5) Kahuzi-Biega highland population.
Our knowledge concerning the abundance of Grauer's gorilla is at present, quite imperfect. A previous review for the mid-1990s estimated a range of abundance of between 8,660 and 25,499 individuals [20], with an overall estimate of 17,000 gorillas, but as these new DFGFI surveys reveal, several populations were drastically underestimated at that time. Given the new information presented herein, we must enlarge these limits to 5,500 and 28,000 (Table 2). Clearly, more surveys are needed in the Kasese-Kahuzi Biega Lowland sector. DFGFI is currently preparing for surveys in the Kasese sector with UGADEC staff, while WCS, WWF, and ICCN are initiating surveys in the Kahuzi-Biega lowland sector. These new surveys can provide us more precision as to how many gorillas remain for this important area. Currently, we refrain from providing an overall estimate of abundance for these gorillas in Eastern DRC, since survey techniques contain many sources of error and surveys for the largest population in the Kasese- Kahuzi-Biega lowland sector have not been conducted since the mid-1990's.
Table 2. Click to enlarge
Current estimates of upper and lower estimates for abundance of Grauer's gorilla
The Next Steps
DFGFI will continue its community conservation program, supporting the members of UGADEC in DRC to help them establish community-managed Nature Reserves modeled after the Tayna Gorilla Reserve. These projects are already providing conservation protection and education initiatives in the areas where their projects are located and will continue to collect field data on the distribution and abundance of Grauer's gorilla, and other fauna and flora from their zones. These field data are not only essential to understanding the distribution of biodiversity in their zones, they enable these projects to identify and locate the human-based pressures that threaten the survival of their gorillas and other fauna and thus allow them to plan interventions to reduce these pressures. DFGFI will also continue its program to support and rehabilitate Maiko National Park, including scientific monitoring, protection, and educational programs.
These programs are supported through DFGFI's strategic partner, Conservation International, which provides funding from the USAID CARPE program and through its own funding agency, the Global Conservation Fund. DFGFI expects continued funding from these programs at least through September 2006, and possibly for another three-year cycle that could continue to 2009. Recently, DFGFI also received a grant award from the U.S. Fish and Wildlife Agency to aid the Tayna Gorilla Reserve to delineate the boundaries of their reserve with metal signs. This boundary demarcation, which will be done with the help of local stakeholders, will enable local people to understand the exact limits of their fully-protected integral zone, so that they will conduct their subsistence hunting and agricultural activities outside of the Reserve. Recently, DFGFI also partnered with the Jane Goodall Institute, which is providing community development and livelihoods initiatives linked to the DFGFI community conservation program.
In addition to these field-based initiatives, DFGFI also participates in national and international projects focused on protecting great apes. DFGFI is an active member of the Bushmeat Crisis Task Force. In early September 2005, DFGFI attended the GRASP (Great Ape Survival Project, United Nations Environmental Programme) Conference in Kinshasa, DRC (First Intergovernmental Meeting on Great Apes and First GRASP Council Meeting) and made available to the GRASP Scientific Commission the findings contained on this web site. This will enable GRASP and its conservation partners (like DFGFI) to prioritize conservation initiatives for African great apes throughout the host-countries where they are found. The table of summary information provided to GRASP by DFGFI for Grauer's gorilla is available as a downloadable PDF file link.
Clearly, these recent findings by DFGFI and our partner scientists from UGADEC and ICCN indicate that there are several high priority centers of Grauer's gorilla distribution that must continue to be protected through a combination of DFGFI financial and technical support for Maiko National Park and for the community project members of UGADEC.
[1] Emlen and Schaller (1960); Schaller (1963); Schaller (1964,1988)
[2] Itombwe: Omari et al. (1999); Maiko: Hart and Sikubwabo (1994) and Hart and Hall (1996); Kasese-Kahuzi: Hall et al. (1998a)
[4] UGADEC (Kakule and Mehlman 2004) -- Union des Associations de Conservation des Gorilles pour le Développement Communautaire à l'Est de la République Démocratique de Congo.
[5] In late 2003, their efforts were further supported by funding received through DFGFI's strategic partner, Conservation International (through USAID CARPE funding and Conservation International's Global Conservation Fund).
[7] Hall et al. (1998b); Hart and Sikubwabo (1994)
[8] ACPN Action Communautaire pour la Protection de la Nature, Mwenga
[11] ICCN is the Institut Congolais pour la Conservation de la Nature, the DRC Wildlife Authority
[12] Funds provided by DFGFI, USAID CARPE and the Conservation International's Global Conservation Fund
[13] Hall and colleagues (1998b) estimated that only 33 Grauer's gorillas were present in this same survey area.
[14] Draulans & Van Krunkoisven (2002)
[17] There is however, a charcoal production industry, especially in forests in the eastern part of Landscape that abut high human population densities. For example, charcoal production around the highland sector of Kahuzi-Biega NP is intense, and villagers are also involved in illegal harvesting of bamboo and other non-timber forest products. Throughout the region, but more intense in the south, there is also a minor presence of hardwood logging and pit-sawing to support a furniture trade in Congo and in neighboring Rwanda.
[18] Although other opinions exist, see Redmond (2001)
[19] John Hart, personal communication
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