Population Estimates of Mountain Nyala on the Rise

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  1. AFRICAN INDABA

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    Population Estimates of Mountain Nyala on the Rise
    by Paul Evangelista

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    The mountain nyala (Tragelaphus buxtoni) is endemic to the highlands of Ethiopia and only known to inhabit the eastern side of the Rift Valley.

    Editor's Note
    I am very grateful to Paul Evangelista of the Natural Resource Ecology Laboratory at Colorado State University for having given us permission to publish this article and the photos.

    The mountain nyala (Tragelaphus buxtoni) is endemic to the highlands of Ethiopia and only known to inhabit the eastern side of the Rift Valley. First reported in 1908 by Major Ivor Buxton, the mountain nyala is considered to be the last large ungulate species discovered in Africa. Nearly a century after it's discovery, scientists still know very little about the population or distribution of the species, which at times has impaired management and conservation strategies. The first significant surveys of the mountain nyala were conducted by Leslie Brown in the late 1960s. Brown was the first to attempt to define the mountain nyala's full range, and determine population densities at both local and regional scales. In 1969, he reported that the total population of mountain nyala was probably between 7,000 and 8,000, not likely to be less than 4,500, and as high as 12,500 at
    best. As a result of Brown's report, the mountain nyala was taken off IUCN's Red List of Endangered Species from 1969- 1974, for the first and only time since it was first listed in 1945.

    The next significant population estimate was conducted by Chris Hillman in 1988. Hillman's work, largely conducted in the Bale Mountains National Park (BMNP), suggested that mountain nyala populations totaled between 2,000 and 4,000. Since then, population estimates have continuously declined with some recent estimates suggesting populations as low 1,000 with 95% of these residing within the BMNP. Once again, there is new interest and concern over the status of the mountain nyala, and both Ethiopian wildlife managers and international conservation groups are actively seeking accurate population estimates to facilitate proper management initiatives and insure the long-term survival of the species.

    Mountain nyala populations are fragmented throughout Ethiopia, and in many cases isolated to mountain peaks or rugged terrain that deter human encroachment. The most northern populations of mountain nyala are found in the Chercher Mountains, also called the Ahmar Mountains, specifically in the KuniMuktar Wildlife Sanctuary, and in Din Din and Arba Gugu Controlled Hunting Areas. In 1998, the mountain nyala was thought to be extinct from Kuni-Muktar which fueled the concern that the species was declining to dangerously low numbers. This was not the case however, and in 2003 the Ethiopian Wildlife Conservation Department (EWCD) confirmed their persistence, suggesting that the Kuni-Muktar population is around 200. I visited the area in 2005 and found that local communities and wildlife managers have been proactive in maintaining the sanctuary, and were engaged in an extensive reforestation campaign. The most recent surveys of Kuni-Muktar, Din Din and Arba Gugu would put the total population of mountain nyala in the northern range at about 350.

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    Mountain nyala in Ethiopia.

    The central Southern Highlands are dominated by the Arussi Mountains, and are also known to have only a few remnant mountain nyala populations. The best known area is the Galama Mountains, which was made famous by early safari hunters and explorers such as Major Buxton, Gertrude Sanford, Sidney Legendre, and James Mellon. I participated in a landscape assessment of the Galama Mountains in 2001, and was disappointed to find the area heavily degraded by annual burning, soil erosion, and large numbers of livestock. Mountain nyala populations and critical habitat in the Galama Mountains were decimated by civil unrest following the collapse of the Derg government in 1991, and have never fully recovered. Using three game scouts to survey Galama Mountains for a ten week period, we estimated mountain nyala to number about 100.

    West of the Galama Mountains is the Munessa-Shashamane State Forest, which is intensively managed for sustainable and multiple-use of natural resources. Mountain nyala populations here were also impacted by the change of government in the early 1990s, but made a rapid recovery. The forests are a mix of old-growth native trees and plantation style timber production that is well protected from communal exploitation. Recent surveys of Munessa by EWCD and the Oromyia Regional Government (ORLNRAD) estimate the numbers in this forest to be around 330. Other areas in the Arussi Mountains that are known to have smaller populations of mountain nyala, mostly limited by available habitat, include Mt. Kaka, Gambo State Forest, and possibly Mt. Kubsa. These areas have not been recently surveyed to my knowledge.

    The most southern range of mountain nyala are in the Bale Mountains, most commonly reported in the northern parts of BMNP near the town of Dinsho, the Park Headquarters, and Hanto Controlled Hunting Area, sometimes called Lajo-Spur. BMNP was established in the early 1970s primarily to protect mountain nyala and Ethiopian wolf populations. Areas near Dinsho and the Park Headquarters were surveyed in 2003 by Befekadu Refera, a student from Addis Ababa University. Using direct counts, Refera's highest count for mountain nyala was 732, while the adjacent Hanto area was estimated to have 375 by EWCD and ORLNRAD. Historical accounts indicate that mountain nyala populations were more prevalent in the upper Web Valley and Senetti Plateau. These areas still have mountain nyala populations, but densities have thinned as a result of human settlements and livestock grazing. I have been unable to find any survey data for either of these areas. The southern portion of the BMNP is covered by the Harenna Forests where several previous reports suggest that mountain nyala are absent and have never inhabited the area. In 2000 and 2001, new mountain nyala populations were discovered on the eastern escarpment of the Bale Mountains, but remain largely over- looked by many recent population estimates. However, EWCD and ORLNRAD have established three Controlled Hunting Areas, Odo Bulu, Abashabe-Demero, and Shedem Berbere, and have conducted multiple surveys in these areas since 2000. Combined, the most recent surveys on the eastern escarpment put populations over 1,200 animals without taking in consideration large tracts of forests outside the hunting areas.

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    Mountain nyala in Ethiopia.

    Not including Mt. Kaka, Mt. Kubsa, Gambo State Forest, Senetti Plateau, and the upper Web Valley, the most recent population surveys total over 3,100 mountain nyala. This information was not difficult to find; yet too often, population estimates tend to overlook some of these areas or fail to thoroughly investigate an area. Throughout my investigation of mountain nyala populations, I have found that the most conclusive estimates have been conducted by the EWCD and ORLNRAD. Unfortunately, these agencies are rarely acknowledged for their work or results by non-Ethiopian researchers. EWCD and ORLNRAD not only employ common scientific methods in their surveys for example transects and direct counts, but also does so on a temporal basis over the majority of the mountain nyala's known range. Outside of BMNP, there have been few surveys conducted that incorporate scientific methodology other than those by Ethiopian wildlife officials and Leslie Brown. This should raise questions as to how and why recent population estimates published in scientific papers and reports continuously hover between 1,000 and 2,000 mountain nyala.

    The simple calculations I present still do not accurately reflect the true population of mountain nyala. There have been several significant discoveries of new mountain nyala populations within the last two years. The first discovery was made in an area between the Galama Mountains and Arba Gugu. Recent surveys by Ethiopian wildlife officials estimate a population of about 350. This is an unusual case, since this region of Ethiopia is heavily settled by people and much of the surrounding land has been cultivated or logged. A new Controlled Hunting Area has recently been established in an effort to curb further degradation of the landscape.

    In the Bale Mountains, EWCD and ORLNRAD have been investigating the remote highlands south of the Dodolla (west of BMNP). There have always been scattered reports from local people of mountain nyala inhabiting the area, but most have discounted any significant numbers due to the high number of people, forestry activities, and the sparse vegetation on the dryer northern slopes. The interior of the highland forests are contrastingly different with more mesic vegetation and rugged terrain which has isolated the area from people and livestock. Surveys have not yet been conducted, but analyses of satellite images indicate that ideal mountain nyala habitat could exceed 800 km2.

    Similar circumstances occur in the Harenna Forest and Mena-Angetu Forest Priority Area on the southern escarpment of the Bale Mountains. These largely intact forests stretch from the town of Rira west to Riripa and Goma. I visited the area earlier this year and estimate that mountain nyala habitat may span as much as 3,000 km2. The total forested area is actually much larger, but drops to elevations that are not as favorable to mountain nyala. The area is continuous with minimal fragmentation from human settlements or land-use. Rugged terrain and deeply incised valleys prohibits human accessibility to the vast majority of the landscape, while creating optimal habitat for mountain nyala. At this point, it would be nearly impossible to estimate how many mountain nyala can be found here, but Ethiopian wildlife officials are actively surveying the area and a new Controlled Hunting Area is scheduled to open in 2007.

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    Mountain nyala in Ethiopia.

    Due to uncertainty of the specie's entire range and inconclusive results from population surveys, the total number of mountain nyala cannot be accurately reported at this time. Howeverevidence clearly indicates that populations exceed estimates reported in recent literature. Despite all the controversy surrounding the status of mountain nyala, credit needs to be given to the work conducted by EWCD and ORLNRAD for their systematic approach of monitoring regional populations, development of intensive management and conservation strategies, and for not succumbing to the pressures that result from low speculative population estimates. Today, Controlled Hunting Areas are well managed with habitat destruction being controlled in most cases, local communities and regional governments receiving economic benefits from hunting revenues, and professional hunters having long-term conservation incentives. But most importantly, mountain nyala populations are largely stable, and in some cases, on the rise. Hunter success rates in 2004/2005 were an impressive 97.6% and trophy sizes are at an all time high with five mountain nyala expected to rank in the SCI top 15 from this past year alone, each sporting horns greater than 38? Wildlife management in Ethiopia still has room for improvement and faces many challenges, however, the current system is a model built on sustainability, conservation, and the distribution of benefits that many African countries could consider following.
     

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