Habitat Quality Assessed with a Habitat Suitability Model and Habitat Selection Revealed by Isodar Analysis for the Mountain Nyala (Tragelaphus buxtoni) in Munessa, Ethiopia


  • S. A. Tadesse Department of Natural Resources Management, College of Agriculture and Natural Resource Sciences, Debre Berhan University P.O.Box 445 Debre Berhan, Ethiopia
  • B. P. Kotler


activity density, habitat suitability models, isodars, mountain nyala, Munessa


Knowledge of habitat quality and adaptive habitat selection behavior of endangered species such as the mountain nyala (Tragelaphus buxtoni) can be invaluable for conservation and management, but quantitative information is lacking. The objectives of this study were to: (1) investigate the environmental variables that determine the suitable habitats for the mountain nyala, and (2) apply the isodar technique to look for density-dependent habitat selection behavior in mountain nyala. Following transects aligned through three major habitat types, environmental variables and activity densities of mountain nyala were estimated. The fieldwork was carried out in the wet and dry season in Munessa, Ethiopia. In addition, with the help of a spotlight, night-time mountain nyala censusing was carried out during the dry season. The result revealed that mountain nyala didn’t show density-dependent habitat selection behavior in the wet season. However, during the dry season, the natural forest was the most suitable habitat for the mountain nyala, when crown diameter of trees and abundance of shrubs affected the habitat suitability. Significant isodars were obtained only across season and dry season comparisons between natural forest versus plantation and natural forest versus cleared vegetation habitats. The regression analyses revealed that the natural forest was qualitatively, but not quantitatively, more suitable than both the plantation and the cleared vegetation habitats. The isodars suggested that the strength of density-dependence was lower in the natural forest than either in the plantation or the cleared vegetation habitat. Spotlight censusing revealed that mountain nyala selected the cleared vegetation habitat during the night-time. The study demonstrated that habitat suitability models are important tools to evaluate the habitat quality for mountain nyala. Isodar analyses support the habitat suitability models by increasing our understanding on the qualitative and quantitative differences in density-dependent habitat selection by mountain nyala and thereby to enhance their conservation and management.

Author Biography

S. A. Tadesse, Department of Natural Resources Management, College of Agriculture and Natural Resource Sciences, Debre Berhan University P.O.Box 445 Debre Berhan, Ethiopia

Department of Natural Resources Management,



Morris, D. W. 2003. How Can We Apply Theories of Habitat Selection to Wildlife Conservation and Management? Wildlife Research. 30: 303–319.

Morris, D. W., Kotler, B. P., Brown, J. S., Sundararaj, V., & Ale, S. B. 2009. Behavioral Indicators for Conserving Mammal Diversity. The Year in Ecology and Conservation Biology. Ann. N.Y. Acad. Sci. 1162: 334–356.

Druce, D. J. 2005. Species Requirements, Coexistence and Habitat Partitioning at the Community Level: Rock Hyrax and Klipspringer. Dissertation, University of KwaZulu-Natal, Durban- South Africa. Pp 122.

Reid, C. 2005. Habitat Suitability and Behavior of Springbok (Antidorcas marsupialis) at Augrabies National Park, South Africa. Thesis, University of Port Elizabeth, Port Elizabeth, South Africa. Pp 106.

Tadesse, S. A. & Kotler, B. P. 2010. Habitat Choices of Nubian Ibex (Capra Nubiana) Evaluated with a Habitat Suitability Modeling and Isodar Analysis. Israel Journal of Ecology and Evolution. 56: 55–74.

Van Horne, B. 1983. Density as a Misleading Indicator of Habitat Quality. Journal of Wildlife Management. 47: 893–901.

Store, R. & Jokimäki, J. 2003. A GIS-based Multi-Scale Approach to Habitat Suitability Modeling. Ecological Modeling. 169: 1–15.

Verner, J., Morrison, M. L. & Ralph, C. J. editors. 1986. Wildlife 2000: Modeling Habitat Relationships of Terrestrial Vertebrates. University of Wisconsin Press. Madison, USA.

Mamo, Y. 2007. Ecology and Conservation of Mountain Nyala (Tragelaphus buxtoni) in Bale Mountains National Park, Ethiopia. PhD dissertation, University of Aberdeen, UK. Pp 132.

Evangelista, P., Norman, J., Lakew, B., Kumar, S. & Alley, N. 2008. Predicting Habitat Suitability for the Endemic Mountain Nyala in Ethiopia. Wild. Res. 409–416.

Fabricius, C. & Mentis, M. T. 1991. The Use of Habitat Suitability Models in Game Ranch Management. In: Renecker, L.A. and Hudson, R.J. (Eds.) Wildlife Production: Conservation and Sustainable Development. AFES misc. pub. 91–6. Univ. of Fairbanks, Alaska, USA.

Rosenzweig, M. L. 1974. On the Optimal Aboveground Activity of Banner-Tail Kangaroo Rats. Journal of Mammalogy. 55: 193–199.

Rosenzweig, M. L. 1981: A Theory of Habitat Selection. Ecology. 62: 327–335.

Uhmann, T. V., Kenkel, N. C., & Baydack, R. K. 2001. Development of a Habitat Suitability Index Model for Burrowing Owls in the Eastern Canadian Prairies. Journal of Raptor Research. 5: 378–384.

Van Horne, B. and Wiens, J. A. 1991: Forest Bird Habitat Suitability Index Models and the Development of General Habitat Models. Fish and Wildlife Research 8. U.S. Fish and Wildlife Service, Washington, D.C., USA.

Farmer, A. H., Armbruster, M. J., Terrell, J. W., & Schroeder, R. L. 1982. Habitat Models for Land Use Planning: Assumptions and Strategies For Development. Transactions of the North American Wildlife and Natural Resources Conference 47: 47–56.

Jeffers, J. N. R. 1982: Modeling. Chapman and Hall, New York, U.S.A.

Johnson, D. H. 1980. The Comparison of Usage and Availability of Measurements for Evaluating Resource Preference. Ecology. 61: 65–71.

Morris, D. W. 1987: Ecological Scale and Habitat Use. Ecology. 68: 362-369.

Morris, D. W. 1988. Habitat Dependent Population Regulation and Community Structure. Evolutionary Ecology. 2: 253–269.

Brown, L. 1969. Observation of the Status, Habitat and Behavior of Mountain Nyala, Tragelaphus buxtoni in Ethiopia. Mammalia. 33: 545–597.

Evangelista, P., Swartzinski, P., & Waltermire, R. 2007. A Profile of the Mountain Nyala (Tragelaphus buxtoni). African Indaba. 5: 1–48.

Atickem, A., Loe, L. E., Langangen, Ø., Rueness, E. K., Bekele, A., & Stenseth, N. C. 2011. Estimating Population Size and Habitat Suitability for Mountain Nyala in Areas with Different Protection Status. Animal Conservation. 14: 409–418.

Ramp, D. & Coulson, G. 2002. Density-Dependence in Foraging Habitat Preference of Eastern Grey Kangaroos. Oikos. 98: 393–402.

Shenbrot, G. 2004. Habitat Selection in a Seasonally Variable Environment: Test of the Isodar Theory with the Fat Sand Rat (Psammomys obesus) in the Negev Desert, Israel. Oikos. 106:359–365

IUCN. 2012. Red List of Threatened Species. Available online at www.iucnredlist.org.

Hillman, J. C. &Hillman, S. M. 1987. The Mountain Nyala (Tragelaphus buxtoni) and Simien fox (Canis simensis) in the Bale Mountains National Park. Walia. 10: 3–6.

Woldegebriel, G. K. 1996. The Status of the Mountain Nyala (Tragelaphus buxtoni) in Bale Mountains National Park 1986-1994. Walia. 17: 27–37.

Refera, B. & Bekele, A. 2004. Population Status and Structure of Mountain Nyala in Bale Mountains National Park, Ethiopia. African Journal of Ecology. 42:1–7.

Teketay, D. 1992. Human impact on a natural montane forest in south-eastern Ethiopia. Mountain Resources Development. 12: 393–400.

Teketay, D. & Granström, A. 1995. Soil Seed Banks in Dry Afro-Montane Forests of Ethiopia. Journal of Vegetation Science. 6: 777–786.

Tadesse, S. A. & Kotler, B. P. 2013. The Impacts of Human and Livestock Encroachments on the Habitats of Mountain Nyala (Tragelaphus buxtoni) in Munessa, Ethiopia. International Journal of Biodiversity and Conservation. 5: 560–571.

Patton, D. R. 1992. Wildlife Habitat Relationships in Forested Ecosystems. Timber Press, Portland, Oregon, USA.

Fish and Wildlife Services. 1980. Standards for the Development of Suitability Index Models. Ecological service manual 103. US Department of the Interior, Fish and Wildlife Service, Division of Ecological Services. Washington, DC.68.

Gutzwiller, K. L. & Anderson, S. H. 1986. Improving Vertebrate-Habitat Regression Models. In: Verner J., Morrison M.L. and Ralph, and C. J. (Eds) Wildlife 2000: Modeling Habitat Relationships of Terrestrial Vertebrates. University of Wisconsin Press, Wisconsin.

Jokimäki, J. & Huhta, E. 1996. Effects of Landscape Matrix and Habitat Structure on a Bird Community in Northern Finland: A Multi-Scale Approach. Ornis Fennica. 73: 97–113.

Morris, D. W. 1990. Temporal Variation, Habitat Selection and Community Structure. Oikos. 59: 303–312.

Morrison, M. L., Margot, B. G. & Mdknnan, R. W. 1998. Wildlife Habitat Relationships: Concepts and Applications. Univ. Wisconsin Press, Madison, USA.

Burnham, K. P. & Anderson, D. R. 2002. Model Selection and Multi-Model Inference: A Practical Information-Theoretic Approach. 2nd edition. Springer. Pp 488.

Black, H., Scherzinger, R. J. & Thomas, J. W. 1976. Relationships of Rocky Mountain Elk and Rocky Mountain Mule Deer Habitat to Timber Management in the Blue Mountains of Oregon and Washington. Pages 11–13 in S. R. Heib, editor. Proceedings of the Elk-Logging-Roads Symposium. Forest, Wildlife, and Range Experiment Station, University of Idaho, Moscow, Idaho, USA.

Mech, L. D. 1977. Wolf-pack buffer zones as prey reservoirs. Science. 198: 320–321.

Brown, J. S. & Alkon, P. U. 1990. Testing Values of Crested Porcupine Habitats by Experimental Food Patches. Oecologia. 83: 512–518.

Ripple, W. J. and Beschta, R. L. 2003. Wolf Reintroduction, Predation Risk and Cottonwood Recovery in Yellowstone National Park. For. Ecol. Mange. 184: 299–313.

Ripple, W. J. and Beschta, R. L. 2004. Wolves and the Ecology of Fear: Can Predation Risk Structure Ecosystems? Vol. 54 No. 8. Bioscience. 755.

Muller, D. M., Kohlmann, S. G. & Alkon, P. U. 1995. Nubian Ibex Nursery: Creche or Natural Trap. Israel Journal of Zoology. 41: 163–174.

Mengesha, G. & Bekele, A. 2008. Diversity, Distribution and Habitat Association of Large Mammals of Alatish, North Gonder, Ethiopia. Acta Zoologica Sinica. 54: 20–29.

Morris, D. W. 2005. Habitat-Dependent Foraging In a Classic Predator-/Prey System: A Fable from Snowshoe Hares. Oikos. 109: 239–254.




How to Cite

Tadesse, S. A., & Kotler, B. P. (2016). Habitat Quality Assessed with a Habitat Suitability Model and Habitat Selection Revealed by Isodar Analysis for the Mountain Nyala (Tragelaphus buxtoni) in Munessa, Ethiopia. Asian Journal of Applied Sciences, 4(4). Retrieved from https://ajouronline.com/index.php/AJAS/article/view/3838