Date of Completion
Honors College Thesis
Wildlife & Fisheries Biology
population viability analysis, distance sampling, Tarangire-Manyara Ecosystem, wildlife density
Declines in wildlife populations represent a serious environmental threat. One cause of declines has been climate change, which has led to increased aridity and droughts in some systems, such as the savannah ecosystems of sub-Saharan Africa. Climate change is expected to result in more frequent and intense droughts and the effects on wildlife populations are largely unknown. I examined impacts of droughts on wildlife in Manyara Ranch, a community-run conservation area in Tanzania, by assessing population trends of herbivores collected over the past decade and modeling the viability of these populations into the future under different scenarios of drought periodicity and intensity. Densities of nine herbivore species were estimated on a yearly basis from 2003 to 2014. These densities were then used to create species-specific PVAs, including models examining the impacts of various periodicities (5-, 10-, and 20-year increments) and intensities (population reductions of 10%, 20%, and 30%). Baseline population persistence varied between species from 0% to 100%, while sensitivity models trended towards most species showing significantly lower persistence percentages for more frequent and intense droughts, particularly with high intensity droughts every five years. Elephants demonstrated the lowest persistence with or without droughts, while Grant’s gazelle had the highest persistence throughout all models. Continued monitoring of populations is a necessity, and increased actions should be taken to preserve populations of priority species, including protecting migratory routes and limiting poaching.
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This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.
Loftis, Ellen E., "Population Viability of Mega-Herbivores in Manyara Ranch, Tanzania, in a Climate Change Context" (2015). UVM Honors College Senior Theses. 61.