Abundance and diversity of wild mammals along a hydrologic gradient in the Usangu Wetlands, Tanzania

Abstract

This study was conducted in the Eastern Usangu wetland in Mbeya and Iringa regions to examine the composition, abundance and diversity of mammals along a hydrological gradient. Data were collected in two seasons using distance sampling method along transects and a handheld GPS to locate positions. Statistical tests (t-test, Kruskal-Wallis and Pearson’s correlation) were employed to determine the association between distance and abundance of animals observed along the gradient. Diversity of mammals along the gradient was determined by a variety of indices using PRIMER 5.0 software. The study revealed that the abundance of animals sighted decreased with distances from the edge of wetland though not statistically significant along the gradient. Flight distances of observed mammals were high indicating higher degree of disturbances related to anthropogenic activities. Indicators of such disturbances in the wetland area included abandoned farms, demolished houses and livestock dung. There was a statistically significant difference in the number of observed mammals in the two seasons, where species richness and abundance were higher in the late dry season. These results indicate that the wetland is an important refuge area for mammals as both abundance and diversity decreased with increasing distance from the edge of the wetland and increases during the dry season. This study recommends a continuous monitoring of birds and mammals populations such as Topi to help in determining the changes in abundance and diversity over time in Usangu wetlands as a result of conservation interventions against anthropogenic disturbances.