Effects of vegetation burning on the foraging strategy of waterbuck, wildebeest and reedbuck in a moist savanna of Tanzania

Abstract

Savannah grasslands are occupied by large mammal herbivores whose ecological separation between and within each guild have resulted to different foraging strategies and preference for forage differing in attributes to reduce competition between them. Therefore, the current study aimed at: 1) measuring the relative use of burnt and non-burnt areas by waterbuck, wildebeest and reedbuck, and their possible shifts between the two patches over time; 2) assessing forage characteristics in grazed sites on burnt and non- burnt sites along with the post fire nutritive quality of the grasses; and 3) testing the notion that waterbuck is an intermediate grazer between wildebeest, a bulk grazer and Bohor reedbuck, a selective grazer. The study was conducted during dry season in Saadan National Park, a moist, tall-grass savanna. The animals were found not equally distributed between the two grassland patches, with most occupying burned areas. On the other hand, previously grazed patches were actively selected for feeding, and Nitrogen content of the main forage grass species was high in grass samples collected 80 days since fire. Contrary, NDF and ADF concentrations were very low in grass samples collected 80 days post fire but increased after six months. Reedbuck had the shortest bout lengths for all behaviours whereas waterbuck showed the longest bout sessions. Reedbuck grazed at taller grass height than waterbuck and wildebeest grazed the shortest grassland patches. Wildebeest grazed mainly on Panicum infestum despite of its greenness status while the waterbuck and reedbuck grazed mostly on green materials. The non-random patterns in animal’s distribution between burnt and non-burnt grassland patches suggests that fire is an important adaptive management strategy for Saadani National Park.