Browsing by goats on three spatial scales in a semi-arid savanna

We tested the theories on hierarchical foraging by large herbivores by studying selection of woody browse by goats in a semi-arid savanna. In the smallest scale, we compared characteristics of woody plants browsed by observed goats with those of all woody plants available for the goats along their feeding paths. Particularly we recorded food selection in relation to plant species, height, canopy cover and previous browsing. In an intermediate scale we compared vegetation characteristics along the paths walked by foraging goats with characteristics of the vegetation available within the feeding site. In the largest scale we compared characteristics of vegetation within the feeding sites with those from the whole landscape. Goat selection was consistent across all scales, and the frequency of the most preferred tree species increased with decreasing scale from landscape to feeding site to feeding path to diet. Within browse species, goats preferred to browse from relatively high trees and from trees with signs of previous browsing. Preference for browse species could not be well explained by intake rate of nutrients or biomass but may be negatively related to intake rate of digestibility reducing compounds.