Importance of woody vegetation for foraging site selection in the Southern Pied Babbler (Turdoides bicolor) under two different land use regimes

摘要

Intensified land use practices have changed savannas worldwide. Both, heavy grazing-induced shrub encroachment and the decrease in tree density due to woodcutting are assumed to reduce animal diversity. However, most studies in animal ecology have focused on the effects of one of these two land use practices. In our study we analyzed the importance of both shrubs and trees, for foraging site selection of the Southern Pied Babbler (Turdoides bicolor) in the Southern Kalahari, South Africa for two different grazing regimes: endemic wildlife at Molopo Nature Reserve versus domestic livestock at neighboring farms. We compared vegetation structure at babbler foraging sites with random sites at the microhabitat scale (5 × 5 m) and the mesohabitat scale (50 × 50 m), and recorded babbler group size and the amount of leaf litter. Our results show for both scales that mean density of shrubs and trees was higher at foraging sites compared to random sites. We found no differences in foraging site characteristics (i.e. vegetation cover at microhabitat scale and composition and density of woody plant species at both scales) and group size between the two grazing regimes. We conclude that shrub encroachment affects the Southern Pied Babbler positively whereas woodcutting has negative effects.