Influence of Agriculture on theResilience and Trophic Cascade ina Savanna Bird Community of theSerengeti Ecosystem, Tanzania

Abstract

Agriculture is one of the factors contributing to the global depletion of natural resources. A total of 228 bird species were recorded in the savanna of Serengeti National Park and 146 bird species in agricultural areas. The richness of bird species endemic to the Serengeti ecosystem, regional and Africa-wide geographical ranges were all higher inside Serengeti National Park compared to agricultural land. However, a greater proportion of endemic bird species dropped out in agriculture compared to the proportions of species with wider geographic ranges. With respect to the trophic level in agriculture, there was a greater proportional decrease of species (compared to savanna) at the predator trophic level (vertebrate feeders) than at the insectivore and herbivore trophic levels. Therefore, higher feeding levels were less able to tolerate changes in habitat structure due to agriculture than species at lower feeding levels. These results suggest that Park managers should encourage through education and participation of local communities on the importance of improving their agricultural habitats by promoting the regeneration of patches of native vegetation so that more vulnerable species, such as endemics, and raptors can exist there.