Beetles, elephants, and an Afrotropical thrush: Ecological cascades in an East African forest reserve

Although many studies have explored how habitat structure and disturbance affect arthropod communities, fewer have explicitly tested the effects of both structure and disturbance level across trophic levels and phyla. I present the results of a study conducted in the Arabuko-Sokoke Forest (ASF) of coastal Kenya, in which abundance of arthropods and one of their avian predators, the Near-Threatened East Coast Akalat Sheppardia gunning sokokensis was compared in relatively undisturbed habitat (outside elephant roaming areas) vs.disturbed habitat (inside elephant roaming areas). Vegetation structure in both areas was measured using several metrics, including leaf litter depth, understory vegetation density, animal disturbance, and fallen log counts. Leaf litter and coleopteran abundance were higher outside the elephant roaming areas, whereas understory visibility, animal disturbance, and dipteran diversity were much higher inside the elephant areas. Species composition of several arthropod taxa (e.g., Hymenoptera, Coleoptera, Diptera, Hemiptera, and Araneae) was also influenced by degree of disturbance. These results suggest that differences in species’ sensitivity to habitat disturbance and vegetation structure across trophic levels should be incorporated into and management and conservation of rare and endangered species.