BEHAVIORAL-RESPONSES OF BUFO-BUFO AND BUFO-CALAMITA TADPOLES TO CHEMICAL CUES OF VERTEBRATE AND INVERTEBRATE PREDATORS

We examined the behavioural responses of two closely related, but ecologically different species of tadpoles, Bufo bufo and Bufo calamita, to seven predator and control chemical stimuli. All tadpoles were hatched and reared in the laboratory to eliminate experience from natural habitats. In the presence of all predator and control stimuli, B. bufo significantly shifted its use of microhabitat in experimental containers from the open-water and benthic refuge to the edge. Conversely, B. calamita significantly shifted its use of microhabitat from the edge to the open-water or refuge. Neither species responded differently to any of the predator or control treatments, nor was there an interaction between species and predator treatment. Our results indicate that tadpoles may possess innate general defensive responses to sudden changes in chemical or tactile stimuli that signal potential danger. We suggest that the divergent responses of each species may be adaptive in its present ecological environment of ponds with and without fish.