Oviposition-site selection in an endangered Madagascan frog: Experimental evaluation of a habitat model and its implications for conservation

The selection of suitable oviposition sites is crucial for successful reproduction of many organisms, including the endangered Madagascan frog Aglyptodactylus laticeps. In a preceding study, a conservation-oriented model of habitat use for this species extracted key habitat factors that reliably predict whether given ponds are used as oviposition sites. However, habitat-use models are descriptive and thus their explanatory power for true causal relationships between habitat variables and species distributions is presumably limited. Furthermore, these models are mostly insufficient with regard to incorporating dynamic components of habitat choice, such as the colonization history. Therefore, the explanatory power of habitat-use models within the context of dynamic components was experimentally investigated by creating artificial breeding ponds in the natural habitat of this frog species and manipulating two environmental factors within these breeding ponds. The absence of tadpoles proved to be the most decisive factor determining colonization. Leaf litter on the pond bottom, that had been suggested to be of importance by the habitat-use model, did not influence oviposition-site selection. Although pond characteristics may be important, the overriding factor affecting pond use in the experimental study was avoidance of pools that already contained tadpoles by ovipositing adults.