Foraging decisions shape the structure of food webs. Therefore, a behavioral shift in a single species can potentially modify resource-flow dynamics of entire ecosystems. To examine this, we conducted a field experiment to assess foraging niche dynamics of semi-arboreal brown anole lizards in the presence/absence of predatory ground-dwelling curly tailed lizards in a replicated set of island ecosystems. One year after experimental translocation, brown anoles exposed to these predators had drastically increased perch height and reduced consumption of marine-derived food resources. This foraging niche shift altered marine-to-terrestrial resource-flow dynamics and persisted in the diets of the first-generation offspring. Furthermore, female lizards ¬¬that displayed more risk-taking behaviors consumed more marine prey on islands with predators present. Our results show how predator-driven rapid behavioral shifts can alter food-web connectivity between oceanic and terrestrial ecosystems and underscore the importance of studying behavior-mediated niche shifts to understand ecosystem functioning in rapidly changing environments.