The American bullfrog (Lithobates catesbeianus Shaw, 1802), an amphibian species native to eastern North America, is considered one of the 100 most harmful invasive species in the world. Previous studies document several feral populations in the Amazon and Andean regions of Ecuador. However, only few adults have been reported in the Coast region, despite some evidence suggesting its introduction 31 years ago. Using visual and auditory cues, we explored a 490-hectare wetland area at Santay Island, a protected sanctuary and a Ramsar site on the Ecuadorian Coast. Bullfrogs were detected in seven out of 15 sampled ponds in all types of habitats except for mangroves. The low abundance of adults and juveniles suggests a recently established population. This is the first record of a feral population inside a protected area or Ramsar site in Ecuador. In accordance with the Ramsar Convention mission of preserving wetlands, we propose two strategies to manage bullfrogs at Santay Island.