Waterbird communities are potential indicators of ecological changes in threatened wetland ecosystems and a potential object of ecological monitoring programs. Waterbirds often breed in largely inaccessible colonies in flooded habitats, so unmanned aerial vehicle (UAV) surveys provide a robust method for estimating their breeding population size. In this study the main breeding colony of Glossy ibis (Plegadis falcinellus) at the Doñana National Park was surveyed.