The long-term population trends (1972-2015) of the herons and egrets breeding in NW Italy were analysed spatially and temporally in relation to environmental and human-related variables. Ardea cinerea and Egretta garzetta increased till 2000 but then began to decrease, mainly in the region of intensive rice cultivation, where the trend was likely driven by reduced flooding of the paddies, the main foraging habitat. Colony site availability is currently not limiting. These results are being applied to develop a strategy for the conservation of the colonies in the remaining wetlands of NW Italy.