The dataset contains records of large mammals (Mammalia) collected in the lower valley of the River Tua and included in the Ecological Monitoring Program (2011-2017) of the Environmental Impact Assessment of the Foz Tua Hydroelectric Dam, promoted by EDP – Energias de Portugal, S.A. Data were collected between June and August 2011 in 24 transects established in favorable habitats on the area of the lower Tua river valley directly or indirectly affected by the Foz-Tua dam. The presence of individuals and the species identification were obtained through direct observations, with torch lights.