Urdaibai Biosphere Reserve holds a diversity of habitats and resources that are essential for migratory bird species’ conservation, and at the same time provides a rich milieu for the development of environmental education programs. This study evaluates the impact of a daylong and place-based environmental education program, performed at the Urdaibai Bird Center (UBC), on secondary education students’ environmental attitudes and knowledge. Students (n= 908) completed a written questionnaire where their perceptions on the Urdaibai Biosphere Reserve and marshes, together with their interest in biodiversity, knowledge about bird migration and bird species identification skills, and attitudes towards conservation were assessed. Results show that students’ knowledge regarding Biosphere Reserves, marshes, and bird migration is limited, and that their bird identification skills are scarce. Although they scored high on environmental attitudes, a significant number of them feel that conservation efforts are excessive and hinder economic development. Students living within the Biosphere Reserve, as well as from rural milieus or who underwent primary education through a bird-centered curriculum hold a better knowledge of the local biodiversity. To adapt the environmental education program at the UBC, its integration in formal teaching/learning contexts via meaningful hands-on and/or project-based activities could be considered, together with the systematic evaluation of the outcomes.