About 13 km from the city of Coimbra is the Paúl de Arzila Nature Reserve, on the left bank of the River Mondego, which is divided into the municipalities of Coimbra, Montemor-o-Velho and Condeixa-a-Nova. It is a wetland that comprises two distinct areas: an alluvial plain and a protection zone. Paúl de Arzila is classified as a Nature Reserve due to its ornithological importance, as it is a crossing area for transarian migratory birds. It is also a feeding and resting area for several species and a wintering place for paleartic species. The symbol of this Reserve is a red heron (Ardea purpúrea), taking into account its importance as a breeding species in this protected area.