Thousands of years ago Castro Verde region was composed by actual Mediterranean forests. The landscape was gradually modified by the practice of extensive agriculture (particularly cereals) and pastoralism, thus giving origin to a man-made high natural value agro-ecosystem.

Known as cereal steppe (or pseudo-steppe), this almost treeless landscape dominated by herbaceous vegetation associated to dryland cereal farming harbors species with high scientific and conservationist value, namely endemic plants, and many rare charismatic birds threatened with extinction at a European and even global level as is the case with the steppe birds.

Due to the rarity, diversity and effective population size of steppe bird, the Castro Verde cereal steppe was classified in 1999, under the scope of the Birds Directive, as the Special Protection Area (SPA) of Castro Verde, thus integrating the ecological network of the European Union (Natura 2000 Network).