Established in 1999 and widened in 2008, the Castro Verde Special Protection Area (SPA) is the largest and most important steppe area in Portugal and one of the most representative in Europe for its size, conservation status and high concentration of birds as the Great Bustard, the Lesser Kestrel, the Little Bustard and the Roller.

With 85.345 ha of total area and around 60000 ha of cereal steppe (or pseudo-steppe), the Castro Verde SPA encompasses 6 municipalities (Aljustrel 19%, Almodôvar 4%, Beja 12%, Castro Verde 85%, Mértola 8% and Ourique 3%), significantly overlapping with the wide plains of Castro Verde regionally known as Campo Branco.