By the end of the 1980’s, the most important areas for steppe birds of Castro Verde Municipality (particularly, for the Great Bustard, the Lesser Kestrel and the Little Bustard) had been acquired by paper pulp companies intending to convert them into rapid growth forests with tree species as the eucalyptus. These changes in soil occupation would lead to the abandonment of traditional agricultural activities and, therefore, to the disappearance of the steppe avifauna which is strictly dependent on dry land cereal in extensive regimen.

At the time, the LPN, the National Parks and Reservations Service and the General-Directorate for the Forest (predecessors of the current Institute for Nature Conservation and Forests), as well as the Castro Verde Municipality and the Campo Branco Farmers Association decided to take concerted action to safeguard the Castro Verde cereal steppe. The following initiatives were carried out:

• The Castro Verde Municipality Municipal Plan (PDM, approved in the Council of Ministries Resolution 59/93 of October 13) forbade forestation in about 85% of the administrative are of Castro Verde. This was an innovative measure at a regional, national and even European level to promote and preserve the favorable conservation status of the natural values of the Castro Verde cereal steppe;

• As a result of conversations with the European Union, the LPN submitted applications to several EU funding mechanisms (namely to LIFE Nature) aiming to acquire most of the land owned by the large paper pulp companies. In consequence, between 1993 and 1999, the LPN acquired five estates in the Castro Verde region with a total of 1700 ha. Interdicted to hunting activities, these estates became Biodiversity Reserves where the conservation of steppe birds is promoted through the preservation of their habitat. This was the formal start of the Sustainable Castro Verde Program;

• The Campo Branco Farmers Association and the LPN conducted a preliminary study on the environmental reference status of the territory which was the basis for the creation of an Agro-Environment Measure specific to the Campo Branco region in the scope of the Common Agricultural Policy (PAC) of the European Union. Beginning in 1995, the Castro Verde Zonal Plan – currently entitled Zonal Support (Order 56/2015 of February 27) – has an important demonstrative value and is nowadays the main Nature conservation tool in the region and is widely seen as an example of excellence in development of a new perspective in managing the rural space both at a national and an European scale.

As a result of those efforts, the Castro Verde region was classified as the Castro Verde Special Protection Area (SPA) for birds in September 1999 within the Natura 2000 Network. Following the litigation between the European Union and the Portuguese State in regard to the Southern Highway (A2) crossing of the Castro Verde SPA, the Castro Verde SPA was enlarged in 2008 becoming the largest SPA in Portugal with about 85 thousand hectares.