Extensive grazing by cattle and traditional cereal crops, in rotation with lying fallow, legumes and other herbaceous crops, has over the centuries altered the landscape of the plateaux and large valleys of the Iberian Peninsula. In this way, habitats similar to natural steppes have arisen. Steppe birds, originally from the great plains of Asia and Central Europe, have adapted to these agrarian systems with high natural values since the Neolithic Age. Nowadays, Spain is home to the last and most important populations of these birds following their extinction in a large part of the rest of the Continent. Specifically, Castilla La Mancha is one of the last refuges for these species. It hosts 40% of the European population of great bustard and Iberian sandgrouse and between 10 and 20% of stone curlew. Over a third of the world population of little bustard lives in Castilla La Mancha. This is also the region with the largest populations of species of hunting interest associated with these crops, such as partridge and quail.
The changes in and intensification of traditional farming practices is one of the most important reasons for the decline of these species. The loss of hedgerows, fallow lands and the cultivation of legumes, the advances in irrigation, or the use of chemical fertilizers and pesticides cause poisoning, food shortage through a smaller number of invertebrates and the destruction of refuges. The introduction of short-cycle cereals has shortened the farming calendar and triggered the destruction of clutches by the use of combined harvesters.