The expansion of olive groves is reducing habitat suitability for the Great Bustard Otis tarda and the Little Bustard Tetrax tetrax in Southern Spain: could Important Bird Areas (IBAs) reduce this expansion?

Olive groves in the Mediterranean basin have undergone a tremendous increase during the last two decades, with most of the new olive groves being planted on arable land. This conversion may affect habitat suitability for steppe birds, which are associated with arable land and other open-land habitats, such as natural pastures. In this work, we evaluate the presence of new olive groves in the distribution of the Great Bustard Otis tarda and the Little Bustard Tetrax tetrax in Southern Spain (the largest olive oil production zone in the world), and we compare the percentage of different land uses in 2000 and 2018 using data provided by the Corine Land Cover. From 2000 to 2018, new olive groves occupied 2.14 and 2.61% of the distribution areas of the Great Bustard and the Little Bustard, respectively. The decrease in arable land and the increase in permanent crops were the main drivers of the landscape composition changes during the study period. The fragmentation index of arable land was higher in 2018 than 2000. These changes in the landscape suggest a decrease in habitat availability and suitability for steppe birds that could affect the distribution and abundance of their populations. Moreover, there were no differences in the proportion of new olive groves planted inside and outside the limits of Important Bird Areas (IBAs) from 2000 to 2018, which were created to protect these steppe birds, thus suggesting that the management policy of the IBAs should be reviewed to prevent harmful land-use changes.