Farmland bird response to land use changes: the role of habitat fragmentation

Abstract

Socioeconomical changes from recent decades in Mediterranean farmland habitats have caused the abandonment of less fertile arable land in many regions. Together, these relatively recent changes in land use patterns have progressively resulted in the loss and fragmentation of many arable habitats for farmland birds. In this thesis I evaluated the consequences of habitat fragmentation driven by land use changes in a pseudo-steppe area in Southern Portugal. Land use changes included afforestation of arable habitats, land abandonment and land intensification. I outlined different approaches to study the effects of the mentioned changes in the farmland community in the Special Protection Area of Castro Verde. Overall results suggested that changes like afforestation may have opposite impacts in the community. Indeed, bird diversity within the area increased, including positive effects in woodland, farmland and ground-nesting birds. Conversely, steppe birds were negatively affected, including species of conservation concern. Also, this study showed that grassland specialists (e.g., Melanocorypha calandra) are very sensitive to current trends of habitat fragmentation. Moreover both habitat fragmentation and grazing regimes are major drivers of grassland breeding densities. Finally, this work supports the view that the conservation and management of steppe birds in Mediterranean farmland requires a multiscale approach.