Farmland birds are one of the most threatened bird guilds in Europe. Intense agricultural practices subsidised through the Common Agricultural Policy of the European Union (EU) on the one hand, and land abandonment caused by depopulation of rural areas on the other hand lead to vegetation homogenisation that negatively affects the abundance and diversity of farmland birds. Land abandonment leads to vegetation succession and such disturbed habitats are prone to invasion of alien plant species. Due to low densities of livestock or insufficient mowing grassland encroachment takes place in lowland Croatia by the false indigo bush Amorpha fruticosa which rapidly alters the vegetation structure. The effects of land abandonment have been examined in two case studies: “Lonjsko polje“ and “Agrale“. In Lonjsko polje the effect of land abandonment has been examined on pastures and arable land that were in part overgrown by the false indigo bush. The case study Agrale examined bird communities along a succession gradient divided into four classes in Central Croatia and Lika area. Birds were sampled by point counts placed in grids in 29 quadrants of 1 x 1 km. Effect of land abandonment has been studied on the point, grid cell and landscape level. Results indicate that the conservation values of the succession classes are different along the abandonment gradient. The abundance of farmland birds decreases, whereas of the forest birds increased. The most abundant and widespread were unspecialized bird species.