A farmland area in southern Sweden used for cereal production was turned into energy production by growing Salix. The breeding birds were censused in these fields after energy foresting had started and the first harvest was taken. The introduction of Salix viminalis in the fields showed to be favourable for species well adapted to bushy habitats like the marsh warbler. The habitat succession from the planted or harvested forest to the four, five years later mature forest is important too, as bird species prefer different growth stages of the brush forest. The whitethroat and the whinchat preferred the sprouts of the recently harvested areas, but the willow warbler and the garden warbler preferred the fully grown bushes preceeding the harvest. Introduction of Salix fields in an open farmland landscape will increase the number of bird species and for some species also the abundance. The biodiversity is improved if the harvest is asynchronous in different subareas. In terms of environment and fauna protection or improvement a limited increase of scattered energy producing Salix fields will probably be favourable, causing an increase in overall biological diversity.