The influence of coniferous afforestation on lowland farmland bird communities in Ireland: different seasons and landscape contexts

Current governmental policy in Ireland is encouraging afforestation, 80% of which is likely to consist of exotic conifer species, in low-lying agricultural areas. Whereas most studies of bird diversity in forest/farmland mosaic landscapes have focused on high quality woodland remnants in a hostile agricultural matrix, this study has considered the influence of man-made plantations in a less intensively farmed context. Bird communities of three lowland agricultural landscapes (each 2000 ha in area) with intermediate or low levels of coniferous forest cover (33% or 8% approximately) were sampled in winter and summer. Though total abundance and species richness of birds of farmland habitats in the partially forested and open sites did not differ, the presence of trees in the surrounding landscape did influence abundance of some common species such as Blue Tit Parus caeruleus, Robin Erithacus rubecula and Blackbird Turdus merula. In winter, species composition of farmland habitats with and without hedgerow trees differed between forested and open landscapes. Also, the abundance of certain species varied between farmland adjacent to and remote from forest edges, in both seasons. In these landscapes, coniferous plantations did not greatly affect the mainly generalist farmland bird community, either positively or negatively. However, if the proportion of land-use occupied by forestry were to increase, reducing the available hedgerow habitat and forest edge/area ratio, diversity and abundance of declining farmland bird species might be negatively affected.