Breeding bird communities of second-rotation plantations at different stages of the forest cycle

Capsule Early stages of the plantation forest cycle have distinct bird communities and bird density was significantly higher in the second rotation than in the first for a given age class. Aims To characterize the bird communities in Irish second-rotation plantations and to compare them with those of first-rotation plantations. Methods Point counts were used to survey 20 plantation forests in four age classes (Pre-thicket; Thicket; Mid-rotation; and Mature) in the breeding season of 2007. DISTANCE software was used to generate bird densities. Ordination, indicator species analysis, and GLM were used to analyse the bird communities. Results Bird communities of Pre-thicket and, to a lesser extent, Thicket age classes were distinct from those of more mature forests. Bird communities of Mid-rotation and Mature age classes were indistinguishable from each other and were therefore combined into a single age class (Closed canopy). Pre-thicket held significantly lower total bird density, but significantly higher migrant bird density, than this Closed canopy age class. Bird density was significantly higher in the second rotation in all age classes except for Pre-thicket, but migrant density was significantly higher in Pre-thicket in the second rotation. There was no difference in species richness between the first and second rotation. Conclusions Differences between rotations are probably due to changes in vegetation structure, and the increase in second-rotation forests in Ireland is likely to be a positive development for bird communities. Especially encouraging is the higher migrant bird density in second-rotation Pre-thicket, as some of these species are in decline throughout Europe. However, the largest differences in population density between rotations were exhibited by common species and such species will likely benefit most from future increases in the area of second-rotation plantation forests