Bird species dynamics in a managed southern boreal forest in Finland

Patterns of 10-year variation (1993–2002) in a bird species community were studied in a managed southern boreal forest in Finland using yearly repeated bird censuses. Specifically, effects of logging on cavity-nesting bird species of coniferous and mixed woods were examined. Logging was based on the recommendations of new forestry practices, which have been designed to maintain biodiversity in Finnish forests. Repeated measures ANOVA with polynomial contrasts was adopted when studying temporal variation of bird abundance. Short-distance and partial migrants showed significant year-to-year variation, whereas the temporal variation in resident birds and long-distance migrants did not vary significantly. Numbers of short-distance migrants declined during the study period, whereas partial migrants had significant non-linear (third-order) variation between years. The temporal variation of partial migrants was largely due to variation in spruce seed eaters, the siskin Carduelis spinus and the crossbill Loxia curvirostra, the numbers of which varied according to the spruce cone crop. New logging practices had a negative effect on the numbers of cavitynesters of coniferous and mixed woods. However, winter temperatures correlated positively with the numbers of resident cavity-nesting tit guild species (Parus montanus, P. cristatus, P. ater, Certhia familiaris), so that mild winters may ameliorate the adverse effects of forestry practices on resident forest species.