Influence of treefall gaps on distributions of breeding birds within interior old-growth stands in Bialowieza Forest, Poland

Breeding birds were counted using point counts at 50 treefall gaps and 50 c losed-canopy sites within one of the largest tracts of old-growth forest in Europe. Numbers of species and individuals were slightly, but significantl y, higher at gaps. Overall bird species composition differed substantially at gaps and non-gaps. Dunnock (Prunella modularis), Blackcap (Sylvia atrica pilla), and Chiffchaff (Phylloscopus collybita) were significantly more abu ndant at gaps. Wood Warbler (Phyloscopus sibilatrix) and Red-breasted Flyca tcher (Ficedula parva) were significantly more abundant at non-gaps. Warble rs (Sylviidae), ground insectivores, ground nesters, and short-distance mig rants were significantly more abundant at gaps, but no species groups were more abundant at non-gaps. Eight species breeding in forest edges and young plantations in eastern Poland were not recorded in natural treefall gaps. The proportion of tropical migrant passerines was considerably higher in cl osed-canopy stands (0.47) than at gaps (0.29), which contrasts with the sit uation in most managed European forests where the highest proportions of tr opical migrants typically occur in young-growth forests.