Structure of avian communities in lowland coniferous forests in Opole Silesia (SSW Poland)

In Poland, forests comprise 31% of the total surface area, while the lowland coniferous forests comprise 51% of 94 000 km² afforested areas. The line transect method was employed in 2002 and 2004 to estimate population densities and dominance of all bird species breeding in a selected fragment of such forest (eight transects with 165 sections and 77.7 km in total length). In total, 54 breeding bird species were recorded. The numbers varied between 37 and 44 on the particular transect. The number of breeding pairs per 10 ha varied on each transect from 41.0 to 93.6 (x=64.8; SD=102.22). Shannon’s diversity index varied between 1.2 and 1.4 on particular transects, while Simpson’s diversity index varied between 0.7 and 0.9. Also Pieleau’s evenness index varied slightly between 0.05 and 0.07. In overall, the differences between densities of breeding species on 8 transects were not statistically significant. The Chaffinch Fringilla coelebs was by far the most numerous bird species, recorded as eudominant in all eight transects and present in all 165 sections. The second to the Chaffinch was the Chiffchaff Phylloscopus collybita; also recorded in all sections and as a dominant in all transects. Three other species, namely the Blackbird Turdus merula, Willow Warbler Phylloscopus trochilus and Blackcap Sylvia atricapilla were recorded each one in more than 90% sections (N=165), and on particular transects their dominance varied between 4 and 11%. Residents comprised 57.5% of all breeding pairs. Short-distance migrants were almost twice more common than long-distance migrants. Insectivores were by far the most numerous feeding guild represented 88.9% of all breeding pairs. Overall density, cumulative dominance, diversity and evenness were unexpectedly very similar in this study (managed forest) and in natural primeval lowland coniferous forests of Białowieża.