Wesołowski T. 1989. Nest-sites of hole-nesters in a primaeval temperate forest (Bialowieża National Park, Poland). Acta Ornithologica 25: 321-351.

The study provides the first description of nest-site distribution of European hole-nesters breeding in natural holes in unmanaged stands. The data are mostly from two types of climax stands, i.e. oak-hornbeam and ash-alder. The species dealt with are: Sturnus vulgaris, Sitta europaea, Ficedula albicollis, F. hypoleuca, Parus major, P. caeruleus, P. palustris, Dendrocopos major, D. medius, D. minor. The following aspects of hole localization are described: tree species, height above the ground, entrance's exposure, tree trunk girth, hole origin (woodpecker-made or „natural\"), tree fragment in which hole was located, state of tree fragment containing hole (live or dead), slope of supporting structure, shape of entrance. Though the species showed differentiation in the majority of variables analysed, their patterns of hole utilization still overlapped. The same holes were often used consecutively by different species. Species of similar body sizes exchanged holes most frequently. It is argued that interspecific competition for holes in primaeval forests though present, is less pronounced than in man-transformed, secondary woods.