Tomiałojć L.,Wesołowski T., Walankiewicz W. 1984. Breeding bird community of a primaeval temperate forest (Białowieża National Park, Poland). Acta Ornithologica 20: 241-310.

During 1975-79 bird censuses (covering yearly 260-358 ha of climax forest) were carried out in the Białowieża National Park (eastern Poland) which preserves the remnants of primaeval lowland forests of a mixed deciduous.coniferous type. Improved version of mapping technique has been used. Overall bird densities ranged from 27.4 pairs/10 ha in coniferous to 105.5 p/10 ha in the forest.edge ash-alder stands, with the most frequent values between 50 and 70 (chiefly in oak-hornbeam stands). The densities of most species did not exceed 3 p/10 ha. Density of hole-nesters was surprisingly low (4.6 in coniferous, 22.3 in oak-hornbeam, and up to 36.2 p/10 ha in riverside forest-edge stands); especially tits (Paridae) occurred in very scattered populations. The structure of bird assemblages was found to be rather similar among various habitats and stable between years. The analysis of data suggests only a weak correlation between bird densities and the food resources available during the breeding season. Very low breeding densities in BNP are tentatively explained as a result of an undersaturation of habitats by several bird species and, for those that saturate habitats, by low densities being an adaptation to heavy predatory pressure.