Tomiałojć L., Wesołowski T. 1990. Bird communities of the primaeval temperate forest of Białowieża, Poland. In: Keast A., Blondell J., Helle P., Kikkawa J., Recher H. W., Holmes R. T. (eds). Biogeography and ecology of forest bird communities. SPB Academic Publ. bv, The Hague, pp. 141-165.

Ten-year bird censuses and parallel population studies in a primaeval temperate forest of deciduous-coniferous type were conducted by means of an improved territory mapping method and observations of some individuaIly marked birds. The Białowieża Forest harbours a bird community very rich in species. The overall density is low. for 50% of species being less than 3 pairs per sq. km. The density of hole-nesters, chiefly Paridae is exceedingly low. The species composition and diversity were fairly similar between habitats and stable between years. Community structure was less variable in bird assemblages rich in species and individuals. No clear signs of numerical compensation of numbers of one species by another were found. OveraIl bird density varied directly with trophic value of habitats and, less obviously, with the relative degree of protection from predators they conferred (nest predation rates are among the highest known). The numbers of several species, mainly canopy insectivores were positively correlated with caterpillar abundance of the previous spring. Białowieża Forest birds have preserved some primaeval features in their breeding ecology and behaviour. Low bird densities in BNP and in some other natural forests of temperate Europe contrast with data from small woods and seem to be a primaeval feature. It is argued that these density differences result first of aIl from man-made transformations of European woodlands by deforestation, fragmentation, predator extermination, and from changed proportion of resident to migratory bird populations (a consequence of climatic differentiation and climate amelioration) and to a smaller extent from differences in forest structure. Resident status and relative safety from predators in man-transformed habitats made the build-up of high densities possible.