Tomiałojć L., Wesołowski T. 2005. The avifauna of the Białowieża Forest: a window into the past. British Birds 98: 174-193.

As a result of some 500 years of protection, parts of the Białowieża Forest in Poland, remain in a near-primeval condition. Studies of the breeding birds in the core part of the forest (Białowieża National Park) over 29 years show that bird community is species-rich but that densities of individual species are usually low, resulting in only moderate overall densities. In some species, low densities are a consequence of large territories and social exclusion, but often they reflect the undersaturation of habitats by birds, despite superabundant food supply and nest sites. Low productivity, resulting from high nest predation, may contribute to undersaturation. Species composition and numbers of birds fluctuate at BNP in relatively narrow limits, with the populations of closely related species fluctuating either independently of one another or in parallel; interspecific competition for resources plays a minor role. Some attributes of the Białowieża ecosystems resemble conditions in undisturbed tropical forests but contrast sharply with those in fragmented, temperate secondary forests. The present Białowieża avifauna provides a glimpse of that existing in central European forests before their historical transformation by humans. Its present exceptional character arises from preservation of most of its pristine features. The forest constitutes a critical reference point for studies of woodland ecology, and its preservation should be a high priority. Unfortunately, commercial logging continues, gradually changing the forest´s structure and affecting the birds, especially those dependent on dead wood and old-growth. the relatively small national park (47.5 km2) is increasingly becoming an ”island”, in which the long-term preservation of primeval forest features would be impossible.