Major trends in the avifauna in old farming districts in the boreal zone of Northwest Russia

Abstract

Major trends have been identified in the alteration of the avifauna under the effect of old agrarian land use in boreal parts of Northwest Russia. The structure of habitats in a northern mosaic agrolandscape typical of the household-based agriculture era, includes open farmland, small villages, wooded pastures/corridors, secondary forests after slash-and-burn clearing, and forests replacing old arable land. The bird population composition is the most specific in open farmland and small villages, where the prevalent aspect is the 'follower' bird species associated with pastures, meadows and residential areas, originating from Neolithic agrarian civilizations of Western Asia and Near East, as well as medieval centres of horticulture in European forest-steppe regions. In the past, habitats in the periphery of a mosaic agrolandscape - wooded pastures and slash-and-burn forests, used to occupy 1.5-2 times as much space as open cultivated farmland or even more. Their contribution to the total effect of agrarian land use in boreal regions on avifauna transformation was the most significant. Logically, man-induced transformation of natural habitats by traditional agriculture affected primarily the fauna and population of forest-dwelling birds. A positive effect of slash-and-burn agriculture on the occurrence and abundance of birds has been observed for 40 species showing preference for early stages of forest succession and for boreonemoral communities. At the same time, the abundance of 19 native boreal species which prefer old-growth coniferous forest has declined considerably, sometimes up to extinction from wooded corridors. Wooded corridors and forests after slash-and-burn clearing, which occupy a substantial share of the present-day forest fund structure, still play an essential role in the current general fauna-shaping process in boreal regions of Northwest Russia.