Dynamics of the Community of Hole-nesting Birds upon Reduction of Industrial Emissions (the Example of the Middle Ural Copper Smelter)

The dynamics of the species richness, breeding density, and structure of the community of birds occupying nest-boxes upon a 50-fold reduction of atmospheric emissions from the Middle Ural Copper Smelter was analyzed based on long-term continuous observations (1989–2020). The total density in the deciduous forest was lower in the heavily polluted zone (impact zone) than in the background zone, while there were no differences in the coniferous forest between the zones. The total breeding density of the community of hole-nesters increased in the impact zone over the 30 years (especially, in the deciduous forest in 2010–2020) after the significant reduction of industrial emissions. The breeding density of the two most abundant species varied in different directions: it increased for pied flycatcher and decreased for common redstart. This led to a change of dominants in the impact zone: redstart dominating until 2012 was replaced by pied flycatcher. The differences in the dynamics of species density are probably determined by the beginning of vegetation recovery near the smelter, which is favorable for pied flycatcher but not for redstart.