The breeding (in 1991–1996) and wintering (1991/1992–1993/1994) avian community were surveyed in a suburban wood (29.27 ha) in Wrocław city (SW Poland). The 1992 breeding season began together with a drastic clearance of the compact undergrowth with the use of heavy machinery. A slump of abundance of the species nesting on the ground and small shrubs (≤1.5 m) followed, coupled with some modifications to their breeding behaviour, such as clustering of several singing males on the remaining bushes (Blackcap Sylvia atricapilla L.) and nesting in the piles of cut branches (Blackbird Turdus merula L.). As a result of the removal of 52% of the whole undergrowth the density of species nesting on the ground and small shrubs in 1992 was by 26% lower than in 1991 (decrease from 61.8 to 46.3 pairs 10 ha⁻¹). After 1993 a spontaneous regeneration of the bushy vegetation took place, with the ground and shrub-nesting species’ density recovering to 49.4 pairs 10 ha⁻¹ in 1996. After 1991 the park was colonized by 9 new hole-nester species, which was accompanied by the increase of density of this group (from 21.9 in 1991 to 37.9 pairs 10 ha⁻¹ in 1996). Throughout the entire study period a slight rise of density of birds nesting in tree canopies was visible (21.3 pairs 10 ha⁻¹ in 1991 and 33.8 pairs 10 ha⁻¹ in 1996). A year after the shrub clearance the wintering bird abundance was significantly lower (half of the previous numbers), with plant-eaters and insectivores hardest hit, especially Great Tit Parus major L. (average number of inidividuals per one count amounted to 59.2 in 1991/1992 and 21.9 in 1992/1993) and Blue Tit Parus caeruleus L. (respectively 37.0 and 16.0 ind.). An adequate timetable of vegetation clearance must be set up in the course of any decision-making process regarding green areas management to ensure the environmental issues are addressed properly
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