The importance of residual habitats and crop management for the conservation of birds breeding in intensive orchards

摘要

Intensive orchards are artificial habitats managed according to production criteria, but they may mimic open woodlands and harbour wild species. We investigated the effect of orchard features on the true abundance (estimated with occupancy models) of some bird species widespread in orchards. Our study was carried out in Val di Non (Trento province, Italy) where apple cultivation is the most widespread and intensive. We counted blackcaps Sylvia atricapilla, chaffinches Fringilla coelebs, and greenfinches Carduelis chloris three times at 44 transects 300-m long. At each transect, we estimated the number of territories/pairs and recorded variables describing the cover of the habitats and management factors. Blackcap abundance was positively affected by the cover of shrubland and broadleaved woodland and by a low cover of coniferous forests. Chaffinch abundance was driven by a negative impact of anti-hail nets and secondarily by bare ground and urbanized areas, with chaffinches more abundant in areas with grassland ground cover and 5-10 % cover of urban habitats. Greenfinch abundance increased with wetland cover, cover of other natural/semi-natural habitats and tree height and decreased with grassland cover. Both the availability of natural and semi-natural vegetation and the orchard traits determined by management can significantly affect the abundance of common species. The conservation of the remaining patches of woodland, shrubland, wetland (and other natural/semi-natural habitats) is essential for bird conservation. The already reported negative impact of anti-hail nets and the importance of the height of apple trees are confirmed; irrigation systems and bare ground may also be important factors.