Impact Type: Deposition of pollutant
This genus includes song thrush, mistle thrush, blackbird, fieldfare and redwing. Green (1998) has suggested that acid deposition can affect eggshell thickness in thrushes (Turdus spp.). Anthropogenic acid deposition can significantly reduce levels of available calcium in soil and the abundance of calcareous items such as snail shells. Recent research in areas adversely affected by acid deposition in continental Europe has suggested that reduced calcium availability has resulted in an increased incidence of eggshell defects in small birds (Pyatt et al. 1998).
Numbers of thrushes especially the song thrush, our resident thrush which is less dependent on berries, are declining, although the blackbird, a more dominant feeder, is on the increase. Human impact via change in land use (garden) management probably presents the greatest threat.
|Critical Load/ Level|
No estimate available