Pollution affects species directly, leading to mortality (in 6% of globally threatened birds) or reduced reproductive success (in 3%), as well as indirectly, through the degradation of habitats (affecting 11%). Pollution associated with agriculture, forestry and industry is the most common threat, and has the greatest impact on marine and freshwater environments and the species that depend upon them.
Pollutants from a range of sources are causing habitat degradation that indirectly affects 11% of all threatened birds; and pollution has direct impacts on 6% of threatened birds through mortality and a further 3% that experience reduced reproductive success (analysis of data held in BirdLife’s World Bird Database 2008). The number of species affected by pollution is low compared with other threats and, significantly, the problems of pollution are relatively easy to solve.
The major pollutants are effluents: from agriculture, forestry, industry, oil spills and the over-application of herbicides and pesticides (see figure). Effluents cause the greatest damage to aquatic environments; both marine and freshwater. A total of 170 threatened species are affected by one or more pollutants. Of those, 97 (57%) are associated with marine or freshwater habitats (compared with 25% of all threatened birds).
Other specific forms of pollution affect a smaller number of species; among them garbage, acid rain and pollution from artificial lights which impacts burrow nesting seabirds such as Newell’s Shearwater Puffinus newelli that return to their colonies after dark and become disorientated by artificial lights.
BirdLife International (2008) Pollution from agriculture, forestry and industry has significant impacts on birds. Presented as part of the BirdLife State of the world's birds website. Available from: http://birdlife.org/datazone/sowb/casestudy/155. Checked: 31/03/2015
|Key message: Pollution has direct and indirect impacts on bird populations|