Sewage works as bird habitats in Britain

Abstract

The bird communities associated with different systems of sewage disposal are described in relation to the components of each system. The data were drawn from published studies and from British Trust for Ornithology data in the Common Birds Census and Register of Ornithological Sites. The bird communities were considered under four divisions: breeding, summer feeding, spring and autumn, winter. The ornithological gains and losses associated with recent changes in methods of sewage treatment are discussed, particularly in relation to the decline of sewage farms. It is concluded that modern works, which are on average smaller in area than sewage farms, support lower populations of wetland species. The variety of ornithological interest is also lower but it is suggested that modern works can be important bird habitats, particularly as feeding sites for several passerine species. Those systems with percolating filters and tertiary treatment by surface irrigation are likely to support the most varied bird communities. Works using other oxidation methods, and no tertiary treatment, are of the least value as bird habitats.