The grey wagtail is associated with fast-flowing streams and rivers and has declined significantly, particularly in upland areas, as water quality and invertebrate prey have changed.
Grey wagtail welfare reflects the health of UK upland and lowland river systems. Acidification, agricultural pollution, and invertebrate decline reduce prey availability. Cold winters freeze streams and prevent foraging. River restoration that improves water quality and invertebrate communities directly benefits grey wagtail populations.