Grey wagtails are elegant stream birds associated with fast-flowing rivers, with welfare challenges from declining invertebrate populations and river quality degradation.
Grey wagtail welfare is threatened by declining river invertebrate communities. Acidification, pollution, and sediment loading of upland and lowland streams reduces the aquatic invertebrate prey that grey wagtails depend on. In winter, cold weather that freezes shallow stream margins eliminates accessible foraging areas, forcing birds to find alternative food sources or face starvation. Flood events that scour stream beds can temporarily eliminate the invertebrate community that adults need to feed themselves and their chicks. Water abstraction that reduces flow rates in summer reduces the oxygenated gravel habitats needed by both the river invertebrates that form their prey and the birds themselves.