Curlew sandpipers are long-distance migratory waders that pass through the UK on their way between Arctic breeding grounds and African wintering sites. Their welfare during passage depends on suitable estuarine stopover habitats.
Curlew sandpiper welfare during passage involves the extreme physiological demands of long-distance migration. Birds arriving at UK estuaries from Arctic breeding grounds may be significantly depleted from their departure fuel load; the quality and accessibility of estuarine invertebrate food directly determines whether they can refuel adequately for the next migration leg. Estuaries with high bivalve, polychaete, and amphipod density enable rapid mass gain; degraded estuaries with reduced invertebrate communities force longer stays with greater exposure to predation and weather. Disturbance by people and dogs on estuarine mudflats during autumn directly affects feeding efficiency and forces birds to expend energy on disturbance flights. The welfare of each individual bird attempting a 12,000-kilometre journey depends on the accumulated quality of each stopover along the flyway.