The merlin is Britain's smallest falcon, breeding on upland moorland and wintering on lowland coasts. Its welfare depends on the health of upland ecosystems and the small bird populations that form its prey.
Merlin welfare is tied to prey base availability on upland moorland. Declining meadow pipit and skylark populations through moorland degradation reduce hunting success, requiring longer foraging flights and potentially compromising breeding condition. Illegal persecution on grouse moors remains documented despite full legal protection. The welfare of merlin prey - small passerines that are pursued in extended low-level chases - involves the stress of predator evasion, though successful evasion demonstrates fitness that benefits prey populations.