Merlins are Britain's smallest falcon, breeding on upland moorland and wintering on lowland coasts and farmland with welfare threats from habitat change.
Merlin welfare at breeding sites depends on moorland quality and prey abundance. Intensively managed grouse moors may support abundant meadow pipits but also carry persecution risk from some gamekeepers. Upland habitats degraded by overgrazing reduce prey abundance forcing longer foraging flights with greater energy expenditure. Individual merlins breeding on high-quality moorland with abundant prey experience better welfare through successful breeding, while those on degraded habitat face repeated failure with associated stress. Protection from illegal persecution and habitat management supporting diverse upland bird communities benefit merlin welfare directly.