Short-eared owls are partly migratory, with winter population levels in the UK varying dramatically based on vole populations in their northern breeding grounds.
Short-eared owl welfare is closely tied to the vole population cycles that determine prey availability in both breeding and wintering habitats. In vole trough years, breeding pairs face food shortage during chick rearing, and many pairs simply do not breed. In vole peak years, the same habitat supports dense breeding populations with high chick survival rates. This creates welfare variation at population scale that is fundamentally natural, but human land management choices amplify or dampen these natural cycles. Coastal and lowland grassland management is critical for winter welfare: birds displaced from upland breeding areas require accessible, prey-rich grassland to maintain body condition through winter. Agricultural conversion of rough grassland to improved pasture or arable eliminates winter habitat, forcing birds to range farther in poorer condition. Illegal persecution on grouse moors, where short-eared owls may be killed as predators of young grouse, represents a direct welfare harm to a protected species. Wind farm development in upland areas overlaps spatially with short-eared owl breeding habitat and requires careful siting assessment to avoid collision mortality during regular low-level hunting flights.