Weasels (Mustela nivalis) are the smallest British carnivore and an important part of farmland food webs. Their populations have declined significantly and their welfare is linked to small mammal prey availability.
Individual weasel welfare is dominated by food security — their extreme metabolic rate means starvation occurs within hours of failed hunting. Cold winters that reduce vole availability cause mass mortality events. Trapping as pest control (in game management contexts) creates welfare concerns around trap design and checking frequency. Secondary rodenticide poisoning from eating rodents killed by anticoagulant baits in farm buildings is a significant and underappreciated mortality cause. Rough grassland conservation that supports vole populations is the most impactful welfare intervention.