The harvest mouse, Britain's smallest rodent, is dependent on tall grassland and cereal field margins that have declined dramatically, creating acute welfare challenges for surviving populations.
Harvest mouse welfare is inseparable from the massive decline in suitable habitat. These tiny mammals have very limited thermal tolerance given their extreme surface-area-to-volume ratio, meaning inadequate habitat quality directly translates to increased cold stress, predation exposure, and starvation risk. The scale of mortality during cereal harvest is essentially unquantified but likely very large - combines operating at high speed through fields containing mouse families causes instantaneous or prolonged death for individuals that cannot escape. Creating and protecting tall grassland margins and buffer strips around fields represents both a conservation and a welfare intervention, reducing the volume of individuals killed and improving survival conditions.