Redwings are the smallest UK thrush and are highly vulnerable to hard frost. They arrive from Iceland and Scandinavia in October and depend on berry crops and soft ground for earthworms throughout winter.
Redwing welfare is precarious in cold UK winters. A period of hard frost lasting more than 3-4 days is sufficient to cause mass starvation as earthworms retreat below frost-hardened soil. Berry crops are typically exhausted by December, leaving redwings dependent on soft ground. Windfall apples in gardens and orchards provide critical supplementary food during freezes. Climate change is creating more variable winters — mild periods that allow earthworm access interspersed with brief but severe freezes that can be deadly for birds that have not built sufficient fat reserves. Providing apples in gardens during cold spells is one of the most direct welfare interventions available to householders.