The wood warbler is a summer migrant to mature British woodland with open canopy. Its rapid decline in England is linked to changes in woodland structure and invertebrate availability.
Wood warbler welfare is closely linked to caterpillar abundance in the woodland canopy. Phenological mismatch, where warbler chick timing diverges from peak caterpillar emergence due to climate warming, reduces food availability at a critical growth period. Woodland management that maintains open understorey, reduces deer browse, and supports a diverse canopy benefits wood warbler nesting habitat and invertebrate prey.