The marsh tit, despite its name, lives in mature deciduous woodland rather than marshes. With a 79% UK decline since 1970, it is one of the most threatened woodland birds, its welfare tied to complex old-growth woodland structure.
Marsh tit welfare is determined by old growth woodland quality. The species requires tall trees for territory and nest sites, a complex shrub layer for foraging, dense leaf litter for invertebrate prey, and scatter-hoarding opportunities across a large territory. Modern forestry management that removes dead wood, clears leaf litter and maintains uniform stand structure eliminates the complexity marsh tits require. Deer overgrazing strips the ground flora and shrub layer that supports the invertebrate communities marsh tits depend on. Nature reserve management that combines deer exclosures with selective coppicing and deadwood retention produces the most welfare-positive outcomes for marsh tit territories.