Large declines in the breeding populations and contractions ofbreeding range have occurred in several woodland birds in Britain in recentdecades. Data from the BTO’s Common Birds Census indicate that 10 out of 32woodland species declined by more than 50% between 1966 and 1999, while 5species increased by more than 50% over the same period.The declining speciesdiffer substantially in their ecology and life-history patterns. No single generalexplanation can be identified for the declines and it is likely that multiple factorshave exerted a combined effect on several of the species. Seven factors emergefrom this review as especially relevant and worthy of further study: (i) pressureson migrants during migration or in winter; (ii) climate change on the breedinggrounds; (iii) general reduction in invertebrate food supplies; (iv) impacts of landuse on woodland edges, habitats adjacent to woodland and hedgerows; (v)reduced management of lowland woodland; (vi) intensified habitat modificationby deer; and (vii) increased predation pressure from Grey Squirrels Sciuruscarolinensis, Great Spotted Woodpeckers Dendrocopos major and corvids.