Demographic and environmental causes of the decline of rural Song Thrushes Turdus philomelos in lowland Britain

摘要: We review current knowledge of demographic mechanisms and environmental factors implicated in the population decline Song Thrushes Turdus philomelos rural Britain since mid-1970s, present new analyses regional variation changes. Increased mortality during first year life (from fledging to recruitment) is highlighted as a potential mechanism having driven decline, while rapidly declining farmland were making too few nesting attempts sustain local numbers. Breeding are strongly associated with non-cropped habitats such woodland edge, field boundaries, gardens scrub; they make substantial use grassland, but avoid cereals when foraging. Earthworms constitute key component Thrush diet availability this prey influenced by moisture levels surface soils. Several lines evidence suggest that dry soils summer deleterious productivity survival Thrushes, rates change 1970–86 was negatively correlated extent under-field drainage on (the main function which promote drying soils). Increasing dryness agricultural loss grassland from eastern arable counties have probably both contributed declines Britain. Loss hedgerows scrub, degradation may also role predators remains unclear. Recovery populations requires challenging policy initiatives should aim restore cover (scrub understorey), grazed arable-dominated areas damper summer.