Species Action Plans - Song Thrush
(Turdus philomelos)
Click to view the Song Thrush Action Plan |
Current Status
National Status
- The song thrush is a widespread resident of the British Isles. It is a partial migrant and a winter visitor. Some continental birds fly to Britain to spend the winter and some resident breeding birds spend the winter further south in Europe, in northern Spain and Portugal.
- The song thrush occupies a range of British habitats, but changes to farming practices in the last 50 years mean that some of its most suitable habitats are now much less favourable.
- Song thrush numbers remained stable until the mid 1970s, after which they declined steadily, with an estimated reduction of 73% in farmland and 49% in woodland habitats between 1971 and 1995.
- Recent trends have been more encouraging, and suggest that the decline may now be reversing. Baker et al (2006) have estimated that the UK population of song thrush in 2000 was approximately 2,288,000 birds. The Breeding Bird Survey of 2004 (Raven, Noble, and Baillie, 2005) indicated that song thrush numbers had increased by 23% over the last ten years; however, they still showed a 51% decline over the last 36 years.
- The song thrush is protected under the EC Birds Directive and the Wildlife and Countryside Act (1981).
Norfolk Status
- Norfolk has a relatively high density of song thrushes, with particular concentrations in north-west Norfolk, mid-Norfolk and south Norfolk. Density is only noticeably lower in Breckland.
- By extrapolating from the data in the Norfolk Bird Atlas (currently available up to the end of the 2006 breeding season and gathered over the seven summers since 2000), the Norfolk population is estimated to be 5,000-5,500 breeding pairs. This is based on the fact that the species was recorded in 88 per cent of the 1,317 tetrads covered up to the end of 2006 (out of a county total of 1,480) and that the average number of pairs per occupied tetrad is four (Moss Taylor, pers. comm.).
- Although there is considerable variation from year to year, data from the BTO/JNCC/RSPB Breeding Bird Survey suggest that there was a 35 per cent increase in the Norfolk song thrush population between 1994 (the start of BBS) and 2005. It is interesting to note that the population in the East of England showed a significant decline of 18 per cent over the same period.
Current factors of concern in Norfolk
The factors affecting the song thrush population are poorly understood but may include the following:
- Changes in farming affecting food supply and the availability of nest sites, particularly: the switch from spring to autumn sowing of cereals (and loss of spring-time tillage); the reduction in hedgerows, field margins and grassland; the move to larger fields; field drainage; and the increased use of pesticides, including the widespread use of molluscides on potato and brassica crops.
- Increased use of molluscides and herbicides in gardens
- Reductions in woodland humidity and the area of damp ground, as a result of wind penetration and field drainage along the woodland edge.
- Reduced shrub layer in woodland as a result of grazing and forestry management.
- Reduction in the areas of appropriately managed scrub, such as scrub edge and scattered scrub features.
- Changes in rainfall patterns, leading to drying and reductions in the availability of soil invertebrates. The recent MONARCH (Modelling Natural Resource Responses to Climate Change) report highlighted the vulnerability of the song thrush to climate change (Berry et al., 2007).
- Hunting in southern France and the Iberian Peninsula. (However, the Norfolk population is largely sedentary, so this is not thought to be having a significant impact on local numbers.)
Current Action in Norfolk
- Little action was taken for the species until census work by the British Trust for Ornithology (BTO) in Thetford highlighted its decline.
- Direct and indirect advice to land managers is provided by the regional RSPB Farmland Conservation Officer and relevant advisory literature distributed throughout the county.
- Wildlife gardening information from the RSPB and NWT has been made widely available to the public (including information about the careful use of slug pellets), and promoted through events such as 'Wild about Norfolk'.
- A postcard identification scheme was run by Norwich 21 in 2003/4. The scheme helped to highlight the plight of the song thrush, particularly among school children.
Action Plan Objectives and Targets
National
- In England, Northern Ireland and Scotland, increase the BBS index to 115% of the 2003 level by 2010. In Wales, maintain populations at the current (2003) level.
- Maintain the percentage of occupied BBS squares at the 2003 levels in the UK and all four countries.
Norfolk
- Increase the BBS index from the 2003 level of 0.72 to 0.83 by 2010 (115% increase).
- Maintain the percentage of occupied BBS squares at the 2003 level of 0.67.
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Send mail to scott.perkin@norfolk.gov.uk with questions or comments about this web site. This page was printed from the Norfolk Biodiversity Website : http://www.norfolkbiodiversity.org/