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Song thrush BAP report

Song thrush eating hawthorn berries in snowy hedgerow
The numbers of this familiar and popular garden songbird are seriously declining

What are we trying to achieve?

The Government agreed a Biodiversity Action Plan for this species in 1995. The targets for this plan were revised in 2006 and are as follows:

  • 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

Between 1974 and 2003, song thrushes declined by 50% in the UK (British Trust for Ornithology (BTO) data). Increased drainage and ploughing up of grassland combined with the widespread loss of ditches, hedgerows, scrub and woodland have probably all affected song thrushes in Britain. Intensively managed farmland is now a hostile environment for song thrushes, and a high proportion of remaining birds breed in or close to gardens, where even here they are in long-term decline. Dry summer weather impacts song thrushes by limiting the availability of earthworms.

What is the RSPB doing to help?

The RSPB has carried out a detailed study of song thrush ecology which so far has shown that thrushes breeding on intensively managed arable farmland fail to make enough breeding attempts each summer to maintain local populations, probably due to lack of food.

In 2006, the RSPB’s work included:

  • Continuing the Volunteer & Farmer Alliance project, whereby farmers receive a free farmland survey from local volunteers, covering all regions and countries
  • Continuing Defra-funded research on agri-environment prescriptions to ‘wet-up’ farmland to benefit song thrushes and other farmland birds

Summary of progress

Population indices for farmland birds are based on long-term monitoring schemes; the JNCC funded Common Birds Census (CBC), for which 2000 was the final year; and its successor, the BTO/JNCC/RSPB Breeding Bird Survey (BBS). Due to the way the indices are calculated there is a lag of one year. The 1994-2005 BBS index showed a significant population increase of 18% across the UK, which suggests that the short-term objectives for this species may be met. The recent population increase is more likely to have been a consequence of a series of relatively damp summers rather than the result of conservation action or advice.

Has our work been effective?

It is hard to gauge the direct effects of advocacy and advisory work on bird numbers but the indications are that our work has been effective in raising awareness of the decline in farmland birds such as the song thrush, both among farmers and politicians. Following intensive RSPB advocacy efforts, suitable prescriptive management options have been included in Environmental Stewardship in England. There are no easy conservation fixes for song thrushes in the UK but it is felt that generic prescriptions in agri-environment schemes offer the most hope. However, these are unlikely to be available on a wide enough scale to allow full recovery to 1970 population levels.

What do we plan to do next?

We will:

  • Continue to publicise the detailed requirements of song thrushes
  • Continue research into ‘wetting up’ of arable and pastoral land and the effects of under-field drainage on soil invertebrates
  • Increase the number of partnerships in the Volunteer & Farmer Alliance project
  • Review and produce new advisory material about farmland birds and habitats
  • Continue to influence agricultural policy and practice, and garden owners, so that more effective management is deployed for song thrushes countrywide
  • Continue efforts at UK and EU level to ensure that rural development funding and, in particular, agri-environment funding is increased, not decreased
  • Continue to advocate climate change mitigation and adaptation policies, with the aim of minimising impacts on species likely to be affected, such as the song thrush
  • Press for reform of the Hedgerow Regulations and introduction of hedgerow regulations in Scotland and Northern Ireland

What are the constraints to fully achieving the targets?

  • Lack of suitable prescriptive management options in agri-environment schemes
  • Song thrushes are known to be sensitive to dry summer weather, a predicted consequence of global climate change. If summers in the UK become hotter and drier, then song thrushes can be expected to decline further

Last modified: 04 September 2007