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Marsh warbler BAP report
Few people in the UK hear this master singer because it is so rare
What are we trying to achieve?
The Government agreed a Biodiversity Action Plan for this species in 1998. The targets for this plan were revised in 2006 and are as follows:
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Increase the marsh warbler population to 15 breeding pairs by 2010
The marsh warbler is a summer migrant and an uncommon breeder, which formerly bred in southern England, in scattered locations, but with a stronghold in Worcestershire. Following a long-term decline, it became extinct in this area but a new population became established in South-east England. It is now a rare breeding species.
Unfortunately where migrant birds are found on the edge of their range there is often little that can be done in terms of effective conservation action.
What is the RSPB doing to help?
The RSPB has concentrated its effort in Kent; co-ordinating local volunteers to monitor the population and provide information on the breeding habitat features; organising habitat management, and where necessary, guarding against the threat from egg thieves.
The sites used by marsh warblers are not publicised to reduce the risks from egg collectors or disturbance from birdwatchers.
Summary of progress
The Kent population had been expanding since its establishment in the 1970s and by 1993 there were over 25 pairs in at least 4 sites. However, since then the population has been declining due to unknown factors. There are now probably less than 10 pairs breeding in the UK each year, with an estimated 3-5 pairs breeding in 2006.
Has our work been effective?
Although the marsh warbler has been maintained as a breeding species the population is at a precariously low level. The number of marsh warblers returning to breed in the UK is small and appears to be unrelated to habitat conditions. Climatic change here and in the winter quarters is likely to play a major factor in influencing future numbers. It is therefore very difficult to plan conservation action for this species.
What do we plan to do next?
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Continue habitat management work where appropriate
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Continue to monitor sites
What are the constraints to achieving the targets fully?
Given the following factors, there is at present no prospect that conservation action will encourage the species to expand its range
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The species is on the edge of its range and is unlikely to have ever been more than uncommon
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Even where appropriate habitat management has been carried out, apparently suitable sites remain unoccupied
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Knowledge of the ecology of marsh warblers in the UK is poor, as is knowledge of the potential effect of climate change on their range
Acknowledgements
The RSPB has worked closely with a number of individuals and organisations during recent years to further the conservation of the marsh warbler, in particular: Kent Ornithological Society, Environment Agency, Royal Gurkha Rifles and the SE Kent RSPB Members Group.
We are also grateful to the individuals, private landowners and volunteers who have helped marsh warbler work during the year. It is not possible to name them all here in order to protect the birds from disturbance.
Last modified: 03 September 2007