Skip navigation
Home > Our work > Projects > Details

Identifying the drivers of the Wood Warbler population decline in the UK

Male wood warbler singing
Male wood warbler singing

In the UK, Wood Warblers have declined by more than 60% since 1995, but the reasons for this are unknown. It is not even known whether the issues are on their breeding or wintering grounds, or at migration stop-over sites. This project is a first step in understanding this species’ decline and a test of whether the drivers are operating on the breeding grounds.

Project objectives

  • To investigate whether the drivers of wood warbler population decline are operating on the breeding grounds.
  • To measure Wood Warbler breeding success in mid Wales, and compare this with data collected in the mid 1980s in some of the same study woods, to test whether increased rates of predation may have driven population declines, and to identify predators of wood warbler nests.
  • To collect invertebrate samples throughout the breeding season in all of our study woods, and compare with data collected in the 1980s to investigate the hypotheses that a reduction in invertebrate abundance, or a mismatch between the timing of peak prey abundance and nesting activity, may have contributed to the species' decline.
  • To collect habitat data from all of our woods, comparing points occupied by wood warblers with other parts of the woods, to help understand whether changes in habitat quality have played a part in the wood warbler's population declines.

Key dates so far

  • 178 nests were monitored in 2009-11 in 18 Welsh oakwoods
  • c.1 million invertebrates were collected during weekly sampling of all our study woods, and are currently being sorted and counted
  • Habitat measurements were taken at c.100 territory locations and a further 200 random points
  • Analyses so far have concentrated on nest predation and habitat associations with territory occupancy.

Work planned or underway

Finish sorting / counting invertebrates

Analysis of faecal samples to identify nestling food

Further analyses: nest survival, habitat associations, effects of invertebrate abundance on breeding success, return rates of colour ringed birds.

Who to contact

John Mallord
Conservation Scientist
E-mail: john.mallord@rspb.org.uk

Partners

CCW

Funding

CCW