In the late 20th century, the UK population of merlin crashed due to the use of organochlorine pesticides, which caused merlin numbers to quickly plummet through the 1950s to just 550 pairs by 1960. The species is now red-listed, legally protected, and a long-term conservation concern in the UK – but its recovery has been slow.
The decline of breeding merlin has also been linked to habitat loss, with favoured moorland habitats lost as they have been planted with commercial forestry or converted to grass moor through overgrazing by sheep. More recently, the intensification of heather management through rotational strip-burning or cutting on remaining moorland, especially that managed for driven red grouse shooting, may have reduced the availability of tall heather for nesting and the numbers of small moorland birds such as meadow pipits and skylarks which are key prey.
In 2015, merlin were returned to the UK Red List of Birds of Conservation Concern as their recovery from a historical decline had faltered. The last national survey of merlin in 2008 estimated that there were 1,162 pairs in Britain, 301 of which were found in England. Comparisons with data from 1993/4 suggest that overall, the population is stable but with some marked local declines, particularly in the south-west where pairs declined by 83% and in northern England, with reported declines of 69% in Northumbria and 47% in both the North York Moors and South Pennines.
This project follows on from the Merlin Magic Project completed in 2023. This project concluded that the main factor limiting merlin population recovery was over-winter survival when birds leave their moorland breeding habitat.
In 2026, the GWCT was granted £124,026 from Natural England’s Species Recovery Programme for a 33-month project, Merlin Recovery in Northeastern England.