Bird Atlas reveals widespread sightings of East Devon’s rare Dartford Warbler
The “remarkable” move inland – to upland moors in south west England, Wales and Staffordshire - has been “in line with climatic warming” says the report which has just been published following a four year mapping programme involving 40,000 volunteers nationwide.
The findings of research into the Dartford Warbler - which is on the amber list of Birds of Conservation Concern - notes that the “breeding range expansion beyond southern England has been recent and rapid, including the colonisation of Wales, central England and East Anglia.” The 1988 – 1991 Breeding Atlas revealed a 52% range expansion, labelled as “modest” compared to the subsequent 198% expansion logged during the most recent research period from 2008 – 2001.
The Bird Atlas also reveals that two successive harsh winters saw numbers of Dartford Warblers fall to an estimated 600 breeding pairs in 2010, from an all time population peak of 3,214 pairs in 2006.
However, according to the Bird Atlas, despite the “setback”, the Dartford Warbler “does have the capacity to recover rapidly and further expand its range.” Seven breeding pairs and 22 males have been recorded this year on the East Devon Pebblebed Heaths.
The Bird Atlas research began in 2007 with the aim of finding out how changes in habitat and climate affect 300 different species of birds. Annual datasets from East Devon, charting the changing fortunes of the Dartford Warbler on the East Devon Pebblebed Heaths were supplied by landowner Clinton Devon Estates who also sponsored the production of the final report. Clinton Devon Estates are the owners of the 2,800 acres of heathland between Exeter and the Jurassic Coast; a registered as a Site of Special Scientific Interest (SSSI), a European Special Protection Area (SPA) and a Special Area of Conservation (SAC).
Dr Sam Bridgewater, Nature Conservation Manager for Clinton Devon Estates said: “The core area of the East Devon Pebblebed Heaths was designated as a Special Protection Area in the 1990s, in part because of the significant population of the Dartford Warbler supported. At the time of designation of this important European conservation site we had 8% of the total UK population, and the Pebblebed Heaths still represent a stronghold for this species in Britain today although the latest research findings appear to show that their breeding range is expanding because the climate is gradually getting warmer.”
Dr Bridgewater continued: “The numbers are still currently low all over the UK, but history shows that the species can rebuild. After a very good summer this year, we are hopeful that each pair can have several broods with better success and we would hope to see an increase in numbers from our count next year.”
The Dartford Warbler’s preferred natural habitat is lowland heath dominated by gorse and heather. They nest here and feed almost exclusively on insects associated with gorse, with beetles and spiders being particularly popular. They do not migrate for the winter which is why the climate plays such an important role in their survival.
Because these long-tailed birds nest close to the ground, the Dartford Warbler is easily disturbed by passers-by and dogs, reducing their ability to breed successfully. Uncontrolled fires can also have a catastrophic impact on the availability of suitably aged gorse for breeding. As well as managing the Pebblebed Heaths to ensure that there is enough suitable habitat for them to occupy, Clinton Devon Estates work hard to protect their nesting grounds from too much disruption.
During the four year study, volunteers submitted records of bird activity to the BTO, to integrate local information on bird numbers into a coherent national picture of the state of Britain and Ireland’s bird populations.
Over the last 40 years the British breeding areas for 74 (38%) of bird species have expanded beyond their previously known range, whilst for 72 (37%) of them the range has shrunk, and for 47 (24%) it has remained relatively unchanged. More importantly, for nearly all of them there has been a shift in where they live.
Simon Gillings, BTO Senior Research Ecologist comments, "Conservation scientists have been desperate for a new atlas. Its comprehensive coverage of all areas and all species gives us the depth of information we need to learn from our recent conservation successes, and plan for the challenges of tomorrow."
For more information visit www.bto.org/volunteer-surveys/birdatlas