Dartford Warbler Numbers Drastically Reduced by Snow
The heavy snow in February may have had a devastating affect on the Dartford warbler in some of its UK’s strongholds.
Initial reports suggest Dartford warbler numbers on important heathland sites in Surrey, Berkshire and Hampshire are down by around 80 to 90 per cent from 2008 due to this year’s snow.
The areas, known as the Thames Basin Heaths and Wealden Heaths, are the third and fourth largest breeding grounds for Dartford warblers in the UK. Both areas are also becoming increasingly important internationally as numbers plummet in Europe.
A fine balance
The full extent of the drop will not be known until the results of breeding bird surveys are released in autumn, but early counts found very low numbers on major sites including Ash to Brookwood Heaths in Surrey, Broadmoor to Bagshott Woods and Heaths on the Surrey and Berkshire border, and Bourley and Long Valley on the Hampshire and Surrey border.
Dartford warblers are classified globally as Near Threatened – one step below species facing world extinction. Changes and deteriation of the bird's habitat in Europe has seen populations decline by an estimated 40 per cent in just ten years.
The restoration of southern English heaths, plus increasingly milder winters, has seen the UK’s Dartford warbler population fare better. Despite crashing to 11 pairs in the harsh winter of 1963, the UK population is now estimated at around 3,200 pairs.
Initial findings suggest this year’s UK crash is localised to the Thames Basin and Wealden Heaths. But conservationists say the drop at these key sites, already under pressure from surrounding development, shows how important it is to protect them, giving the Dartford warbler populations in these areas the best chance of survival possible.
Sam Dawes, conservation manager in the RSPB's South East region, said: “The impact of this winter’s snow shows what a fine balance there is for these birds between success and failure.
“Dartford warblers have generally been doing well on the Thames Basin and Wealden Heaths in recent years due to milder winters and better protection of the sites.
"The Thames Basin and Wealden Heaths, and the special birds they support, have never been so important but it’s a rare habitat that desperately needs protecting.
“Climate change could also see Dartford warblers ousted from their traditional grounds in Europe and north-west Africa, and if the birds can’t find refuge here, on our heaths, the future for them could be very bleak indeed.”
The Dartford warbler surveys are carried out by a team of experienced volunteers based in Hampshire, Berkshire and Surrey, co-ordinated by local ornithologists John Clark and John Eyre.
The RSPB has been campaigning for better protection of the Thames Basin Heaths from the effects of increasing housing development in the area.
Press release from RSPB