Natural England

Britain’s most colourful warbler is spreading its territorial wings because warmer winters and better heathland management have increased its chances of survival.

The latest UK survey of Dartford warblers, by Natural England, RSPB, BTO, and Forestry Commission England, shows that numbers have soared by 70 per cent since the last count in 1994. The bird has returned to Wales, the Midlands and East Anglia and now there are more than 3,000 pairs – the highest tally for more than 40 years.

But while the Dartford warbler is flying north, west and east from its strongholds in southern England, conservationists say that more is needed to protect and restore heathlands to help the bird further its advance.

Phil Grice, senior ornithologist at Natural England, said: “Part of the spectacular increase in Dartford warbler numbers is no doubt down to the massive £25 million plus investment in the Tomorrow’s Heathland Heritage, a ten year programme led by Natural England together with a consortium of 140 partners, with support from the Heritage Lottery Fund. The result is the restoration of many of England’s treasure trove of heathlands to a healthy condition supporting delightful native wild species like the marsh gentian, Dartford warbler, natterjack toad and silver studded blue butterfly that depend on it for survival.

“We remain concerned about the very recent decline in numbers on the Thames Basins Heaths which reflects the vulnerability of this beautiful bird, which is why we are working hard for to maintain the right conditions for Dartford warblers and other key species on the internationally important wildlife site.”

Simon Wotton, Research Biologist at the RSPB, said: “This survey is fantastic news for a very vulnerable bird, particularly because it has moved to higher ground not used by Dartford warblers for many years.

“Warmer winters mean the birds are likely to push even further north but they can only do that if there are heathland sites available, which are protected from development. If the government is to help wildlife adapt to climate change it should be assigning more land for the creation of habitats to help birds like these.

“The Dartford warbler is a wonderful species but its vulnerability to the cold and wet, which could still be a problem as our climate alters, means all safeguards possible must be put in place.”

Two harsh winters left just 11 pairs of this attractive bird in 1963 and the warbler’s revival, to an estimated 3,208 pairs from 1,890 in 1994, is due both to milder winters and heathland improvements, partly funded by the £25 million Tomorrow’s Heathland Heritage (THH) initiative.

But the bird remains vulnerable, and on the Thames Basin Heaths in Berkshire, Hampshire and Surrey, where surrounding land is being targeted by house builders, numbers fell by 40 per cent from 2005 to 2006.

The reasons are unclear but losses like that underline the importance of the THH and of protection and management of the bird’s existing strongholds. The creation of new heathland sites is vital to help Dartford warblers move further afield.

The Dartford warbler is an active, inquisitive bird rarely allowing us more than a fleeting glimpse before diving for cover in gorse and heather. If they are lucky, heathland visitors may now see males singing from low perches or skulking with their mates between dense bushes and scrub.

Greg Conway, Research Ecologist at the BTO, said: “We are all very grateful to the hundreds of birdwatchers across England and Wales that made this survey such a success. Not only did they go out and count birds on traditional Dartford warbler sites, they also found new sites in areas where the species had been absent for forty years or more. We organise lots of surveys of disappearing species and it is great to be involved in a survey with some good news.”

For further information contact the Natural England press office on:
Telephone: 0845 603 9953, or out of hours 07970 098005
Email: press.office@naturalengland.org.uk

-ENDS-

Notes for editors:

Dartford warblers (Sylvia undata) have a long tail and are about 13cm long. They have grey-brown upper parts, a wine-red chest, white belly and red eye-ring. Their song is a short, rattling warble, usually sung from a gorse perch. They also have a distinctive buzzing call. Dartford warblers eat insects, spiders and berries. They are on the amber list of conservation concern because of previous population declines. Hear the Dartford warbler singing on the RSPB website at http://www.rspb.org.uk/wildlife/birdguide/name/d/dartfordwarbler/index.asp.

The best places to see them in the UK are Arne, and Canford Heath and Holt Heath in Dorset, Chobham Common, Surrey, Dunwich Heath, Suffolk and the New Forest, Hampshire. They stay in the UK all year.

In the UK, they usually nest low in gorse bushes mostly on lowland heathland in Dorset, Hampshire and Surrey, although more birds are now using upland heaths in south-west England and gorse areas on the coast. The highest territory found in the 2006 survey was just below the summit of Dunkery Beacon, the highest point on Exmoor.

In Spain, France, Portugal and Italy they are typically found in scrub habitats such as maquis and open pine or oak woods. The can raise two or three broods each year. They also breed in north-west Africa.

The first Dartford warbler in Britain was identified after a pair were shot at Bexley Heath near Dartford, Kent in 1773. In the 19th century, they were found in Oxfordshire, Hertfordshire and Shropshire as well as south and west England. Its skins, nests and eggs were all sought by collectors. Loss of heathland to development, agriculture and forestry also severely curbed its distribution. Heath fires are a serious hazard. They became extinct from the Dartford area in the early 20th century.

There were about 450 pairs of Dartford warblers in 1961, before the harsh winters of 1961/62 and 1962/63.

The Dartford warbler was the only one of Britain’s eight warblers to stay for the whole year until the Cetti’s warbler colonised the UK in the early 1970s.

Spain hosts more than 80 per cent of Europe’s two to four million Dartford warblers but numbers there have dropped by more than a quarter in the last ten years. Conservationists say losses in Spain make the increasing number of British birds even more important.

Dartford warblers are known to feed stonechat young when they have no chicks of their own.

Dartford warblers are currently threatened by plans to build 40,000 homes in the Thames Basin in the next 20 years. The Thames Basin Heaths together form a EU-protected Special Protection Area because of their importance to Dartford warblers, nightjars and woodlarks. The heaths also host smooth snakes, sand lizards and silver-studded blue butterflies. The increasing housing around these heaths is putting important heathland wildlife under pressure from urban effects, such as recreational disturbance, uncontrolled fires and cat predation. Their fragmented nature makes the heaths even more vulnerable to these effects. In the 18th century, about 12 large heathlands formed the Thames Basin Heaths. Since then, development has broken up the area into at least 30 heaths. Of these, 13 are Sites of Special Scientific Interest including Chobham Common SSSI and Ash to Brookwood Heath SSSI in Surrey, Sandhurst to Owlsmoor Bog in Berkshire and Castle Bottom to Yateley and Horley Common SSSI, Hampshire.

Increased recreational use of the large, relatively open heathland areas is one of the biggest problems facing the Thames Basin Heaths and other lowland heathlands. Increased visitors to these fragile areas, particularly by dog-walkers, can cause direct disturbance, leading to nest desertion, or the increased risk of predation to the chicks and adult birds by natural predators such as crows and foxes. The three priority heathland birds all nest on or close to the ground and are therefore particularly susceptible to this type of disturbance or predation.

In the UK, more than 80 per cent of lowland heathland has been lost since 1800 yet about one fifth of the world’s lowland heathland is still found in the UK.

Tomorrow's Heathland Heritage, a Natural England initiative backed by the Heritage Lottery Fund and others, was established in 1997 to help hit the government’s targets of restoring 58,000 hectares of lowland heathland (about the size of the Isle of Wight) and re-creating another 6,000 hectares by 2010.

This is the fourth national Dartford warbler survey. The first was in 1974 (560 pairs), and was repeated in 1984 (420 pairs) and 1994 (1,890). The population estimate for England and Wales is 3,208 pairs. Dartford warblers were also surveyed on the Channel Islands for the first time, where 85 pairs were found. The Dartford warbler survey forms part of the SCARABBS (Statutory Conservation Agencies and RSPB Annual Breeding Bird Surveys) agreement, and will be surveyed every 12 years (formerly every 10 years).

Monitoring involved two or more visits to 2,500 sites between early April and early June. The new Dartford warbler population figure is an extrapolation based on the amount of suitable habitat in sections not surveyed in a defined area and a correction factor for survey squares visited less than four times.