The Demise of the DARTFORD WARBLER as a breeding Buckinghamshire bird

Sadly, despite numerous searches, I have failed in my quest to find DARTFORD WARBLERS in Buckinghamshire this year - they appear to be extinct as a Buckinghamhsire bird. This mirrors my experience on some Surrey heaths, where from a high of 23 singing males on Chobham Common in 2008, I have managed to locate just 3 males in 2009.

The species really was hit hard in last winters two weeks of severe weather, where hard-crusted lying snow remained for ten days. This really shows how critical this species is of concern and it seems that we are looking at an 87% decline nationally overall. Strangely enough, the only area of the country where they seem to be unaffected (excepting Cornwall which largely escaped the snow) is in East Anglia, where numbers have upheld in the coastal heaths of Suffolk and Norfolk.

The History of Dartford Warbler in Buckinghamshire

The first Dartford Warbler to be recorded in Buckinghamshire was as recent as 1993. That year, a female which was wintering at Slough Sewage Farm (Berkshire) strayed over the county boundary on 1st and 31st January (Dave Carter)

It was not until five years later that we got the second - an exceptionally elusive first-winter female on Steps Hill from 25th November until 6th December (Don Otter et al). This bird was seen again on 9th January 1999 (Rob Andrews).

In September 1998, I had heard what I believed to be a Dartford Warbler in suitable breeding habitat near Burnham and in early 1999, a singing male was present from 14th January to 15th May. A further male was present in Black Park on 21st March 1999 (Don Otter).

Later in the year, two different males were located near Burnham, with both remaining from 28th October (Dave Rear, D. Taylor, Peter Stevens, Dave Ferguson, LGRE, et al).

In Year 2000, the population exploded, with up to 7 singing males at the main site throughout the first half of the year, with four remaining on territory from 5th April until at least 25th May (LGRE) and two still singing until 20th June, especially towards dusk. Despite trying, I never confirmed breeding at the site and towards the latter part of the year, just a single male was regularly located.

A further female was in residence at a second heathland site in the south of the county from 20th August and this increased to two birds - a pair - in December. In early January 2001, I located three birds at this site but at the original location, just a single male seemed to be present throughout 2001.

2002 saw a further demise in the population with the male remaining at the main site until 29th June and a female at the Black Park site from 30th August to 7th September.

2003 saw the first confirmed breeding in the county, with two pairs successfully fledging youngsters (7 in total) at the core site (LGRE et al) and a second pair yielding four young from a further nest in Black Park. Dartford Warbler had become an established resident bird in the county at last (or so I thought).

In 2004, a pair remained at the core site until mid-March whilst in Black Park, a pair bred successfully again, fledging three young. At least three of these birds remained into January 2005, when, on 23rd January, a first-winter was discovered just outside my recording area in a weedy field at Sarratt Bottom (Steve Younger). This individual was consorting with a pair of Common Stonechats and I recorded it almost daily until 28th January.

Two singing males were present at the Black Park breeding site on 10th April 2005, both remaining throughout the summer. In June, a pair were constantly flying back and forth with food but the outcome was not recorded.

A single pair bred successfully again in 2006, with three juveniles fledging from a nest in Black Park. At the original breeding site, a female was again present on 11th January but not subsequently.

In 2007, a single male was present in Black Park from 23rd January until at least 1st July, with a pair together on 25th April. An additional singing male was located at nearby Fulmer on 11th May whilst a single bird was disturbed at the original site on 21st October.

Breeding was once again successful in 2008, when on several occasions in June and July, I witnessed a family group of up to seven birds. This was at the Black Park location. Elsewhere. I failed to find any birds and much of the former habitat had become overgrown and unsuitable. I last visited the area in December 2008, when at least three birds were scolding from gorse clumps in Black Park.

So, in summary, a viable population of Dartford Warblers survived in the county for just over ten years and during this time, over 20 young were successfully fledged. The severity of last winter's winter weather however proves how precarious a foothold this Mediterranean species has in southern Britain.

Hopefully, this is just a blip in an ongoing attempt to colonise northwards of its core breeding areas such as the New Forest and Surrey heathlands. Hopefully, another pair will set up territory and start the whole chain of events off again.