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Wintering Warbler Survey 2006/07


Six species of warblers can be found regularly wintering in Britain and Ireland. These include two mainly resident species: Cetti’s Warbler and Dartford Warbler; plus four mainly migratory species: Chiffchaff, Blackcap, Firecrest and Goldcrest. In addition, there are at least ten other species, which occasionally winter. The most frequent of these are Lesser Whitethroat, Yellow-browed Warbler and Willow Warbler, occurring almost annually.

Very little is known about the current status of our wintering warbler populations, at a national level. The most recent population estimates are given in the BTO winter Atlas 1981-1984, as follows: Blackcap (3,000), Chiffchaff (500-1,000), Cetti’s Warbler (500-1000), Dartford Warbler (1,500-1,800), Firecrest (200-400) and Goldcrest (2-4 million). With the exception of Goldcrest, the majority of species are distributed along the southern and western coastal counties, see below, where the winter climate is mildest. This is particularly true of the Chiffchaff and Firecrest, which remain entirely insectivorous throughout the winter.

There have been two previous national BTO surveys, which were undertaken in 1945-1954 and 1978/79 but these only focussed on Blackcap. Between these two surveys the number of wintering Blackcap showed a substantial increase. Since the early 1980’s, the number of Blackcap, Chiffchaff and Firecrest, (as noted in county bird reports) have all shown further increases. Two major factors associated with the increases have been the expanding breeding populations together with a run of mild winters, thus assisting winter survival. Given the increasing numbers, we now want an up-to-date picture of where these birds occur during the winter and what numbers are involved. This new survey will provide a baseline against which to monitor future changes

Many of the Blackcaps wintering in Britain and Ireland breed in Central Europe, which is a recently adopted migration strategy for birds that would usually winter around the Mediterranean. As for Chiffchaff and Firecrest, not a great deal is known as to the exact populations from which they originate. However, ringing data for Chiffchaff show that birds from northern Europe across to western Siberia, all winter in Britain.


The main aims of this survey are to find out how many individuals spend the winter in Britain and Ireland and collect information on where they occur. The survey will run for at least two winters, commencing in November 2004. This will help provide updated population estimates and a more detailed understanding of where these wintering species occur.

In addition, we would also like to collect information on the following aspects to help understand the actual distributions:

1) Number of each sex (mainly Blackcap)
2) Number of singing individuals
3) The general habitat type in which the bird is situated
4) Food items (mainly for Blackcap)
5) Number of Chiffchaffs with grey plumage (individuals from Eastern populations)
6) Plus any other notes on behaviour.

How to contribute

Survey Period: 1st November 2006 to 31st March 2007 (15th April for Blackcap only)

All records of wintering warblers are required, particularly for the three key species (Blackcap, Chiffchaff and Firecrest), during the survey period; Goldcrest is optional due to it’s widespread distribution. Observations may be consist of daily garden sightings, casual observations or counts made as part of your regular bird watching activities.

Other counts are required from the following types of location: i) gardens, ii) sewage works, iii) wetlands/water bodies, iv) rivers/canals and v) coastal sites.

Recording your sightings

Records can also be submitted on-line using the BirdTrack website: birdtrack.net/ . If you are not already a BirdTrack recorder, register using the link on the BirdTrack homepage ‘Register for BirdTrack’. To enter sightings click on the link ‘login to enter sightings’ and set up your sites and records.

A set of instructions and recording form can be downloaded from the website, see below. Also, an Excel version of the recording from can be downloaded, in which your observations can be entered and then returned via email at the end of the winter.

To download the instructions as a .pdf file click here.

To download a recording form as an Excel spreadsheet (for entering you records and emailing back at the end of the winter) click here.

Colour-ringed Chiffchaff © Dawn BalmerRelated studies

Colour-ringed Chiffchaffs. Since December 1999, over 700 wintering individuals have been marked in southern England as part of a study investigating wintering ecology. Each bird carries a total of four rings (two on each leg), consisting of a metal ring and three coloured rings. All sightings are required to help monitor survival and movements. Please send sightings to Greg Conway ( ).

See the results

You can look at the latest results for Blackcap, Chiffchaff, Goldcrest and Firecrest on BirdTrack. These pages have graphs that show the number of records and the proportion of lists submitted with these species on. To view the animated maps for these species click here and select the species you are interested in.

For more information on this survey please contact: Greg Conway, Wintering Warbler Survey Organiser, BTO, The Nunnery, Thetford, Norfolk IP24 2PU. Email: Tel: 01842 750050.